Wild Mammals of Wisconsin (Faunistica)

THE WILD MAMMALS OF WISCONSIN Charles A. Long

INTRODUCTION

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THE WILD MAMMALS OF WISCONSIN

The Wild Mammals of Wisconsin Charles A. Long

SOFIA–MOSCOW 2008 INTRODUCTION

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THE WILD MAMMALS OF WISCONSIN Charles A. Long Professor Emeritus at the University of Wisconsin – Stevens Point, Stevens Point, Wisconsin AN

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PRO TIS TA

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Publication No. 56 Museum of Natural History University of Wisconsin-Stevens Point Reports on the Fauna and Flora of Wisconsin* *Also published as Reports of the Museum, and Reports on the Fauna and Flora. Publication Costs and the Museum’s Distribution of this Book were funded by Harold Roberts – Stevens Point, Wisconsin

First published 2008 ISBN 978-954-642-313-9 (paperback) ISBN 978-954-642-303-0 (hardback) Pensoft Series Faunistica No 68 ISSN 1312-0174

© PENSOFT Publishers All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the copyright owner.

Pensoft Publishers Geo Milev Str. 13a, Sofia 1111, Bulgaria Fax: +359-2-870-42-82 [email protected] www.pensoft.net

Printed in Bulgaria, January 2008

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THE WILD MAMMALS OF WISCONSIN

CONTENTS

PREFACE

7

ACKNOWLEDGMENTS INTRODUCTION

9

11

THE WILD MAMMAL FAUNA IMPORTANCE

OF

MAMMALS

PLAN OF THIS BOOK SCOPE

AND

11 13

17

PLAN

17

FREE EXPRESSION

IN

PRESERVATION

OF

SPECIMEN COLLECTIONS

COUNTIES

TYPE LOCALITIES

22

EARLY MAMMALOGY AND NOW

25

AND

TAXONOMY

21 AND

HABITATS

ENVIRONMENTS AND ECOLOGY OF MAMMALS GENERAL ECOLOGY

OF

WISCONSIN MAMMALS

FORMER GLACIATIONS CLIMATE

31

31

32

33

PHYSIOGRAPHY SOILS

21

34

36

COMMUNITIES MICROHABITATS

38 41

ECOLOGICAL SUCCESSION ZOOGEOGRAPHY

AND

LAND USE

43

47

PREHISTORIC MAMMALS

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REINTRODUCED AND EXTIRPATED MAMMALS OF WISCONSIN WITH HYPOTHETICAL LIST OF SPECIES POSSIBLY IN WISCONSIN CHECK-LIST OF WISCONSIN’S WILD MAMMALS

59 64

KEY TO ORDERS AND FAMILIES OF WISCONSIN MAMMALS

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TAXONOMIC ACCOUNTS OF MAMMALS OF WISCONSIN ARRANGED IN ORDERS, FAMILIES, GENERA, SPECIES AND RACES OPOSSUM (ORDER MARSUPIALIA)

68

68 INTRODUCTION

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INSECTIVORES (ORDER INSECTIVORA) MOLES (TALPIDAE)

75

76

SHREWS (SORICIDAE)

84

BATS (ORDER CHIROPTERA)

108

HARES AND RABBIT (ORDER LAGOMORPHA) RODENTS (ORDER RODENTIA)

143

155

WOODCHUCK, CHIPMUNKS, GROUND, RED, GRAY, FOX

AND

FLYING SQUIRRELS (SCIURIDAE)

156

NORTH AMERICAN BEAVER (CASTORIDAE) POCKET GOPHER (GEOMYIDAE)

220

229

MURID MICE AND RATS (MURIDAE) JUMPING MICE (ZAPODIDAE)

235

304

NORTH AMERICAN PORCUPINE (ERETHIZONTIDAE) CARNIVORES (ORDER CARNIVORA) COYOTE, WOLF,

AND

321

FOXES (CANIDAE)

BLACK BEAR (URSIDAE) RACCOON (PROCYONIDAE)

315

321

351 359

MARTENS, WEASELS, MINK, SKUNKS, RIVER OTTER, NORTH AMERICAN BADGER (MUSTELIDAE) CATS (FELIDAE)

366

427

DEER (ORDER ARTIODACTYLA) 438 WHITETAIL, MOOSE (CERVIDAE) GLOSSARY

439

453

LITERATURE CITED AND BIBLIOGRAPHY

461

APPENDIX A. Longevities of Some Mammals That Occur in Wisconsin APPENDIX B. English and Metric Measurements

529

APPENDIX C. Preparation of the Mammal Study Skin with Label and Skull APPENDIX D. Dental Records

528

530

533

INDEX TO SCIENTIFIC AND VERNACULAR NAMES OF WILD MAMMALS OF WISCONSIN

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539

THE WILD MAMMALS OF WISCONSIN

PREFACE The mammals of Wisconsin were studied by my friend, the late Dr. Hartley H. T. Jackson, who published his findings in 1961. In the past 45 years the fauna has changed. Some mammals have vanished, others have established new populations here, and the names of the mammals, both scientific and popular, have undergone many changes. In Jackson’s day science was more observational and descriptive than today. Although superficially they may seem similar, his book is different from this one. Jackson began his work in the early part of this century. In his later years he carefully studied the status of Wisconsin mammals from their relations with pioneers through the decades of exploitation by hunters, and heavy land use by settlers, farmers and townspeople. His work focused on the turn of the century to about 45 years ago. This work reviews Wisconsin mammalogy in light of many new scientific findings, and at the turn of another new century, indeed, at the beginning of a new millennium. In the presentation of natural history, with particular emphasis on the sign of mammals observed in the field, on material of historical and popular nature, and on the clear descriptions of specimens and species, Jackson has no peer except perhaps Ernest Thompson Seton. The bibliography in Jackson’s work (1961) is a supreme Wisconsin compilation up to that time. However, there is no mention of many modern concepts, even echolocation in the bats; there is too great a dependency on temperature zones to explain the ecological and geographical distribution of Wisconsin mammals; and there is not a word about the strongest rationale for modern taxonomy, including evolution, fossil record, and speciation of taxonomic categories. Nevertheless, Jackson’s work is a “tough act to follow.” I will repeat a famous saying, “cosa ben fatta e` fatta due volte” [anything worth doing is worth doing it twice]. This book is written to serve three groups of readers. First, serious professional mam-

malogists in Wisconsin, and in many other states and provinces, need an updated source of information about Wisconsin’s mammals. For this group, the taxonomy was updated, and the new collection of mammals at Stevens Point’s Museum of Natural History was studied and processed. The information obtained here and from other studies provides a source book for mammalogical investigations. Second, there are many nature lovers in Wisconsin who have curiosity about animals. For this group, nature and wildlife provide the joie de vivre. Even many children have a bent in this direction, and this curiosity and passion should be encouraged with source books about nature. I was one such child myself. My fifth grade teacher, Velma Kane, gave me a fine book by Frank M. Chapman that set my path. I make no apology for anecdotal and even poetic commentary, for those appreciative of that are a welcome audience. Hopefully this book will serve the nature lover in pursuit of enjoyment, enthusiastically finding a “joy for life”. Third, professional and amateur conservationists need factual information on the status of Wisconsin wildlife. They must convince politicians and bureaucrats of ways and needs to save wildlife in Wisconsin. Human population growth and expanding land use have reduced and altered wildlife habitats throughout the State. In my travels on this continent and abroad I have always been impressed with the natural beauty of our own Wisconsin. There is much wonder and aesthetic pleasure here at home, in Wisconsin, but how little of it there is to go around. How easy it seems for people to convert a scenic and natural place into an unnatural commercial development, unsuitable for wild creatures. Some sportsmen serve both as nature protectors and conservationists. Aldo Leopold was one, and my friend Fran Hamerstrom was another. Some teachers fit into this category, as do those people who keep informed on environment while enjoying nature, apart from aesthetic enjoyment. PREFACE

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Hopefully they will in future continue to conserve important habitats for wildlife, because that will be needed. *** Anyone curious enough to put forth effort in nature study will find that nature takes a person into her confidence, and life will be made richer for such effort. This book contains interesting and useful information on the wild mammals of Wisconsin. I hope that it may stimulate some important study and conservation of this legacy and resource. Though few people know about it, the scriptures of the Old Testament and the Torah provide those of us interested with a wise lesson in conservation. God says we “strangers” must provide “redemption of the land” (Leviticus 25:24).

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THE WILD MAMMALS OF WISCONSIN

HOW TO USE THIS BOOK There are special features that help the reader locate particular topics of interest. * The Table of Contents at the beginning of the book. * The Index for species names at the end of the book. * A Glossary of mammalogy terms near the end of the book. * A Check-list of the species accounts of the wild mammals of Wisconsin, immediately preceding the accounts, which comprise most of the text. * The Plan of the Book explaining the format and rationale for the way the explanation is presented.

ACKNOWLEDGMENTS I am sincerely grateful to my family for the support they provided for this study. My wife Claudine and two sons Alan and John, his son Tyler, have traveled to all corners of Wisconsin, to all four borders, even into Upper Michigan, Minnesota, and Ontario. The family put up with me, while I taught heavy course loads and kept at this project for 40 years in Wisconsin. Secondly, I wish to acknowledge the enduring, patient, and competent editorial work on this book by Professor Lowell L. Getz, Department of Ecology, Ethology, and Evolution, University of Illinois, Urbana, Illinois. He was outstanding and necessary. The Wisconsin Department of Natural Resources (Bureau of Endangered Resources) provided one grant, jointly with the Stevens Point Bill Cook Chapter, Isaak Walton League and the U.S. Department of the Interior. This state agency and the United States Fish and Wildlife Service provided me a grant (1979-1981) to study Wisconsin bats. The University Personnel Committee provided several summer grants that paid part of summer salary. It supported my University of Wisconsin Sabbatical, which I spent at St. Olaf College working on fractal geometry and chaos theory (in the same class as my son John). While there, I wrote up about l5 species accounts and made over l00 maps for this project. Paul Humke, Math Department, helped greatly. Faculty who helped in various ways include deceased George Becker (I used his base map for distributions), Philip Bjork, Virgil Thiesfeld, Shelley Jansky, Robert Bell, Frank Bowers, David Hillier, born for computers, Robert Freckmann, Stephen Taft, Vincent Heig, Sol Sepsenwol, gifted and kind, Daniel O.Trainer, Mark Boyce, Stan Szczytko, Christopher Yahnke, Isabelle Girard, and at the Madison campus Frank Iwen and Scott Craven. I am grateful to former teachers from Kansas, especially the late E. Raymond Hall, Robert Wilson, and Horace Hays. Many students helped making up specimens and helping with fieldwork. I cannot list

any without being unfair. Adrian Wydeven, Tom Jessen and others (Wisconsin Department of Natural Resources) helped early in several ways. Thor Purrinton helped me survey Detroit Island. Catherine Ladd (Information Technology) and Teodor Georgiev (Pensoft Publishers) were very helpful. I had the much-appreciated help of two undergraduate students: Nicholee Theiss, and Sarah Miller. Museum curators allowed me to examine specimens or sent them here on loan including John Paradiso, Robert Fisher, the deceased J. Knox Jones, Jr., Robert Baker, the deceased E. Raymond Hall, Michael Carleton, Al Gardner, the deceased Elmer Birney, Frank Iwen, Philip Humphrey, Rollin Baker, Donald Hoffmeister, Scott Craven, the deceased Fred and Fran Hamerstrom, Don E. Wilson, and Wendell Johnson. Photographs were given by the late Roger Barbour, Matt Lovallo, Frank Iwen, Chuck Pils, Al Cornell, D. Shelley, C. Yahnke, Ron Jurawski, R. Johnson, and Scott McDonald. James Spero’s (1978) collection of photos, published by Dover Publications, was useful and appreciated. Sylvia Myhre made the drawings of skulls of moles, shrews and bats. If there are helpers overlooked, please feel appreciated. The U.S. Postal Service permitted the stamps showing mastodon and mammoth, both prehistoric elephants, 1996. Reviewers of various accounts include Getz, who read them all, Scott Craven, Robert Freckmann, Jerry Choate, [the late] Karl Koopman, Wayne H. Davis, who both read the bats, Stephen Taft, Mark Boyce, Jerry Wolff, John Whitaker, Jr., Tim Lawlor, Bruce Kohn, W. E. Berg, K. McCaffery, Joe Merritt, Adrian Wydeven, Tom Howard, L. R. Petersen, and Rebecca Sealfon. I relied on the wolf book by Dick Thiel and a paleontological contribution by R. M. West and J. E. Dallman. Hartley H. T. Jackson, deceased, helped in the beginning years. Wanting of some quality illustration, I gathered some drawings from early and historic sources. Becoming quite interested in ACKNOWLEDGEMENTS

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Raccoon. Artist Roger Tory Peterson. Courtesy Virginia Peterson, her “first choice” for this book. R. T. Peterson and James Fisher 1955, © RTP and J. M. M. Fisher, reprinted by permission of Houghton Mifflin Co. Rights reserved. 

the art, I expanded the search. Hoping for a kind of legacy of former mammalogists, not only of quoted observations, I resurrected some of their art, for old published works are becoming rare. Although the artists themselves are not always mentioned, they may be credited in the works. Included are black and white works from Anna B. Comstock, Anna Stryke, and A. MacKinnon, H. H. T. Jackson (artist B.O.M[cMaugh]), Spencer Fullerton Baird, Charles Cory (artist Leon L. Pray), Elliot Coues, C. Hart Merriam, Gerrit Miller, Jr. (artist Tertzli), Dan Metz, Ernest Thompson Seton ( = Ernest E. Thompson), Vernon Bailey, Elva Hamersrtom-Paulson, D. G. Elliot, W. H. Flower and R. Lydekker, H. E. Anthony, William J. Hamilton, Jr., Will-

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THE WILD MAMMALS OF WISCONSIN

iam T. Hornaday, E. Raymond Hall, W. H. Burt (artist Richard Philip Grossenheider), John Dean Caton, Cantlon and Garry A. Heidt, Baron Georges Cuvier, John Litvaitis, Joseph Holder and Sir John Richardson et alia, James Bee and Hall, Susan E. Smith; Tom Swearingen, Thornton Burgess, Karl Schmidt (artist Walter A. Weber) and artist G. Mutzel in Wood’s Nat. Hist (a favorite book from the author’s Grandmother Long (J. G. Wood, 1865). My son Alan made the muskrat years ago (1985). Virginia Peterson and the Houghton Mifflin Co. gave permission to photocopy two drawings by Roger Tory Peterson. Elizabeth Schwartz and the University of Missouri Press gave permission to use two drawings by Charles Schwartz. Other artists are credited in the legends herein. While living, my former teacher E. Raymond Hall gave permission to use several drawings. The styles include stylized scratchboard-sketches, steel cuts, woodcuts, and zinc engravings. Color prints were provided by Virgil Beck and Clark Bronson. This book could not have been published without Harold (“Hal”) Roberts. I told him more than once that he was “one of the nicest men that my wife and I ever knew”. Unassuming, kind, a true naturalist, he was and is always helpful. Military service interrupted several years of his graduate work at UWMadison, where he took every possible course he could from Aldo Leopold and had obtained a masters degree. All together we hope to express tribute to nature, and wildlife poetry and art!

INTRODUCTION THE WILD MAMMAL FAUNA “Wild” mammals try to survive in nature without human care, not as provided for “domestic” mammals. They are seldom seen, for most are secretive and nocturnal. Many spend the day, some the entire winter in burrows. Mammals have attractive ellipsoid bodies, with graceful legs and movements providing swift locomotion. Their warm-blooded bodies are generally covered with hair (i.e., fur) often richly colored. It may be coarse, felt-like, or soft, and often is marked in tasteful patterns. The eyes are large, bright, and expressive, except in the bats, shrews, and moles. Mammals are endeared to us because of their interesting ways and intelligence, to some extent having behavior almost human. Technically, a mammal is a vertebrate animal noted for its fur (technically called pelage) and for the maternal behavior of nursing (i.e., suckling) its young. Mammals evolved long ago from mammal-like reptiles, in the Triassic geological period. Although mammary glands and hair were never fossilized, the fossil record of skeletal transition from reptile to mammal, especially in South Africa, can be traced out stage by succeeding stage. Searching in stratified rocks down into the earth, back into the stony records of many millions of years ago, transitional specimens have been found showing a regular trend of replacing the archaic, reptilian jaw connection with a brand new jaw joint on each side. Replacement began (of course, on either side) by doubling the jaw hinges, i.e., adding an articulation between a newly evolved squamosal bone of the cranium with the adjacent dentary bone of the lower jaw. By subsequently reducing the older (quadrate-articular hinge) of each newly doubled jaw joint, while gradually enlarging the newer squamosal-dentary joint, the “new” and “old” joints, paired together on each side, define those fossils (having “two articulations”) as “mammal-like.” The

derived “ true mammals” almost lost the older, reptilian quadrate-articular hinge, but not quite. A consequential attachment of the old, non-functional hinge (both bones already connected together) to the nearby reptilian hearing bone called the stapes formed a new “chain of ossicles.” That is how the derived “true mammals” came to possess three ossicles in each ear instead of one. Gould (1990) cogently called this story “an earful of jaw”. All three bones, “malleus” (descended from the articular), “incus” (from the quadrate) and even the “stapes” (a transformed hyomandibular jaw bone of fishes) were originally jaw bones in ancient fishes. Archaic mammals from the late Triassic Period were probably warm-blooded. Tactile bristles, such as those on the scaly tail of the recent-day opossum, spread over the body conserving internal heat (Long, 1972b). There are two, perhaps more, comprehensive accounts on mammalian hair (Ryder, 1973; Noback, 1951). Long (1972) proposed that Darwin’s speculation on the origin of lactation in primitive mammals was correct. Darwin had believed the mammae first appeared in the pouch. Long believed glandular moistening of the egg and young in a pouch provided an ever-improving nutrition that became “milk”. This sequence of associated microevolutionary preadaptations fits well with neo-Darwinism. Long (1969c) reviewed the evolution of mammary glands. Other characters seen only in mammals include a diaphragm to enhance breathing, a large cerebrum related to intelligence, and the loss of the nucleus from every red blood cell leaving only a membrane and net-like cytoskeleton of biconcave form containing endoplasma and hemoglobin. It has a great surface area for water and gas exchange. This deformable erythrocyte is driven in blood plasma into tiny capillaries, and easily unloads oxygen to the tissues (Long,2006). There are 69 to 75 kinds of mammals that are considered wild Wisconsin species. A species is a population of organisms that INTRODUCTION

11

breed among themselves, but seldom interbreed with other species. If hybrids occasionally are found, especially those resulting from pairing in captivity, the two stocks are usually regarded as separate species, not necessarily as “good” species. The short-tailed prairie deer mouse (Peromyscus maniculatus bairdii) possibly in one or two places far away, in western states, shows evidence of intergradation with long-tailed deer mice. That is actually little evidence to prove that this little mouse hybridizes freely with any race of maniculatus (which is a long-tailed climbing species). In any case, bairdii acts as a “good” species in the Wisconsin fauna, not hybridizing naturally with long-tailed deer mice, and, therefore, is added to the Wisconsin species count. Jackson (1961) did the same; and Baker (1983) described them separately. Some workers consider the prairie vole race Microtus ochrogaster minor to be a valid species, and it may be (see account of M. ochrogaster). The introduced European stone marten Martes foina is now established in southeast Wisconsin (Long, 1995). The introduced Norway rat and house mouse were established long ago. Removed from this Wisconsin faunal list are the native elk Cervus elaphus [C. e. canadensis Erxleben], bison Bison bison, wolverine Gulo gulo [= G. g. luscus (Linnaeus)], mountain lion Felis concolor [F. c. schorgeri Jackson], and caribou Rangifer tarandus [R. t. caribou (Gmelin)] because they were eradicated at the turn of the 20th century. The elk was reintroduced (see Reintroductions) more than once, and now is protected on a preserve in northwest Wisconsin, as well as many hunting preserves. The bison is now raised as a domestic beef animal on many game farms in Wisconsin. The mountain lion, also called cougar (Felis concolor), probably has been released by unauthorized individuals leading to some of the numerous reports of cougars in Wisconsin; however, there is no verified population, or even a recent specimen or photo of the cougar. I learned of a likely re-

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THE WILD MAMMALS OF WISCONSIN

lease (female or pair) in the Blue River area of two pets brought here from Florida about 25 years ago. At least three of our mapped Wisconsin species may have recently been extirpated. Therefore, our recognized fauna (6869 species) may have declined. Many Wisconsin species have two or even three geographic races, called subspecies, so that the number of named kinds is about 79 (a few less than recognized by Jackson, 1961). If the problematical elk, bison, wolverine, mountain lion, and caribou, and the minor prairie vole, were all added to the total, the number of species rises to 75. The feral house cat, and escaped fallow and Sika deer add species, but are not included; without human support they would likely disappear, and the two released deer probably have. The house cat is usually a domestic pet. The domestic horse (Equus caballus) is not wild in Wisconsin. Humans and domestic dogs have long been on the scene in Wisconsin, but are not a wild resource. The 69 species treated herein, including the probable prairie deer mouse species, provisional stone marten, and three possibly extirpated species (not found in recent years), are classified into distinct accounts. Some of these species have no close relatives; others are grouped in “taxa” of two or more species of similar form. These groups are called genera (the singular is genus). There are about 49 genera; some recognize Microsorex as distinct from Sorex, Eutamias as distinct from Tamias, and Pitymys as distinct from Microtus. There is controversy whether or not to call the Canada lynx and bobcat Felis instead of Lynx, either use does not change the number of genera. Neovison for mink adds one. The genera are classed in 17 families belonging to 7 orders. These orders are the primitive Marsupialia and Insectivora, aerial bats Chiroptera, rabbit and hares Lagomorpha, abundant rodents Rodentia, famous meat-eaters Carnivora, and hoofed Artiodactyla.

IMPORTANCE

OF

MAMMALS

Mammals are important to the people in Wisconsin. On the positive side, they help fulfill human needs for nature. They provide aesthetic experiences, i.e., life-long memories fondly recalled. They have provided substance for literary anecdotes, legends and tales inspiring intellectual communication among people. They furnish highly valued recreation for hunters, and flesh to eat. The deer hunting alone adds millions of dollars to the state economy. Furbearers provide fur for warmth and decoration. Many small mammals serve as foods for carnivores and raptors, and their burrows may be taken over for shelter by other mammals. The burrows of some mammals (e.g., North American badgers, ground squirrels, pocket gophers, moles, and innumerable mice) turn up soil, aerate it, provide nutrients, and facilitate natural soil formation. The beaver turns riparian forestland into vast meadowlands. There are many mammals considered beneficial because they eat insects (as do shrews, moles, especially bats, and to lesser extent numerous other species that occasionally eat them). Some mammals are beneficial because they prey on the injurious mice and rabbits. Much carrion is consumed by opossums, carnivores, and many other mammals. On the negative side, rodents and rabbits steal our crops and girdle small trees and bushes. The white-tailed deer, lovely and graceful as it is, causes over a million dollars damage to Wisconsin crops annually, hundreds of thousands of dollars damage to cars, and in recent years unknown but immense costs for damage in urban landscaping. In recent years outbreaks of urban deer have devastated gardens and shrubbery. The scriptures call for a tithe of our land to nature, but deer, rabbits and rodents often eat more than a tithe, sometimes everything we grow. Although generally beneficial, weasels, raccoons, skunks, opossums, and foxes occasionally may eat the farmer’s chickens. Some large canids have preyed on domestic animals.

Some mammals carry deadly diseases (Table Intro-1; Davis et al., 1987), which they transmit directly or indirectly by parasitic ticks and fleas (such as plague, Rocky Mountain spotted fever, and Lyme disease). Rabies in Wisconsin is caused by a virus known in dogs, cats, cattle, foxes, bats and especially striped skunks (Table Intro-2). Rabies, also discussed below under bats (Chiroptera), foxes, raccoon, and striped skunk, is a terrible disease and always fatal in humans. Usually transmitted by mammal bites, rabies can be prevented by vaccinations. Hantavirus killed one student in Kansas, that collected mice. In the years 1996-1997, recent cases include one person killed in northern Illinois, and another person almost killed (April-May, 1997) from Chippewa Falls, who cleaned a mouse nest out of an old car. Additionally, about 20 kinds of mammals carry hemorrhagic and arbovirus diseases (Davis et al., 1987), and others are involved with plague, tularemia, typhus, spotted fever and other diseases (Childs et al., 1995; Mills et al., 1995; Gage et al., 1995; Schmid, 1985). Even wild animals sold as pets may harbor deadly diseases, such as “monkey pox” in African rodents and American prairie dogs. Lyme disease is caused by a bacterium Borrelia carried by the ticks Ixodes dammini and I. scapularis, and perhaps in other Ixodes. Untreated, the disease is dangerous. Borrelia is reported in Wisconsin in foxes and coyotes (Kazmierczak and Burgess, 1989), bears (Kazmierczak et al. 1998), and small mammals (Godsey et al. 1987; Walker et al., 1996). See status in Caporale et al. (2005). Arboviruses, those transmitted by arthropods, include in Wisconsin the La Crosse encephalitis virus, and probably the St. Louis virus, transmitted by mosquitoes. The La Crosse virus is reported in red and gray foxes, raccoons, and opossums (Amundson and Yuill, 1981 b). Tamias striatus also carries this virus (Gauld et al., 1975), as do Sciurus and Glaucomys (Seymour and Yuill, 1981). Herpes was reported in cottontails (Schmidt INTRODUCTION

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Table Intro-1 Intro-1. Important infectious diseases of Wisconsin’s wild mammals. Most can afflict humankind. Additional diseases include tuberculosis, herpes, W. Nile virus, and possibly terrorist dangers such as hoof and mouth and anthrax particularly in our artiodactyls. Rodents are susceptible to plague. Davis et al., 1987, and sources cited in text. 

Mammals

Rabies Distem- Hemorrhagic Several Tulare- Rocky Brucello- HistoOther Diseases =X per Diseases Arbomia Mtn. sis plasmosis PseudoX, Hanta viruses Spotted TB Virus Fever

Opossum Some bats X E. cottontail P-TB Lepus P-TB Marmota Tamias Eutamias Sciurus Tamiasciurus Harvest mouse Peromyscus Clethrionomys P-TB Microtus P-TB Ondatra P-TB Porcupine Beaver P-TB Wolf X Coyote, Foxes XX, P-TB Raccoon X, P-TB Mink P-TB Weasels Mephitis X Lontra P-TB Taxidea Martes Martes Bobcat X Cervus elaphus P-TB Odocoileus P-TB Alces Bison Rattus Mus musculis Felis catus X

X

X

X X

X X X X X X

X X X X, Hanta virus

X XX X X X

X

X X

X X

X X X X

?X?X X X

X

X

Lyme Disease X Errington’s enc.

XX X

? ? ?

Mange, Parvo-virus Mange,Parv. Blastomycosis Parvo, St. Louis enc. Lyme dis. tick

X X

X X

St. Louis enc.

X

?X

X X

X

X

X

X X

X

X X X(rare) X X

Canine hep. Plague

X X X X X X X X

X X X

et al., 1992) and considered in relation to flea parasitism by Spieker and Yuill (1976). Arboviruses in deer populations were surveyed by Murphy (1989). The recent invasion into the United States, and into Wisconsin, of the West Nile virus, carried by mosquitoes, mostly affects birds such as crows. However, it is transmitted to mammals (e.g, horses, humans) and can cause and already has caused some human mortality.

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X

THE WILD MAMMALS OF WISCONSIN

X

X

Salmonella, Lyme Disease

X X X

Plague Mange, Parv.

Tularemia is an important zoonotic disease found in cottontails, hares, beavers, muskrats, voles, red fox, gray fox, Mustela, and North American badger (Addison et al., 1987). The carnivores often get the disease by scavenging carcasses. Distemper was found in wild and domestic dogs, the raccoon, mink, striped skunk, badger, least weasel, and Microtus pennsylvanicus. Ringworm was found in juvenile muskrats.



Table Intro-2 Intro-2. Rabies in Wisconsin mammals (19521974). Vaccinations have practically eliminated dog rabies. Bats are low.  Year/bats

Skunks

Dogs

Total

Skunk, Bat/Total

1974/ 2 1973/ 9 1972/ 8 1971/10* 1970/ 4 1969/ 4 1968/ 6 1967/ 1 Totals 51 1966/ 1 1965/ 1 1964/ 6 1963/ 5 1962/ 5 1961/ 2 1960/ 0 1959/ 1 1958/ 3 1957/ 6 1956/ 0 1955/ 0 1954/ 0 1953/ 0 1952/ 0 Totals 30

68 76 96* 46 33 21 21 28 389 22 21 12 17 12 5 5 64 184* 37 13 19 36 25 27 499

17 35* 24 15 11 6 13 11 132 — — — — — — — — — — — — — — — —

107 154 163 91 60 46 54 61 736 68 64 95 62 42 30 24 92 227* 74 41 39 90 49 56 1,053

.64//.02 .49//.06 .59//.05 .51//.11 .55//.07 .46//.09 .39//.11 .46//.02 .53//.07 .32//.01 .33//.02 .13//.06 .27//.08 .29//.12 .17//.07 .21//.00 .70*//.01 .81*//.01 .50//.08 .32//.00 .49//.00 .40//.00 .51//.00 .48//.00 .47//.03

Anthrax outbreaks, usually arising from soil, are dangerous to many grazing mammals, and especially those that wallow in mud, such as bison. Unknown in Wisconsin, it is, nevertheless, an imminent threat to man and beast, harbored by terrorists and other beasts, and is often disseminated by carrion eaters, ranging from gulls to coyotes. Much the same can be said for bovine TB (= brucellosus) (see Davis et al., 1981). Parvoviruses are often lethal to carnivores, especially to dogs; this dog virus may have mutated from the feline parvovirus. The canine strain of virus went around the world in the brief interval 1976-1980, providing an example of the incredible cosmopolitan danger of mutated viruses dispersing in short times, and the importance of mammals in transmitting viruses. Today it is found in coyotes, red foxes, raccoons, and probably the



Cases of rabies in the United States in wild mammals, 1955-1991. Krebs et al., 1992. Raccoon incidence is highest in eastern states. 



Rabies in domestic and wild mammals in Wisconsin 1953-1992. Rare since then in domestic animals. 

wolf, at least in some states. The incidence was reviewed for several species by Short (1989). Vaccination helps control parvovirus, protecting our domestic dogs, and has practically rid the country of rabies in dogs. Rapid action by government and the Department of Natural Resources hopefully can prevent a great calamity following discovery (winter 2001-2002) of Chronic Wasting Disease in deer near Mt. Horeb. This disease, caused by virus-like “prions” that attack the central nervous system, is lethal, and, transmitted by unknown means, threatens to decimate the entire Wisconsin deer population. That would create an economic disaster, because of the economic importance of deer INTRODUCTION

15

hunting. See account below of the white-tailed deer and see Manwell (2001). The introduced Rattus and Mus defile our homes and belongings, as well as bringing us diseases. The house cat, either feral or domestic, eats millions of mammals and our wonderful songbirds (Coleman, 1993). Any time a mammal reproduces to excess, a problem develops, whether the mammal is as small as house mice or as large as the whitetailed deer. Usually mammal populations are kept in line, especially by predation, diseases, and starvation. Raptors certainly do their work limiting population outbreaks of small rodents. Therefore, biodiversity in nature, a desired goal of modern conservation, actually benefits the entire ecosystem and most of its members because of the so-called “balances” in nature. Mortality in wild mammals is generally equal to natality (birth rate). In time they balance, so long as populations are stable. Both subjects (mortality and reproduction) are treated herein. In nature, potential longevity (see Appendix A) is usually shortened by natural mortality or hunting and trapping harvests. Most mammals should not be judged as bad or good, but managed for a useful function in the community. “Useful” includes econ-

16

THE WILD MAMMALS OF WISCONSIN

omy and aesthetics, i.e., harmony and beauty. If a creature lives in association with humankind, it should be studied carefully by people with training so that by scientific management the negatives can be minimized and positives can be emphasized. The status and conservation of wild mammals must be continually studied. Then the problems of co-existence of human and animal may be recognized and solved. Modern-day land use has cost us some irreplaceable species. Wise management has saved some valuable species and replaced others. Today there are famous societies and agencies that set aside habitats, regulate some populations, and conduct research on mammals that need support. There are other agencies, landowners, and users that care little about preservation. They must be opposed. We should let no mammal, no matter how little or secretive it is, escape our notice and protection. Those who undertake the study of mammals, or any wild creatures for that matter, will find them far more interesting and valuable than they ever might have imagined. Hopefully this work will bring the subject of Wisconsin mammalogy, especially biology and known status of the wild mammals, up to date, at least to 2007.

PLAN OF THIS BOOK “In pursuing our researches we are often compelled to differ from the views of previous writers. . . . we will endeavor to be swayed simply by a love of truth, treating all with respect, and adopting such language as can be offensive to none.” – John James Audubon and John Bachman, The quadrupeds of North America 1842-1846.

SCOPE

AND

PLAN

In this book, the 20th century mammals of Wisconsin are emphasized, but some information is included on prehistoric mammals and those mammals extirpated during the 19th century. The Prehistoric Mammals are discussed in a separate section. The Wisconsin mammals documented in historic and scientific literature but extirpated before 1900, and some species that may be found in Wisconsin but are unverified so far (Hypothetical Species, Reintroduced and Extirpated Mammals beyond) are briefly discussed. The treatment of the mammals is taxonomic; the classification is based on evolutionary relationships including even the integral concepts from ecology and physiology. Unlike humans, fettered but diversified by customs, fads and television, the wild mammal lives an odyssey more genetically programmed, common to its kind. Success for a wild mammal is survival and successful reproduction. Naturalists say the mammal “prefers” a particular habitat. It occurs in this habitat partly by preference. Usually it was born there, of parents and ancestors adapted to it, as beavers are born near water, prairie mammals in grasslands, or forest mammals amid trees. Since “habitat” means home in a general way, the den site and nest for most mammals is its important home within a home. The beginning of the odyssey, called “dispersal” by scientists, is departure from the natal den. Actually it is weaning, the departure from mother. This rejection may happen in the natal den or near-

by, or at some outlier used as a den. The young beaver walks or swims away, the bat flies off, the mole burrows, and the leveret hare jumps across the prairie. They search for food sources and den sites, adventures shape their destinies, the winds carry the bats to strange places, and eventually each mammal has sexual yearnings. The dispersing young mammal must find a home or resting place, for security, sleeping, and for its offspring. Perhaps it selects a tree cavity, or digs or appropriates a burrow. Eventually the mammal may breed and bring forth young hopefully with the same adaptations that served the parents. The genetic program for form and function passes from parents to offspring. Thus, it is important for us to determine what kind a mammal is (description and names are provided herein) and where it can be found (geographic range or distribution and status). The habitat and home are described. Foods, mortality, and reproduction are reviewed. Population parameters are discussed, such as the extent of a species home range and how abundant it is within an area (density). Under Remarks various subjects are discussed. Speciation is ascertained for Geographic Variation. The specimens, mostly in museum collections, are ascribed to county. Some general and characteristic adaptations, and their phylogeny, are usually discussed for the higher taxonomic categories, such as wings in bats, bunodont molars in bears, or slenderness in weasels. All of this is modern taxonomy, and all is based on paleontology, physiology, morphology, and ecology, important and inseparable concepts. The mammals of Upper Michigan cannot be separated from the Wisconsin fauna except by the political boundary drawn between the states. There is no apology necessary for confining an investigation to an unnaturally bounded region, such as a state, but in my opinion the Upper Peninsula is so continuous with Wisconsin ecologically that this entire natural region should be appraised as one. There is continuity of southern WisconPLAN OF THIS BOOK

17

sin and northern Illinois, and on occasion (e.g., for Cryptotis, Nycticeius, Pitymys) I also ignore that political boundary. Nevertheless, the specimens studied herein, in the main, are from Wisconsin, and the book is essentially about Wisconsin mammals. The east (Lake Michigan) and west (Mississippi River) boundaries of Wisconsin are barriers sharply limiting geographic range of some mammals. Modern comprehensive references for the surrounding states are Baker (1983) for Michigan, Hoffmeister (1989) for Illinois, Bowles (1975) for Iowa, and Hazard (1982) for Minnesota. Wisconsin mammals have been wonderfully studied in the past by Cory (1912), and the late Hartley H.T. Jackson (1961), a Wisconsinite formerly of the U.S. Biological Survey. The reader is urged to consult these fine books. No comprehensive work in Wisconsin has appeared since Jackson’s book, written over 40 years ago. The taxonomic sequence of species used follows that of Hall (1981), with exceptions explained in the accounts. Comments describe variation on geographic variation, because it is such a nebulous concept, and is usually referred to subspecies, i.e.races. They appear alphabetically, unless otherwise noted. However, the nominate race is mentioned first if present in the state. A controversy today in mammalogy is what to do with geographic races, formally called subspecies. These kinds are named and described with trinomens, and too many were based on trivial characters. However, some are quite distinctive, and others were discovered by carefully appraised comparisons made on specimens collected over a wide region. Once considered as incipient species the subspecies at best is a recognizable population more or less adapted to a geographic region. Changes in habitats and other ecological factors may have affected the gene frequencies and phenotypes (appearance) of this struggling population, but a distinctive geographic race has genetic properties passed on for generations, usually for thousands of years. An isolated

18

THE WILD MAMMALS OF WISCONSIN

fragment of a population may undergo speciation leading to the evolution of a new kind. It follows that some races are differentiated as quite distinct, as are the Florida and Wisconsin fox squirrels. The prairie and forest deer mice in Wisconsin are distinct. Other races seem less distinctive and may be recognized only by careful comparisons of average and significant differences from place to place. If I perceive the described geographical differences, the formal names seem appropriate to me. If a former student of geographic variation drew a line arbitrarily between two different kinds, I may follow his lead. This book attempts to provide rationales for using current scientific (Latinized, postLinnaean) names. It broadens the statewide study enough to ascertain geographic variation extending into some other states. There is no aim toward revising the taxonomy of mammal species and subspecies in adjacent states. I searched for resemblance in characters in neighboring states to assign some Wisconsin mammals to their taxa. The foregoing rationales for formal classification of geographic variation would not be necessary to convince the scholars Hoffmeister (1989) and Jackson (1961), who studiously attempted to make careful taxonomic assignments in this region. This raised a peculiar problem for Wisconsin and Illinois. The political boundary between Illinois and Wisconsin unrealistically separates some geographic races. This dilemma arose in part from inadequacies of earlier studies and in part from numerous taxonomists assigning specimens on geographic grounds to either the nominate subspecies or the nearest geographic race. Respect for colleagues and their use of names often resulted in illogical acceptance of a name based on trivial or invalid characters. The divergent views of the aforementioned two men often obtained different results. Fourteen pairs of subspecies are divided by the Wisconsin-Illinois border, called herein the Hoffmeister-Jackson Phenomena (Table Plan-1). They defy the tenets of specia-

tion (e.g., geographic barriers, or former climates (Long, 1965) that separate evolving populations). Some reasons for this pattern include (1) natural hiatuses barring population movements, i.e., valid taxonomy, (2) provisional names, and (3) utter speculations. Wisconsin taxa are listed first. Synonymies are used to head up the species and subspecies accounts. These list the original use of name for a described kind of mammal (the scientific name is immediately followed by the Author’s name, which is not printed in italics). The synonymy also includes changed names, the most modern or recent name combination with the name of the taxonomist who first published that combination. Obviously all published usages of popular mammal names today need not to be cited. Between the name of the author of a new name combination (not for the original name itself) and that combination is a colon, because the International Code on Zoological Nomenclature recommends that kind of punctuation be used. To follow that recommendation defies some precedence in mammalogy. Other names listed in the synonymy include invalid



synonyms and homonyms with their authors’ names. The citations are sufficient enough, so they need not be duplicated in the Literature Cited (unless they need to be cited elsewhere in text). The use of parentheses around an author’s name in the synonymy means that the author named the mammal with a different generic name in the binomen or trinomen combination than is presently used. A scholar, then, would never look for the scientific name Cryptotis parva (Say) in old literature. In fact, the original combination was Sorex parvus Say. Most geographic distributions are discussed with reference to state maps. The entire North American geographic range of each species (after Hall, 1981). is presented in an accompanying map of North America. Where there is information available, such as for some Wisconsin carnivores, maps based on Department of Natural Resources work showing primary range, or denoting rare, less common and common occurrence are often included. The dots on the state maps are black for specimens I have examined, and bull’s-eyes or open circles for other records from Jackson

Table Plan-1. The Wisconsin-Illinois border separates 14 pairs of subspecies. 

Disjunct pairs caused by a natural hiatus, due probably to former climate Synaptomys cooperi Geomys bursarius Lontra canadensis

cooperi Baird wisconsinensis Jackson canadensis (Schreber)

gossii (Coues) illinoensis Komarke & Spencer* lataxina Cuvier

Races not carefully identified, or given hypothetical names Mus musculus Castor canadensis Canis lupus Felis concolor

M. m. rutty michiganensis Bailey lycaon schorgeri

? carolinensis Rhoades ? ?

hypophaeus Merriam minnesota Allen noveboracensis (Fisher) ocythous Bangs hirtus Nelson & Goldman hudsonica Richardson superiorensis Peterson & Downing

pennsylvanicus Ord loquax (Bangs) leucopus (Rafinesque) cinereoargenteus (Schreber) lotor Linnaeus avia Bangs rufus Schreber

Problematic taxonomy Sciurus carolinensis Tamiasciurus hudsonicus Peromyscus leucopus Urocyon cinereoargenteus Procyon lotor Mephitis mephitis Lynx rufus

PLAN OF THIS BOOK

19

(1961) for Wisconsin and from Burt (1948) for Upper Michigan. Other symbols are occasionally used for personal observations, examination of road kills, and other valid records. Most “other records” in this study are designated with open dots. Therefore, for most of the state maps the black dots may be compared with the bull’seyes or open circles to roughly appraise and compare the present and earlier distributions. Some changes in distribution are delineated with bold dashed lines. (Smaller dashed lines already were on the outline maps; they delineate drainage divides.) When localities are dubious or near one another, I arbitrarily chose one good locality for mapping and the others unplotted are italicized in the records of specimens. The comparison of ranges past and present show real changes (in which I follow the ornithologists in calling shifts “dispersal”). In some cases, such as many in Wisconsin, the change observed is in known range (where the specimens were recently obtained, unseen by Jackson). Usually it is possible to distinguish one change in geographic range from the other. The descriptions include cranial and anatomical characters, color of pelage, dental formula, size and other known traits. Terms for color are from common lay use unless quoted verbatim from studies of other workers. Terms such as narrow, or narrower zygomata, or elongate, and such qualitative generalities are most useful when actual specimens are examined. The drawings and photographs of skulls should be consulted. The finest set of mammal skull drawings I have seen are in Hall (1981) or Hall and Kelson (1959). Dental formulas used herein are the sequence of incisors, canines, premolars, and molars, written for humans (as an example) as DF= I 2/2, C 1/1, P 2/2, M 3/3 = 32. The premolars 1-2 are not the first and second ones; they are the posterior third and fourth premolars because in evolution the anterior premolars are first lost. The total 32 is a product of the summed teeth on either

20

THE WILD MAMMALS OF WISCONSIN

side times two. The dental formula was developed after Baron Georges Cuvier had tabulated comparative formulas for numerous mammals to express serial analogy. Unless there is solid evidence to identify a tooth as one kind or another, and especially in the problematic insectivores, I prefer to avoid use of implied homologies, and prefer to use descriptive symbols such as B for bicusp or bicuspid, U for unicusp (above) and unicuspid (below), and so on. In the section Insectivora further problems with the nomenclature of these so-called unicusps are discussed. I have been advised to at least refer to the first tooth above in shrews as an incisor, but am not convinced it is the first incisor. An upper fourth premolar is given as P 4/, and P /4 is the lower analog. External and cranial measurements and many other terms used herein are defined in the Glossary. Measurements usually are in millimeters. Dial calipers were used to measure the skulls. For weights and some linear measurements either English or metric may be quoted, and in instances where the writing is difficult and jerky from switching back and forth, both values may be given together. I am persuaded to provide both values, because of both general and scientific readers. Appendix B at the end of this book provides a conversion table for English and Metric Measurements. Statistics given, unless cited from another worker, will provide individual measurements, or if the number (N) is practical the mean usually will be calculated. The observed ranges and standard deviation are often listed in the tables. After each account there is Additional Natural History, including one or more works cited and otherwise deemed appropriate. There is no intent to be judgmental or comprehensive in so doing, some fine works may be left out. Finally, geographic variation is described and discussed. In Specimens Examined, counties are listed alphabetically for easy reference. The county names and their locations are shown in the

aforementioned map of counties and type localities. In addition to the specimens I have examined from the UW-SP collection, I have examined hundreds of University of Wisconsin—Madison museum specimens (UW) documented by Jackson (1961). To preserve the aforementioned rough comparison between the distributional ranges of his day and mine seldom did I blacken up the circles on the maps used to represent his old records, even after I had seen them, or list those specimens with my specimens examined. They are listed in his book. With Frank Iwen’s (Univ. Wisconsin Madison, Museum of Zoology) help, I tried to examine important UW specimens accumulated since 1961. Some specimens examined by me in the University of Minnesota Bell Museum are listed as UMinn., in the Illinois Museum of Natural History collection as UI, and in the U.S. National Museum as USNM. Dr. Scott Craven permitted me to examine a useful collection in the Wildlife Ecology Laboratories in Madison (UW-Wild. Ecol.). Although some state accounts today omit precise localities taken from specimen labels, there are important reasons to list them. Other taxonomists then learn about the specimens, which they may borrow for their research. If the specimens become lost or destroyed, too often the case in museum collections, the known occurrence is documented. Re-examination by future taxonomists may uncover errors in identification and lead to geographic range corrections. Against these positives stand two negatives: the work of listing and the expense of publishing. Here, the listing was accomplished, but the cost of publication was hard to defend. I followed a middle road; specific localities were uncommon and marginal records. The Literature Cited and Bibliography include some references used by Jackson (1961), some overlooked therein, many papers cited herein, and some worthy but not fully discussed due to the length and expense. To great extent it is bibliographic since Jackson’s publication.

FREE EXPRESSION

IN

TAXONOMY

Some mammalogists may find some of my divergences from established taxonomy disconcerting, I would like to make clear that the taxonomy one uses may express a view based upon a biological rationale. Darwin (1859) once said, “Naturalists differ most widely in determining what characters are of generic value.” Every species is distinct, and it often becomes subjective to recognize long phylogenetic separation (i.e., generic divergence) from closely resembling (i.e., evolutionarily related) species. In Wisconsin six mammals present dilemmas: (Microsorex and Sorex, Eutamias and Tamias, Pitymys and Microtus, Mustela and Neovison, Lontra and Lutra, Lynx and Felis). Some add Puma and Felis and Bison and Bos. Nomenclature is a system based on rules and regulations compiled and published in the International Code of Zoological Nomenclature, revised and amended by an International Commission. The Code provides for the free expression of diverse classification. Alternative expression is welcome. Opinions may be consigned to synonymy by other workers hopefully by presenting new evidence.*

PRESERVATION OF SPECIMEN COLLECTIONS AND HABITATS When wild mammals are studied and carcasses obtained or salvaged, voucher specimens should be made and preserved. Students making a study should do it themselves as a nec* The interested reader is referred to an excellent and recent synopsis on the subject of mammalian taxonomy edited by Wilson and Reeder (1993, 2005). For higher categories, Simpson (1945) and McKenna and Bell (1997) are recommended. Highly recommended is the new The Smithsonian Book of Mammals, by the same Wilson with Sue Ruff (1999) and a host of contributors. A revised Wild mammals of North America updating Chapman and Feldhamer (1982) has appeared. PLAN OF THIS BOOK

21

essary part of that study. Although difficult, time consuming, and requiring skill, invaluable vouchers should be deposited in a permanent repository, i.e., a museum collection. Specimens should be well made, including at the least a skin and skull with labels (Appendix C). Today frozen tissues and soft tissues preserved in alcohol often are preserved. Permanent field notes should be kept with the specimens, and all information obtained should be accurate, complete as possible, and meant for permanent record. If there is no way to preserve a specimen, even by putting it in a jar of alcohol, or saving the skull or teeth of a decomposed carcass, the carcass may be turned over to a mammalogist. That lays a burden on someone else to make up the specimen. Most of the work herein is based on collections of mammals gathered in the last quarter century. Such collections are priceless. Wisconsin specimens are found in several state collections and in several public museums outside Wisconsin, but I have not attempted to document every specimen. The Mammal Collection at the University of WisconsinStevens Point Museum of Natural History is one of several large vertebrate and invertebrate museum collections. The Museum, a division of the University of Wisconsin— Stevens Point, is supposed a responsibility of the University of Wisconsin System. The Museum has been the foremost university museum in the state in research collections, exhibits, and museum activities. The Museum of Zoology at the Madison campus has about as many or more mammal specimens, mostly representing earlier collections. The two collections taken together provide a respectable repository of Wisconsin mammals (Tables Plan 2-3). Field notes of many students are preserved, and the Department of Natural Resources has provided some voucher specimens. Some specimens of endangered species have accumulated in the collections throughout the years. On the basis of the museum specimens, significant taxonomic changes, since l961,

22

THE WILD MAMMALS OF WISCONSIN



Table Plan-2 Plan-2. The UW-SP Mammal Collection, the Wisconsin specimens. The Museum contains specimens preserved from nearby states of the several species not in this collection. It contains specimens of Myotis sodalis, Nycticeius humeralis, Gulo gulo, Spilogale putorius, Cervus elaphus, Bison bison, and Rangifer tarandus.  Order Marsupialia Insectivora Chiroptera Lagomorpha Rodentia Carnivora Artiodactyla

Families

Genera

Species

1 2 1 1 6 5 1

1 5 6 2 21 11 2

1 8 7 3 27 17 2



Table Plan-3. Wisconsin specimens at the UW-Madison Museum. Archaeological bison and the introduced stone marten are included.  Order Marsupialia Insectivora Chiroptera Lagomorpha Rodentia Carnivora Artiodactyla

Families

Genera

Species

1 2 1 1 6 5 2

1 5 5 2 21 11 3

1 7 7 3 27 19 3

have been made or will be for the following species: Sorex (Microsorex) hoyi, Tamias striatus, Sciurus carolinensis, Castor canadensis, Microtus (= Pitymys) ochrogaster, Microtus (= Pitymys) pinetorum), Peromyscus maniculatus, Urocyon cinereoargenteus, and lesser changes for others.

COUNTIES

AND

TYPE LOCALITIES

The counties with their names are shown on the accompanying map. The records of occurrence of mammals studied in this book are mapped for the counties, which are listed alphabetically. Because a boreal-southern division of mammals is important, it is good to know northern counties from southern. The northern ones are often toward the beginning of the alphabet (such as Ashland, Burnett,

Bayfield). Exceptions such as Washburn, Sawyer, Iron and Vilas are quickly learned. The Door Peninsula, important for the geography of Wisconsin mammals, is primarily Door County. The populous southeastern counties are known by big cities of the same name (Racine, Waukesha, and Milwaukee). In central Wisconsin is a square of three counties (Marathon, Wood and Portage) where much of the University of Wisconsin-Stevens Point mammal collection was collected. Similarly, the Madison collection is mostly from Dane, Columbia and Sauk counties. For convenience, the 17 type localities of mammals named from Wisconsin are plotted on the county map. A type locality is the loca-



tion where a mammal specimen was collected and subsequently chosen to represent a subspecies or species of mammal named formally in a scientific published work. Other specimens from that same locality are called topotypes, and they, with or without the type (= holotype), are important for taxonomic comparisons of one named kind with another, to associate specimens from other places in the same kinds. Most but not all named kinds from Wisconsin are valid names in use today. All the names based on types collected at our type localities are available for future taxonomic opinions. All are cited in the Synonymies that head up the species and subspecies accounts beyond. The type localities are as follows:

Map showing counties and type localities.  PLAN OF THIS BOOK

23

Ashland County — Basswood Island, Apostle Islands: Canis latrans thamnos Jackson 1949. Clark County — Withee: Sorex palustris hydrobadistes Jackson 1926. Worden Township: Pitymys pinetorum schmidti Jackson 1941. Columbia County — West Point Township: Reithrodontomys megalotis pectoralis Hanson 1944. Door County — Peninsula State Park: Tamias striatus doorsiensis Long 1971. Jessen’s meadow on Swenson Road, Washington Island: Synaptomys cooperi jesseni Long 1987. [Honoring Tom Jessen, type taken nearby on his brother’s meadow.] Douglas County — Lake Superior, probably Valley of the Brule River near Solon Springs, Bruleand Iron rivers. Not Minnesota as reported, because Geomys does not occur on the Minnesota shore or near it. Mus saccatus Mitchill 1821. New York Med. Repository 6:249 (=Geomys bursarius). Grant County — Platteville: Urocyon cinereoargenteus ocythous Bangs 1899. Iowa County — Blue Mounds: Cervus whitneyi Allen 1876. Blue Mounds listed by

Jackson (1961) was omitted from his synonymy, and also by Hall and Kelson (1959) and others. The “lead region” of the Mississippi River is not much like Dane County; in any case, the subfossil elk was considered an extinct fossil species. Nevertheless, it is an available synonym for the American elk. Oconto County — Lakewood: Microsorex hoyi intervectus Jackson 1925. Oneida County — Crescent Lake: Eutamias minimus jacksoni Howell 1925. Outagamie County — Near Appleton: Felis concolor schorgeri Jackson 1955. Racine County — Racine: Sorex hoyi Baird 1858 (= Sorex (Microsorex) hoyi). Probably collected somewhere northward of Racine (Long, 1972a). Racine: Arvicola austerus Le Conte 1853. Richland County — Lone Rock: Geomys bursarius wisconsinensis Jackson 1957. Rock County — Milton, 4 mi. E: Taxidea taxus jacksoni Schantz 1946. No exact locality known except Wisconsin. — Cariacus wisconsinensis Belitz 1919 (= Odocoileus virginianus, see Jackson, 1961).

Rhyme to Louis Agassiz: And he wandered away and away, with Nature the dear old Nurse, Who sang to him night and day the songs of the universe, And when his way seemed long and his heart began to fail, She sang a more wonderful song, Or told a more wonderful tale. — Henry Wadsworth Longfellow

24

THE WILD MAMMALS OF WISCONSIN

EARLY MAMMALOGY AND NOW What is mammalogy? It is the study of fourlimbed furry animals secretive and mostly nocturnal. They climb trees or rocks, dig in the ground a little, and are adapted to our grasslands, forests or forest edge. Some species run or hop, and others can even fly. They feed on seeds and nuts, sometimes on fruit or grasses, or instead may specialize on insects or flesh. They may breed in the spring or fall, sometimes throughout summer, and a few may breed in winter. Usually the young are born blind, naked and helpless, but some are more precocial. They nurse, grow, disperse, and try to carry out their life activities faced with mortality from predators and diseases. People observed mammals in what is now Wisconsin over 600 years ago, probably as early as 9,000-11,000 years ago, the time the great Pleistocene mammoths died out. Fishing and hunting were pragmatic activities of native Americans. There were myths and superstitions about mammals. Their lore cannot be regarded as science, even though our science is a changing and imperfect perception of nature (no matter how elegant we believe that it is), we who practice and see our results in retrospect. Retrospection is possible because of publications, books, journals and other written records. Publication and testable science began in Wisconsin with the Caucasians (French, English, Americans). The French established schools, trading posts, and churches in this region about as early as the Pilgrims landed at Plymouth Rock. After the early 1500’s, the active and curious French explored central Canada and our land via the mighty Ottawa River, leading westward from Quebec. Jean Nicolet arrived at Green Bay in 1643, and he was not the first. Some coureurs de bois arrived as early as 1662 (Gilman, 1974). Most of the fur trapping and in early years even the transport to Quebec of the furs were carried out by Native Americans. The various tribes were often at war with one another, displaced from region

to region, and therefore the economics of fur not only affected the history of the American West, but it affected the very early history of Canada and the United States. Fur also profoundly affected the destinies of several Indian nations especially along the Mississippi River, and in Wisconsin and Upper Michigan (see Gilman, 1974). Eventually the city of Sault Ste.-Marie was settled at St. Mary’s Narrows, at the east end of Lake Superior. Explorers such as Etienne Brule, Pierre Radisson, M. Chouart Sieur des Groseilleiers, Perrot, Jean Nicolet, Father Jaques Marquette, Louis Joliet, and Daniel G. Dulhut explored what is now Wisconsin, establishing schools, churches and fur trading posts throughout the region, from Madeleine Island in the Apostles to Green Bay eastward and Prairie du Chien and La Crosse southwestward. The French eventually established settlements along the entire length of the Mississippi River. These activities of developing a fur trade, and eventually of copper mining, fishing and farming all began in the early 1600’s. After the French were defeated at Quebec in 1759, giving up their American possessions in the treaty of 1763, the British ruled as best they could over the wilderness posts and the lucrative fur trade, until 1783. Then, the Treaty of Paris ceded American lands to the United States. Nevertheless, French, British, and Indians, with the help of some Americans, continued shipping furs to European markets. The Americans were kept out by the British troops until about 1815. Eventually the fur trade and other activities were assumed by the Americans, meaning by this term the people from the United States. By 1836, Wisconsin was a territory. Its southern lands were settled by farmers who early on moved along the Lake Michigan shore to French-established Green Bay and the Door Peninsula (named after the strait called Porte des mortsor Door of Death). Lumber was harvested in the center of the region, shipped down the Wisconsin River, and eventually lumbering yielded great quantities of lumber from the EARLY MAMMALOGY AND NOW

25

tall white pines and spruce of the North Woods. Lead and copper were mined in the southwest of Wisconsin. Forest fires were commonplace. The infertile, sandy savannas of the center were eventually settled by farmers. Swamps and marshes were drained, forests cleared, and towns and roads established. Thus, there were, in what is now Wisconsin, several Indian nations, the French, British, Canadian, and American governments. Even Spanish soldiers visited in the southwest parts of this land, after moving up the Mississippi River. For a while the region was known as the Michigan territory. Wisconsin’s borders with Michigan were established by a series of political negotiations. Today there are several Indian nations with more or less authority over the northlands. The earliest French civilization was more accurately a French-Indian civilization, with mixed culture and free intermarriage. Although these races were amicable, there was always trouble between Sioux and Chippewa, Chippewa and Huron, etc. Basically the entire region had developed in one way or another primarily by the economics of fur, until after statehood, after which time the region was settled by farmers, lumbermen, miners, businessmen, immigrants, and descendants. Although scientists in those early years faced formidable challenges, and spent much effort in survival, the French scientists and some others, too, named and described animals from many of the furs obtained in the fur trade at St. Louis and Hudson Bay. None of them is known to have come from Wisconsin. The badger type may have (see Long, 1972) because it was a St. Louis pelt supposedly taken in “les pays des Esquimaux” which generally was French-Canadian fur territory. French explorers such as Joliet and Nicolet made general observations on wild mammals in their accounts of the regions explored. Joliet [“Louis Jolliet”] described a mountain lion in what is now Grant County in 1673 (Jackson, 1961). With the fur trade flourishing in the early 1800’s, H. R. Schoolcraft made several Amer-

26

THE WILD MAMMALS OF WISCONSIN

ican government-sponsored expeditions to explore the Michigan Territory. His explorations circled from Sault Ste.-Marie to Grand Marais, to Pictured Rocks, and westward along Lake Superior to the Apostle Islands (in what is now Wisconsin), down the St. Croix and Mississippi rivers as far as Galena, Illinois, and in Wisconsin, Prairie du Chien, then traveling up the Wisconsin River to Portage, northeastward to Green Bay, and back north to Sault Ste.-Marie. He made casual observations (1834) of bears and deer killed, sightings of wolf, porcupine, and in Wisconsin a red fox, beaver and “jerboa” (probably a jumping mouse). This mouse was from Madeleine Island (Mossman, 1992, 1994). On his expeditions Schoolcraft was accompanied by a bona fide scientist named S. L. Mitchill. Mitchill wrote, “Description of two mammiferous animals of North America”, Medical Repository 21: 248-250, 1821, and “Detection of a mistake into which naturalists have been led, in relation to Mus bursarius, or pouched rat of Canada”, Amer. J. Science, 4: 183-185, 1821. In these early years Wisconsin was visited by two of the world’s greatest intellectuals. Both were greatly interested in nature, and only their brief tenure in Wisconsin keeps them from being recognized as Wisconsin’s greatest naturalists. Both were primarily writers and realist philosophers, but they were amateur naturalists besides, with strong interests in making plant specimens. John Muir (1913) arrived from Scotland in the 1840’s and was raised with hard work on a farm at Montello. He left Wisconsin and became an eloquent preservationist of nature, so elegant in prose to be almost biblical, so outraged and stately he resembled a biblical prophet. Never has there been another like him, and nobody from Wisconsin is really educated if he knows nothing of the lyrical and sacred environmental scriptures that he wrote. Muir described the nest and a hibernating specimen of the thirteenlined ground squirrel Spermophilus tridecemlineatus. Quite interesting was the observed

attack (about 1846) of a shrike, even following a ground squirrel into its burrow. The other intellectual giant was Henry David Thoreau, who briefly visited Wisconsin, and paid more attention to mammals than did Muir. Accompanied by Horace Mann, Jr., the transcendental realist Thoreau came by steamboat up the Mississippi River hoping eventually to write up an account of the Great River and the Volga-like towns here and there along the river’s steamboat route. These included Prairie du Chien, La Crosse, Red Wing, Minnesota, and others. Some little towns are still isolated along that river today, although a highway and railroad now extend along the river shore. Thoreau unfortunately died before he wrote the book, although publishing a few articles. His notes are preserved at Harvard University. His favorite mammals were the thirteen-lined ground squirrel Spermophilus tridecemlineatus and the pocket gopher Geomys bursarius (Sweetland, 1962), which is indeed a more interesting mammal than most people realize. The woodcut of Thoreau was made after he returned to New England from Wisconsin, shortly before he died. Several works on the Wisconsin mammal fauna appeared in the late 1800’s. I. A. Lapham (1852-1853) and Moses Strong (1883) wrote lists of the mammals. As early as 1853, Dr. P. R. Hoy wrote a paper on the thirteen-lined ground squirrel. Hoy sent numerous specimens to Spencer Fullerton Baird at the Smithsonian Institution. He actually named with Kennicott a kind of deer mouse found in Wisconsin, named bairdii, and had a shrew Microsorex hoyi (=Sorex (Microsorex) hoyi) named after him by Baird. In 1882, Hoy wrote a brief account of the mammalia of Wisconsin. H. Gillman (1873) wrote an early work on the caribou near Lake Superior. Other naturalists at this time were Charles F. Carr, John Clark, Henry Nehrling, and the two Kumleins (Thure, died 1888; Ludwig, 1880’s). One of the earliest mammalogists living in Wisconsin, and, indeed, the first woman mammalogist in America, was Martha Maxwell. Fa-



John Muir. Great naturalist-philosopher. Raised near Montello. Photo by W. Dasselville, about 1909. Courtesy of the Sierra Club. 



Henry David Thoreau. Naturalist and transcendental philosopher. after returning home from Wisconsin Mississippi River trip. Woodcut.  EARLY MAMMALOGY AND NOW

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mous for her Colorado exhibition at the 1876 Centennial celebration in Philadelphia, Maxwell was mainly a self-taught collector and taxidermist of birds and mammals. When living in Baraboo she married, had a daughter, and got work at the Baraboo Collegiate Institute. Her work was to assist in the preparation of mounted birds and mammals for the Zoology Department, a practice prevalent at state schools at least until 1906. When she left Wisconsin for Colorado she had learned to observe, study, collect, and prepare specimens mounted in natural positions, including large mammals. She corresponded with Joseph Henry, Secretary at the Smithosonian, and also with Robert Ridgway and Elliot Coues. A screech owl that she collected was named after her by Ridgway. She also confirmed the existence of th black-footed ferret described earlier by Audubon. She attended college in Wisconsin (Lawrence University) at a time when women were generally not welcome in college. Like Muir she subsequently made her fame in a western state. Her collections of specimens apparently are all lost (Stein, 1996), unless a few are in the United States National Museum (Natural History). About 1900, workers from the United States Biological Survey, under the direction of Dr. C. Hart Merriam in the Smithsonian Institution, began to collect specimens in Wisconsin. Two young Wisconsin naturalists, Ned Hollister and Hartley H. T. Jackson, learned about the Smithsonian and actually got jobs with the Biological Survey. Classmates at Milton College, and fellow workers in the Survey, it is not surprising that early works on Wisconsin were produced by both of them. Hollister (1910) wrote an early check-list, and in his youth Jackson (1908) wrote a preliminary listing of Wisconsin mammals. Two scholars who wrote several early papers on Wisconsin mammals at the turn of the 20th century were W. E. Snyder (1902) and H. L. Ward (1907, 1908, 1911). In 1912, C. B. Cory wrote the “Mammals of Wisconsin and Illinois”, which is a comprehensive and well-written book on mammals from southern

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THE WILD MAMMALS OF WISCONSIN

Illinois to boreal Wisconsin. As comprehensive as Jackson’s work on Wisconsin was in 1961, no one should overlook Cory’s practical discussion on any Wisconsin mammal. Dr. Hartley H. T. Jackson (1881-1976) was born in Milton and studied at Milton College. He worked for his masters degree at U.W.-Madison and obtained a doctorate from George Washington University in 1914. His undergraduate teacher was Ludwig Kumlein (see Robbins, 1991). His first paper on Wisconsin mammals was published in 1903. In 1910, he joined the U.S. Biological Survey, and although he spent most of his life outside Wisconsin he may be the greatest naturalist the state has produced. He was instrumental in founding the American Society of Mammalogists, and was a longtime editor for the Journal of Mammalogy. He was a meticulous scholar, and wrote a classic taxonomic monograph on the shrews of North America. He also collaborated with Stanley Young on books such as The Clever Coyote and finally wrote the Mammals of Wisconsin (1961). Aldo Leopold (1899-1948), born a century ago, was a forester acknowledged as a great naturalist-philosopher. His books (e.g., Sand County Almanac, Round River) expound a “land ethic” philosophy. He provided classical foundations for game management, recognition of the ecosystem, and an appreciation of the role of predation in regulating prey populations. For Wisconsin he published on wolves, cottontails, and the “killing technique” of the [long-tailed] weasel. In the 1940’s, bat banding was popular in the caves of Wisconsin. Pioneer bat banding carried out by professors and students at Madison was done at Eagle, John Gray, and nearby caves by John Emlen and William Elder. James Beer, Frederick Greeley, and Arnold Jackson banded bats in southwest Wisconsin, at Lac du Flambeau and sites near Hurley. Wayne Davis, who reviewed the bat accounts herein, and W. Z. Lidicker, graduate students at the University of Illinois, studied bats from southwest Wisconsin.

L. B. Keith, Department of Wildlife Ecology at Madison, and his associates made numerous contributions on the cycles of hares and lynx. A. W. Schorger, Wildlife Ecology, studied the newspapers and county histories to compile histories of several mammals and birds of Wisconsin, and he made a list of the mammals of Dane County. Since then we have seen quite a lot of ecological work by the Department of Natural Resources (formerly the Wisconsin Department of Conservation) including that of Jim Hale, W. E. Scott, G. J. Knudsen, N. R. Barger, and others. Today there are at least three departments of the DNR directly related to mammalogy, the Bureau of Research, the Bureau of Wildlife Management, and in recent years an important new Bureau of Endangered Resources. One person who may never have visited Wisconsin at all, but who mapped and classified its mammals often, with authority and in a broad scheme of classification was E. Raymond Hall, University of Kansas, my former teacher. In his The Mammals of North America (1959, with K. R. Kelson, and 1981) he summarized the literature including some of his own papers treating Wisconsin specimens, e.g., microtines, weasels, lagomorphs and others, and mapped every species in the state not only for Wisconsin but providing maps of their geographic ranges throughout North America. [I relied on them heavily for the North American maps herein.] Today, in spite of great population growth and intensive land use, Wisconsin still maintains a rich diversity of natural communities under federal and state protection. Since 1971, the state DNR has provided increasing attention to endangered species. Many studies on wild mammals are done cooperatively with state agencies in nearby Upper Michigan, Minnesota, and with the Federal Government. Two national forests (Chequamegon and Nicolet) were established between 1928 and 1933. The DNR established great reserves for wildlife at Horicon, Crex Meadows in Burnett County, the Mead Wildlife Area in central Wisconsin, and in other places. Some

counties have set aside county parks not entirely developed for recreation. Since 1960, The Nature Conservancy has preserved or encouraged the preservation of about 40,000 acres of Wisconsin wilderness. Robbins (1991:32) has mapped the national wildlife refuges, state wildlife areas, and major research stations of the state. There are about 194 scientific areas preserved by legislative action by 1951. Much of this conservation stems from the teaching, eloquent philosophy and sincere efforts of Aldo Leopold and his students. Other important naturalists of the past included John Muir, William T. Hornaday, Ernest Thompson Seton, and even President Theodore Roosevelt, who instilled by eloquent writings in those days a widespread caring for nature. They sparked necessary action to preserve our natural heritage. Some Basic Procedures. In the earliest years American mammals were examined in hand after collecting them with gun or steel trap, or when carried in by native Americans. They were mounted usually in a fierce demeanor, in some sort of natural position, or prepared as a pelt. The skull was often discarded, or the skull might have been left in the stuffed head. Invention of the snap trap, effective for catching small mammals and cheap to manufacture in quantity, led to huge collections of the mice and rats in our museums, with an occasional shrew or ground squirrel. The specially designed museum special trap, which is an expensive trap, strikes the small mammal on the neck or back and seldom crushes the skull. This development, following the technique discovered of using dermestid beetle larvae to thoroughly clean small mammal skulls, led to better skull collections—useful in taxonomic work. “Skin and skull” became the specimen of modern mammalogy, with practices instilled in scientifically trained professionals by the likes of Joseph Grinnell and Spencer Fullerton Baird, and eventually E. Raymond Hall. They all stressed keeping permanent well-written field notes on the ecology of the mammals. Mole traps, pocket gopher traps, and EARLY MAMMALOGY AND NOW

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the Japanese mist net made of fine threads (invisible to flying bats) led to better collections of some heretofore obscure mammals. The use of empty cans sunk into the ground flush with the surface of it, often called a pit trap or can trap, has led to easy collection of shrews (Handley and Kalko, 1993). Drift fences designed to funnel mammals into the traps increase the catch. Once dug in, the cans are easy to check over a period of days or weeks. Today mammal characters also are obtained from blood sera, DNA, isozymes, the post-cranial skeleton and other body parts. Live traps permit marked mammals to be released and re-captured. Small radio transmitters allow some mammals to be followed wherever they wander. Keen observation of animal and habitat always was important, and a fine camera and pair of binoculars are often useful in research. Field collecting has its difficulties because for nocturnal mammals the traps must be set on one day and checked on the morning of the next. Preparation of the specimens, and securing both skins and skulls from loss or damage, take much time and effort. Traps must be set so that mammals will find them, which requires some knowledge (“lore”) about the secretive behavior of the mammal, and of the mammal’s “sign” (e.g., tracks, hairs, runways, burrows and scats). Hall, in Hall and Kelson (1959), and other references describe the steps for making study skins. This procedure is given in Appendix C. Proper state permits must be obtained from state natural resources agencies to collect mammals. These rarely are available for amateurs, and are reserved for professional mammalogists to further scientific investigations. Skins and skulls in personal collections are often illegal. Rare and endangered species are seldom permitted to be collected, and seldom are game animals allowed to be killed out of season unless a rationale is approved. Some natural history museums should be selected for final deposition of specimens, even of carcasses found. Most mammalogical studies would benefit by the preparation of voucher specimens espe-

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THE WILD MAMMALS OF WISCONSIN

cially of rare carcasses obtained for deposition in a museum. Unfortunately, too often the salvaging of specimens does not happen in Wisconsin. Common sense and tact are important for mammalogists, who should not jeopardize their opportunities to study animals by alienating people who object to cruelty and killing of animals. After all, it is in the best interests of the wild animal for workers to know its biology for proper management and its preservation. A policy statement (Acceptable Field Methods in Mammalogy. . . . 1987) of the American Society of Mammalogists has been issued on this subject to all members. The American Society of Mammalogists’ publications Journal of Mammalogy, Mammalian Species, and Special Publications, is an important resource. The annual meetings and constant appraisal of the role in society by mammalogists lead to a respectable and scientific enterprise. The Journal of Wildlife Management, published since 1937, also contains many articles on mammals.



Hartley H. T. Jackson. U. S. Biological Survey, Washington, D. C. Born in Wisconsin, wrote on mammals more than 60 years. 1938. 

ENVIRONMENTS AND ECOLOGY OF MAMMALS GENERAL ECOLOGY OF WISCONSIN MAMMALS Prairie, Forest Edge, and Forest From The prairies — ”... My heart swells while the dilated sight takes in the encircling vastness... The clouds sweep over with their shadows and beneath, the surface rolls and fluctuates to the eye... Breezes from the South who toss the golden and the flamelike flowers and pass the prairie hawk that, poised on high, flaps his wings, yet moves not. From Entrance to a Wood — “Enter this wild wood and view the haunts of nature. The calm shade shall bring a kindred calm, and the sweet breeze that makes the green leaves dance... of green and stirring branches alive and musical with birds... The squirrel, with raised paws and form erect, chirps merrily. Throngs of insects in the shade dance in the warm beam that waked them into life... Even the green trees partake as they bend to the soft winds, the sun from the blue sky... From Forest Hymn — “All these fair ranks of trees. They, in thy sun, budded and shook their green leaves in thy breeze, and shot toward heaven... When I think of the great miracle that still goes on, in silence around me — the perpetual work of thy creation, finished, yet renewed forever.” — William Cullen Bryant.

The southern prairie soils, rich in organic matter, support dense grass and forbs; the friable and well-drained soils shelter numerous burrowing mammals, especially seed, grass and insect eaters. The extensive and often continuous northern and eastern forests of Wisconsin provide mast crops, tree canopies useful to arboreal mammals, nest cavities and loose bark for their homes, and correlated ecological factors such as less snow cover, more leaf litter and less wind chill. The southern hardwoods provide mast and cover, and in the clearings the forest edge mammals thrive. Rivers and lakes are homes for many semi-aquatic mammals, as are the vast swamps and countless marshes of Wisconsin.

These wetlands provide homes, feeding and breeding areas to many kinds, such as jumping mice, shrews, bog lemmings, beavers, muskrats, mink, and otters. Great rivers (see section on zoogeography) restrict some mammals mostly from dispersing eastward, but the sandy floodplains were routes of dispersal for the pocket gopher. Rocky bluffs with caves and mines provide shelter for millions of bats. Basically, the chief contingents of mammals are boreal, i.e., northern (e.g., northern flying squirrel, Canada lynx, moose) and southern (e.g., prairie (= eastern) mole, least shrew, opossum). Boreal species have occupied the North Woods for centuries, and have dispersed southward even somewhat beyond the limits of present day boreal forests. Southern invaders from the deciduous woodlands, forest edge, and prairies in the south have moved northward into the northern forests. By way of sand dunes and beaches, wetlands, wet prairies, and savannas the dense, shady forests were penetrated by many sun-loving prairie and forest-edge mammals. This invasion occurred even before Europeans and Americans arrived. After human settlement, the clearing of forests by farmers and lumbermen and tree removal for road rights-ofway encouraged the northward dispersion of southern species. But at the same time numerous boreal species, and some grassland kinds such as the least shrew (Cryptotis parva), were disappearing probably because of agricultural practices. Chemicals used in the environment may have decimated and eradicated local populations of some mammals. Until there was sensible management of game animals and furbearers, some mammals were eradicated by unregulated hunting and trapping. A few such species have been reintroduced. Habitat destruction and agricultural practices in Wisconsin are the greatest threats to Wisconsin mammals today, although the latter is often beneficial to animals that need openings and forest edge. There are many positive things that should be emphasized regarding wild mammal conENVIRONMENTS AND ECOLOGY OF MAMMALS

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servation in Wisconsin, and the preservation of mammal environments (many by hunters and for hunting). Reintroductions of some lost species, protection of wilderness areas, acquisition of new refuges, scientific management of harvested mammals, and protection by the rare and endangered species programs have been remarkably successful, to name only a few programs. These are primarily the responsibilities of the Wisconsin Department of Natural Resources. But recent losses from our fauna of some species without notice, the dramatic decline of others, and the relentless assault on natural habitats by urban sprawl, highway development, and many farmers and builders (in both city and country) should not be allowed to cause further losses of any mammals from our fauna. Even counties and individuals must get into the conservation effort. No resting on the laurels of past successes is sensible. Much proposed land use today is detrimental to nature, and many political maneuvers nationally and at local levels seem to be intensifying environmental change as so-called “progress”. In the popular rationale of profit and jobs, even a protected nature preserve seems for some people merely a reserve. I am advised that at our state level, large area land use planning, comprehensive land management, and ecosystem management present a sound approach and method for accomplishing the goals of genuine conservation. They are all based upon the science of ecology. Updating ecological information from Jackson’s treatise (1961) on mammals is necessary particularly in comparing the concepts of his day to those of modern ecology. The fundamental concept in Jackson’s work is the singular effect of temperature roughly dividing Wisconsin into three faunal subdivisions, namely three of C. Hart Merriam’s life-zones. Jackson’s perception of temperature was inadequate and in some places inaccurate. Furthermore, the life-zone concept does not work well except in mountainous regions of western America. Neither latitude nor elevation relates

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THE WILD MAMMALS OF WISCONSIN

much to temperature in central Wisconsin. I suppose Rib Mountain may be even warmer in summer on its high crest than downhill by the Rib River. Central Wisconsin shows more effects of wind chill and deep frost than do northern habitats near Lake Superior. Much greater ecological importance than temperature effects should be attributed to the geomorphology of this state, the major plant communities that developed after the recession of glaciation, the effects of ecological succession and land use, and the zoogeographical interactions of invading and retreating mammals.

FORMER GLACIATIONS The Pleistocene Epoch, popularly called the Ice Ages, consisted of four continental glaciations extending as far southward on the North American continent as central Iowa and northeastern Kansas. The epoch lasted about 2 million years, and the climate created most of our landforms and soils over vast regions (Dorr and Eschman 1971). The glacial stages were not simple advances followed by melting and recession, but were often complex, consisting of two or more advances with various side lobes from the glaciers. Low hills comprised of glacial sediments (called drift) were deposited by the ice fronts and are identified as lateral or terminal moraines. They mark the extent of the advances of ice. The moraines can be dated (i.e., aged). Interspersed with the four cold glacial periods were three interglacial periods comparable to our present day climate. Although the southwestern hills of Wisconsin were bypassed by glaciers repeatedly (giving basis for the name “Driftless Area”), the climate was doubtless frigid during the glaciations. Where forests subsisted at all, they were mostly spruce, and the mammals in them were boreal. On the snowfields and ice, the mammals were like those in the Arctic. Glaciation scoured much of the Wisconsin terrain during the Pleistocene Epoch end-

ing about l0,000 years ago. Just preceding the end of Pleistocene glaciation, late in the Wisconsin glaciation, a huge glacier sprawled across the northland, lay in the Lake Michigan basin, and extended westward across the valley of the present day Fox River (Long 1974). Earlier glaciations had already planed much of what is now southern Wisconsin. Except for the non-glaciated Driftless Area in southwest Wisconsin and scattered exposed outcrops of rock, the terrain today features post-glacial phenomena of either the Wisconsinan or earlier glaciations. Glacial processes affected geomorphology almost everywhere. Two subsequent processes, of course, have been at work: (1) stream erosion, and (2) soil formation. The vast glacial outwash sands and sands eroded from a sandstone bedrock in central Wisconsin may lead to deep frosts there in winter and relate to extreme summer heat and drought. Large elongate and interconnected glacial moraines extend across the state. These hills are usually covered with woods. Sands, boulders and clays, with acid soils, are prevalent. Lying southward of the Wisconsin glaciers, in what is now Illinois and southern Wisconsin, the flat country scoured by earlier glaciation was left to nature. The prairies that developed there had deep, black topsoil, rich in organic material. This has been largely put to the plow in historic times, but here and there prairie remnants and old field habitats have allowed most of the prairie species of our Wisconsin mammals to survive in spite of farming. A huge lake called Glacial Lake Wisconsin drained from the terminal moraine near Stevens Point southwestward. It exists even today as marshes, flowages and drained marshes from the Buena Vista in Portage County to the enormous Pettenwell Flowage, extending southwest toward the Driftless Area of the hilly and rugged Coulee Country in southwestern Wisconsin. Over most of the state is a thin wind blown glacial loess intermixed with forest humus and soils derived from the underlying bedrock.

CLIMATE The climate is relatively uniform today in Wisconsin, in average temperature, winter and summer temperature, and precipitation (Table Env-1). The warm air of summer pushes northward from the south, and it is warmer in the southern and central counties with more hot days. Winter or summer, the cold air masses originate in the Canadian Arctic regions and usually swing eastward from Minnesota or flow across Upper Michigan and southward along Lake Michigan. Prevailing westerlies bring moisture eastward, usually from Minnesota. There is a mingling of cool Arctic air and southern warm air. As a consequence from temperature and atmospheric pressure changes, precipitation increases eastward, and the eastern forests have higher humidity. The temperature gradients change regularly and gradually north to south, as does photoperiod (= day length) and snow cover (with exceptions). The great freshwater lakes Superior and Michigan moderate climates near the shores causing the seasons there to lag. The growing season (100 days in the north, 170 days in the south), based on frostfree days, is variable in Wisconsin. Though roughly related to latitude, the season varies from one city to another (Moran and Morgan, 1976), and the extreme numbers are variable and not always as expected. Frost



Table Env-1. Climatic Factors of Southern and Northern Wisconsin (After Curtis, 1959), generally prairie and forest.  Prairie // Deciduous Forest January mean temp* July mean temp Annual mean Growing season* Annual precipitation Annual total snowfall* Number days 0 precip* Ave. evaporation (July)* Warm, days above 68 0F*

15.1 degrees F // 11.40 F 71.1 // 68.0 44.6 // 41.5 148 days // 126 days 31.5 // 30.1 in. 41 in. // 5l in. 90 days // .05 days 5-6 in //3-5 in 60-90 days // 0-60 days

*Apparently significant to mammalian distribution. ENVIRONMENTS AND ECOLOGY OF MAMMALS

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penetration of the ground is a variable phenomenon from place to place in Wisconsin, as is the effect in some places of summer drought. Both of these seem most severe to the small mammals on the sandy soils, especially of central Wisconsin. Greater snowfall in Upper Michigan and northern Wisconsin limits frost penetration there, thereby diminishing frost-caused mortality of small mammals. Snow cover affects distribution, favoring mammals such as deer that move into the deep coniferous woods, and hares and lynx, which run easily over the snow. Some temperature data are mapped herein (see accompanying Fig.). Slight differences in mean temperature throughout Wisconsin do not sharply influence mammal distributions. Rocky outcrops, humuscovered forest soils, sun dappled prairie sod and bare sands, shaded barren woodland soils, riparian vegetation and wet soils, and other innumerable local factors provide a diversity of mean temperatures. These allow an intermingling of boreal and southern species across the middle of Wisconsin, a grouping that helps define the “Tension-Zone.”



Winter Severity (includes temperature). Mild to 50, Moderate, over 50 is Severe. 1961-90. Bartelt et al. Compare Vernon and Marinette. 

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THE WILD MAMMALS OF WISCONSIN

At dawn of a new millennium there is great concern that the climate is steadily warming, due to so-called “greenhouse effects” of atmospheric pollution, El Nino ocean effects, and other causes. So far it seems difficult to confirm such a trend, but one notes the past eight or ten winters have been mild, especially 19992006 (but 2000-2001 was colder). Record high winter temperatures for three years relate to the waters of Lake Michigan that receded significantly (although U.S. Army engineers dredged out its outlet eastward). Nationally there are severe droughts and shortages of water; and there seem probable effects on wildlife (e.g., increasing deer densities).

PHYSIOGRAPHY To better understand the ecological role of physiography, often called geomorphology, will reveal interesting and paradoxical effects in Wisconsin. In this author’s experience, in the rugged mountain-basin topography of the Rockies, and even in the flat cuestas of Kansas, there is a correlation of natural effects of temperature, climate, vegetation, and animal distribution, all relating to the basic land forms. In Wisconsin, the provinces mapped by Martin (1932) in his classic works derive almost entirely from the single source of underlying bedrock. Indeed, both non-glaciation (in the rugged Driftless area of southwest Wisconsin and as well in the vast swampy marshlands southwest of Wisconsin Rapids) and Pleistocene glaciation have subtly affected the Wisconsin landscape. They have drastically modified the land of granitic rocks of northern Wisconsin showing an almost recent effect (youthful stream development, marshes, lakes). On the Central Plain vast deposits of sand and subsequent sandy soils (drained out of glaciers) are found. The igneous bedrock in the north and the underlying sandstone in the center primarily create the different physiography. Perhaps the mammals that range through several provinces only follow certain plant communities,

and since the land is not tremendously varied in elevation the pervasisive factor of physiography seems less important than in other states. In 1932, Martin described the physiography, or geomorphology, of Wisconsin as five provinces. 1. Lake Superior Lowland: The good soils there are underlain with ancient pre-Cambrian rocks of igneous and metamorphic structure, and lie approximately in the basin of Lake Superior. 2. Northern Highland: This province consists of most of boreal Wisconsin, and contains swamps, lakes, marshes, and shallow streams of youthful drainages since the retreat of the Wisconsinan glaciation. Here are found boreal forests, probably held over from the climate of the late Wisconsin. This land was not planed off by glaciers as is often thought, but is an old peneplain of a great, worn-down mountain range, with its hard bedrock foundation submerged in seas, but re-emerged from them about 200,000,000 years ago. Nevertheless, the peneplane was often scoured and planed by Pleistocene glaciers from several sources. 3. Central Plain: This consists of sands and savannas with extremes of heat, drought and frost, but also includes the unglaciated swampy, marshy areas southwest of the edge of the Wisconsin ice sheet. This entire region of some 13,000 mi2 of generally infertile soils (but blessed by irrigation and now becoming useful for peat and cranberries) is entirely underlain by Cambrian sandstones that border the northern igneous bedrock northward and several sandstones and limestone bedrocks eastward, and southward. 4. Western Uplands: These are largely prairies or savanna regions, including important river terraces and lakes of the Mississippi River, and the presence of other deep rivers (Black, Chippewa, St. Croix, and the lower reaches of the Wisconsin). Rugged bluffs of sandstone and limestone are found in this region important to cave-dwelling bats, but the elevation of these hills is not high.

5. Eastern Ridges and Lowlands: This region is associated with good soils, flat terrain and cuestas with limestone and shale bedrock including a higher, more rugged outcropping of the Niagara Formation lying eastward along Lake Michigan. All of these physiographical provinces relate somewhat to the distribution of mammals, except that the mammals range freely through one to another depending on the prevailing vegetation and their mobility. For example, moose and lynx enter Wisconsin in the Lake Superior Lowland, but both species range southward and eastward in the boreal forests of the Northern Highland, and some boreal mammals range even into the swamps near Necedah, the hills of the Baraboo Range, or the forests along Lake Michigan. There are Western Upland prairies more or less connected ranging from the low Mississippi Valley and grassy western “goat prairies” on the unforested ridges, through the openings in the savannas of the Central Plain. These rolling grasslands become intermixed with hardwood forest, creating much forest edge and savanna, extending along the Wisconsin River’s southern boundary. There the proximity to the Grand Prairies Province of Illinois and rich soils dating from the early glaciations allow the free dispersion and deep penetration of prairie flora and fauna into Wisconsin. To the five physiographic provinces I add two important geological features: Wetlands and Islands. Islands. There are numerous islands today clustered in Lake Michigan (e.g., Big Summer, St. Martin, Rock and Washington) and Lake Superior (e.g., the Apostle Islands: Madeleine, Outer, and others). Both areas were glaciated perhaps even 10,000 years ago, so that only in protected places could mammals have survived there. Probably these mammals were boreal (see Pre-historic Mammals). Today the waters are cold and rough, so that rafting on floating logs and branches is uncommon, and hibernators, inactive in winter, cannot cross the winter ice. Therefore, many mammals cannot invade these ENVIRONMENTS AND ECOLOGY OF MAMMALS

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isles, but if somehow established there those species were isolated on the isles. This has led to some interesting evolution, even in a brief 10,000 years (geologically speaking). Two races have been named from the Door Peninsula, a chipmunk Tamias striatus doorsiensis and a bog lemming Synaptomys cooperi jesseni. No significant speciation has been observed on the more recently uncovered Apostle Islands. Deer mice show microgeographic variation on both island groups. Bats and aquatic mammals easily traverse the water barriers, and carnivores readily cross either water or ice. Humans have introduced some species to some isles (Long 1978c; Long and Long, 1993). Islands are discussed more fully in the section on Zoogeography. Wetlands. Neither forest nor prairie can establish itself well when conditions are too wet. The “wetlands ecosystem”, if extensive enough, consists of a mosaic of variable microhabitats in association with semi-aquatic and somewhat aquatic mammals. Recently and suddenly, Wisconsin wetlands have come to the fore, and have been popularly protected. Mammalogists must study them. Bats, raccoons, voles, and the semi-aquatic muskrat are found in most of them, and Blarina, deer mice, jumping mice, red-backed voles, tree squirrels and chipmunks inhabit copses of trees and shrubby areas at many wet localities. The wetlands differ in their vegetation, water quality, and wildlife. Generally, the greater the amount of vegetation, the more mammals are found. Some wetlands, such as Shorelines and Sand beaches rarely provide habitat for mammals, but even sand dunes, with scattered vegetation of peculiar and regular beach-dune flora, shelter an occasional white-footed mouse and local populations of the prairie deer mouse Peromyscus maniculatus bairdii. Beaches of lake-pebbles and gravel are visited by mammals from shrews to bears, but have no known permanent residents, occasionally housing a lodge of beavers. Tamarack, cedar, spruce, and alder swamps and bogs contain Arctic and masked

36

THE WILD MAMMALS OF WISCONSIN

shrews, snowshoe hares, red-backed voles, meadow voles, bog lemmings, weasels, whitetailed deer, and even an occasional bobcat, Canada lynx, or moose. Open marshland with wet soils near standing water containing plants such as swamp loosestrife, royal fern, blue vervain, sedges, rushes, grasses, and such shrubs as red-osier, dogwoods, willows, Spiraea, and aspens have mammals including red foxes, coyotes, weasels, meadow voles, jumping mice, occasional bog lemmings, Franklin’s ground squirrels, mink, and otters. Cattail marsh is an important habitat for masked shrews (Sorex cinereus), muskrats, jumping mice (Zapus hudsonius), Franklin’s ground squirrels, mink, and otters. Southern fens, as described for Wisconsin by John Curtis, with alkaline water, generally contain a few mammals, such as the Southern bog lemming, and, nearby on the brushy shores, white-footed mice. Red squirrels (Tamiasciurus hudsonicus), gray squirrels (Sciurus carolinensis) or flying squirrels (Glaucomys volans) may inhabit the nearby trees. Riparian streamsides provide important habitat and streamside corridors for many kinds of mammals. Wet meadows, with sweet flag, milkweed, golden rod, sedges, bulrushes, marsh marigold, and transitional plants stand between forest and aquatic habitats, so that the mammal fauna is rich, varied, and usually seral.

SOILS The topography, about 1,000 feet (= 305 m) elevation overall, may lack dramatic relief, but there are several outstanding features of the terrain apart from the vegetation on it. The non-glaciated hilly southwestern part (the coulee country, meaning valley country) is a rugged region with high wooded slopes and numerous crevices, ravines and caves. The sand plain in the center of Wisconsin, although heavily wooded and penetrated by streams and rivers, is an important geological feature due to such vast deposits of sand. The lakes

and marshes that dot the North Woods constitute a vast wetland-boreal wilderness still not much cleared by human hands. The pale soils and outcrops of the Niagara Rock Formation on the Door Peninsula and isles offshore, as well as the isolation and semi-isolation of mammal populations there, comprise a highly interesting laboratory of recent evolutionary processes. Outcrops of bedrock, such as granite or limestone, the post-glacial soils and till, sandy outwash deposits, river bottoms, peatlands and sandy loam prairies are diverse habitats necessary for particular mammals in Wisconsin. Most of the soils are acidic, often infertile, and range from very dry to very wet. They are classified as follows: 1. Coarse, bouldery acid soils derived of igneous and metamorphic rocks of the Northern Highland (see above). 2. Acidic and infertile sands from sandstones and glacial outwash. 3. Fine-grained alkaline soils derived mostly from dolomite (limestone). The former glaciers produced clay, sand, gravels, silt and indirectly (with accumulated mossy vegetation) deposits of peat. Reddish lake clays and sandy loams were produced, mostly in eastern Wisconsin along Lake Michigan and Lake Winnebago, but also along the Lake Superior shore. Sands were deposited up to 60 feet (18.3 m) depth on the Central Plain, and are widespread across six or seven counties (a broad band often exceeding 100 miles (= 161 km) width). Another band of sand extends along the St. Croix River northeast to nearly as far north as Bayfield. A deep (up to 16 feet), so-called silty loess lies along the Mississippi River in southwest Wisconsin. Loess is also found in Dane and several adjoining counties (Zimmerman, 1991). A quick overview (Hole et al., 1966) of Wisconsin soils, named generally from geographic names, mentions some clayey soils concentrated along the shores of the Great Lakes (Hibbing, Ontonagan soils near Lake Superior; Manawa and Kewaunee soils near

Lake Michigan). Most of northern Wisconsin is overlain with poor acid soils on the uplands (Iron River, Kennan soils) and reddish brown sandy soils on flat and rolling terrain (Omega and Vilas soils). These may cover the granitic and basaltic Cambrian rocks. In the south are rich sandy loams (Fayette, Dubuque, Wea, Warsaw, Dodge, McHenry, and Casco soils). These prairie soils merge northward into poorer sandy soils based on sandstones and siltstones in the west (Hixton, Norden, Sparta soils) and on glacial outwash sands in the center (Plainfield, Oshtemo soils). The Fox and Wolf river valleys are limey and sandy soils overlying drift and limestone strata, which often are conspicuous outcrops and bluffs in Door County. A surprisingly large total area in Wisconsin consists of low, flooded soils (Elba, Poygan, Newton, and Arenzille) comprised of peat and muck (e.g., Houghton soil). The prairie mammals, such as Spermophilus tridecemlineatus and Peromyscus m. bairdii, both of grassland and scattered brushy copses, inhabit the southern loams and range onto many accessible open sandy soils northward. The boreal mammals, such as Clethrionomys gapperi, Glaucomys sabrinus, and Myotis lucifugus occupy mainly the forested gravels and coarse, sandy acidic soils derived of igneous and metamorphic rocks. They make up much of the terrain of the northern counties. Aquatic and marsh-dwelling mammals thrive on the low, flooded soils in peat bogs and other wetland communities. Outcrops of limestone (dolomite), granite, and rough country generally, are habitats of mammals such as chipmunks and long-tailed deer mice. Both large and small caves in the sandstone or limestone outcrops and river bluffs in southwestern and western Wisconsin are homes to thousands of bats. There may be remarkable differences between the humus and topsoil of deciduous forest and coniferous forest stands. Pine needles cause soils to be remarkably acidic. Deciduous leaves produce a deep leaf litter with less acidity. Grasslands have more alkaline soils that ENVIRONMENTS AND ECOLOGY OF MAMMALS

37



Table Env-2. Env-2 Some mammals and their soils, listed generally from north to south, and important beach dunes from Door County. 

1. Valders’ Clay and Loams including coarse northern soils and some extending along Lake Michigan: Boreal species, such as snowshoe hare Lepus americanus, red-backed vole Clethrionomys, and star-nosed mole Condylura cristata dwell there. 2. Northwest sands: pocket gopher Geomys, white-footed mouse Peromyscus leucopus 3. Peaty soils: Shrews, Condylura,Woodland jumping mouse Napaeozapus, southern bog lemming Synaptomys, muskrat Ondatra, and ermine Mustela erminea. 4. Central Sands: P. leucopus, eastern cottontail Sylvilagus, prairie vole P. ochrogaster minor. 5. Prairies, light loess about four feet deep more or less: Scalopus aquaticus, Cryptotis parva, Reithrodontomys megalotis, Spermophilus, P. m.bairdii, Taxidea taxus. 6. Beach Dunes: P. maniculatus bairdii 7. Thin loess or forest topsoil of only a few inches depth where the other soils are not exposed: Includes many mammals of prairie and forest lands.



Including Three Wisconsin Biomes (grand communities) of North America. V. Shelford (U.Illinois Press). 

38

THE WILD MAMMALS OF WISCONSIN

encourage dense root development even when dry; the result is called sod. In winter the entire prairie generally freezes and loses all green leaves and grasses, which must be renewed in the coming growing season. Herbivores and, indirectly, insectivores or carnivores are affected by this seasonal effect.

COMMUNITIES Three Grand Floral Communities. In the simple binary subdivision of the Wisconsin environments, the so-called “North Woods”, consisting of a boreal woodlands biome (deciduous, coniferous, and mixed forests) is northward, and the prairies intermixed with deciduous woods on the one hand, and on the other, many open agricultural fields and old fields, bottomlands, boreal remnants, local fens, bogs, and large marshes lie in the south. Open prairies are extensive grasslands; they not only look like great rippling seas, but are as adverse as seas to some mammals, while to others are essential. Woodland forms include eastern chipmunk, southern flying squirrel, and others. Prairie mammals include grazers, formerly including Bison, and numerous burrowers such as the prairie mole Scalopus, ground squirrels Spermophilus, and the prairie deer mouse, P. m. bairdii. Therefore, southern mammals seem divided as prairie and deciduous woodland species. Zimmermann (1991) in “Wisconsin Birdlife” discusses how three important floral areas meet in central Wisconsin: the boreal North Woods (mixed and conifer forest); in the southwest and south-central, the extensive dry prairies (intermixed with maple, basswood, prickly ash, and oak on the rugged highlands in the coulee country); and in the southeast part of the state extensive broadleafed forests (beech, hardwoods). In Jones and Birney (1988) these same regions are termed: “hemlock-white pine-northern hardwoods” which in Wisconsin studies also have been called conifers and mixed woodlands; in

the southwest, known in Wisconsin more often as the Driftless Area or the Prairie-woodlands, are many interconnected prairies and extensive stands of “maple-basswood”; in southeast Wisconsin are deciduous “Oak-hickory forest” and “Beech-Maple” forest. Curtis (1959) has written a classic study of plant communities of Wisconsin. Stearns and Kobriger (1975) extended this descriptive study for the watershed of Lake Michigan. The analysis of the occurrence of mammals in these plant communities facilitates understanding of certain ecological relationships (Table Env-2). Some extirpated and abundant mammals are not included in this survey. Lying along the Wisconsin moraine is an ecotone separating communities generally into northern (N) and southern (S) groupings. N1. Cat-tail or Reed Marsh // S1. Cattail or Reed Marsh N2. Northern Sedge Meadow // S2. Southern Sedge Meadow N3. Alder Swamp // S3. Shrub Carr (willow, dogwood) N4. Northern Lowland Forest (tamarack and black spruce) and Relic Bogs // S4. Southern Lowland Forest (maples) N5. Northern Wet Mesic Forest (white cedar) // S5. Southern Wet-Mesic Forest (American elm) N6. Northern Mesic Forest (sugar maple) // S6. Southern Mesic Forest (maples) N7. Northern Dry Mesic Forest (white pine) // S7. Southern Dry Mesic Forest (red oak) N8. Northern Dry Forest (jack and red pines) // S8. Southern Dry Forest (black oak) N9. Jack Pine Barrens // S9. Xeric Dry Prairie (sunflowers, bluestems) N10. Birch-Aspen Forest // S10. Mesic Prairie (legumes, luxuriant grassland) N 11. Boreal Forest (spruce-fir) // S 11. Oak Opening [savanna] (white and pin oak). Nearly twice as many uncommon mammal species occur in the northern communities as in southern ones. These include the

boreal kinds and recent southern invaders. There is much ecological diversity in forest lands. Most northern communities are well represented by mammals, except Dry Mesic Forest and Dry Forest. The most depauperate is the Jack Pine Barrens. These have poor soils. Birch-Aspen Forest is not quite so well represented with species as are the remaining northern communities. The southern communities are not strongly represented by mammals, except Oak Savanna, followed by Mesic and Dry Mesic Forest. There is much intermingling of habitats, even merging communities of the three major biomes. For example, in central Wisconsin, where I have lived 40 years, there is a great deal of local plant diversity (spruce, hemlock, white pine, sugar maple, red maple, butternut, pin and bur oak, hickory, cottonwoods, aspens, bluestem as tall or taller than 2 m, basswood, paper birch, cat-tails, marsh grasses, and jack pine in abundance). Likewise, in central Wisconsin there is an amazing, large mixture of mammal species (Long, 1970). By use of average resemblance coefficients to indicate faunal resemblance (of mammals), Long (1970) showed that in central Wisconsin the prairie assemblage of mammals resembles the Dry Forest edge (Oak Savanna) most and the Jack Pine Barrens next. These dry communities are not greatly dissimilar in terms of temperature, precipitation, floras and faunas. They are often combined. The community faunas seem to reflect generally the faunas related to the aforementioned physiographic provinces. Tension Zone. In addition to describing carefully and generally mapping the plant communities of Wisconsin, many of which are essential for the distribution of certain mammals, Curtis (1959) described an ecotone, which he called a “tension zone” extending across Wisconsin like a climatic belt. It is roughly 50-60, as much as 100 miles (= 161 km) wide. There is no clear explanation for this ecotone, except that boreal organisms extend southward to their limits and southENVIRONMENTS AND ECOLOGY OF MAMMALS

39

ern organisms disperse northward into boreal habitats of the north. Temperature plays a subtle role, and in earlier ages it may have played a stricter determining role. The vegetation types are correlated with the presence or absence of animals, northern mammals



with northern vegetation and southern ones with southern vegetation. The vegetation is related to precipitation and soil patterns. Apparently there is some competition between northern mammals and southern invaders coming face-to-face.

Table Env-3. Select animals related to plant communities. Revised Long 1974. 

Species

Plant community

Comments

Cryptotis parva Peromyscus maniculatus bairdii Pitymys ochrogaster Taxidea taxus Condylura cristata Sorex palustris Napaeozapus insignis Sorex cinereus Sorex hoyi Sorex arcticus Blarina brevicauda Vulpes vulpes Myotis keenii, M. lucifugus, Eptesicus fuscus Lasionycteris Nycticeius trichopterans Peromyscus leucopus Clethrionomys Microtus pennsylvanicus Pitymys pinetorum Ondatra zibethicus Castor canadensis Sylvilagus Lepus americanus Canis latrans Canis lupus Ursus americanus Tamias s. doorsiensis Eutamias minimus Marmota monax Spermophilus franklinii Lontra canadensis Lynx canadensis Tamiasciurus Glaucomys sabrinus Synaptomys cooperi Erethizon Urocyon Neovison vison Odocoileus Mustela frenata M. erminea M. nivalis

S9-S11 ditto ditto ditto + S2, N2, N9 N1-N6, N10-N11 ditto ditto ditto+S1-S5, S10 N1-N11, S1-S8, S11 N1-N4 ditto ditto Wide-spread ditto ditto wide-spread SE Wisconsin ditto N1-N6 ditto 6, S6,S7 ditto ditto ditto N1-N5, N11, ?N6 ditto + S1-S11 N1-N11, formerly S1-S8, S11 remote ditto Open woodlands N1-N6, N8-10 N6-N8, S6,S9, S11 N1,N2,S1,S2, S10 N1-N6, N10, N11 N1-N11 N4-N11 N5-N10 N6-N8, N11, S10, S1-S6 N1-N11, S1-S8,S11 N4-N9, S4-S8,Sll ditto ditto Usually N5-N8, S5-S8,S11 N1-N5,?N11, S1,S3,S10 N1-N2, S10,S11

Sandy loam, rare ditto ditto ditto Wet, mesic ditto, brooks, marsh ditto ditto wet, dry, disturbed, water. Marsh, alders, Canary grass Most habitats ditto Needs hibernacula ditto ditto Forests, needs trichopterans, beetles, etc. Ash, silver maple, oak Woods, brush Woodlands Wet, mesic grasses Leaf humus, clay soils usually Wet, mesic ditto Brush Wet, mesic, winter snow cover Ubiquitous

40

THE WILD MAMMALS OF WISCONSIN

Mast, remote Open woodlands, rock outcrops, range retreating Open woods, forest edge Wet, mesic Wet, protection Forest, mesic, hares, winter snow cover Forest, savanna Mast, tree cavities Grasses, sedges, black soils, boulders Northwoods, tree canopies Brush, rock outcrops Wet, mesic Most habitats Mesic Wet, mesic, snow cover Rare

MICROHABITATS “Microhabitat” refers to one subdivision “preferred” by a species above others within a larger habitat. The word focuses on an organism’s specific and localized environment, particularly the physical parameters. Microhabitat differs from “niche”, which is an organism’s function in an ecosystem. Not only have few microhabitats and their microclimates been studied in Wisconsin, even the nests of some obscure mammals have never been found or described. Heat and water availability play an unknown role for mammals in Wisconsin’s local habitats; but water metabolism is important in lactation, kidney function and heat loss. Summer drought and heat, inseparable problems, may become lethal and profound in the general effect, but probably it is especially so, spottily and sporadically important in variable microhabitats. I have observed chipmunks basking in the morning sun on rocks that heat up to 50o C on a summer day. As important as heat and water are, they are not so dangerous to mammals in Wisconsin as is the bitter winter. Starvation, disease, and hypothermia lead to drastic mortality in exposed species during winter, and even for those sheltered below ground if the frost is deep. However, many mammals are well adapted to winter and do not seem to suffer stress or high mortality. Some that do, seem to recover. The white-footed mouse (Peromyscus leucopus) suffers terrible mortality in some winters in central Wisconsin, but it is the commonest mouse. Some mammals hibernate such as ground squirrels (Spermophilus), woodchucks (Marmota), and jumping mice (Zapus and Napaeozapus); some cache food to last through the winter such as the short-tailed shrews (Blarina brevicauda), both chipmunks, tree squirrels, the pocket gopher, beaver, and some mice (Peromyscus); and some mammals forage below ground to eat roots and insects. Some mammals den up and slow their metabolic rates, whereas others forage actively

above or below the surface of snow. One can well imagine a diversity of microhabitats for all these kinds, which have one common protection, a den or nest with a moderate microclimate below ground and out of the wind. To conserve body energy, mammals may use burrows (badger, moles, and pocket gopher), lodges (beaver and muskrat), tunnels under the snow (shrews, mice, and weasels), or caves (bats and occasionally other mammals) to provide more moderate environments. Even wolves and deer seek dense woods and shrubs, out of the wind, and lie partially buried with snow (Ozoga, 1968; Mech, 1970). Many mammals drag insulating materials into the den (bears, weasels, voles) or plug the openings to provide additional insulation (badger, pocket gopher, ground squirrel), or dig down below the frost line (moles). Some huddle together to conserve heat locally (e.g., pine voles, southern flying squirrel, the rare Indiana bat, and occasionally striped skunks, raccoons, even porcupines). Some mammals allow their gonads to regress and cease breeding (deer mice Peromyscus, pocket gopher, some squirrels). At least three species of bats migrate southward in winter (Lasiurus and Lasionycteris), while thousands of cave bats move into the moderate microclimates of caves or opportunistically into human buildings. Few studies have addressed microclimate in homes of mammals. In a model study of the western ground squirrel (Spermophilus beldingi), Mohrhardt and Gates (1974) provide an example. Getz (1968) showed that microclimatic differences do not separate the redbacked vole and the white-footed mouse, but water use by the former causes it to prefer swamps compared to the drier uplands used by the white-footed mouse. The microclimate has been studied in the winter lodges of beaver (Novak, 1987) and muskrats (Huenecke, Erickson and Marshall, 1958), and in the dens of some large carnivores (Long and Killingley, 1983). Some studies of microclimates have been made in bat caves (Ainsley, 1983; Beer, 1955; Barbour and Davis, 1969). Promising ENVIRONMENTS AND ECOLOGY OF MAMMALS

41

detailed, systematic and technological methodology is suggested by Bakken and Kunz (1988). Whereas caves have been studied, the climate in the hollow trees or rock crevices used by bats has been seldom studied. The effect of the bat, itself, warming its immediate surroundings, and the warmth of the sun have been seldom measured. The nature of the substrate in the hibernaculum or maternity site of bats, differing temperatures at various elevations, the effects of wind currents and humidity, the warmth possible from solar heat, heat from the bats themselves, depth of the cave and distance from the entrance, and other factors all divorce the interplay of variable microclimates from general weather. The temporal and spatial microhabitats theoretically provide opportunities for some “lucky” or opportunistic mammals and disadvantages for others: available foods of insects, shoots, buds, seeds, fruits or mast; or home security of burrows, tree cavities, lodges, dead falls, and dense shrubbery. Relationships also include distance to standing water; relative humidity and snow fall; and open space space to see and escape by running away or scurrying up a tree for safety. All of these vary over the landscape, and from season to season. One opportunistic example is provided by the raccoon, known to use tree cavities and fallen logs for nests (Steuwer, 1943), but which adapts to prairies, savannas and marshes by building ground nests. Another example, the white-tailed deer feeds opportunistically on plant droppings of a porcupine in winter (Shapiro, 1949) or on plants thrown out of a muskrat’s opening on river ice (personal observations). The river current and condition of the stream banks may influence beavers to build lodges or to dig bank burrows; the same dilemma affects nest building for the marshdwelling muskrat, which cannot tunnel where the water table is high. In the American West a mammal may be limited to a mountain, or even a northern slope of a mountain, or to a basin or desert by macroclimate, in a word temperature

42

THE WILD MAMMALS OF WISCONSIN

(Long, 1965, and others). In Wisconsin, the microclimates are influential, especially in open forests. Owing to the layering of plant species, forests provide many more microhabitats and possible niches to specific mammals. This is one of the reasons species richness tends to be high in Wisconsin forestlands. Even the weather cycles of the ages, perhaps from the long ago glaciations to this day, may have evolutionarily fixed some responses and other behavior, of hibernation and migration, to mention but two. We do not yet know the role of long-term microclimatic fluctuations on the Wisconsin mammals. We do not know the long-term interrelationships of organisms within microhabitats, the role of the millipede in the forest, of the sod worms and beetle grubs in the prairies, the role of shrews in the marshes. Lately some conservationists, even the game managers of big game, are beginning to assess the small animals in the managed units. To understand the total environment, the scheme of life, the importance of all members of our communities, and their relationship to humankind, it is essential to study the cryptic and subtle ways of all the mammals and other life forms dwelling in and relating to their microenvironments. Knowledge of microhabitats can be summed up as a paucity.



Table Env-4. Ecological successional seres and selected small mammals in them. Baker, 1983.  Mammal

Crop Annual Perennial Shrubs Mature Land Grasses Grasses Saplings HardForbs Forbs wood

Sorex cinereus Blarina

+

+

+

+

+

+

+

+

+

+

+

+

White-footed Mouse +

+

Meadow Vole

+

+

+

Meadow Jumping Mouse Zapus

+

+

+

Prairie Deer mouse

+

+

ECOLOGICAL SUCCESSION

ÀND

Species simply occupy favorable sites as they become available (Table Env-4-5). The dynamic process of succession following ecological disturbance has permitted mammal populations to disperse into developing habitats here or there, while their own habitats changed adversely whence they came. Fire. Aridity and fire helped prairies develop on many post-glacial soils, reducing competition of grassland with developing forests. Although prairie fires are formidable, and I never forget the sight of rabbits and opossums struggling to escape from one, fire probably does not destroy many of the mammals. Mobile kinds may escape the flames and return. Some mammals hide in burrows, but the prairie vole (Pitymys ochrogaster) may be adversely affected (although observed effects resulted from both fire and plowing). Pure prairie stands of grasses and forbs are cleansed of encroaching thickets and trees, and the prairie plants quickly return. In the northern forests, when the weather is dry, fire adversely affects many small mammals. In a three-year study following a

LAND USE

Succession. Habitats change in sequential stages called “seres”. These may take many years to elapse. Some mammals prefer Early stages, relatively brief, whereas others prefer the late (Climax) stages, which may last indefinitely (Table Env-4). Therefore, in good wildlife management the seral stages must be maintained as well as the climax vegetation (i.e., dominant vegetation that lasts). Early successional plants such as the transient blackberries, shrubs, aspens and seemingly insignificant understory and ground vegetation may be more essential to many mammals than the mature trees. Succession and its impact on mammal habitats are illustrated (Table Env-4) for six common small mammals. In Baker’s example, the shrew Blarina was found in all five successional stages. Excluding this shrew, only one mammal (Peromyscus maniculatus bairdii) occurred in the earliest stage, and only three occur in the climax. If succession is staggered the fauna may include six mammals.



Table Env-5. Env-5 Choice of seral and climax communities in north (left) and south Wisconsin. Shade eradicates some mammals. 

Mammal

Sorex palustris Lepus americanus Sylvilagus fl. Marmota monax Tamias striatus Tamiasciurus Sciurus niger S. carolinensis Glaucomys volans R. megalotis Peromyscus m. bairdii Peromyscus leucopus Clethrionomys Pitymys ochrogaster Meadow Vole Mustela erminea American Marten White-tail Deer

Shrub carr

Cattail

Sedge Meadow

X X

X X

X X Rare

X X

Dry Pines

X X X X X X

X X

X

X X

X X

X X

Rare

X

X

X

X

Climax Forest

Sand Barrens

Oak Barrens

S. Dry Prairie

X

X X X

X X

X X X

X X

X Rare

X X X

X X X X X X

X X Rare

X Rare

Rare

X X

X

X

Rare

Climax Forest

Rare X X X X X

X

X X

ENVIRONMENTS AND ECOLOGY OF MAMMALS

43

huge forest fire (in the summer of 1976, of 60 square km) in the Seney National Wildlife Refuge of Upper Michigan, Anderson (1982) showed an immediate adverse impact on numerous small mammals. After the fire the most abundant small mammal was the masked shrew (Sorex cinereus) and it was the only species taken in the sedge marshes. By October 1977, the number of small mammals was significantly higher in the burned habitats. Meadow and red-backed voles were abundant, as were chipmunks and other species. By 1980, an abundance of jumping mice (Zapus hudsonius) raised the diversity even higher. Through the succession, deer and black bear seemed unaffected. The fire increased plant diversity, leading to an increase in small mammals. “Edge”, Patchy habitats, Savannas. In ecology, the term “edge” has often been used to describe organisms that dwell at the interface of two distinct habitats. Usually the organism does not survive as well in either of the pure adjoining habitats. There are, of course, many kinds of edge interfaces. In Wisconsin the most common is that between grassland and forest. The woodchuck Marmota is considered an edge species, because it digs a den on an open slope providing visibility, easy digging, and access to plants for succulent foods. Forests may lack all three. Flat fields have poor drainage and less visibility if the vegetation is dense. The woodchuck is often observed on grassy road embankments today, or on open hillsides with nearby woods. Game managers recognize that openings in the forest and old fields increase “edge habitats” which are favorable to deer and some other game animals. Presently there is used in scientific circles the trendy phase, which may last, “habitat fragmentation” or “landscape fragmentation”, suggesting or inferring that as “edge” increases, by whatever means, the pure habitat species are isolated and often lost. This isolation needs much study, for “clear cutting” and worn out fields are becoming commonplace. However, many

44

THE WILD MAMMALS OF WISCONSIN

mammals in Wisconsin certainly benefit by the appearance of grassy openings. The whitetailed deer, eastern cottontail (Sylvilagus floridanus) and fisher (Martes pennanti) adapt to them especially well, and cottontails, fox squirrels and woodchucks thrive. White-footed mice and southern flying squirrels may be favored over their northern counterparts. Where fragmentation has created a mosaic of local habitats, the landscape is said to be “patchy” and in scaling and complex patterns of food sources, cover, and distribution of animals, these may exhibit fractal geography. Fractal analysis, a new approach to appraising any complexity that scales down and elaborates as it scales, may increase understanding of such elaborate patterns. The savanna community is open grassy habitat with little continuous tree canopy. The scattered, mature trees are usually oak, in some places jack pines, or various kinds of thickets. If the shrubby thickets are not continuous, interfaces in the savannas may be “edge” for numerous species of animals. The openings made by humans (such as railroad or roadside rights-of-way, fields, lumber camps) in forests may qualify as savannas, and are often grown to weedy vegetation. Good examples of savanna mammals are eastern cottontails Sylvilagus, ground squirrels Spermophilus, white-footed mice P. leucopus, the prairie vole Pitymys ochrogaster, and probably in western Wisconsin even the western populations of P. pinetorum. Forest Openings. Our northern forests are closing their grassy openings by ecological succession, especially on loamy soils. Thus, succession causes deterioration of summer range for many mammals. Usually 3-5 percent of forest land maintained as open grassy range would be of benefit to deer and other wildlife (McCaffery and Creed, 1969). Openings can be preserved easier than created. Since the Wisconsinan glaciation, forest openings created by frequent natural forest fires have been extensive. Most of northern Wisconsin was forested by mature timber with lit-

tle undergrowth, but vast areas of barrens and burns were commonplace. Savanna-like shrub lands and pine barrens were widespread in the northern forests. However, wet forests may show little effect of fire. On the Upper Peninsula a popular description is “asbestos forest.” Today most forest openings are less than 10 acres in size and result from land use. Invading weedy species may thrive in such openings. Bracken grasslands and treeless exposures on sandy soil result from timber cutting and fires. Many meadows on the heavier soils resulted from logging camps, pastures, and failed farms. Plants present on loams include Agropyron, Poa, Cirsium, Rubus, and Achillea. On medium soils today plants such as Poa, Hieracium, Agropyron, and Fragaria occur. On sand soils Hiracium, Myrica, Vaccinium, and Poa are found. Other studies show Pteridium, Myrica, Carex and Gaultheria on bracken grasslands. These openings improve summer range for white-tailed deer and provide habitat for a variety of small mammals such as voles and shrews, and carnivores preying on them. In the southern grasslands, and in the pine barrens on thin soils are conspicuous assemblages of prairie plants. Notable are Andropogon, Liatris, Amorpha, Artemisia, Aster, and Carex. Such plant communities allow free dispersion of prairie mammals into the northern forests, and cause the strong affinities of prairie assemblages of mammals with those of the pine barrens and forest edge. Land Use. Land use such as clearing dense forests, plowing fields and leaving some fields fallow, mowing rights-of-way along railroads and roads, and lawns in urban areas, has allowed the recent invasion of many southern species into the North Woods and up the Door Peninsula. By the middle of the 20th century, some southern species (e.g., Spermophilus tridecemlineatus, Glaucomys volans, Peromyscus leucopus, Peromyscus maniculatus bairdii, and Sylvilagus floridanus) had found their way through open woodlands, wetlands and along Lake Michigan dunes and beaches

northward in Wisconsin as far as Marinette County, Michigan (Burt, 1948). Today that movement northward is accelerated, and some boreal forms such as the northern flying squirrel (Glaucomys sabrinus), the least chipmunk (Eutamias minimus), and the forest deermouse (P. m. maniculatus) may suffer because of competition. Water shrews and some jumping mice, and perhaps other mammals, may also be losing habitats due to land practices and water pollution. Forest and wetland preservation, if it continues in Wisconsin, may help save many of these mammals. Excellent maps of former vegetation and the present day pattern of agricultural and urban regions are given in a recent Wisconsin report (Anon. 1995, see maps). Roadsides and railroad rights-of-way not only are grassy openings in forest, but they provide linear (traversed faster) routes of dispersion. Many mammals (e.g., voles, deer mice, probably others) expand their range following these routes, and some (e.g., Marmota monax) build up their highest densities in such habitats (Woodward, 1990). The slaughter of mammals from mice to deer, including opossums, raccoons, skunks and thirteen-lined ground squirrels, by automobiles is excessive mortality. To manage rare mammals such as wolves along paved roads such as Highway 53, in northwest Wisconsin, is a primary cause of concern. The Dairy Farm in Wisconsin, one of America’s most unappreciated treasures, was an almost biblical provision of wildlife habitat. Dairy farms are found throughout Wisconsin. A typical dairy farm may have woodland, open fields and edge communities. The edge and woodland provide wildlife over many years. Many farms failed, and their worn out soils lie fallow. Prairie-like grasslands, thickets, and forest may develop from the old-field habitats. Lumbering nearly devastated Wisconsin’s northern forests early in the past century, and removed many of our finest trees throughout the state. Clear cutting in strips today is a controversial practice that hurts some organENVIRONMENTS AND ECOLOGY OF MAMMALS

45

isms and benefits others; the harvest of old timber does the same thing. Replanting of the forests and conservation by both private, state, and even county agencies have led to forest renewal and continuous use of some trees for paper and lumber. Forestry was decidedly beneficial to most Wisconsin forest and forest-edge mammals. Urban mammals. In cities and suburban areas, besides the introduced Norway rats and house mice, and unwanted or free-ranging domestic cats, there are today numerous deer, raccoons, cottontails, big brown bats, chipmunks, cottontails, gray squirrels, voles, opossums and occasionally other species that thrive in our midst. Besides the parks and boulevards, even our finest estates tend to preserve some natural habitats and native mammals to look at, even in the largest cities. This coexistence of humans and wild mammals does not include a great many kinds of mammals. Neither does it extend much to the mammals of the north, the wetlands, vast prairies, or dense forests. Mammals that fit well into the urban surroundings, are those usually active and seldom seen at night that climb to safety into tree canopies or burrow in lawns, that have generalized diets, perhaps including mast from desirable lawn trees, and den in areas of ecological disturbance. Some perceived as cute and beautiful may become great nuisances. Insecticides and other contaminants. In this century natural history students must study the laboratory science of biochemistry, because many problems of pollution and chemical contamination of ecosystems will develop. Insecticides and other poisons such as DDT caused great problems to wildlife, since their use after World War II, but their effects on mortality of animal populations are not well known. Fortunately, the use of such poisons has been restricted greatly. After Rachel Carson, in her famous book Silent Spring, alerted the world about the eminent danger of insecticides, Wisconsin became the first state to ban DDT. Joseph J. Hickey and his student D. W. Anderson studied at the UW-Madison the reproduc-

46

THE WILD MAMMALS OF WISCONSIN

tive problems of raptors and DDT accumulation in their egg shells, which seemed to galvanize opposition to pesticides (1968-1969). Frederick Baumgartner, George C. Becker, Hickey, Hugh Iltis, Lorre Otto, Fred Ott, Leoni Vrtilk, William Reeder, and other supporters of the Citizens Natural Resources Association won this political battle. Other toxic substances that have been studied in our ecosystems include PCB’s, mercury, and numerous organophosphates. These have both direct and indirect dangers to wild mammals. For example, PCB’s poison fishes, which are eaten by mink, raccoons, and other mammals that feed extensively on aquatic animals. Bounty systems and other politics. Bounties have hurt some rather harmless species. Today this waste of taxpayer’s money is curtailed. A valuable role of predators in any ecosystem is now recognized. However, government often takes the side of businesses and urban development at a relentless expense of nature, and there are more and more, wider and wider roadways. Some people are satisfied if we save the big trees along the roads. But these old trees eventually will die. If most wild mammals could choose saving the great old elm or maple on the right-of-way or to save a patch of hazelnut, bluestem and cattail, they would not vote for the big tree. Why not save some of the native shrubby, grassy habitat along roads, and focus wildlife toward roadside culverts? Agencies involved with preservation of habitat include the Wisconsin Department of Natural Resources, state and private colleges and universities, some enlightened county governments, and several conservation societies such as The Nature Conservancy. Environmental education is stressed by several natural history museums and nature centers. In addition, the Wisconsin Academy of Science, Arts and Letters Transactions was an influential voice through Wisconsin history, publishing many studies on Wisconsin’s natural history.

ZOOGEOGRAPHY “So greatly has the climate of Europe changed that in Northern Italy, gigantic moraines left by old glaciers are now clothed by the vine and maize... a large part of the United States reveals a former cold period... As the cold came on, the temperate inhabitants would be supplanted by Arctic productions. The inhabitants of the more temperate regions would at the same time travel southward... the present circumpolar inhabitants, which we suppose everywhere travelled southward are remarkably uniform around the world... As the warmth returned, the arctic forms would retreat northward, closely followed up in their retreat by the productions of more temperate regions.” — Charles Darwin, On the origin of Species, 1859.

Nowhere does Darwin’s profound and pioneer thoughts on glaciation and animal distribution apply better than Wisconsin zoogeography. The distribution maps compiled herein may be compared with those made by Jackson (1961). The difference between the patterns is mainly due to current effects of land use. That is the chief factor now encouraging some southern mammals to disperse northward, and causing some kinds to vanish altogether. Zoogeography is a study of how the history and dynamics of climate and soils, both past and present, affect the vegetation patterns, which in turn influence animal distributions. Since the history of mammal geography in Wisconsin begins in the late Pleistocene following the Wisconsin glaciation, there are no records here of the early evolution of our marsupial, shrews, rodents and so forth, which took place long ago and far away. Three dramatic phenomena subsequently have affected our mammals. First, amelioration of the frigid Wisconsin glaciation, with subsequent warming of temperature, outwash of glacial meltwater, deposition of sands and loess, soil formation southward of sandy loams and many infertile soils, and the establishment of boreal forests chiefly spruce and fir. Some boreal mammals remained in the region and

some vanished from the warming lands. Later, invasions of southern prairie and deciduous woodland floras alternated (Thomson, 1940). Frye et al. (1965) discussed glaciation in Wisconsin and Illinois. With the new vegetation came the invasion of new mammals from the south, a few from the west, and a few that moved around Lake Superior into the boreal mixed and coniferous forests. Thus, a Holocene (i.e., Recent) fauna rich in diversity was established. Quite a number of interesting mammals became extinct (Lundelius et al., 1983; Graham, 1976; Semken, 1983; see Prehistoric Mammals below). The next upheaval of the mammalian fauna came when Caucasians settled Wisconsin. Native Americans had perhaps helped to eradicate some of the Pleistocene mammals, but insofar as is known, no habitats were destroyed by them. White settlers, however, left hardly an acre of good soil unplowed, seldom a square mile of heavy timber, or rarely a large game animal or valuable furbearer remaining anywhere. Only in remote regions did these mammals linger, until people with conservation ideals influenced society. That impact was preservation of forest reserves, reforestation, even re-establishing prairies, and scientifically managing game animals. Another dramatic change in mammal geography came in the past century from land use of modern society. Cities grow enormously, roadways multiply exponentially as does the population. Urban sprawl occurs when people try to escape from the cities, and many villages become towns, towns become cities, and everywhere people cut brush, plant lawns, and remove trees. DeVos (1964) discussed some changes in the known ranges of mammals in this region. Probably a general rule around the world, eradication of the largest meat mammals took place early. Eventually some mammals were eradicated for fur, or fear of their depredations. Reintroduction follows that rule in reverse, the reintroduction favors the largest mammals (Table Zoog-1, bats excluded). However, land use ENVIRONMENTS AND ECOLOGY OF MAMMALS

47

and climatic change have recently and adversely affected mammals of all sizes. Most state collecting of Wisconsin mammal specimens prior to the 1970’s was done around the UW-Madison campus. The U.S. Biological Survey spent time and effort circling the state to pick up all possible species that peripherally entered it. Although noting some northward dispersion of mammals through the Central Sands area, my students and I (1970, 1974) collected numerous boreal mammals and some southern kinds endemic there. This gives the impression that boreal mammals unknown in the Central Sands, on Islands of Green Bay, and elsewhere were moving south. They were extensions of known range, not dispersions of actual range. For this reason, in my comparison with older zoogeography (prior to 1961, back to the turn of the 20th century) I include my records showing the occurrence of mammals (1965-1970), some of which now seem to be vanishing. Semken (1988), even without knowledge of my records in the Museum Reports and elsewhere, concluded that species richness in this region is greatest near Curtis’ tension zone. The mixture of northern and southern, i.e., boreal versus prairie and deciduous woodland species, is fantastic in west-central and central Wisconsin. Such a rich fauna should become famous and prideworthy for Wisconsin. Jones and Birney (1988) wrote a chapter on zoogeography for mammals of the Northcentral states. They mapped the range limits (boundaries of known ranges) for over 90 species in a so-called “spaghetti” map of the region. They found the aggregation of boundary lines notably intense in three areas, including one in southwest and south-central Wisconsin. They too concluded that the mammal pattern was largely congruent with vegetation patterns, and the vegetation developed on interesting soils and features of the PostWisconsin glaciation. I mapped my own “spaghetti” diagrams, one for Jackson’s (1961) maps with my early records included, especially based upon surveys

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THE WILD MAMMALS OF WISCONSIN

of central Wisconsin (Table Zoog-2). This map showed two belts of grouped lines, one along the tension zone, the other a little southwestward. The more southern belt is basically a prairie boundary, for species (e.g., Bison) that did not range as far north as the Tension Zone. In the second map, based on more recent distributions discussed in this work, some populations seem, unfortunately, to have vanished recently (Cryptotis parva, P. maniculatus gracilis in the south, also Lepus townsendii, and Spilogale putorius). The major change primarily from land use in recent years is a loss of species in the center— of boreal (Sorex palustris, Eutamia minimus, western glacial-sands dwelling Pitymys ochrogaster minor), and southern affinity (Reithrodontdomys megalotis, Pitymys pinetorum, and perhaps others). Furthermore, numerous mammals recently (in historic times) have extended their actual ranges northward (Didelphis virginiana, Sylvilagus floridanus, Spermophilus tridecemlineatus, Sciurus niger, Glaucomys volans, Peromyscus leucopus, and others) and northeastward up to



Spaghetti diagram showing range limits of Wisconsin mammals approximately 1900. The packing of species near the tension zone is extraordinary for eastern North America. See text. 

the tip of the Door Peninsula and into Upper Michigan (Didelphis virginiana, Spermophilus tridecemlineatus). Bats are not credited much as records, because of their mobility and extensive wandering, but the southern forms Perimyotis subflavus, Nycticeius humeralis, Myotis sodalis, and even Lasiurus borealis are not common in the northern counties. Tree removal in towns and along boulevards may have somewhat restricted the numbers and range of the red bat, even in the south, for Jackson (1961) reported it was the most abundant bat in [southern] Wisconsin. Jones and Birney (1988) used faunal “units” for assemblages relating regions to their mammals. A region is considered the origin for the mammal in our state if the mapped geographic range extends (peripherally) into this state from that direction. Widespread species have a more dubious origin. Ecological requirements, such as strict preference for grasslands, were used to help form these assemblages (i.e., “faunal units”). In their study of seven states ranging from the Canadian border to southern Illinois and Indiana, some of their



Spaghetti diagram for species from approximately 1960, showing range changes. 

faunal areas extend well beyond Wisconsin’s borders. Excluding the out-of-state species used in their analysis, and many wide-ranging species such as bats and mobile carnivores, I also omit wide-ranging aquatic species such as muskrats (Ondatra zibethicus) and beavers (Castor canadensis) (in its former range).



Table Zoog-1. Zoog-1 Body size and extinction or eradication of known animals. Pleistocene to Recent. Game management saved some species. Only game animals and furbearers have been reintroduced. Mammals, weights, times.  Wooly mammoth 5,000kg, Late Pleistocene Mastodon 5,000 kg, Late Pleistocene ?Ground sloth 3,000-5,000kg, Late Pleistocene Pleistocene bison 908 kg Pleistocene Plains bison 386 kg Late Pleistocene-historic American elk 363 kg Late Pleistocene,Historic Black bear 272 kg Late Pleistocene-Present Pleistocene caribou 227 kg Late Pleistocene Woodland caribou 182 kg ?Historic White-tailed deer 113 kg Late Pleist.-Present Cougar (Mountain lion) 91 kg Historic Giant beaver 91 kg Late Pleistocene Timber wolf 55 kg Historic, reintroduced American beaver Historic, vanished in south Canada lynx 20 kg Historic-Present rare Wolverine 18 kg Late Pleist. –?Historic Coyote 18 kg Historic-Present Bobcat 18 kg Historic-Present Raccoon 18 kg Historic-Present American badger 11 kg Late Pleist.-Present Fisher 6.8 kg Historic, Reintroduced Red Fox 6.8 kg Historic -Present River otter 11.3 kg Historic – Present Striped skunk 4.5 kg Historic-Present White-tailed jack rabbit 5.4 kg Historic-Present American marten 1.4 kg Historic, reintroduced Mink 1.5 kg Historic – Present Muskrat 1.5 kg Historic-Present Large weasels 100, 200 g Historic-Present Eastern chipmunk 100 g Historic-Present Meadow vole 50 g Historic-Present Vole P. pinetorum 40 g Historic-Present Vole P. ochrogaster 40 g Historic-Present Phenacomys 40 g Pleistocene Peromyscus 24 g Historic-Present Blarina shrew 18-24 g Historic-Present Water shrew 12-18 g Rare Historic-Present Harvest mouse 12-16 g Historic-Present Masked shrew 4-6 g Late Pleist.-Present Pygmy shrew 4-5 g Historic-Present rare Cryptotis shrew 5 g Historic ?eradicated ENVIRONMENTS AND ECOLOGY OF MAMMALS

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1. Widespread mammals — most of North America and having obscure direction of origin. 2. Eastern widespread — deciduous forests of the southeastern United States. 3. Eastern Austral — extreme southeastern United States. Perhaps Nycticeius humeralis. 4. Eastern New England — Northeast United States and southeastern Canada. 5. Plains/Grasslands — prairie forms from the south and west. 6. Boreo-montane — Forests of the Rockies or Canada. Widespread Mammals. In Wisconsin, the widespread mammals of obscure origin include bats Myotis lucifugus, Lasionycteris noctivagans, Eptesicus fuscus, Lasiurus borealis, and L. cinereus (which seems a southern species to me), wide ranging semiaquatics Ondatra zibethicus and Castor canadensis, deer mouse Peromyscus maniculatus (which acts as a species pair, i.e., both a boreal and a southern species in Wisconsin), porcupine Erethizon dorsatum, and carnivores Canis latrans (which seems southern in Wisconsin in relation to the wolf), C. lupus, Vulpes vulpes, Urocyon cinereoargenteus, Ursus americanus, Procyon lotor, Mustela frenata, N. vison, and Taxidea taxus (which is southern, perhaps Neo-tropical in origin except it was ages ago adapted to this frigid land even in the Pleistocene Epoch). Mephitis mephitis, Lontra canadensis (which is a northern Wisconsin species today), Felis concolor (which was eradicated), Lynx rufus (which is more southern possibly because of the boreal Canada lynx, but today has moved northward), Cervus elaphus (eradicated), and Odocoileus virginianus. There probably would be no objection to consider Peromyscus maniculatus bairdii and Lasiurus borealis as southern species, the former as a Plains/Grassland form, the latter perhaps the same (but it is highly mobile, always associated with trees, and migrates far to the southward). Eastern widespread faunal unit. Eastern species include the insectivores Crypto-

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THE WILD MAMMALS OF WISCONSIN

tis parva and Scalopus aquaticus; bats Perimyotis subflavus; Nycticeius humeralis; cottontail Sylvilagus floridanus; and rodents Tamias striatus; Marmota monax; Sciurus carolinensis (but perhaps it invaded from New England?); Sciurus niger; Glaucomys volans; Peromyscus leucopus; and Pitymys pinetorum. Some of the above species now have occupied the entire state of Wisconsin and much of the Upper Peninsula. Most of them were, because of Lake Michigan intervening, from southern invasions, and are approaching or invading the boreal forests of the North Woods. Cryptotis and both Pitymys, however, seem eradicated or at least in peril. For the most part, land use favors these eastern species. This faunal unit thrives on roadways, park lands, and forest edge in modern Wisconsin. Eastern New England faunal unit. Apparently this assemblage had origin in the vicinity of the Gaspe Peninsula, and perhaps they even came from the north. Those species occurring in Wisconsin or approaching from northeast Minnesota have circled around the north shore of Lake Superior and invaded from the west. Therefore, to say they are eastern is like saying black is white; but their origin is east. These include Blarina brevicauda; Condylura cristata; Myotis keenii; Synaptomys cooperi; and Napaeozapus insignis. With the possible exception of the shrew Blarina, all these mammals are adapted to the northern conifers and mixed forests. They resemble in habitat the Boreo-montane element. Plains/Grassland faunal unit. These include: Lepus townsendii (probably eradicated recently); Spermophilus franklinii (southern grassland); Spermophilus tridecemlineatus (southern grassland); Geomys bursarius (western); Reithrodontomys megalotis (southern or western); Pitymys ochrogaster (one race is western, the other southern); Spilogale putorius (probably eradicated,

western); Bison bison (eradicated, western) (see section on Eradicated Mammals). Jones and Birney (1988) listed Reithrodontomys megalotis from the Southwestern Faunal Element, because the harvest mouse ranges into Mexico. It is a grasslands species that invaded Wisconsin arriving from southern or western states. Not discovered in Illinois until the 1950’s, the harvest mouse has moved eastward and northward. From southern and southwest Wisconsin it dispersed into central Wisconsin. It is restricted to prairies, meadows, old fields, hayfields, and marshes. The mouse seems to have a western-southwestern affinity with Geomys, Spilogale and the western race of Pitymys pinetorum, all from the Great Plains. Boreo-montane faunal unit. Even without including the somewhat boreal Eastern New England assemblage, this boreal and montane assemblage is the majority of Wisconsin mammals: Sorex arcticus; Sorex cinereus; Sorex palustris; Sorex (Microsorex) hoyi; Lepus americanus; Eutamias minimus; Tamiasciurus hudsonicus; Glaucomys sabrinus; Clethrionomys gapperi; Microtis pennsylvanicus; Zapus hudsonius; Martes americana; Martes pennanti; Mustela erminea; Mustela nivalis; Lynx canadensis; Alces alces. The two Martes are now reintroduced. The woodland caribou Rangifer tarandus and wolverine Gulo gulo have possibly historic records in Wisconsin; they also fit in the boreal faunal assemblange. Boreal Phenacomys intermedius might range into northwest Wisconsin from adjacent Minnesota. Although Sorex cinereus is obviously of boreal origin, and restricted from some southern habitats in Wisconsin, the evidence from mitochondrial DNA (Stewart and Baker, 1997) suggests Michigan shrews, and presumably Wisconsin shrews, show intermediacy between western populations (including Sorex haydeni ) and those from eastern Canada (and New England). The masked shrew probably invaded Canada after the Wisconsinan ice receded,

from refugia in southern and eastern (what is now) United States. Paleontological evidence proves the species has been here in early Wisconsin boreal habitats. That occurrence supports Stewart and Baker’s statement, based on the DNA “clock”, that the differentiation of these Sorex populations was probably before early Wisconsin time. Origin from the Deep South. The adaptable opossum (Didelphis virginiana) arrived centuries ago from a South American origin. It has invaded the northern counties, and finally reached Lake Superior, in upper Michigan. Zoogeography of Wisconsin Islands. The zoogeography of the islands at the mouth of Green Bay was discussed by Long (1978). New species of mammals (endemic Synaptomys cooperi jesseni, introduced Urocyon cinereoargenteus, and Peromyscus leucopus) are recognized from Washington Island. Unlike the Beaver Islands, more central in Lake Michigan, this group called the Grand Traverse Isles had a few endemic kinds in the early Holocene (i.e., Recent). They arrived by Fox River rafting, swimming, and crossing of the Lake ice in winter. Bats fly freely from isle to isle. Most hibernators are absent. Some kinds were introduced by humans (Long, 1978). Long (1978) reported that: 1. Only a few species were present on most islands, except the large Washington Island. 2. Often a species was exceptionally abundant. Never were two species abundant at the same time, except very different kinds such as red-backed voles and little brown bats on Poverty Island or deer and raccoons on Chambers Island. 3. The abundant species often had a widened ecological niche. For example, red-backed voles on Big Summer Island, Michigan, tunneled extensively. 4. Some species occurrences were unexpected, probably from chance rafting. Condylura on Big Summer Island is a good example. 5. Introductions by man was often a factor (e.g, Mephitis mephitis). 6. Animals that crossed lake-ice occur on most ENVIRONMENTS AND ECOLOGY OF MAMMALS

51

if not all islands. 7. Large islands with diverse habitats have the most species present. 8. Islands in Green Bay resemble the Beaver Islands, eastward in Lake Michigan, only in the boreal mammals present. 9. Boreal mammals probably colonized these islands by crossing ice and by rafting, not by land bridges connecting isles together. However, Rock and Washington islands were once connected, and show faunal resemblance. On Washington Island are 15 species (including new P. leucopus, Urocyon cinereoargenteus, and Synaptomys cooperi), on Rock 8 species (new S. cooperi), and nearby in Michigan waters St. Martens Island (5), Poverty Island (4), Big Summer Island (8), and Little Summer Island (3). Chambers Island, in Green Bay, had six. The Garden Peninsula of Michigan had 23 species, and the north end of the Door Peninsula had 29, and they had a strong faunal resemblance. Resemblances were determined by a formula (Long, 1963) allowing comparison of large and small assemblages fairly, without so much influence from the large-value denominator due to the larger faunal assemblage. The first percentage is that of the Peninsula assemblage, the second is of the Wisconsin assemblage as listed by Jones and Birney (bats excluded). The percent resemblances are in Table Zoog-3. High values were found for Rock, Washington, and St. Martin’s islands. Big Summer and St. Martin’s islands had strong faunal resemblance. Across Green Bay, the boreal Garden and Delta peninsulas compare closely with the boreal north end of the Door Peninsula (containing Erethizon, Clethrionomys, Glaucomys sabrinus, and others). Three island species are unknown on the north end of the Door Peninsula, surprisingly, because it is so close to nearby Detroit, Washington, and Chambers islands. These are Condylura cristata, Synaptomys cooperi

jesseni, and Peromyscus maniculatus maniculatus (= gracilis). The forest deer mouse, driven off the Door Peninsula by P. leucopus (Long, 1996), persists on most of the isles (Long, 1974a; 1978 c; 1978a; 1990; 1996; Long and Long, 1993). Condylura cristata probably arrived at nearby Big Summer Island from Upper Michigan. Numerous mammals swim or cross the ice to these isles from the north shores of Green Bay, mostly Upper Michigan (Ursus, Lynx rufus, Urocyon, Vulpes, Canis latrans, Lepus americanus, and others). The bog lemming, Synapatomys cooperi, probably was endemic for thousands of years because it shows some speciation. The greatest faunal resemblance to the Peninsula fauna, using the simple ratio of number in common to total compared, is that of Washington Island (50 percent) and the least is that of tiny Poverty Isle (only 4 percent). Again we find that Rock shows a high affinity to Washington Island. All its kinds occur also on Washington Island. Comparing the fauna of the island group to that of the Faunal Units of Jones and Birney’s definition, all bats excluded, the results are given below. Boreo-montane 18%/ 36%; New England 7*/75*; Eastern 6**/22***; Plains/ grasslands 0/0;Wide-ranging 25/30. These percentage values are influenced by low numbers of Southeast, Grasslands and Neo-tropical units. The denominator is small, so the percentage is high. The north end of Door, decidedly less prairie-like than at the base of the Peninsula, has these affinities with Wisconsin units (bats excluded): Eastern 21% ; Eastern New England 25 % (only a single kind, Blarina); Plains/grasslands 4 %; Boreo-montane 25% . Much like mammals, not mobile and inactive in winter, the “herps” (reptiles and am-

* The bat Myotis keenii would swell this resemblance if bats were included. ** 7 percent if the recent white-footed mouse was counted. *** Includes the gray squirrel, which seems to me a New England kind.

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THE WILD MAMMALS OF WISCONSIN

phibians) of this region faced similar difficulties in colonizing islands. Long and Long (1976) and Long (1994) studied the zoogeography of herps of the islands in Lake Michigan, finding little affinity with western Wisconsin herps, quite a strong resemblance to those from the south, and some to those from the east. The fauna of the land of Door, both peninsula and isles, is a mixture of boreo-montane and deciduous woodland mammals or herps. Surveys in the Apostle Islands have proved less interesting. Little speciation is apparent and the small mammals and most bats are boreal. The red bat may not be long established. Only a few species of mammals are present. Zoogeography Of The Central Sands. Comparing the rich tension zone fauna of the Central Sands area, within the square area of Marathon, Wood and Portage counties, with the list in table Zoog-2, the faunal resemblance (bats excluded and extirpations not considered) is 91 percent (N 33). That is extremely high, a rich mixture of all kinds of mammals, as mentioned above. Central Wisconsin mammals of aforementioned Faunal Units [percent of central species/percent of faunal unit] are: Neotropical 1, 3%/50%; Plains/grasslands 4, 12/66; Eastern widespread 9, 27/90; Eastern New England 4, 12/100; Boreo-montane 17 50/100. This species-rich savanna area with boreal forest northward and hickory-maple, oakjack pine, wet and dry grasslands, and other habitats, has a fauna involved with all the aforementioned units. It is primarily eastern (deciduous woodlands) and boreo-montane. Some grasslands forms are present, and the opossum from the southern United States is now well established. Future Changes And Grounds For Optimism. The future biogeography of Wisconsin will probably show a proportion of the mammal fauna invading farther north, some reintroduced carnivores (and also the moose) dispersing farther south, and other mammals driven northwards by the advancing southern mammals. Some boreo-montane mam-

mals receding northwards will vanish in numerous counties within their former range. The forests in the north are now favorable to these species. The interesting and diminutive glacialsands race of the prairie vole, Pitymys ochrogaster minor, has been greatly decimated. Its status is confused, probably extant, but the whereabouts at present are unknown. A few other species have vanished or become rare. Most of the Eastern Widespread species are doing well and will likely continue to do so. The introduced mammals may continue to flourish, except Lepus townsendii. Mar-



Table Zoog-2. Some species used for spaghetti diagrams and faunal estimates. Wide-ranging species excluded. Origin (N, S, W) and species. 

Opossum N Star-nosed mole N or NE Prairie mole S, SE Arctic shrew N Water shrew N local, rare Pygmy shrew N Uncommon Least shrew S, SE extirpated White-tailed jack rabbit W eradicated Snowshoe hare N 13-lined ground squirrel S Franklin’s ground squirrel S, scarce Least chipmunk N Red squirrel N Fox squirrel S Southrn flying squirrel S, SE Northern flying squirrel N Plains pocket gopher W Harvest mouse W, SW uncommon Prairie deer mouse S Forest deer mouse N, NE White-f ooted mouse S, SE Pine vole S, W also. Rare Prairie vole S, W also. One race rare. Red-backed vole N Woodland Jumping mouse NE Porcupine ?N Ermine N Least weasel N Scarce Spotted skunk W River otter N Canada lynx rare NW Bobcat S Moose N, NW ENVIRONMENTS AND ECOLOGY OF MAMMALS

53

tes foina may expand its range and numbers. There need be no protection provided for Mus, Rattus, or feral cats, all of which should be humanely disposed. Along the southern border of Wisconsin, we may expect rare bats to retreat southward, even if the temperature continues warming. They are incompatible with intense urbanization and sprawl. Some western species may extend their ranges eastward across Wisconsin, crossing and working northeast along the rivers, if they can cope with land use. One or two of the “New England” kinds may enter Wisconsin in the northwest, from Minnesota. In the forested north most kinds should sur-

 54

vive. In Door County, southern invaders will move up the peninsula, and some may cross to nearby isles. Some species there may not survive (Erethizon dorsatum, Glaucomys sabrinus, several carnivores) because of land use and growing population there. The rich species diversity in central Wisconsin may lose some species. Who cares what happens in the center? With future efforts of our modern Wisconsin natural resources agency, I expect that few species will disappear from Wisconsin. Probably some eradicated mammals may be transplanted and reintroduced. There are so many lovers of nature in this wonderful state that one can guarantee a happy future.

Wooly Mammoth. Woodcut G. Cuvier. Regne animale.  THE WILD MAMMALS OF WISCONSIN

PREHISTORIC MAMMALS All of the prehistoric mammal kinds of what is now called Wisconsin invaded from outside this region. Their Wisconsin history does not extend far back in geological time, their fossils are unknown in our long-buried sedimentary rocks. In many places the heavy glacial ice of ages past scoured away these rocks, and the resulting outwash sands buried other rocky strata. The early history of Wisconsin mammals must be traced back through time in far away places. The Pleistocene glaciations, mentioned earlier in the Environment section, were, in chronological order, the Nebraskan, Kansan, Illinoian, and finally, and least extensive of the four, the Wisconsinan. Many Kansan and Nebraskan deposits are confused and often identified as “Pre-Illinoian.” The last stage, the Wisconsinan glaciation, probably ameliorated (melted, retreated) in southern Wisconsin some 15,000 years ago, and the complete withdrawal of ice from northern Wisconsin and the Great Lakes occurred about 10,000 years ago. This marked the end of the Pleistocene, and commenced what is called Recent time (also called the Holocene Epoch). There were several advances of Wisconsin ice. Pollen analysis and carbon dating have helped us understand Holocene events by the occurrence of certain trees and grasses. Near Green Bay (Two Rivers, Peter’s Quarry, Duck Creek) and westward near Iola (the Iola Bog) bogs provide a record of former plants and pollen. It shows that black spruce, tamarack, and some grasses (Cyperaceae) were replaced 11,640-11,850 years BP [BP= before the present], after the Cary ice advance and during the warmer Two Rivers Interval by a shift to more composites and dry prairie grasses. After the last advance of ice, called the Valders Re-advance, the great invasion of the region by white pine and oak (Schweger, 1969) commenced. Boreal forests and probably boreal mammals gave way to, or were mixed with, the arrivals of southern mammals associated

with the pine and oak forests, especially throughout the southern half of present Wisconsin. Open country became prairie lands and wet marshes. Forests on Valders moraines joined those of Cary moraines. The Door Peninsula and the surrounding waters were uncovered of ice. Evidently early humans arrived about this time. Since then the climate has fluctuated, becoming even warmer than we enjoy at present. Giant beavers (Castoroides), which did not build dams or lodges, lived in glacial meltwater lakes (Dallman, 1969). Two huge members of the elephant family, the plant-foraging mastodon (Mammut) and the woolly mammoth (Elephas), ranged through the woodlands and dense spruce forests near the ice fronts. The mammoth probably ate grasses, leaves, and twigs. Giant flat-headed peccaries (Platygonus ), huge bison (Bison occidentalis), a large boreal caribou (Rangifer tarandus), and even musk oxen (both Symbos and Ovibos) inhabited the boreal woodlands near the retreating ice fronts. The lemming Dicrostonyx, a small rodent, lived in this region, and was preserved at many Pleistocene sites outside Wisconsin. Now it is confined to the Arctic. One huge mammal not yet found or reported in Wisconsin is the giant ground sloth (Megalonyx). The elk-like long-legged moose (Cervalces scottii ) was recently found in Marathon County, buried where the Wisconsin ice front had melted away (Long and Yahnke, in press). Several species of whales and the walrus swam in Lake Michigan (Handley, 1953) and probably visited the western shore. [I examined a Pleistocene whale vertebra from a Wisconsin gravel pit, but the antiques dealer who owned it refused to divulge the locality of this “valuable dinosaur find.”] Both warming climate and activities of early human cultures seemed adverse to the large (and probably shaggy) ice age mammals, for many became extinct. They left only teeth and bones buried in bogs, swamps, and flood plain soils to document their presence. Many PREHISTORIC MAMMALS

55

medium-sized and small species persisted, some retreating northward following the retreating cool conditions. Others from the southern hardwood forests (deciduous forest species) and steppe species (Hoffmann and Jones, 1970) from the vast interior grasslands (or Great Plains) invaded the “uncovered” and open habitats. Some deciduous trees and mammals may have overextended northward in the warmest seasons, as oaks, hickories and other southern plants established themselves into northern Wisconsin, some mammal populations persist today as relicts. Most boreal species in Wisconsin today inhabit northern spruce, pine, maple, and eastern beech-maple forests. There is a rich “amalgam” of these and warmth-adapted species especially in southwest and central Wisconsin. Along Wisconsinan ice fronts the Holocene and late Pleistocene fossil sites reveal diversity (Semken 1988; Thompson, 1940; Foley, 1984; Thieling, 1973; Rasmussen, 1971). Whether microhabitats were diverse, free intermingling of the post-Pleistocene mammals, or climatic fluctuation caused this species stacking is uncertain. Some small fossil assemblages were concentrated together (by means unknown, probably by snakes, in some cases by owls, possibly by ants) in rock fissures, sinks, and caves. Fragmentary parts of the skull and teeth are most abundant at such sites. Cave deposits on the Door Peninsula carbon-dated at one level at 600 BP, according to Robert Howe (personal comm.), contained numerous remains of some modern-day mammals, probably even Pitymys pinetorum. Mastodons excavated by Dallman (1968) near Deerfield, Wisconsin, in Dane County, were aged as 9,480 BP, and 10,095 (or a little older). Dallman aged a woolly mammoth, roughly contemporary in time and place with the mastodons, as 9,065 BP. This elephant was found at Lake Mills, in Jefferson County. Other large mammals (Bison occidentalis, Castoroides ohioensis, and Rangifer tarandus) are likely as old.

56

THE WILD MAMMALS OF WISCONSIN

The Moscow Fissure in the “Driftless Area” yielded fossils carbon-dated at roughly 17,000 BP, at the peak of Wisconsinan glaciation (Rassmussen, . The hilly area was practically encircled by massive ice fronts, both westward and eastward. Many boreal and Arctic species and genera were present, including Dicrostonyx, Synaptomys, and Phenacomys, including some species known today far to the westward (Table Pre-1). There are no records of Deciduous-Woodland species. The number of species of shrews and voles is high, suggesting boreal climate (Graham 1976). The Moscow Fissure fauna showed greatest affinity with mammal communities of present-day, southeast Manitoba and southwest Ontario (and perhaps northern Minnesota). From one site in western Wisconsin, now destroyed to make a park, Palmer (1954) discussed 300 Bison occidentalis that were associated with Native American remains. He (1974) also found the giant peccary Platygonus. The fauna of Lost River Sink (Table Pre-2) seems similar to the same fauna found there today. At Lost River Sink, at level 3, the age is 2,720 BP, and at level 4, it is 3,970 BP. The



Table Prehist.-1 Prehist.-1. Recent and former species’ facies from the Moscow Fissure, Wisconsin. This area not covered with glacial ice. However, the fauna changed drastically. All the older species either retreated out of Wisconsin, or live mostly in northern counties. Sorex hoyi ranges south.  17,000 BP

Recent species

Sorex arcticus Sorex palustris Sorex hoyi Thomomys talpoides* Clethrionomys gapperi Synaptomys borealis* Phenacomys intermedius Microtus xanthognathus* Dicrostonyx torquatus* Zapus princeps*

Didelphis virginiana Cryptotis parva Scalopus aquaticus Tamias striatus Glaucomys volans Geomys bursarius Reithrodontomys megalotis Peromyscus leucopus Pitymys pinetorum Zapus hudsonius

*No longer in Wisconsin



Table Prehist-2 Prehist-2. The Lost River (L) , Moscow Fissure (M), and other sites are represented by numerous species. The older species from M are shown here. L seems recent. 

small mammal fauna, then, has been fairly stable for nearly 4,000 years in southern Wisconsin. The modern species are, of course, described in their species accounts beyond. Elk antlers from Portage County were buried after being shed along streams, and may not be of great age. A huge subfossil specimen from NE Columbia County is in the UW Wildlife Ecology collection. I saw a bison tooth from a field near the Wolf River east of Stevens Point, but there is no certain evidence of a natural burial. Archeological digs often yield some fossil remains, and many fossils are discovered by accident (in excavations). Attention to cave deposits and fissures provides many Recent fossils and subfossils. The small mammals are often obtained by washing and screening techniques. The huge bones of the large species are often found buried in lake beds, bogs, and

Sorex arcticus M, S. palustris M, S. hoyi M, S. cinereus M, L, Myotis sp. L, Perimyotis L, Lepus americanus ?M, Thomomys talpoides M, Sciurus sp., L, Tamias striatus L, Spermophilus tridecemlineatus L, Tamiasciurus hudsonicus M, Peromyscus maniculatus L, Synaptomys cooperi L, Clethrionomys gapperi M, Pitymy pinetorum L, P. ochrogaster (large race) L, Phenacomys intermedius M, P. ungava (M?), Castor canadensis, Castoroides ohioensis, Mammut americanun, Elephas primigenius, Tayassu, Platygonus compresses, Cervus elaphus, Rangifer tarandus, Bison occidentalis (= latifrons), B. bison, Ovibos, Symbos cavifrons, Ursus americanus L, Procyon lotor L, Mephitis mephitis L, Vulpes vulpes L, Canis cf. lupus, Gulo gulo, Jackson 1961.



Pleistocene Bison latifrons. After Hamilton, 1939.  PREHISTORIC MAMMALS

57



Bison bison. William T. Hornaday. His writings probably saved this species. It is now domesticated in Wisconsin. 

flood plain sediments where the smaller forms are not preserved. When a fossil site is dis-



covered it should be immediately reported to professional geologists, and if possible left undisturbed. Fossils collected without accompanying data are worthless. Usually a plan can be worked out to accommodate all interested parties at a fossil site.

Pleistocene and post-Pleistocene records of large Ice Age mammals showing Mammut mastodon; Elephas mammoth; Bison; and Rangifer caribou. The Wisconsin drift and lobes are also shown. The Bevent site contained two caribou and the only Cervalces scotti elk-moose (above) known in Wisconsin. The fossil elephant sites lie south of the Laurentide Wisconsin ice sheet, or near it as it receded. The large caribou are from the glaciated southeast or central part of what is Wisconsin, found in wetlands near moraines. Bison, as in pioneer times, ranged along the west border of Wisconsin as this region was to become prairie and woodland. West and Dallman, 1980, Long, 1986, West, 1978. Map and photo by C. Yahnke.

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THE WILD MAMMALS OF WISCONSIN

REINTRODUCED AND EXTIRPATED MAMMALS OF WISCONSIN WITH HYPOTHETICAL LIST OF SPECIES POSSIBLY IN WISCONSIN How does one know whether secretive species are unknown or eradicated? Some species are very difficult to detect. This listing supplements the list of earlier Pleistocene and early Post-Pleistocene mammals eradicated by warming climate, human activities, and unknown causes. Eradication of mammals from Pleistocene and Holocene Wisconsin generally was related directly to the mammal’s body mass (probably important both for cold weather subsistence and for the Native Americans for food—Table Zoog-1), climatic warming (which affected Ice-Age mammals regardless of their mass), fur use, intolerance to predators by farmers and hunters, and land use (i.e., habitat alteration, which is affecting the holdovers from earlier eradications). Natural and scientifically managed reintroduction generally follow the same rules (without any reintroductions of Arctic species, of course), generally in the same sequence, but eradication of the small mammals may be far from ending. Their geographic ranges are constantly changing, favoring in some cases the species scientifically managed, with some others indirectly benefiting from the management, many southern invading species, such as Glaucomys volans, and some that adapt well to modern land use (e.g., Didelphis, Eptesicus, Sylvilagus, Spermophilus, Sciurus niger).



Felis concolor. Woodcut. Joseph B. Holder. The Mus. Nat. Hist., by Sir John Richardson et al. 1877. 

The reintroduction of small mammals has not yet begun (Long, 2001). Some mammals introduced or reintroduced in Wisconsin are surviving, and even thriving. They are mentioned here and treated in detail in the species accounts below. Some eradicated native kinds reintroduced are sometimes of a different geographic race (e.g, Cervus elaphus nelsoni). If eradicated before historic time, the species are discussed in Prehistoric Mammals. If eradicated in historic times, up to approximately 1900, they are included immediately below. Cryptotis parva. Least shrew. This shrew may have vanished about 1940. See account of the least shrew. Lepus townsendii. White-tailed jack rabbit. Possibly native in southwest and northwest Wisconsin, introduced in many places in the state, and possibly eradicated about 1970. See account of this species. Rattus norvegicus. Norway rat. An introduced and established pest. See account of this species. Mus musculus. House mouse. An introduced and established pest. See account of this species. Martes americana. Pine (or American) Marten. See account of this reintroduced species. Martes pennanti. Fisher. See account of this reintroduced species. Gulo gulo. Wolverine. Possibly eradicated. Jackson (1961) reviewed the history of this problematic, large mustelid, under the name Gulo luscus luscus, the only specimens of which are sub-fossils from cave deposits. There are dubious reports in early newspapers. See Prehistoric Mammals. Felis concolor (= Puma concolor) probably the race coryi. Mountain lion or cougar. The native lion Felis concolor schorgeri was eradicated in the last century. Unauthorized releases of cougars, likely the Florida cougar, have occurred. Department of Natural Resources biologist Adrian Wydeven records all reports annually, so far dubious, invalid, and possibly valid. Jackson (1961) reviewed early

REINTRODUCED AND EXTIRPATED MAMMALS OF WISCONSIN

59

records. One record I investigated that may have led to several of the reports in the Richland Center and Blue River areas probably was a release of one or both of a pair brought from Florida and fed on road-killed deer. The owners left the state separately, and the cougars did not leave with them. Observations were frequent in the region; these were among the first reports of cougars thought to have returned to Wisconsin. Cervus elaphus nelsoni. A reintroduced species, in spring, 1995, into the Clam Lake Area, were 25 individuals, some that died, but some are producing calves under strict protection. This race might replace in remote areas our extirpated Cervus elaphus canadensis. The Yellowstone-Jackson Hole herd that provided so many reintroductions of elk in America (see Long, 1965) provided at least one in Wisconsin (at Trout Lake in 1913 and 1917). These elk were reportedly in poor condition, but the photos in Jackson (1961) are of healthy Montana stock. These introduced elk did not range out of Vilas and Oneida counties, and did not survive later than 1950. The Jerome Hunting and Fishing Club at Mercer, in Iron County, near Trade Lake, used elk from Montana, and failed to establish elk. In 1995, the governor T. Thompson and others persuaded the Department of Natural Resources to make another attempt. Cervus elaphus canadensis. American Elk, Wapiti. Jackson (1961) reviewed the historical records, and there are numerous antlers from prehistoric Wisconsin (see that Section). He believed this race of elk was eradicated by 1875. It formerly was wide-spread. Alces alces. Moose. American Moose. The moose was probably eradicated at the turn of the century, with the last record near the Minnesota border in 1921 (see Jackson, 1961). Some small groups may have survived in remote northern marshes. Today there are breeding records nearly every year for moose that apparently reintroduced themselves in northern Wisconsin. See account of that species.

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THE WILD MAMMALS OF WISCONSIN

Rangifer tarandus sylvestris (Richardson, 1829). Caribou. There are no records of this species, which may have been present and eradicated about 1910 (Jackson, 1961). The species seems to have persisted in northern Minnesota. A possibly valid record for Wisconsin is given by Schoolcraft (1831). There are some records of a larger bodied strain of caribou, from Prehistoric Wisconsin (see that Section). Bison bison bison. North American Bison or American Buffalo. Eradicated. Bison ranged into southwest and southern Wisconsin on the prairies and savannas. Their status was reviewed by Jackson (1961), who reported that the last of them was killed by “Sioux Indians” in 1832. In the display at Kettle Moraine State Forest there is a buffalo robe donated by James Brom (“from Lower Hebron Road”, ostensibly shot by John Mall’s grandfather in the early 1840’s. It was shot on Mall’s farm near Rome Pond [Jefferson Co.]. If this record is valid (which seems likely) then the buffalo survived in some small numbers nearly ten years longer than Jackson thought, and this robe, preserved (“rolled up”) in Mall’s barn, is the only known bison specimen from Wisconsin from the pioneer stock. Bison have been reintroduced into several protected areas, such as the Sand Hills Demonstration Area near Babcock, and to numerous game farms. Today there is a growing number of people undertaking to raise bison as domestic beef animals. This is a great example of what can happen to an animal once nearly extinct, but through extensive efforts of William T. Hornaday and his supporters was saved from extinction (see Long, 1965). Now it is useful to humankind again. Hybrids called “cattalo” may be obtained by crossing Bison and domestic cattle. Some mammalogists refer Bison to the genus Bos. I note the hybridization is not successful in some crosses and the hybrid is obviously less viable than the bison. Therefore, I am not persuaded to consider the bison in Europe and North America, with their many fossil species, as conspecific with domestic cattle.

Felis catus. The house cat is not treated in this book as a wild species. It is more domestic than, say the house mouse (Mus musculus), although feral cats are important and in many situations (especially in the southern counties) as self-sufficient as the mice. If humans would cease partially feeding and renewing the numbers of feral cats (by releases and keeping too many), probably the feral cats would soon disappear. House mice require no care from humans except in laboratories. John Coleman (1995) and Coleman and Temple (1993) found that farm-dwelling house cats (Felis catus), more or less feral and especially in southeast Wisconsin, make a huge impact in ecosystems by predation on songbirds, and even more on small wild mammals. The feral and domestic cats together may be the major predator in the state, especially in the agricultural and urban habitats. Coleman estimated that over 14,000,000 Wisconsin songbirds were killed annually by free-ranging cats, and double that number must be added to the predation by city and rural pets. The incredible total should make every cat loving naturalist pause for thought, 14 million song birds in only one state. Many more small mammals than that are killed, although these may be less beneficial. The average number of farm cats was between 8-9 cats, and at non-farm rural homes about 4 to 5 cats. The presence of up to 35 cats at a single farmstead was not uncommon. Farmers seemed overwhelmed by their own cats, hoping someone would help with their disposal. Farmers limit the numbers of cats by how much they feed them, but usually provide only sufficient food for approximately five. Ten cats survive on the rations for five. Each hungry cat may kill as many as 100-600 birds locally per year, as well as many small mammals. Although unwanted cats on farms may be shot, few (only 13 percent) are neutered. Compared to a density of about 34 raccoons, five skunks, and 18 opossums per square mile, the density of cats, at 104 per square mile, seems incredible. Cars and diseases kill many

cats, which show rapid turnover, especially of males. Some diseases are transmitted to humankind by cats, and Toxoplasma is a real threat to the offspring of pregnant humans. Exotics. Some exotics and interesting records that I have learned about in Wisconsin include a prairie dog living at least 8 years



American elk (= Wapiti). Tho(?) Lundeen,1835, Cuvier’s Animal Kingdom, 1863. 



Sika deer Japanese exotic. Flower and Lydekker, 1891. By Lord Powerscourt. 

REINTRODUCED AND EXTIRPATED MAMMALS OF WISCONSIN

61

in southwest Wisconsin (brought to my attention by Scott R. Craven), and one nutria near Stevens Point (1963) (see Long, 1970). Sika deer (Cervus nippon) escaped or were released from a game farm in southeast Wisconsin, and, reportedly, Fallow deer were released as well, where hunters have reported seeing adult deer with spots. Sika deer are smaller than either Fallow or white-tailed deer, and have slender antlers in the males. In addition to white spotting, there is a dark mane in winter and a conspicuous white rump patch. The fallow Deer (Dama dama) is probably eradicated. It can be identified by larger body size and flattened palmate antlers (in males only) having numerous points. Wydeven and Wiedenhoef (2002) record the odyssey of a wolverine that escaped from a game farm in Marquette County, apparently was observed several times in the wild, and likely was the wolverine killed on the road in Rock County in December 2001.

HYPOTHETICAL LIST OF MAMMALS POSSIBLY OCCURRING IN OR INVADING WISCONSIN Some mammals that may in the future be found in Wisconsin may have been here all the time, undetected, or they may invade the state if habitats become favorable for range dispersion. Most of the mammals listed here are nearby or mobile enough to invade Wisconsin. Sorex fumeus fumeus Miller, 1895. A dubious record is the U. S. National Museum specimen from southeastern Wisconsin, sent from Racine by Dr. P. R. Hoy, in 1853. There are no other Wisconsin records, nor do the habitats at Racine seem appropriate. The known geographic range of the species was hundreds of miles away (Kentucky and northern Ohio). Probably the Wisconsin locality was that of Hoy, not of his specimen. A mistaken Racine locality was likely also for Microtus xanthognathus (see below) and Sorex (Mi-

62

THE WILD MAMMALS OF WISCONSIN

crosorex) hoyi (holotype, see Long, 1972a). However, the species S. fumeus reportedly (but never verified) recently invaded northeast Minnesota, near the northwest Wisconsin border, circling around the north shore of Lake Superior. I have not seen the specimens (see Jannett and Oehlenschlager, 1994). The species is clearly recognizable by flattened skull, dark venter, and size intermediate between the masked and arctic shrews, which have high arched crania and mistakenly have been said to resemble fumeus closely. The tail exceeds 38 mm in length. Perognathus flavescens Plains Pocket Mouse. This heteromyid, having external cheek pouches and elongate hind limbs, has four upper cheek teeth on each side, the dorsum is cinnamon buff, the venter creamy white, and the upper incisors are grooved. It inhabits dry sandy prairies across the Mississippi River in Minnesota, but is rare there. Microtus chrotorrhinus Rock Vole. Known from one record in northeast Minnesota. The vole is boreal and might have lingered in Wisconsin in some boreal, rocky habitat. It has an orange patch on the nose, and tends to yellowish brown dorsally, whereas the venter is white. Microtus xanthognathus. Yellow-cheeked Vole. Recorded under the name Arvicola xanthognathus, yellow-cheeked vole, by Lapham (1853: 340). The locality Racine would indicate the record was based on Hoy’s notes. The species is unknown from Wisconsin. Phenacomys intermedius. The Heather Vole may occur in northwest Wisconsin on sandy grassland or dunes. It occurs in northeast Minnesota, and I have collected it in Ontario a short distance north of Lake Superior. The cheek teeth are dark blackish, and especially in the lower jaw show deep re-entrant angles that almost cut through the teeth. The nose and rump are tan, and the venter is white. Rattus rattus. Roof Rat or Climbing Rat. This long and scaly tailed rat, also called the black rat, regardless of its color, will likely be

found in Milwaukee, Green Bay, or at some port city on Lake Michigan, establishing itself briefly as an introduced rat. It was once taken in Chicago. The tail is longer than half the total length, but see account of one long-tailed rat under Rattus norvegicus. Antilocapra americana. Pronghorn. By the name Antilope americana, included with the Wisconsin mammals by Lapham (1852: 44; 1853: 340), who cites only “N. W. Territory, (Mr. Say)”. Hoy (1882: 255) concurred, believing the pronghorn ranged as far east as Lake Michigan”. There is no evidence the pronghorn ever occurred in Wisconsin, although ranging into Iowa.

VISITANT BATS Transported by winds, and often flying in long dispersals of young-of-the-year, various bats often are found far from their normal breeding ranges. Those taken near Wisconsin include the Mexican free-tailed bat, Tadarida brasiliensis, which has the tail extending well beyond the uropatagium; the small-footed Myotis, Myotis leibii, which is yellowish, has a dark mask on its face, and the calcar is keeled; the gray bat Myotis grisescens, which has gray color all the way from the tips of the hair to the bases, and the wing membrane attaches to the ankle above the foot.

REINTRODUCED AND EXTIRPATED MAMMALS OF WISCONSIN

63

CHECK-LIST OF WISCONSIN’S WILD MAMMALS

Sylvilagus floridanus Eastern Cottontail ..................................... 150

With the names of orders and families

Order Rodentia Sciuridae Marmota monax Woodchuck or Groundhog ................................... 158 Spermophilus tridecemlineatus Thirteen-lined Ground Squirrel ...... 164 Spermophilus franklinii Franklin’s Ground Squirrel ........................... 171 Eutamias minimus Least Chipmunk ..... 175 Tamias striatus Eastern Chipmunk ...... 180 Tamiasciurus hudsonicus Red Squirrel ........................................ 187 Sciurus carolinensis Gray Squirrel ...... 193 Sciurus niger Fox Squirrel ................... 203 Glaucomys sabrinus Northern Flying Squirrel .............................. 210 Glaucomys volans Southern Flying Squirrel .............................. 214

Order Marsupialia Didelphidae Didelphis virginiana Virginia Opossum .... 69 Order Insectivora Talpidae Condylura cristata Star-nosed Mole ...... 76 Scalopus aquaticus Eastern or Prairie Mole ................................... 81 Soricidae Sorex cinereus Masked or Cinereous Shrew ............................................ 86 Sorex arcticus Arctic Shrew .................. 89 Sorex palustris Water Shrew ................ 93 Sorex (Microsorex) hoyi Pygmy Shrew ............................................ 97 Blarina brevicauda Northern Short-tailed Shrew ........................ 101 Cryptotis parva (eradicated?) Least Shrew .......................................... 106 Order Chiroptera Vespertilionidae Myotis keenii (= Myotis septentrionalis) Keen’s Myotis or Keen’s Bat ......... 114 Myotis lucifugus Little Brown Bat ....... 117 Myotis sodalis Indiana or Social Bat .... 121 Lasionycteris noctivagans Silver-haired Bat ........................... 124 Perimyotis subflavus Georgian Pipistrelle ..................................... 127 Nycticeius humeralis Evening Bat ....... 130 Eptesicus fuscus Big Brown Bat .......... 131 Lasiurus borealis Eastern Red Bat ....... 135 Lasiurus cinereus Hoary Bat ............... 138 Order Lagomorpha Leporidae Lepus townsendii (eradicated?) White-tailed Jack Rabbit ............... 144 Lepus americanus Snowshoe Hare ..... 146

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THE WILD MAMMALS OF WISCONSIN

Castoridae Castor canadensis American Beaver ... 220 Geomyidae Geomys bursarius Plains Pocket Gopher ........................................ 229 Muridae Reithrodontomys megalotis Western Harvest Mouse ............................. 236 Peromyscus leucopus White-footed Mouse ..................... 241 Peromyscus maniculatus (maniculatus and bairdii) Forest and Prairie Deer Mice ................ 252, 257 Clethrionomys gapperi Red-backed Vole ............................................ 262 Pitymys ochrogaster (= Microtus ochrogaster) Prairie Vole .............. 267 Pitymys pinetorum (= Microtus pinetorum) Pine Vole ................... 274 Microtus pennsylvanicus Meadow Vole ............................... 280 Synaptomys cooperi Southern Bog Lemming ..................................... 286

Ondatra zibethicus Muskrat ................ 292 Rattus norvegicus (introduced) Norway Rat .................................. 299 Mus musculus (introduced) House Mouse ......................................... 301 Zapodidae Zapus hudsonius Meadow Jumping Mouse ......................................... 305 Napaeozapus insignis Woodland Jumping Mouse ............................ 311 Erethizontidae Erethizon dorsatum North American Porcupine .................................... 316 Order Carnivora Canidae Canis latrans Coyote .......................... 323 Canis lupus (reintroduced, from Minnesota?) Timber Wolf or Gray Wolf .... 330 Vulpes vulpes Red Fox ....................... 339 Urocyon cinereoargenteus Gray Fox .... 345 Ursidae Ursus americanus Black Bear ............. 351 Procyonidae Procyon lotor Raccoon ....................... 359 Mustelidae Martes pennanti (reintroduced) Fisher .......................................... 369 Martes americana (reintroduced) Pine Marten or American Marten ......... 375 Martes foina (introduced) Stone Marten ......................................... 378 Mustela nivalis Least Weasel .............. 382 Mustela erminea Ermine ..................... 387 Mustela frenata Long-tailed Weasel .... 392 Neovison vison Mink .......................... 398 Gulo gulo (Prehistoric or eradicated) Wolverine*

*

Mephitis mephitis Striped Skunk ........ 404 Spilogale putorius (eradicated?) Eastern Spotted Skunk ................. 410 Lontra canadensis (= Lutra canadensis) River Otter ................................... 414 Taxidea taxus North American Badger ......................................... 421 Felidae Felis concolor (= Panthera concolor or Puma cougar) (eradicated) Mountain Lion or Cougar Lynx canadensis (nearly eradicated) Canada Lynx ................................ 428 Lynx rufus Bobcat .............................. 433 Order Artiodactyla Cervidae Cervus elaphus (eradicated, now partially domesticated) Elk or Wapiti Odocoileus virginianus White-tailed Deer ............................................ 440 Alces alces (eradicated?, re-colonized from Minnesota) Moose ........................ 450 Rangifer tarandus (eradicated) Caribou Bovidae Bison bison (eradicated, now partially domesticated) Bison or American Buffalo

A “Trivia” question: What Wisconsin mammals are known by fewer than five reports or specimens today? Least Shrew, Indiana Bat, Evening Bat, White-tailed Jack Rabbit, Franklin’s Ground Squirrel, Stone Marten, Spotted Skunk, Canada Lynx, and several kinds eradicated long ago.

Gulo gulo. Jackson (1961) recognized the wolverine Gulo luscus (= Gulo gulo) as a Recent mammal; it is no longer in the state and perhaps eradicated. Possibly this mammal was prehistoric. CHECK-LIST OF WISCONSIN’S WILD MAMMALS

65

KEY TO ORDERS AND FAMILIES OF WISCONSIN MAMMALS 1

Incisor teeth 1-5/1-4 (= 5/4) on each side; marsupium present in females, epipubic bones present, hallux opposable to hind toes ............ Order Marsupialia: Didelphidae Opossum 1' Incisor teeth not 5/4, marsupium and epipubic bones lacking, hallux never opposable to toes ................................. 2 2 Flight membrane comprised of finger webbing, fingers elongated but claws lost from disuse excepting that of thumb .... .............................. Order Chiroptera: Vespertilionidae Bats 2' Flight membrane lacking except lateral membrane between wrist and pes present in Glaucomys, claws or hooves present on digits ........................................... 3 3 Upper incisors absent, digits provided with hooves .......... Order Artiodactyla: Cervidae Deer 3' Upper incisors present, digits having claws ............................................... 4 4. Diastema present behind gnawing incisors ................................................. 5 4' Diastema lacking in tooth row ........... 6 5 Incisors 1-2/ 1 (=2/1) but the second is a minute peg, hind limbs elongated for saltatorial locomotion, pinnae of ears elongated ............. Order Lagomorpha: Leporidae Hares and rabbits 5' Incisors 1/1, hind limbs and ears usually short .......................... Order Rodentia: Sciuridae, Geomyidae, Castoridae, Muridae, Zapodidae (this group has long hind legs but short ears), and Erethizontidae 5A External cheek pouches present, front feet larger than hind feet .................... ................. Pocket gopher Geomyidae 5A' External cheek pouches lacking, front feet smaller than hind feet ............. 5B 5B Infraorbital canal wider than foramen magnum, quills prominent on dorsum and tail ........ Porcupine Erethizontidae

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THE WILD MAMMALS OF WISCONSIN

5B' Infraorbital canal narrower than foramen magnum, quills lacking .................. 5C 5C Tail flattened dorsoventrally, hind feet webbed, cheek teeth each having 10-12 transverse ridges ..... Beaver Castoridae 5C' Tail not flattened dorsoventrally, hind feet not webbed, teeth lacking 10-12 transverse ridges ................................... 5D 5D Upper cheek teeth number more than three, or in Napaeozapus an elongate tail is tipped with white ................... 5E 5D' Upper cheek teeth number three, tail not tipped with white ................................ ....................... Rats and mice Muridae 5E Postorbital processes absent, tail long and scaly, hind feet elongate ..................... .................... Jumping mice Zapodidae 5E' Postorbital processes present, tail fairly long to elongate and always well-haired or bushy ................ Squirrels Sciuridae 6 Fur on dorsum short and felt-like, zygoma lacking or exceedingly slender, premaxillary-maxillary suture fused and indistinct or if present manus is much larger than hind foot ...... Order Insectivora 6A Manus larger than hind foot, zygoma slender ........................ Moles Talpidae 6A' Manus smaller than pes, zygoma lacking ............................... Shrews Soricidae 6' Fur long on dorsum, especially guard hairs, zygoma deep and functional as origin of masseter muscle, premaxillarymaxillary suture distinct, and canine tooth prominent and anteriormost in the maxillary bone ................. Order Carnivora 6'A Four toes on hind foot ................... 6B 6B Only one upper (vestigial) molar present on each side, retractible claws, five toes on front foot .................... Cats Felidae 6B' More than one upper molar present, claws never retractible, four functional toes on front foot .......... Dogs Canidae 6'A' Five toes on each hind foot ............ 6C 6C Cheek teeth bunodont, carnassials not adapted to shearing ....................... 6D 6D Tail long, annulated, only two lower molars, head of head and body less than 41

inches (= 1027 mm) ........................... ........................ Raccoon Procyonidae 6D' Tail short, never annulated, three lower molars present, length of head and body exceeds 42 inches ........... Bear Ursidae 6C' Cheek teeth not bunodont, carnassials adapted for shearing ........... Mustelidae

On mammalian biodiversity “There are several definitions of biodiversity. One is qualitative—the variety of life forms, the ecological roles they perform, and the genetic diversity . . . An-



other is quantitative—the number of species in a specified region, or species richness.” — Robert S. Hoffmann. . . . The Value of Abundance, Western Wildlands, 1991.

Wisconsin has been blessed with both a grand variety of mammals, from pygmy shrews to bears and moose, from the primitive opossum to the incredible star-nosed mole, and, of course, the courageous and fossorial badger. Especially along the “tension zone” between boreal and southern forms, there is a fantastic richness of species coexisting together so long as humans permit.

Photo of opossum Didelphis virginiana. By John E. Long 

KEY TO ORDERS AND FAMILIES OF WISCONSIN MAMMALS

67

TAXONOMIC ACCOUNTS OF MAMMALS OF WISCONSIN ARRANGED IN ORDERS, FAMILIES, GENERA, SPECIES AND RACES “One of the marvels of early Wisconsin was the Round River, a river that flowed into itself, and thus sped around and around in a never-ending circuit. Paul Bunyan discovered it.... Wisconsin not only had a Round River, Wisconsin is one. The current is the stream of energy which flows out of the soil [and sun] into plants, thence into animals, thence back into the soil.... Ecology is destined to be the lore of Round River. Diversity [of plants and animals] means a food chain aimed to harmonize the wild and the tame in stability, productivity, and beauty.” — Aldo Leopold, Round River, 1953.

Order MARSUPIALIA The Marsupialia is one of the most ancient groups of extant mammals. In earlier ages it inhabited all the major continents, but today it is confined to the Americas and the Australian region. The marsupials are mammals known by their marsupium, a pouch in which the female carries and protects her young. However, other mammals have pouches, and some marsupials lack them. No other mammals in North America have “epipubic bones”, also called “marsupial bones”, one attached to each pubic bone. Marsupials are grouped because of common ancestry in an ancient lineage. They show much adaptive radiation, and taxonomists have split the group into subgroupings that are problematic and subjective. Many taxonomists today regard marsupials as a superorder, or even a cohort, comprised of several subgroupings formerly known as families considered to be orders themselves. One such is Didelphimorphia. Didelphidae, including the Wisconsin opossum, have been included with thylacines and other Australian marsupials. Such submarsupial categories (orders, or suborders)

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THE WILD MAMMALS OF WISCONSIN

include the “order” Polyprotodontia Kirsch, or a quite different grouping, Marsupicarnivora Ride. American Didelphids do not properly belong to any grouping of Australian marsupials, nor even with the South American Microbotheriidae (tiny Dromiciops australis) from Chile (unless this little family is ancestral or nearly so to American marsupials on the one hand and to all Australian marsupials branching off the line separately). A possibility might be that Dromiciops is separate from both American and Australian assemblages. All the American opossums, Didelphidae, seem allied by foot morphology, biochemical resemblances, and sperm-pairs (except little Dromiciops). Marshall et al. (1990) placed this little marsupial in a separate “order” Microbiotheria. This arrangement is not much different from the classical classification (of George Gaylord Simpson), of a marsupial superfamily Didelphoidea containing Didelphidae and Microbiotheriidae.

Family DIDELPHIDAE Gray The fossil record reveals that marsupials were generally replaced on one continent after another by the advent of modern placental mammals (which all have villi rooting the chorioallantoic placenta into the flesh of the uterus). The Didelphidae has become an exception to this geographic replacement, having successfully invaded (or reinvaded) North America af-



Opossum woodcut. [J. G.] Wood’s Nat. Hist. 1880’s. 

ter the Pliocene Epoch. This American family, existing since the Cretaceous Time Period in North America, shows little evolutionary change for some 70,000,000 years of evolution. Didelphis virginiana is the only marsupial species found in the temperate habitats of the United States and southern Canada. It is still expanding its range northward from its South American origin (Gardner, 1982).

the state of Virginia. R. H. Baker (1983), quoted the early settler John Smith’s note that “opossum” is derived, from the Algonquian “apasum.” The name Didelphis marsupialis, formerly applied to this species, is now restricted to the Central American opossum (Gardner, 1973), which differs significantly from our species in chromosomal pattern (fundamental number 20 instead of 32).

Genus Didelphis Linnaeus Opossums

Didelphis virginiana virginiana Kerr

“The brain ... indicated by the structure of the skull is remarkable for the proportionately large size of

1792. Didelphis virginiana.The animal kingdom... p. 193. Type locality Virginia. 1952. Didelphis marsupialis virginiana: Hall and

the olfactory lobes, and the small size of the cerebral hemispheres; these contracted in front and destitute of convolutions. As compared with the

Kelson. Univ. Kansas Publ., Mus. Nat. Hist.,5: 322. 1961. Didelphis marsupialis virginiana: Jackson,

brain of the Mammalia ... the opossum furnishes the most remarkable contrast in its small size in proportion to the bulk of the animal. [However] ... the young return to the pouch to suckle and when danger threatens. During this time the female ... will suffer any torture rather than permit the pouch to be opened.” — G. B. Waterhouse, 1848, Natural History of the Mammalia, Vol. 1.

The description for the genus in Wisconsin is written in the description for the subspecies Didelphis virginiana virginiana Kerr (see below).

Didelphis virginiana Kerr Virginia Opossum The name Didelphis was proposed by Linnaeus. The word, literally “double love”, possibly means two penises, for the penis is forked. There are also two uteri, which is what the Greek Dis + Delphus means according to Waterhouse (1848). The name doubtfully refers to the double womb in time, i.e., an internal one for the embryos and an external pouch in which undeveloped young are nourished following birth. The name virginiana refers to

Mammals of Wisconsin, p.17.

Both of the aforementioned species names have been used by numerous Wisconsin workers. Description. The opossum is about the size of a house cat, muzzle slender, eyes conspicuous and dark, fur shaggy and grayish, paler below where guard hairs are sparse, ears rounded and paper thin, tail scaly (with clusters of ancient tactile hairs called “Dreiartgruppen” projecting outward from among the scales), large toe (hallux) on hind foot thumblike, set apart from other toes (opposing them) and lacking a claw or nail. The plantar surfaces show friction ridges for climbing. Skull with prominent sagittal crest, small braincase, numerous incisors (5/4 = 18), prominent canines, and tribosphenic (trituberculate) molars. The nasal bones widen posteriorly. There are two pairs of palatine vacuities. No other Wisconsin species has marsupial (epipubic) bones on the pelvic girdle, nor a marsupium in the female. There are five toes on each foot. Males possess a pendulous prepenile scrotum, and a urogenital sinus connects to the rectum in either sex. There are anal scent glands in the rectum used for defense. The paired vaginae TAXONOMIC ACCOUNTS / ORDER MARSUPIALIA

69





Opossum’s left hind foot. After Jackson. 



Photo of mother and four young riding in the dorsal fur. F. M. Blake & J. Spero. Some deny that this happens. 

combine as one that opens into the urogenital sinus distally and at the other end, near the time of birth, to a temporary birth canal for the young. In males and females the urogenital sinus and rectum although separate are surrounded by a common sphincter muscle. There are sweat glands on the feet and tail. Chromosomes number 2N = 22, the Y small, the fundamental number (i.e., containing elements of biarmed and acrocentric chromosomes) is 32 (Gardner, 1973). Fur in the opossum is grayish, but some specimens are white, dark brown, or even

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THE WILD MAMMALS OF WISCONSIN

Skull of opossum. 

blackish. A typical fur is mottled gray and whitish, the face whitish and feet blackish (with white toes). The eye-ring, eyes, and the inner surface of each ear flap are black. Yellowish stains on the chest (from skin glands) are seen in males. A winter-killed albino was found in Stevens Point. Hartman(1952) called this color phase “albinotic” because the eyes are black. Although Jackson (1961) mentioned that females are larger, Gardner (1973) found males are significantly larger, in 11 measurements. Hamilton (1958) found males about 32 percent heavier. Some standard measurements vary from a mean 24-35 in (609-900 mm) for total length, tail length 10-15 in (approximately 242-381 mm), hind foot 2-3 in (50-76 mm), and ear length about 2 in (4050 mm). The greatest length of the skull varies from 80-127 mm, and weights from 4 to 15 pounds (1.8-6.8 kg). Weights reported from nearby states are given in the table Mar1. A 14-pound old male would be exceptionally large. About a third and even more of the weight may be stored body fat, to endure the winter. Cleven (1988) gives the length as up to 36 inches (92 cm), with weights to 12 pounds (5.5 kg), and females up to seven pounds (3.2 kg). Dental formula. I 5/4, C 1/1, P 3/3, M 4/4 = 50. Young opossums may have unerupted teeth. The four molars above are primitive trigons, the lower trigonids each has a talonid heel.

Geographic Range. The opossum is to be expected now throughout most of the state. It is not found on offshore islands in Lake Michigan and Lake Superior. On the Door Peninsula it has been found only in recent years from north of the canal at Sturgeon Bay. See Map. Status. According to Jackson (1961) the opossum was known as early as the 1850’s in southern Wisconsin. It began rapidly expanding its range northward in the early 1920’s, possibly with the opening up of the North Woods (by the extensions of roadways, cutting of timber, etc.). Most records prior to 1961, and since then, are from southern



Maps showing geographic distribution of the Opossum in Wisconsin & North America. 

TAXONOMIC ACCOUNTS / ORDER MARSUPIALIA

71

counties. Since 1965, specimens in the University of Wisconsin-Stevens Point museum, a few from northern counties where no opossums were reported, permitted a crude, singular estimate of the rateof dispersion (Long and Copes, 1968). Other range extensions for the Upper Peninsula have been reported (Baker, 1983), some that invite the question whether the estimated rate as calculated was correct. However, in the sample used by Long and Copes the dispersion was measured point by point, representing new arrivals (according to people that lived in those areas). The rates measured in two separate estimates were a little more than four miles per year, in a northward direction. Other records from the eastern counties and in Upper Michigan may be pioneers in a different advance. Along Lake Michigan, where frost is less severe, and opossums are spared some of the frostbite of tails and ears so common in central Wisconsin, the opossum invaded Upper Michigan even faster than at the rate measured in central Wisconsin. Smith (1988) recently reported three separate records a little northward in Delta County, Michigan (1986-1987). Almost directly north of Menominee County, penetrating wilderness all the way to Lake Superior, the opossum was reported in 1984, on Highway 41 at Marquette, only 1 km from



Table Mar-1. Some weights (kg) of opossums from nearby states, based on data in Brocke (1970), Hamilton (1958), Blumenthal and Kirkland (1976), Wiseman and Hendrickson (1950), Pippitt (1976), and Lindsay (1960). Compiled by Gardner (1982).  Location

N & Sex

Michigan

40 M 12 F 83 M 60 F 10 M 18 F 5M 10 F 9M 7F 11 M

New York Pennsylvania Iowa Illinois Indiana

72

Mean & Range 3.6 2.4 2.8 1.9 3.4 2.4 3.1 1.8-3.1 3.8 2.4

THE WILD MAMMALS OF WISCONSIN

2.8-4.6 2.0-3.2

2.2-4.0 1.8-3.1

1.7-5.9 1.8-3.1 5.4

Lake Superior (Robinson and Heitman, 1986). By 1996, opossums had advanced in western Wisconsin northward as far as Luck, Wisconsin. Another advance is to 9 mi. E Fifield, in Price County (4 Nov. 1996). Recently (2005) it extended the known range to northwestern Douglas County (see Records, Ron Parmela). The opossum is more than a curiosity of nature, our only Wisconsin marsupial, because its food habaits involve numerous food webs in our ecosystems. For one thing, it eats many harmful insects. It also cleans up much carrion. It has some fur value. On rare occasions it has killed domestic chickens. But today domestic chickens are seldom kept outside or even in outside pens. In Wisconsin, the opossum is not legally protected. However, hunting and trapping for it and other furbearers are allowed only in late autumn or winter. Although the flesh is edible, and savored in some areas of the southern United States, and the fur is fairly luxurious, not many are harvested and the pelt price is low (compared to other furbearers). In 1935-1943, the highest harvests of this species in America exceeded 2,300,000 pelts, but peaks dropped off to about 150,000 in 1958-9 (Deems and Pursley 1978). The opossum builds a nest of leaves in a hollow snag, a crevice, in farm buildings, or even brushpiles. It may carry bundles of leaves to its nest in its prehensile tail. It usually spends the winter in a burrow, often one abandoned by a striped skunk. In its wanderings it may use many dens for day resting, often only a day. Foods. Opossums are omnivorous, and feed on a wide variety of insects, other invertebrates, mice, birds, worms, eggs, seeds, berries, soft fruits of plants, and even shoots or leaves. They have varied fare of carrion (especially rabbits, and including other dead road-killed opossums). Knudsen and Hale (1970) examined the stomachs of 151 Wisconsin opossums from all months of the year, and reported 65 different foods. See Table Mar-2 for seasonal use. Mammals comprised



Table Mar-2. Seasonal use of important opossum foods (values based on 5 percent of occurrences) studied in southern Wisconsin, 1953-1958. 

Food Earthworms Insects Mice Songbirds Cottontail Frogs Garbage Snakes Apples Chicken

Winter

Spring

Summer

Fall

— 14 23 6 29 3 16 — 6 10

31 11 17 19 9 10 9 10 6 4

54 29 4 25 — 25 4 13 4 13

35 31 19 15 19 12 — 8 15 —

After Knudsen and Hale, 1970.

25% occurrence of the diet and 41% by weight. Most of the animals were decayed carrion. Earthworms, insects, songbirds, frogs, snakes and chickens were common summer foods. Other foods included cottontails, shrews, moles, squirrels, muskrat, Norway rat, dogs and cats, even swine, bobwhite, ducks, pheasant, pigeon, screech owl, crow, crayfish, snails, even fishes, apples, other fruits, grains, vegetables, mast, and garbage. The most amazing food is venomous pit viper snakes, which cause no harm to opossums even when snake bites are successful and fangs eject their poison (Gardner, 1982, Kilmon,1976, and Werner and Vick, 1977). Reproduction. Opossums reportedly mate lying side by side, by means of a bifid penis inserted into the female’s vagina. Copulation is brief. Mating begins as early as January in northern states, but usually peaks later in March. Gestation is no longer than 13 days. The litter of partially developed young may number as high as 22 or 25, but usually 18 or less. A late litter was observed on 18 July, 1993, in northern Door County. These naked young were only 35-37 mm in crownrump length. After birth, the reddish, naked, undeveloped young (length approximately 13 mm, weight 0.13 g) clamber quickly from the opening of the vagina anteriorly to the pouch, swinging their heads from side to side, eyes

unopened, crawling overhand like swimmers through the fur for a distance of approximately 3 inches (76 mm) (Hartman, 1920). Inside the pouch they each seize a nipple and hang on. Usually there are 13 nipples, as many as 17, in a horseshoe pattern. Not all the anterior nipples may produce milk, but approximately 11, and sometimes 12 or 13 young become attached. The number of young that survive is usually limited to only 7 or 8. For several days, if the young is detached from the nipple, it attempts again to seize a nipple. After three days the expansion of the distal nipple anchors the offspsring for some 50 to 60 days. The young weighs less than half a gram after several days. Thus, the mother’s nipple elongates during the period of lactation, and expands distally to help keep the young attached until they grow larger. When detached from older offspring, the elongated nipple facilitates nursing outside the pouch. After 60 to 70 days, when the young weigh about 25 g each, they leave the pouch occasionally, returning for milk and shelter until weaning. The young stay with the mother as long as 3-4 months. Weaning is completed at approximately 90-100 days. The mother calls her offspring by a clicking noise, similar to that of the male as he pursues a female. Often the opossum leaves her young in the den to forage for food. It is often said emphatically little opossums do not cling to the mother’s fur, but see Fig., also Hamilton, 1939: fig. 59). Females may breed at six months of age. Young males also might breed the first year. Most opossums breed first as yearlings. They seldom live beyond 2 years; some apparently live four. Opossums show a progressive irruption of the dentition. Behind the canines the premolars and molars erupt roughly in this sequence: At 3 months, dp 2/2, M 0/0; at 4 months 3/ 3, 1/2; at 5-8.5 months, 3/3, 2/3; from 7-11 months, 3/3, 3/4; about 10 months or older, 3/3, 4/4 (the full adult complement) (see Gardner 1952). Mature opossums show tooth wear on the anterior molars before showing wear on TAXONOMIC ACCOUNTS / ORDER MARSUPIALIA

73

all of them. Growth of the young is fairly regular (almost linear) the first year, by which time sexual maturity is attained. Mortality. Cars in Wisconsin kill innumerable opossums. Dogs hunt them, hounds trailing them at night and often treeing them so hunters may shoot them. Trappers take them for their fur. Coyotes, foxes, badgers (probably), and great horned owls feed on them (Jackson 1961). The chief enemies are people, dogs, and automobiles, and long, cold winters (especially in underweight juveniles, less than 1400 g each, Gardner, 1982). Seidensticker et al. (1987) mention in this order, weather, nutrition, and disease, with natural enemies owls, hawks, coyotes, domestic dogs, raccoons, bobcats and some large snakes (on young opossums). Statistics given were cars (35%), parasites (17%), winter freezing (9 %), only 4 % due to trapping, and 35% unknown. Jackson (1961) listed diseases and parasites including tularemia, ticks (Dermacentor usually), fleas, and internal worms (Physaloptera usually). Rabies virus can infect opossums, but usually there is little incidence. Several arboviruses infect opossums and could pose a threat to other animals. Karl E. Shewmake, M.D., told this writer (1999) that opossums present a problem as a carrier of a virus (called EPM) that causes a polio-like disease in horses in Wisconsin. It does not infect humans, and is transmitted by opossum feces. Horses eat the fecal material with meadow grass or in hay, but are more likely to eat it mixed with horse food when the two mammals share the food trough. Spotted fever, plague or tuberculosis organisms may infect opossums. Other diseases are listed in Addison et al. (1987) and Barr (1963). Home range and Density. In Wisconsin, Cleven (1988) mentioned home range of the opossum as 20 to 40 acres (= 8-16 ha). Hunsaker reported home ranges up to 20 ha. Gillette (1980) studied radio-tagged opossums in the warm seasons and found that the males wandered on average some 270 acres (108 ha). The home range for females was 127 acres

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THE WILD MAMMALS OF WISCONSIN

(51 ha). Younger or nonresident individuals wander long distances, as far as 7 miles (11.2 km) in Missouri (Reynolds, 1945). Through one winter month (January, 1996) I observed one old opossum (until it disappeared) that wandered nightly, within an area of no more than 2 acres. Males have larger ranges than females, and juveniles smaller than either. Population density is known to be as high as one opossum per hectare in Illinois (Stieglitz and Klimstra 1962). Hunsaker (1977) found density to be 0.26 / ha (0.2-1.16 / ha). Opossums seldom live longer than 2-4 years, but in captivity one lived six (Baker 1983). In a land so cold that the ears and tail freeze, the longevity is short (only 3-4 years according to Crandall, 1964), and the intelligence of the animal questionable, then, when all things are considered, it is surprising that opossums are expanding range. Remarks. Hair from the fur of opossums is used as nesting material by white-footed mice and chickadees. Titmice were observed pulling hairs from a live opossum (Packard, 1949). Small opossums hole up during freezing weather, but those larger than 4 kg changed dens and moved about even then (Pippitt 1976). In winter the opossum sleeps a lot in its more permanent winter den, but its body temperature does not appreciably drop. Year round, it varies 32-38 degrees C, and thermoregulation begins at 55 days (completed at 94 days). Opossums use their scaly, prehensile tail not only to clamber about in trees, but to curl it around clumps of leaves to transport them to their nests (dens). “Playing ‘possum,” of course, is feigning death, mouth gaping, body limp and prostate, a physiologically comatose state. I have seen it in a young opossum, after it was attacked by our dog. Males make an open-mouthed threat in encounters, screeching and weaving from side to side, fighting, and even killing the opponent on occasion. Females also gape and show agonistic threats to other adults, but aggression ceases if the female is receptive to mating. Such attitudes ensure a rather solitary life,

with opossums often avoiding one another. Noises include clicking, growls, hissing, and in anger a loud screech. McManus (1974) reviews opossum behavior. Additional Natural History. Hartman (1952), McManus (1974), and Gardner (1982) reviewed natural history for the opossum. Geographic Variation. There is only one race in Wisconsin. Specimens examined. Total, 55. Adams, Brown, Dane, Dodge, Door, Douglas*, Green, Jefferson, Juneau, Kenosha, Kewaunee, Manitowoc, Milwaukee, Monroe, Oneida, Polk, Portage, Price, Racine, Richland, Rock, Sheboygan, Trempealeau, Vernon, Washington, Waukesha, Waupaca, Winnebago counties. Other Records. Jackson (1961) examined 9 specimens from Wisconsin. Sauk Co.: Leopold’s shack (Mossman, 1980, not mapped). Michigan. Robinson and Heitman (1986) “On Hwy 41” at Marquette, 1 km from Lake Superior. 1984. Roadkills between Marinette and Escanabe.

Order INSECTIVORA The Insectivores “In the dark and cold embrace of Mother Earth, away from the cheering sunlight and the beautiful upper world that we enjoy, there dwells a group of mammals so strange and yet so useful to man, that they excite our admiration.... Pass not unthinkingly the moles and shrews, for they have been most cunningly designed to serve a definite and important function in the economy of nature.”— W. T. Hornaday, in The American Natural History, 1904.

The order Insectivora, as old as Cretaceous Period, is found on all continents except Australia. These some 400 species are comprised of medium-sized to tiny mammals having elongate and pointed snouts, small eyes, * Hwy 13, Amnicon R., sect.10, May 9, 2006. Roadkill reported by R. Perala.

primitive ears (lacking much or all of the entotympanic and much of the ear pinna), the genitalia and anus are in close proximity (almost resembling the cloaca of monotremes), and five toes are on each foot. The zygomata are absent in shrews, and slender in moles. The antemolar tooth-rows are divergent posteriorly, and the cheek teeth are typically dilambodont (W-shaped). The anterior teeth are procumbent, i.e., scalpal-like or forcepslike, on the one hand, or are tiny incisiform teeth and caniniform teeth, on the other. The fur is short and felt-like in the shrews, and soft and fleecy in the moles. Although some shrews, and all moles, have white teeth, the shrews of Wisconsin show chestnut-brown tips, which more specifically tend to comprise an outer layer made of several sublayers, the outermost brownish. Each lower, anteriormost tooth has almost a straight-edged brownish outer wall enclosing the inner, elongated white enamel crown, with humps of red-brown in tandem in some species analogous to cusps, and in Sorex arcticus showing anteriorly even an inner brown tipping on one hump. In these teeth, Blarina and Cryptotis have nearly straight-sided red-brownish walls. They show, as does Microsorex, accessory cuspules on the upper “unicusps”. The terms unicuspid, unicusp, even unicuspate are not technically correct for such shrews. The Wisconsin insectivores belong to a distinctive suborder Lipotyphla. The other suborder Menotyphla includes the African jumping shrews and the Tupaiidae (except some workers, including myself, assign Tupaiidae or tree shrews to the order Primates). In shrews W-shaped ectolophs are conspicuous. In moles, not far removed from the ancestral insectivoran Leptictid pattern, the ectolophs are said to be W-shaped. Moles seem primitive in molar pattern, retain a slender zygoma, are about the same as shrews in construction of their auditory bulla (some have the bulla complete by addition of an entotypanic expansion), and the dentition of Condylura has the primitive number of teeth (44). Therefore, moles are discussed TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

75

before shrews, which is not conventional, but in line with evolution of tiny size in shrews.

Key to Families of Wisconsin Insectivores 1

1’

Size larger (total length exceeds 150 mm, weight more than 30 g), external ear pinnae lacking, forefeet broad, twice the width of hind feet, zygomata slender but always present, teeth exceeding 2 in number ...................... Talpidae, Moles Size smaller (total length less than 150 mm, weight less than 30g), external ear pinnae inconspicuous but present, forefeet small, hardly wider than hind feet, zygomata lacking, teeth 32 in number or fewer .................. Soricidae, Shrews

Family TALPIDAE Fischer Moles “These beasts are all blind... and therefore came the proverb, Talpa caecior tuphlotaeros alpalacos, blinder than a Mole; to signifie a man without judgment... yet if any man look where the eies should grow he shall perceive a little passage, [and] by drawing up the little skinne... therefore of them. — Topsell, Historie of foure footed beastes, London, 1607.

Chief characters are summarized in the Key above. These fossorial mammals feed mostly on earthworms (Oligochaeta) and beetle nymphs.

Key to Wisconsin Moles 1

76

Twenty-two tentacles surround nosepad (rhinarium), anteriormost upper teeth spoon-like, elongate tail tapered at anterior and posterior ends ....................... ................................. Star-nosed mole Condylura cristata THE WILD MAMMALS OF WISCONSIN

1’

Snout devoid of tentacles, anteriomost upper teeth elongate, chisel-like and robust, tail short and not tapered ............ ...................... Eastern or Prairie mole Scalopus aquaticus

Genus Condylura Illiger Star-nosed Mole Condylura cristata cristata (Linnaeus) 1758. Sorex cristatus Linnaeus. Systema Naturae, ed. 10. Vol. 1, p. 53. 1819. Condylura cristata: Desmarest. J. de Phys., Chim., Hist. Nat., et des Arts. 89:230.

The name Condylura Illiger, 1811, is Greek, and means knobbed tail based on a faulty drawing by De la Faille. Linnaeus provided the name cristata, which means little crest, and is often featured in moles. External measurements are given in Table Ins-1. Dental Formula. DF = I 3/3, C 1/1, P 4/4, M3/3 = 44, the so-called primitive number of placental mammals. Howard Whidden (personal communication) informs me the genus is known in the Pliocene of Poland, supporting my view that the mole is primitive. Some premolars are triconodont (3 cusps aligned) and do not occlude with their analogs in the opposite jaw. The canines are caniniform, which is not always the case in moles. The I 2/ is so minute it may be obscure (see skull fig.).attributed to a peculiar sagittal ridge, but much more likely refers to the rosy-pink cluster of tentacles on the snout. In Latin, crista also means a tuft on the head. This corona of 22 bilaterally arranged tentacles, tactile in function, provides a basis for the name “star-nosed mole.” Description. This mole has the typically broad hands with robust claws characteristic of moles. They are narrower than in the Eastern mole Scalopus. The star-nosed mole is readily identified by the 22 pinkish or gray (in dried skins) tentacles surrounding the two





Musculature and tendon structure of the nasal rays of Condylura. After Grand et al. 1998. 

nostrils, and a long, sparsely haired, fleshy tail (tapered at either end). The eyes are small, auricular openings prominent, feet have scales, and 5 toes are on each foot. The fur is relatively coarse for a mole, dense and long, with a softer underfur. Molts occur in June and October, when winter fur is attained. The skull is long and narrow, zygomata short and slender, jaws narrow with widely-spaced (sawlike) antemolar teeth, molars mostly W-shaped with interior portion a shelf, premolars somewhat tricuspate, lower molars similar to upper molars, but portion a shelf, premolars somewhat tricuspate, M-shaped, auditory bullae incomplete. Chromosomes number 34, with a fundamental number of 64 (Petersen and Yates, 1980). The karyotype is much different than in other moles. The star-nosed mole is nearly black dorsally, the venter a paler blackish brown, tail, feet and head concolor with body. The wrists are tan. Worn pelages are browner or grayer. The sexes are similar in size, unusual in moles. External measurements are given in Table Ins-1.

Skull of the star-nosed mole. 

Geographic Range. The star-nosed mole dwells in northern Wisconsin and Upper Michigan, restricted from most islands in Lake Michigan, and apparently from the Door Peninsula. Status. Condylura is uncommon, restricted to wet, boreal soils of swamps and stream valleys in northern counties. The status seems unchanged from the turn of the century, although the loss of wetlands and application of pesticides probably had an adverse effect. The soils where this mole dwells are usually too wet for agriculture or building, and this animal is seldom a nuisance. Habitats. This semi-aquatic mole is found in black, wet soils, mucky humus, or sandy loam, of stream and river valleys, swamps, lake shores, and marshes mostly of northern counties. Occasionally it lives in lawns near water, in cedars, spruce, tamaracks, birches, alders, jewelweed, marsh grasses, and sedges, often in association with jumping mice and shrews. I have taken this mole (2) and Blarina (2) from the same partially flooded tunnel (Jordan Marsh, Portage County) on alternative nights. Don Follen, Sr., trapped two Blarina and two Condylura sharing the same tunnel (Oct. 16-28, 1967) near Arpin, Wood County. Condylura swims under ice and moves about on snow (Jackson 1961; also see photo). Star-nosed moles tunnel less extensively than the prairie mole Scalopus, and the ridges are usually less than two inches wide. Where surplus dirt is mounded up, in wet globs TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

77

and layers, the mole hill may extend above the vegetation to a height of six inches, and may be as much as two feet wide. In a series of mole hills found in farmyards in eastern Wood County, the huge hills resembled those of Scalopus. Small trails, almost trenched runways, extended on the soil surface to a small intermittent ditch of water. The nest is a loose wad of leaves, grass, or both, constructed in an ovate chamber nearly seven inches in diameter and three to five inches in height. The nest has been observed sited between tree roots and under a decayed stump. Audubon (Audubon and Bachman, 1842-



78

Maps showing geographic distribution of Condylura cristata in Wisconsin and North America. 

THE WILD MAMMALS OF WISCONSIN

1846) found one made of withered grasses in an excavation under a stump to which a tunnel was excavated. The nest is usually three to ten inches underground. As many as three tunnels enter the nest; each is about 40-50 mm in diameter. Young have been found in the nest (Jackson, 1961; Schmidt, 1931; Audubon, loc. cit.; Rust, 1966). Foods. Star-nosed moles feed mostly on terrestrial and aquatic worms, insects, other invertebrates, and to a lesser extent aquatic vertebrates (frogs, fishes) (see Jackson, 1961). Don Follen found earthworms in a Wood County mole’s stomach (October, 1967). One kept in captivity was fed earthworms in a bowl of water daily. The mole dived in swimming about beneath the surface with its tentacles actively searching. When the worm was encountered the male seized it, carried it from the water to a corner of the aquarium, and noisily ate it. A plastic bass bait closely resembling a worm was never seized by the swimming mole unless the plastic worm was rubbed with a live worm, whereupon the mole seized the bait and carried it out of the water. One could hear gnashing of tiny teeth, suggesting that somehow the mole had tasted the juices of the live worm. Whether the tentacles function in the tasting is unknown, for no one has ever searched for taste buds in the tentacles. Possibly the tongue is used in tasting the surface of a prey animal that was detected with the tentacles. Gould et al. (1993) described a new function of the oral tentacles, as electroreceptors.. This new sense was unknown in mammals except for its recent discovery in the Australian platypus (Ornithorhynchos anatinus). Gould et al. found attacks of moles correlated with specific parts of the worms, especially the clitellum, where electroactivity from secretions was measured as particularly strong. Other electrical “hot spots” were likewise selected as targets by the moles. Data from electrified fields in tunnel-mazes suggested electroreception in the oral rays. Moles even selected simulated worm fields of elec-

tricity over non-electrical areas. Whether the Eimer’s organs, small tactile sensory organs on the tentacles, are responsible for this sixth sense is not clearly stated, but Gould et al. suggest there is a great density of these organ -receptors around the center of each set (of eleven) rays. They suggest the disparate size of the rays enhances sensory or electrical perception. Catanla et al. (1993) identified “stripes” on each side of the neopallium of Condylura, which areas apparently have evolved for the special afferent impulses from each set of eleven rays. Taken altogether the evidence supports an explanation of an amazing electromechanical sense in Condylura used to detect prey and to explore surfaces, such as the water surface. There are some students of moles who are unconvinced. No one doubts that this mole has some sort of incredible sense (taste?) for detecting worms. Reproduction. Jackson (1961) suggests the adult star-nosed moles that pair in autumn may mate, but probably not until winter. Males apparently breed in February to mid-March. Gestation is believed about 45 days. Breeding reportedly extends from mid-March through April. There are usually six young, but the number may vary from 3-7. Eadie and



Condylura cristata from Portage County. 

TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

79

Hamilton (1956) found a mean litter size of 5.4. There are eight mammae. Naked and blind at birth, the young are pinkish and only the vibrissae are visible hairs. Partially developed tentacles are obvious even in developing embryos. Newborn young are remarkably large, reportedly measuring 70-75 mm including the tail (25 mm). The young are born in late April to mid-June (which may account for the paucity of breeding records, because little field work is carried out in the North Woods until winter’s end). There is but one litter per year. In six to eight days short fur appears dorsally, and in two days more the abdomen is haired. When the young leave the nest at about one month or more of age their sleek fur covers the body. They each weigh about 30 grams. Mrs. John Pollock of Rhinelander found five young in a nest on May 3, 1932 (Jackson 1961). Alan Long caught one by hand weighing only 20 g, in Whiting, Wisconsin, in early July. This mole may have been born in early June. Although small it was well furred (see Table Ins-1). The teeth erupt before the young moles leave the nest. Jackson (1961) mentions a small sagittal crest appearing in old adults. Small moles in this collection yield measurements given in Table Ins-1. Mortality. Carnivores that prey on starnosed moles, usually catching them above ground, are dogs, red foxes, fishers, striped skunks, and house cats (Hamilton 1936, Murie 1936, Schmidt 1931, Timm 1975, Toner 1956). Aquatic predators include large-mouth bass, bullfrog, and mink (Christian 1977, Pine 1975). Mike Eber told me a northern pike ate a star-nosed mole in Monroe County. Hawks and owls take them (see Baker 1983) and even the great gray owl (3 specimens in this collection are from owl pellets from Ashland County). Ticks, mites, fleas, tapeworms, and roundworms parasitize this mole (Hamilton 1931, Jameson 1949, Scharf and Stewart 1980, Timm 1975, Yates et al. 1979). Home Range and Density. Jackson (1961) thought as many as 30/ acre might

80

THE WILD MAMMALS OF WISCONSIN

be found in ideal habitat. These concentrations are likely family groups, and some have doubted that the density is so great. In central Wisconsin I have taken several together, suggesting about 3-4 per acre, and nearby none at all were trapped. In their wanderings by use of water (they even swim under ice) and tunnels in the snow they may disperse from one habitat to another, and often find themselves in some farmer’s yard by access of an ephemeral ditch of water. Remarks. Large star-nosed moles (60 g) consume oxygen at a rate of 4.2-4.5 cc/g/ hr. Juveniles had lower metabolism, about half as much (see Petersen and Yates, 1980). Additional Natural History. Peterson and Yates (1980) reviewed biology for Condylura. Specimens examined. Total, 61. Ashland (Outer Island, Apostle Islands, 1), Bayfield, Brown, Calumet (Kiel, 1), Clark, Dodge, Kewaunee, Jackson, Juneau, Manitowoc (Branch River Country Club, 1, Point Beach State Forest, 1 UW), Marathon, Marinette,



Table Ins-1. External measurements and weights of Condylura from Wisconsin. Specimens selected having weight data on the labels.  No.

Locality / Measurements

5971

Drummond 184-75-28 Westboro 168-70-23 Eagle River 179-70-24 Abbotsford 188-76-25 Portage Co. 190-72-21 Wood Co. 176-70-25.5

Sex/ Weights g.

Adults

3795 1005 1753 63 3716

Of Weaning Size 3107 Marinette Co. 77-70-26 3895 Whiting 141-53-25

M 46 M 37.1 M 46.9 M 49 F 42.7 M 45.8 F 30.1g (Oct.6, 1971) ? imm. Estimated wt < 20 g (July 11, 1974)



Head and forefoot of Scalopus. Scratch sketch H. E. Anthony. 

Oneida, Portage, Price, Rusk, Sheboygan, Taylor, Vilas, Waupaca, Waushara, and Wood counties. Michigan. Other record. Big Summer Island, Lake Michigan. Schoolcraft Co.: Seney 1 UMinn.

Scalopus E. Geoffroy Saint-Hilaire See Description for Scalopus aquaticus.

Scalopus aquaticus (Linnaeus) Eastern or Prairie Mole Scalopus aquaticus machrinus (Rafinesque) 1832. Talpa machrina Rafinesque. Atlantic Joumal, 1:6 1. Type from Lexington, Kentucky. 1832. Talpa servicea Rafinesque. Atlantic Journal, 1:62. Type from Nicholasville or, Harrodsburg, Ky.

Jackson (1961) and others refer to it as the prairie mole, which is an excellent and meaningful name. Description. The eastern mole is ratsized, stout, with huge hands and enormous foreclaws (used for digging and pushing soil), head short and almost conical, lacking visible ear pinna or conch, and the auricular openings are small. The eyes are tiny, present but suspended in skin, covered with fused eyelids; the snout naked anteriorly with nostrils opening upward; tail short (about one fifth of total length), scantily haired so as to appear naked, feet all with five toes, all webbed, pelage plush (velvety) dense and smooth. The skull has stout, large but slender zygomata, complete auditory bullae, truncated nasals, and anteriormost teeth (probably I 1/) large and directed vertically (almost chisel-like as in rodents). Chromosomes 2N = 34, fundamental number reportedly 64 (Hoffmeister, 1989). The eastern mole is grayish black or brownish black, often washed with a silvery sheen, usually browner in winter, occasionally with an orange or rusty sheen on venter (environmentally caused?). Feet are dirty whitish above, with naked gray skin below. No. UW 2040 taken June 1, 1969, in Crawford County, is an albino. Male eastern moles are slightly but significantly larger than females in most external and cranial measurements. Weights of males are given in Table Ins-2.

1842. Scalops argentatus Audubon and Bachman. J. Acad. Nat. Sci. Philadelphia, 8:292. Type, from southem Michigan. 1905. Scalopus aquaticus machrinus: Elliott. Field Columb. Mus. Publ., 105, Zool. Series, 6:470.

The name Scalopus comes from the Greek Skalops, to dig. The word “aquaticus” means, of course, aquatic, but this is a misnomer because the mole is not aquatic. This is not the only mole found in eastern United States, but it is common and wide spread.



Skull of Scalopus aquaticus. 

TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

81

Dental Formula. Reported often as I 3/ 3, C 1/0, P 3/3, M 3/3 = 36. However, there is no way to account for the tiny spicules variably present in the lower antemolar series, nor to know with certainty the serial homology with the upper ones. Some antemolars are spicules either reduced in size in their evolution, or perhaps were retained milk teeth. Consequently, one often observes teeth in excess of 36, and their presumed homology with, for example, Condylura, cannot be confirmed. For practical purposes, the upper series of teeth of the eastern mole can provisionally be regarded as 3, 1, 3, 3. Geographic Range. This prairie mole is confined to the prairie counties of southern and western Wisconsin, ranging to the southern marshes of Portage and Wood counties, and northwest to Burnett County along the west border. See Map. Status. Unchanged since the 19th century. This eastern (or prairie) mole is often a nuisance in lawns, cemeteries, and golf courses. It is beneficial in soil formation and in eating beetle nymphs (grubs). It eats earthworms (of no appreciable or practical loss) and corn seedlings on occasion. Habitats. The eastern mole occurs basically in sandy loams, grasslands, prairies, roadsides, pastures, railroad rights-of-way, lawns, golf courses, cemeteries, and cultivated fields. Hoffmeister (1989) mentioned their occurrence in almost any friable soil in which the moles can push or dig dirt in their tunnels. At the edge of their range in central Wisconsin, the moles seem limited in their northward dispersion by the extensive marshlands, which, after draining by ditches and allowed to develop as prairie (for prairie chicken management in some cases) become suitable for moles. In western Wisconsin the moles are found both in the valleys and on the uplands, often sandy where soil is established on the summits (e.g., at Ellsworth, Wisconsin). The ridges or mole runs of the eastern mole usually are wider than those of the starnosed mole, and the hills larger, wider and

82

THE WILD MAMMALS OF WISCONSIN

more flattened heaps of soil. Often found and confused with pocket gophers, the tunnel ends are not plugged (by pushing soil upward and out), nor are the hills of dirt thrown in some particular direction, but raised upward and spread more in a circular pattern. Such tunnels in the topsoil seem like wrinkles in a lawn, but in winters the tunnels lie deeper where the worms and beetle larvae are more likely to be found. This deeper series of tunnels, reportedly 8 to 24 inches (Jackson 1961) and doubtlessly a great deal deeper in winters of deep frost, is the home of the eastern mole. Jackson reports that this mole digs in lawns 18 feet per hour, and in a night can create a ridge 50 or more yards in length. The nest is about 5-6 inches (127-152 mm) in diameter, usually at a depth of 13 to 18 inches. Sometimes the nest is only 5-6 inches underground. The nest is comprised of grass and rootlets, occasionally of leaves, and at times is practically void of nesting materials. The nest is sited in an ovate chamber about 8 inches long with diameter about 5 inches. Foods. Jackson (1961) and Hisaw (1923) considered the primary foods (80 percent) of the eastern mole to be earthworms, grubs and adult insects. The remainder is plant material. On occasion, snails, centipedes, and millipedes are eaten. Plants include rootlets and seeds, and captive moles feed on a variety of fruits and vegetables (summary in Baker 1983). West (1914) and Whitaker and Schmeltz (1974) found comparable percentages. The season and habitat are important according to West who found moles feeding on carpenter ants, and in May and June on emerging May beetles. One mole caught in winter had eaten 150 ants. Reproduction. Conaway (1959) obtained information from Dane County moles. They breed but once a year, and young-of-the-year do not breed. Breeding commences as early as February or March and continues into April. Gestation is thought to be about 45 days, but may be only one month (Jackson, 1961; Conaway, 1959). No parous females were found

in late March when breeding was at peak. Conaway notes a few pregnancies after 5 May; one was as late as 4 July. The naked young are large at birth (about 50 mm in length). The litter size varies from 1 to 5, usually 4. There is some resorption of embryos. Testes develop rapidly in December, but mating occurs several months later. The young are haired out in about 7-10 days. In about five weeks, the young are more than half the size of their mother (Yates and Schmidly 1978; Jackson 1961, Hoffmeister 1989). Mortality. Eastern moles have few enemies because they so seldom come out above



Maps showing geographic distribution of Scalopus aquaticus in Wisconsin & North America. 

TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

83

ground. Hawks and owls eat them on occasion, and foxes, coyotes, and domestic dogs kill them (Arlton 1936, Davis 1951, Wallace 1950, Wilson 1938, Errington 1935, Murie 1936, Schofield 1960, Van Hyning 1931). Often the mole is rejected as food because of its rank odor. Parasites include the louse Euhaematopinus abormis, fleas (Ctenophthalmus and Corypsylla), mites, and intestinal worms (Monoliformis, Filaria, and Spiroptera) (see Jackson 1961, Baker 1983). Home range and Density. Arlton (1936) and Harvey (1976) found home ranges for the eastern mole from 0.86 acres to two acres (0.75 -8.0 ha) and 10.6 ha (for males) or 2.7 ha (for females). Arlton found a branching tunnel system covering an area about 0.35 ha. Moles wander much more extensively than pocket gophers (Yates and Schmidly, 1978). Baker (1983) suggests that 1-2 moles/acre (2-5/ha) are probably normal density. He disputes Jackson’s (1961) estimate of 8-10 per acre. Additional Natural History. Yates and Schmidly (1978) reviewed the biology of Scalopus aquaticus. Geographic Variation. There is a cline (i.e., a gradual change over some wide area) in increasing size northward from Tennessee, but it is not continued into central Wisconsin. That is because the eastern moles in southern Wisconsin are likely recent invaders from the southeast. Specimens examined. Total, 29. Adams, Burnett, Chippewa, Crawford, Dane, Eau Claire, Grant, Iowa, Juneau, Monroe, Portage, Richland, Sauk, Vernon, Waushara, Wood counties.

Other Records. Milwaukee Public Museum records. Pierce, Grant, Columbia, Sauk, Adams, and Buffalo counties. Ellsworth, No specimen (mole hills observed). Nottingham Ridge, No specimens. 2 mi. SW Osseo, also Osseo (No specimens, mole hills observed). Town of Grant, Prairie Chicken Area on Buena Vista Marsh, T21 N, R7E (no specimen, hills observed). Clark (Schmidt, 1931).

Family SORICIDAE Linnaeus Shrews Shrews are small to tiny mammals (including some of the smallest mammals in the world) with conical, elongate and flexible muzzles (or snouts), tiny eyes hardly visible, ear pinnae small but usually evident, front feet smaller than hind feet, tail well-haired with short hairs, each foot having five tiny toes, skull bird-like with ovate braincase and slender rostrum, and zygomatic arch incomplete. Anteriorly it persists as a vestigium, the maxillary process, and the jugal bone is lacking. The anteriormost upper tooth is bicuspate, its lower analog in the dentary remarkably elongated, and usually along each border slightly tetracuspidate. The functional points (apices) of the cusps and crests are usually red-brown unless worn away, the auditory bullae are undeveloped, the tympanic bone ring-like, and the pelage felt-like (short and dense).



Table Ins-2. Body weights of male Scalopus from Wisconsin , after Conaway 1959.  Months Adult Adult Adult Juvenile Juvenile

84

March-April May-July August-November6 May-July August-November10

N

Mean

sd

34 27 117.6 28 107.8

121.5 g 120.6 5.15 95.7 10.79

11.35 14.10

THE WILD MAMMALS OF WISCONSIN

8.75



Sorex cinereus and the larger S. palustris. Spencer Fullerton Baird, 1858. 

Shrews have high metabolism per gram of body weight. In Blarina the metabolic rate is 3.18 cm 2/g/hr, with heart rate of 740-760/minute, and a body temperature of 38o C. (Doremus 1965, Neal and Lustick 1973). In smaller shrews the metabolic rate per gram of body weight is even higher, highest of all in the pygmy shrews Microsorex (Buckner 1964:260). Animals that have such high metabolism need to eat regularly. In winter they must eat to compensate for loss of body heat because their surface area to mass ratio is high. The dense fur is efficient insulation, but a great deal of protection is afforded the shrews by deep snow in the north (under which the temperature is warmer). Shrews are found in Wisconsin in soils having a high content of moisture (Sasse 1978; Getz 1961d). Sorex arcticus prefers marshes and shrub communities, Blarina brevicauda is at home in grasslands or woodlands, Sorex palustris is restricted to stream banks and wetlands, and Sorex (Microsorex) hoyi is an enigma and, although rare, found in diverse environments. Cryptotis parva is probably eradicated from Wisconsin sandy prairies. How to study shrews. The advent of pitfall trapping, i.e., sinking empty 1/2 or 1 gallon cans into soil (the rim flush with the soil surface, soil packed closely against it) in a variety of natural habitats (punching holes in the bottoms in wet soils so the cans will not float up) has led to greatly increased catches of the rarest and tiniest shrews. It is possible to obtain density data, distributional data, and of course, more information on embryo counts, parasites, and so on. By checking the cans regularly in the night, and leaving food in the cans (insects, worms, canned dog food), it is possible to capture shrews alive. That could lead to capture-recapture information if marked shrews are released. A wonderful opportunity exists to keep the rare shrews alive in large enclosures with natural soils and native vegetation.

Key to Wisconsin Species Of Shrews Note: Sorex fumeus ought to be confirmed, an unlikely member of the Wisconsin fauna, and it is not treated herein. The locality of Racine may as well refer to the home of the collector Hoy as to the shrew. It resembles Sorex cinereus, but is recognized by dark underparts, flattened braincase truncated posteriorly, and inner lophs of unicuspate teeth less pigmented. The skull is longer than 17.5 mm. 1

1’

2

2’

3 3’ 4

4’

Tail short relative to the body length, less than 30 mm (1 1/4 in), more than a third of the total length, external ear conch hidden in the fur of the head ............. 2 Tail long relative to the body length, more than 30 mm and more than a third of the total length,ear pinna tiny but visible ....................................................... 3 Size larger (head and body more than 90 mm), tail 18-30 mm, mature skull exceeds 23.0 in length, 5 unicuspate teeth ............... Northern Short-tailed Shrew Blarina brevicauda Size small, about 90 mm or less in head and body length, skull much less than 20 mm, 4 unicuspate teeth .... Least shrew Cryptotis parva Third unicuspate tooth smaller than fourth .............................................. 4 Third unicuspate tooth larger than fourth ....................................................... 5 Size larger, total length 131 or more, pelage dark blackish or slate-gray dorsally, hind feet fringed with hairs, third unicuspate tooth somewhat smaller than fourth ...................................... Water shrew Sorex palustris Size small, total length approximately 91 mm or less, hind foot tiny, never fringed, third unicuspate tooth a minute and inconspicuous disk squeezed between adjoining teeth, anterior teeth (bicusps) spaced apart with expanded medial tines .................................... Pygmy Shrew Sorex (Microsorex) hoyi

TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

85

5

5’

Size small, total length 102 mm or less, length of skull less than 16.5 mm, unicuspate teeth even except diminutive peg-like fifth, rostrum exceptionally slender, cranium slightly arched ................ .... Masked Shrew or Cinereous Shrew Sorex cinereus Size medium, total length greater than 102 (106-121) mm in adults, length of skull exceeds 16.5 mm, unicuspate teeth large, rostrum wide, cranium prominently arched, tricolored pelage (black dorsally, brown, pale brown) in winter pelage .... ...................................... Arctic Shrew Sorex arcticus

Genus Sorex Linnaeus Long-tailed Shrews There are five unicuspate antemolar teeth and the tail is relatively long. Mammae: 6.

Sorex cinereus Kerr Masked or Cinereous Shrew 1792. Sorex arcticus cinereus Kerr. Animal Kingdom, p. 206. Type from Fort Severn, Ontario, Canada 1842. Amphisorex lesuerii Duvernoy. Mag. Zool. d’Anat. Comp. et Paleontol., 1842. 25:33. Type from Wabash Valley, Indiana. 1827. Sorex personatus I. Geoffroy St.-Hilaire. Mem. Mus. Nat. Hist. Paris, 15:122. Type from eastern United States. 1942. Sorex cinereus lesuerii: Bole and Moulthrop. Sci. Publ. Cleveland Mus. Nat. Hist., 5:95. See also Jackson 1961, for southern Wisconsin. 1925. Sorex cinereus cinereus: Jackson. J. Mamm., 6:56.

Sorex cinereus cinereus Kerr The name Sorex by Linnaeus means shrews, and cinereus means gray. The name Cinereous Shrew used by Jackson (1961) and others

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THE WILD MAMMALS OF WISCONSIN



Skull of Sorex cinereus. 

is not entirely appropriate, for the shrew is brownish gray, but it is far more appropriate than “masked” shrew because there is no mask. Besides, Jackson’s classic work on shrews may allow him to set precedence on names for shrews, based on his extensive work on them. Furthermore, the animals called masked shrews recently have been divided into several species. Description. This tiny mammal is one of the smallest mammals in Wisconsin, perhaps a little larger than Wisconsin shrews of the species Sorex (Microsorex) hoyi. The masked shrew has a slender snout, and the rostrum of the skull is correspondingly slender. The tail is relatively long. The bicuspate teeth are hardly separated by expanded tines, therefore nearly adjoined in front, and the four anterior unicuspate teeth on each side are small and evenly aligned (the fifth is peg-like and diminutive). There is no post-mandibular canal in the dentary. The pelage of the masked shrew is brownish gray or dark brown, with paler underparts (grayish white, smoky gray, or buffy white). The feet are brown, and the bicolored tail dark brown above, paler below; in winter, the upper parts are more grayish. Molts April through June, and winter fur is acquired in October (Jackson 1961). The sexes seem similar in size. Some representative external measurements for adults from Outer Island of the Apostle Islands, Brick Creek, Clark Co., and six young from Portage County (with cranial measurements as well) are respectively as follows: 94.0 ± 11, 105.9 ± 4.6, 95.5 ± 3.8; 38.14 ± 1.6, 39.4 ± 2.6, 38.2 ± 3.7; 10.3 ± 1.0,

12.8 ± 1.1, 10.8; wts. 4.63 ± 1.1 g, —, —, N = 6: greatest length of skull 16.7 ± 0.3, cranial breadth 7.48 ± 0.2; interorbital breadth 2.69 ± 0.11 mm. Twenty specimens of various ages from Portage County averaged 16.4 ± 0.2 (16.1-17.1), 7.5 ± 0.2 (7.1-7.8), and 2.7 ± 0.18 (2.5-3.2) mm. Dental Formula. The teeth of the masked shrew number 32; five unicuspate teeth are present. The formula is I 1/1, U 5/2, P 4 1/0, M 3/3. (I = incisor; U = unicusp or “unicuspid”). Geographic Distribution. Jackson (1961) had no specimens from any of the southwestem counties, suggesting this species did not



Maps showing geographic distribution of Sorex cinereus in Wisconsin and North America. 

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occur in these prairie counties. The species has been obtained from most of them, and appears to range throughout the state. Status. The masked shrew is abundant throughout most of the state, and decidedly beneficial in controlling insects. The masked shrew is important in many food chains (see Mortality below), and it preys on injurious insect pests of crops and spruce trees. Habitats. This boreal species ranges southward and westward into the prairies, and is often taken in dense, wet prairies. Usually it inhabits wet forests, swamps, bogs, and marshes. It occurs in many habitats (Getz, 1961d, Long 1974), including some sandy, grassy and forested. The nest of the masked shrew is composed of leaves and grasses, located near the surface of the ground in a cavity, under a log, stump, or rock. The shape about three inches in diameter, with the inner nest scarcely more than one-half inch in diameter. There seems to be a single entrance (Jackson 1961). Foods. A variety of insects, insect larvae, worms, spiders, flesh of mice and other shrews, seeds, and other vegetal material comprise the foods of the masked shrew. Frequencies are insects (65.3%), small vertebrates (7.1), centipedes (6.8), worms (4.3), mollusks (1.4), sowbugs (1.2), vegetal (0.9), Arachnida (0.9), and undetermined (10.9) (Hamilton 1920). The mammals eaten may in some cases be carrion. Whitaker and Mumford (1972) examined stomachs of 50 masked shrews in Indiana finding 26 kinds of foods, mostly larval moths, butterflies, crickets, beetles (adults and grubs), and leaf hoppers. Reproduction. Young-of-the-year masked shrews do not normally breed. Their second year is perhaps the only opportunity. Breeding commences in March and lasts into October. Usually one, but as many as three litters a year, is produced. Males exhibit narrow dorsolateral “flank” scent glands during breeding. They also occur on the flanks of females but are much smaller. There are six mammae. Six pregnant females from central and northern Wisconsin, and one from Upper Michigan, averaged 5.3 (2-9) litter size. They were preg-

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THE WILD MAMMALS OF WISCONSIN

nant on dates from April 24 to October 24. Two lactating females were seen on October 8 and October 18. The young are born pink, naked and blind, after a gestation period of about 18 days. They are about 13 mm long and weigh 0.1-0.3 g (Blossom 1932, Kilham 1951). After 12 days, young weigh as much as 2.8 g each and are haired out. The erupted teeth are not yet visible. Teeth begin to erupt between 9 and 14 days. After 19 days young are weaned and ready to follow the parents about. Buckner (1970) observed parents feeding numerous fritillary butterflies to their young, gathered together in the shade of a log. The butterflies had been sucking water from wet sand. Shrews do not live long in nature, and the populations may be practically categorized as two age groups. These have been classed as I and II, or young and old adults. The youngof-the-year usually have longer skulls, with the braincase more arched. Their teeth are usually less worn. The cingulum or circular ridge around the base of the crown portion of the bicusp in young animals “is oppressed to the dentary” (sic, i.e., the premaxillary, Hoffmeister 1989; Diersing 1980). With increasing age and growth the exposed root increases in length and pushes the cingulum away from the alveolus. The distance seems directly correlated with age, at least in comparing one specimen with another from the same place. Mortality. Sometimes carnivores refuse to eat masked shrews owing to their odor, which probably results from the rectal glands. Weasels, skunks, foxes, badgers, wolves, and bobcats all kill shrews (Murie 1936). Occasionally large frogs catch and eat these tiny shrews, as do snakes and birds of prey (Gould et al. 1964). Even a brown trout caught one in Schoolcraft County, Michigan (Baker 1983). A variety of fleas and ticks infest these shrews (Jackson 1961, Timm 1975). A comprehensive list of parasites was published by Whitaker (1974). Home Range and Density. Jackson (1961) says the home range of the masked shrew does not exceed one-fourth acre (or 1200 square yards). Ozoga and Verme (1968) found Sep-

tember populations contained 40 percent young-of-the-year. In Marquette County (Upper Michigan), Manville (1949) found four shrews per acre (10/ha) in northern cedar swamp, and three per acre (7.5/ha) in black spruce. In Baranga and Marquette counties, Haveman (1973) found 11 per acre (27.5/ha) in spruce swamp, nine per acre (22.5/ha) in bogs, and four per acre (10/ha) in spruce barrens. Anderson (1977) found 93 per acre (240/ha) in hardwoods. Deep frost kills small mammals, both shrews and their prey, and the cessation of reproduction prohibits replacement of shrew populations suffering mortality. Density in shrew populations falls throughout the winter. Remark. Long and Affeldt-Gehring (1995) reported a partially albinistic masked shrew showing the Valais goat color pattern. This pattern of pigmentation of the fur in which the anterior half of the animal is normally pigmented, and the posterior is white, has been reported as developmentally possible in only medium-sized mammals, such as goats. This single record of the Valais pattern in such a tiny mammal may falsify the mathematical rule of Valais color pattern pigmentation and size-dependence (Murray, 1989). Patterns that show bicolored patterns white at each end also were never to be found (but see the Blarina account beyond). To make a long mathematical story short, little mammals, such as shrews, were thought to develop too fast for such a constrained pattern of pigmentation to develop. Additional Natural History. Significant works on masked shrews and other shrews are written by H.H.T. Jackson (1928), Junge and Hoffmann (1981), and Findley and Yates (1991). Geographic variation. There is a single geographic race in Wisconsin. Jackson (1961) referred shrews from southeastern Wisconsin to S. c. lesuerii (Duvernoy), but Hoffmeister (1989) determined its boundary was much farther southward, in Illinois. S. haydeni, which some regard as a distinct species, reportedly occurs together with S. c. cinereus in Iowa and Minnesota.

Specimens examined. Total, 530. Adams, Ashland, Bayfield, Burnett, Calumet, Clark, Columbia, Dane, Door (Rock Island, 1. Pedants Road, north end Washington Island on Lake Michigan, 2. Swenson Road, 1/2 mi. E Jesson’s Place, 3. Jessens Place on Swenson Road 2. Washington Island, 1. Detroit Island, 2. Bailey’s Harbor, 1), Douglas, Florence, Forest, Green, Grant, Iowa, Jackson, Jefferson, Juneau, Kewaunee, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Milwaukee, Monroe, Oconto, Oneida, Ozaukee, Pepin, Portage, Price, Racine, Rock, Rusk, Sawyer, Sauk, St. Croix, Taylor, Trempealeau, Vilas, Washburn, Washington, Waupaca, Wood counties. Other records.— Ashland Co. Apostle Islands including Madeline, Oak, Outer, Raspberry, Rocky, Sand, Stockton and York isles (Kantak, 1981).

Sorex arcticus Kerr Arctic Shrew 1792. Sorex arcticus Kerr. The animal kingdom. p. 206. Type from Fort Severn, Hudson Bay 1837. Sorex richardsonii Bachman. J. Acad. Nat. Sci. Philadelphia. This name also used by Lapham (1853), Strong (1883), Snyder (1902), Hollister (1910), Jackson (1908), and Cory (1912). Type from Saskatchewan. 1858. Sorex pachyurus Baird. Mammals. In Reports Explor. Survey... Pacific Railway Route, 8(l):20. Type from Pembina, North Dakota. A homonym of Sorex Pachyurus Kuster, 1835, from Sardinia.

Sorex arcticus laricorum Jackson 1952. Sorex arcticus laricorum Jackson. Proc. Biol. Soc. Washington, 38:127. Type from Elk River, Minnesota.

The scientific name literally means arctic shrew. The adjectives “tricolored” or “sadTAXONOMIC ACCOUNTS / ORDER INSECTIVORA

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dle-backed” shrew were descriptive names applied in the past. Never in the original description, his revision of the long-tailed shrews or his book on Wisconsin mammals did Jackson ever discuss the meaning of his word laricorum. The Latinized name may be loosely translated as “a denizen of larches” (American tamaracks). This is a fine epithet, for tamarack marshes are a preferred habitat. Description. Arctic shrews are mediumsized, with long snout and long bicolored tail. The body and skull are larger than those in Sorex cinereus (see Measurements). Pelage in summer, and in young-of-the-year, is brown dorsally, slightly paler below; in adults there is a black mid-dorsal longitudinal band extending from nape to base of tail, and the belly is grayish brown. This pattern is tricolored: black, brown, and paler grayish brown. Three specimens in molt were taken from late September to late October. The cranium is arched, never flattened, the unicuspate teeth brightly pigmented on the tips of unworn cusps, the third unicusp tooth is larger than the fourth, the fifth a minute peg. The skull of the water shrew has the third unicusp smaller. The rostrum, though narrow anteriorly, is broader across the cheek teeth. A post-mandibular canal is found in the dentary in S. arcticus. Arctic shrews have trivalent sex chromosomes, X and two Y’s. Females are XX. The

 90

Skull of Sorex arcticus.  THE WILD MAMMALS OF WISCONSIN

diploid number is 29 in males and 28 in females (Kirkland and Schmidt, 1996). Standard external and some cranial measurements are included here from several localities in northern Wisconsin (Drummond, one Ad, F. and Medford 4 Yg and Ad M), respectively: Total length, 116; 114.25 (106119), tail 45; 42.0 (39-45), hind foot 14; 14.5 (12-17), weights 7.0 g; 8.8 (7.8-10) g; greatest length of skull 21.1; 19.8 (19.6-19.9); cranial breadth 9.54; 9.1 ( 9.08-9.11); and breadth across the maxillary processes 7.0; 5.01 (4.93-5.09). From Portage County, 16 Yg and Ad males measured 111.7 ± 0.74, 40.5 ± 5.3, 13.5 ± 1.2,and N = 5 M, age class 2: 19.6, 9.47, and 5.05, respectively. Other measurements are listed in Kirkland and Schmidt (1996) and in Clough (1963). Dental Formula. The dental formula for Arctic shrews is the same as in Sorex cinereus, but teeth are larger. I 1/1, U 5/2, P4 1/0, M 3/3 = 32. Geographic Range. Common in Upper Michigan, but restricted from the Lower Peninsula by Lake Michigan, the Arctic shrew ranges throughout most of the northern counties of Wisconsin, and occurs in southern Dane and Dodge counties (Clough 1960; Lowell Getz, personal communication). Status. The Arctic shrew is seldom common, but lives in remote marshes and wet prairies so that it maintains fair abundance, except where these are drained or polluted. It has little economical importance, except that it feeds on larch sawflies and other forest insect pests. Habitat. Arctic shrews dwell in marshes, the grassy edge of cedar, spruce and tamarack swamps and bogs, stream valleys, and near some lakes. Whitaker and Pascal (1971) found them in old fields in Minnesota. This species seems limited to the boreal, coniferous forest region in North America, in the appropriate marshy and tamarack habitats. In central Wisconsin, I have taken them in dense grassy marsh, quite hummocky, but also where the black soil is level and evident through the grasses. Cedar, alder, tamarack,

and a few spruce were at the edge of the marsh. Clough (1963) also caught them in hummocky marshes. Schmidt (1931) caught one in a sphagnum bog. Little information is available on homes of Arctic shrews. Reportedly the nests are globular “surface” structures comprised of grasses and other vegetation (Clough 1963, Baker 1983). Foods. Clark (1972) found some arthropods in several stomachs of Arctic shrews. Arctic shrews are often snap-trapped with rolled oats and peanut butter. In 62 specimens from Manitoba, the diet was exclusively



Maps showing geographic distribution of Sorex arcticus in Wisconsin and North America. 

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Arctic shrew. P. Kim Van. 1995. 

insects (Buckner, 1964), especially noteworthy the pest larch sawfly. A captive from Stevens Point fed regularly on mouse carcasses, never feeding on dead songbirds. Reproduction. Clough (1963), Baird et al. (1983), and Baker (1983) reported litters as large as ten, averaging seven. Birth occurs in April and May, and occasionally later. Jackson (1961) suggested that September breeding indicated that a female might have two litters each summer. Buckner (1966) found a few female youngof-the-year may breed. This suggests a typical pattern of small mammal breeding in Wisconsin. Arctic shrews have winter carry-overs, which reproduce and may die, and young of the year reproducing later in summer. Nora Lopez-Rivera found an entry in the Hamerstrom’s field journals of a pregnant Sorex arcticus taken 30 April 1979 in the Buena Vista Marsh. It contained 7 embryos. I collected a lactating female 1 mi. E. Jordan Pond on 5 August 1968, and Carl Becker caught one 30 October in winter pelage with teats barely visible. Embryo counts range from 4-9 in central Wisconsin ( mean 6.6, N=10). In Minnesota, near Minneapolis, 113 female Arctic shrews showed evidence of breeding from April (lactation) into September (observed lactation). Reproduction ceased by October. Males were reproductively active from April to August. Young entered the population in June. Most did not breed the first year. Litter size in Minnesota was 7.7+ 0.42 SE, range 5-9 (N=10). Mortality. Nelson (1934) found the remains of an Arctic shrew in a great-horned owl pellet. One dead Arctic shrew observed in central Wisconsin was dropped by a coyote

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on snow. A long-tailed weasel killed one. There are various parasites such as fleas, mites, and ticks reported by Timm (1975), Kirkland and Schmidt (1986), and Whitaker and Pascal (1971). This shrew lives up to 18 months. Home Range and Density. There is no information on home range in Wisconsin Arctic shrews. They may occur in densities as high as five per acre (12.5/ha) (Banfield l974). Clough (1963) estimated densities as 3.5 per acre (8.8/ha). Haveman (1973) found densities to be four per acre (10/ha). Bucker (1966) reported home range based on 79 shrews to be 1.46 acres plus or minus 0.14 acres (0.6 ha). Kent (1983) found in his studies in Clark County, Wisconsin, that Sorex arcticus occurred in Northern Hardwoods and Northern Sedge Meadow. He only trapped approximately 6 specimens in 1979-1980. Although Sorex cinereus and Sorex (Microsorex) hoyi were much more abundant, Arctic shrews were taken along drift fences at the rate of 0.01 (N=3) and 0.02 (N = 3) per day in these two communities. Whereas Kent found S. arcticus rare in these communities, Sasse (1978) found it the most abundant of any of the six shrews present in this same study area, except rare in the Hardwood Forest. In 1976 (6-17 August), Sasse (1978) caught up to 22 specimens per night in Marsh and Shrub communities. The Arctic shrew was the most abundant mammal trapped in Shrub and Marsh communities, exceeding even the prolific meadow vole. I found Arctic shrews abundant in the Jordan Marsh, Portage County, co-existing with Sorex cinereus. Remark. Clough (1963) observed that captive Arctic shrews were docile, never bit, and in nature they are active either night or day. Geographic variation. There is no geographic variation evident in Wisconsin and Upper Michigan. The shrews exhibit constancy in cranial and external characters over a wide range. Specimens examined. Total, 151. Bayfield, Burnett, Calumet, Clark, Juneau, Langlade, Lincoln, Marinette, Marathon,

Portage, Price, Sheboygan, Taylor, Waushara, Wood counties. Other records. Hamerstroms’ Journals, Portage Co.: Buena Vista marsh. Clough, 1963. Jackson, 1961.

Sorex palustris Richardson* Water Shrew “Every individual of this species [Sorex palustris] was either in or at the edge of the water. In the water they swam beneath the surface; encountering obstructions... they crawled up and over these.... one was seen June 30, 1924, making its way up a small stream... it traveled on the ground, but it took to the water where the bank became too steep. Within a few minutes another individual came along, following the path of the first.... Along Manzanita Creek, June 6, 1926, a female was trapped at the opening of a small tunnel at the edge of the stream. This tunnel except for its smaller size appeared like the ordinary surface tunnel of a mole. Active individuals were observed at various times of the day, and on at least five occasions; twice animals swimming after dark were seen by aid of light reflected from a camp fire.... the animals appeared silvery, due to the air [bubbles] contained in their fur .” — Joseph Grinnell, Joseph Dixon, and J. Linsdale. In Vertebrate Natural History of a Section of northern California through the Lassen Peak Region. Univ. California Publs., Berkeley.

Sorex palustris hydrobadistes Jackson 1926. Sorex palustris hydrobadistes Jackson. J. Mamm., 7:57. Type from Withee, Clark Co., Wisconsin.

The name Sorex palustris means marsh shrew. Very seldom does this shrew range away more than 2 m from a stream, lake or *

The nominate race’s type was from “marshes” [of Canada].

standing water in a marsh, hence its vernacular name “Water Shrew.” Description. The water shrew is large for its family, largest of the Sorex in Wisconsin (see Table Ins-3), with a long tail, long pointed nose, hind foot broad and fringed with stiff hairs as an adaptation to swimming. The cranium is large, broad and flattened; rostrum narrow but abruptly becoming broader spanning across P 4/ to P4/ or M 1/1. The third unicusp is smaller than fourth. The pelage, especially of the dorsum, of the water shrew is slate gray to black, and usually blackish. Underparts of head, body and tail silvery gray to brownish gray. There is an iridescent purplish sheen on the dorsum in bright light (Baker 1983). Molt is observed on specimens in July-late August and early January-March, suggesting two molts per year (Jackson, 1928). External measurements of seven Sorex palustris adults from Seney Nat. Wildlife Refuge, Upper Michigan, and USNM specimens from St. Germain, Vilas Co., 1; Basswood L., Iron River, 1. Danbury, 2. Mercer, 1. Total length, 148.3 ± 5.2 (142-156), length of tail, 65.7 ± 3.6 (62-73); 19.25 ± 0.89 (18-20). The sample size was N = 9. One adult weighed 10.3 g. From several localities in northern Wisconsin, 3 adult males and 7 adult females averaged, respectively, as follows: 152, 150 ± 5; 76, 67 ± 1.4; 21.7, 18.57 ± 0.8; —, 11.91 ± 0.95 g, and five adult females aaveraged in cranial measurements 21.42 ± 0.39; 10.2 ± 0.46; and 5.9 ± 0.21 mm. Dental Formula. The dental formula is the same in Sorex palustris as in Sorex cinereus. DF = I 1/1, U 5/2, P4 1/0, M 3/3 = 32. Geographic range. Occurs throughout the Upper Peninsula of Michigan ranging southward in Wisconsin as far as Portage County. Status. An interesting and poorly known boreal species, the water shrew is chiefly insectivorous and, if not beneficial, certainly harmless to humankind. In Portage County the shrew has seemingly disappeared from some former habitats (e.g., Hay Meadow Creek), I TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

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Skull of Sorex palustris. 

suspect from the effects of insecticides. Possibly the use of toxins, including fish management poisons, may adversely affect these semiaquatic forms. Seldom abundant in any place, the small numbers in museums suggest rarity. Jackson (1961) observed only 10 specimens in all the collections he studied. Our collection contains only 22 Wisconsin specimens. Lacking evidence to the contrary, the species may be regarded as in peril. Management of streams and wetlands, therefore, should include this species for protection. Habitat. The water shrew dwells at the edge of streams, bogs, lakes, rivers, and standing water in marshes and swamps. It favors rocky, log-strewn cold-water streams, with numerous crevices and overhanging banks, and bordered by boreal woodlands (Borell and Ellis 1934, Conaway 1952). This animal forages on the banks, swims in the water, walks on the bottom, and runs across the water tension of still water (aided by light weight, large feet and bubbles in the fur). Jackson (1961) reports four water shrews from sphagnum and swamp laurel (Kalmia glauca) accessible to water near Rhinelander. In western Montana, from the distant race S. p. navigator, Conaway (1952) made a fine study on this poorly known species. The habitats he observed were always near cold-water streams with rapid currents, running through boulders, crevices, and stony areas. The vegetation along the water included liverworts, mosses, green and sidebell Pa-

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rola, baneberry Actaea rubra, bearberry Arctosphylos, and water cress Rorippa. The nearby forest was fir. In Canada I have taken the water shrew from the stony beach of the rushing outlet of a lake, with only a few grasses growing there, and in central Wisconsin from the black muddy sand along shallow creeks in marshy and swampy places, where the grasses and jewelweed were dense and tall. Little information is available on the burrows of water shrews. One nest was found in a beaver lodge (Seigler, 1956). The nest is about four inches in diameter, made of twigs and leaves. Bankside burrows are used for security, probably as homes (see quote preceding this account). Foods. The water shrew feeds chiefly on invertebrates, aquatic insects, water spiders, snails, small fishes, and on occasion vegetal material (Hamilton 1930, Whitaker and Schmeltz 1973, Buckner and Ray 1968, T. Clark, personal comm.). Buckner and Ray (1968) found carabid beetles the chief prey, with larvae of Lepidoptera and Hymenoptera, snails and other insects. In Montana, Conaway mentions insects in 49 per cent of the stomachs examined, and the chief foods were insects, a few planarians, and a little vegetation. Three shrews had fishes, either scales in the stomach or remains in the mouth. His captive water shrews also caught tiny fish. Occasionally he found mouse hair in a stomach, one contained hair of a nearby eviscerated water shrew. Reproduction. Very little information is known for water shrews in Wisconsin. The breeding season extends usually from January through August. Jackson (1961) suggests the gestation period is 21 days. Several litters, usually of six offspring (3-8) may be produced in a season. Young appear in the population by July, and probably breed their second year. The life span may not extend beyond 18 months (Conaway 1952). A specimen taken near Stone Lake, in Sawyer County, had 3 embryos measuring 5 mm in crown-rump length on 9 April 1969. Spiegler (1956) found four immature

water shrews in a water shrew’s home in the sticks of a beaver lodge (May 1954). They weighed 6.0-6.9 g (mean 6.4), and measured 72-75 mm in length (tail 24-27 mm). Conaway (1952) reported and reviewed reproductive records of water shrews, finding that in Montana the males begin spermatogenesis in January and February. Females show ovulation and lactation in March and as late as August. Three young females were breeding in June, and one was pregnant. No young males were observed to be sexually active. Old males were usually show-



Maps showing geographic distribution of Sorex palustris in Wisconsin and North America. 

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ing sperm development, or at least some stages of gametogenesis, after the winter. In Montana the streams were usually open in winter, and the shrews were active under ice shelves, but seldom on the snow. Being active, perhaps reproduction was not impeded much by winter. In any case, some embryos appeared in February. Altogether, Conaway’s records of litter size ranged from 5 to 8, with a mode of 6, and one female showed the transfer of blastocysts to the opposite uterine horn (5: 1 to 3: 3). Conaway (1952) found only two age classes in water shrews. His age classes were based on toothwear studies, and related to reproductive maturity. Mortality. Jackson (1961) listed predators that occasionally kill water shrews as weasels, garter snakes, and possibly hawks, owls, mink and large fishes, including trout (Doutt et al., 1966). Fleas, ticks, and mites are reported by Timm (1975) and Whitaker and Schmeltz (1973). Conaway (1952) found two fleas, Neactopsylla and Corrodopsylla, two mites Hirstionyssus and Euphagamogamasus, 4 species of nematodes including Capillaria, and two tapeworms Hymenolepis and Tetrahyridium. Home range and Density. Little information is available for Wisconsin water shrews. Buckner and Ray (1968) retrapped a shrew in Ontario six times, from five traps, providing an estimate of home range as 0.8 acres. Another was captured four times, providing an estimate of 0.5 acres. The first was taken in August, the latter in September. Geographic Variation. None was observed in Wisconsin. Specimens examined. Total 27. Bayfield, Clark, Forest, Langlade, Lincoln Marinette, Portage, Sawyer, Taylor, Vilas counties. Jackson’s (1961) records were examined, and also were mapped for comparison of range then and now. Vilas Co.: Lake St. Germain 1. Bayfield Co: Barswood Lake, 1. Burnett Co.

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Subgenus Microsorex Pygmy Shrews The genus Microsorex was relegated to the genus Sorex and given subgeneric status by Diersing (1980). Some students (e.g., Junge and Hoffman 1981, and others) have followed him in this arrangement, and others (e.g., Hall 1981) have not. Long (1972a) mentioned the utility of the name, meaning in Latin “little shrew” or shrew-mouse (versus “shrew” or shrew mouse). That is rather appropriate for possibly the smallest terrestrial mammal on earth. Do the pygmy shrews belong to a separate genus or under the umbrella of Sorex spp? The answer is not straightforward. Diersing (1980) considered the Microsorex as one end of a transition, being an extreme both in diminutive third unicuspate teeth, and in hypertrophy of an inner “tine” or style along each upper incisor for about half its exposed length. The tines are often worn away in older shrews (e.g., UWSP5014). He might have added another specialization, on the two anteriormost unicusps, which is the serial development of tiny but distinct internal cuspules on the so-called “unicuspate” or “unicuspid” teeth, set off from the apices of these teeth where the ridge from the apex meets the cingulum. This trait is developed also in Blarina. This same evidence can be taken instead as evidence for generic status for these shrews,



Sorex (Microsorex) hoyi. Philip Wright. Courtesy of J. Paradiso & the Johns Hopkins Press. 

for in these trenchant characters Microsorex is not intermediate (Table Ins-3). Some shrews with a diminutive third unicuspate tooth, such as Sorex palustris (in Otisorex) and Sorex merriami (in Sorex), essentially lack tines on the bicusps. Repenning (1967) and Guilday (1962) mention another character, reduced entoconid height relative to the hypoconid, distinguishing ancient fossils of pygmy shrews from Sorex. There is no hybridization between Sorex (Microsorex) hoyi and other Sorex, although opportunity exists, and indeed the two kinds have been separated since the mid-Pleistocene (Hibbard 1944). The crux perhaps is the importance of the peculiar third unicuspate tooth. Is it really the extreme form of a transition? Or are diminutive third unicuspate teeth in other soricine shrews a parallel in evolution? They retain pigmentation seen serially in the teeth, whereas in pigmy shrews the disk has no pigment, no inner loph, no function at all except, perhaps, as a spacer. In the evolution of crowded teeth and exceptionally tiny body form spacing seems adaptive, and the “tines” of the upper incisors serve the same use. The disk tooth seems functional, not vestigial, and is seldom lacking, except in an observed specimen (UW-SP 648). In this abnormal specimen the disk is lacking along with the adjacent tooth adjoining anteriorly, on one side only, and this anomaly may have resulted from an injury. Feldhamer and Stober (1993) also reported a missing tooth



Table Ins-3. Characters of Wisconsin shrews: Blarina, Sorex, and Sorex (Microsorex) hoyi. 

Species

“Tines”

4th < 3rd Inner

Blarina S. arcticus S. cinereus S. palustris S. (M.) hoyi

None Small Small Minute Large

No* Yes Yes No No**

Cuspules Hypoconid high Large Small Medium Medium Medium-large

*U3/ is pigmented but approaching discoid form; **U3/ is an unpigmented disk.

Yes No No No Yes

possibly resulting from injury. The disk is a specialization, altered beyond the ancestral typical unicuspate tooth. In company with the other advancements, Microsorex seems differentiated from other Sorex. The homolog (or analog) in Blarina (see below) suggests the origin of discoid form.

Sorex (Microsorex) hoyi Baird Pygmy Shrew 1858. Sorex hoyi Baird. Mammals, in Reports Explor. Surv. for a Pacific Railway Route. Vol. 8(partl):32. For 1857. Type from Racine, Racine Co., Wisconsin. Also, Diersing (1980), Long (1999a). 1858. Sorex thompsoni Baird. Mammals, in reports Explor. Surv. for a Pacific Railway Route. 8(l):34. See Long (1972a). Type from Burlington, Vermont. 1925. Microsorex hoyi intervectus Jackson. Proc. Biol. Soc. Washington, 38:125. Type from Lakeland, Oconto Co., Wisconsin. 1901. [Microsorex] hoyi: Elliot. Field Columb. Mus. Publ. 4 Zool. Series, 2:377.

Sorex means shrew, and the name Microsorex means little shrew. Philemus R. Hoy was a well-known amateur scientist from Racine, who sent a specimen to Dr. Fullerton Baird, who subsequently named the species in Hoy’s honor. Concerning “pigmy” versus “pygmy,” Hall’s students, except in this case, always went with American usage instead of a British or Canadian spelling. Jackson (1961) and (1972) also followed that convention, pigmy over pygmy, but Hall himself used “pygmy,” and others followed suit. An appropriate French saying is, Je crois il va du blanc au noir, il est petit n’est ce pas? Description. Sorex (Microsorex) hoyii is a tiny shrew with long tail, a pointed but relatively broad snout, tiny eyes and feet, and five toes on each foot. It very closely resembles the masked shrew in size, form and color, but is slightly grayer dorsally, tail shorter, TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

97

and muzzle or snout less slender. The skull is more flattened, especially in older shrews, with rostrum broader, cheek teeth with entoconid reduced, compared to the hypoconid (posterior margin of the molar). The most trenchant character is the third unicuspate tooth, which is minute and hardly visible, squeezed between adjoining teeth as a wedge or disk, somewhat tilted and unpigmented. Difficult to observe, even with a dissecting microscope, the disk is practically invisible to the naked eye. The tiny fifth unicuspate tooth is also small and practically hidden by the tooth posterior to it, so that it is often said that when one casually examines the unicusp row only three teeth can be seen. In Sorex cinereus four (all except the fifth) are visible and they are rather even in form. In the pygmy shrew, the first and second unicuspate teeth are even, and conspicuous, the third cannot be seen, the fourth is much smaller than the anterior two, and larger than the fifth. The patterns can be suggested by the following: cinereus ////o and in Microsorex ll.lo where “o” is the tiny fifth unicuspate tooth and the period is the disk. This pattern can be discerned with careful examination with the naked eye. Additionally the gap between the upper bicusps is filled, except in some old specimens, with inner extensions called ‘tines.’ These spacers are elongate, extending along and adjoined to each inner bicusp. The pygmy shrew is brown or brownish gray above with bicolored tail, underparts

 98

Skull of Sorex hoyi.  THE WILD MAMMALS OF WISCONSIN

grayer, sometimes whitish or buffy, and often tinged about the throat with rusty brown. Molt occurs in late April-May and in OctoberNovember (Long 1974). Wisconsin pygmy shrews do not belong to the dwarf races of the subgenus Microsorex (Long 1972; Whitaker and Mumford 1972), but the Racine specimens were extremely small. One winter specimen, found by Dr. Robert Freckmann, in Stevens Point, may be the smallest adult, terrestrial mammal ever found. Weighing only 1.8 g, and having teeth extremely worn (indicating great age), the tiny specimen may have lost some weight by desiccation, although it was found frozen in ice. Measurements and weights are as follows for four adult males from Bayfield, four from Drummond, and one from Pray: Total length, 81.25 (80-84), 85.5 (84-88), 94; length of tail 29.5 (28-31), 29.8 (28-31), 31; hind foot 9.75 (9-10), 9.75 (9-10), 9; 5.4 g (N = 1), —, 2.9 g; greatest length 15.6, — , 15.4; interorbital breadth 2.8, —, 2.9; cranial breadth 6.55, —, 6.6 mm. Adults weight about 4-4.5 g, in Wisconsin, but from the same race Jackson (1928) reported 2.1 and 2.9 g, from Elk River, Minnesota. Dental Formula. I 1/1, U 5/2, P 4/ 1/ 0, M 3/3 = 32. The disk is a permanent tooth. Geographic Range. The pygmy shrew probably is restricted from hot, dry prairies in the west and south, where few specimens have been found. Specimens formerly referred to M. thompsoni (Long 1972a) were referred to S. hoyi hoyi (Diersing 1980), and in this I do not demur. Status. In many parts of the range of pygmy shrews the animals are spottily distributed, low in density, and over most of the vast range extremely rare. Some workers have taken them repeatedly with Sorex cinereus, but in the low ratios of say 50:1, or even 100:1. In southern Wisconsin the pygmy shrew is even rarer; only a few specimens have ever been caught. Their habitats are disturbed by man so much the species seems likely extirpated there. In central and northern Wis-

consin the shrew is uncommon but habitats for the species are being devastated by “urban sprawl”. Habitat. This boreal shrew inhabits most northern habitats (except the frozen tundra), occurring in a variety of climax forest and even seral habitats. Not found in dry prairies, it does occasionally occur in dry grassy areas, in tamarack, cedar, alder, and spruce swamps, with sedge grasses or sphagnum, in marshes, grassy meadows (dry, wet, even mowed), on stream banks, in coniferous and mixed coniferous forests, and even dry woodlands not too far from water. Beech-maple



Maps showing geographic distribution of Sorex hoyi in Wisconsin and North America. 

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forest, pine barrens, and sphagnum bogs are all inhabited on occasion by pygmy shrews. Usually the habitat is near a stream or standing water, and soils are patchily wet and dry (Long 1972c). The use of pitfall traps provided a precious number of modern-day specimens to be accumulated. In Manitoba, the pygmy shrew displayed a wide tolerance for diverse habitats, except tundra, arid grasslands, and cultivated fields. They were collected in fen, marsh, bog, and shrub thickets, also deciduous and coniferous forest and savanna (Wrigley et al., 1979). One was taken in “prairie.” No information is available on dens of the pygmy shrew. It is said to dwell in burrows, under a rock, or in roots of fallen trees. A captive shrew made several nests of cotton, open at both ends. Foods. Little information is available. Captive pygmy shrews have fed on flesh of mice, other shrews, earthworms, but more likely in the wild they feed on small insects and insect larvae. The tiny, southernmost race S. hoyi winnemana fed on insect larvae, spiders, beetles, and ants (63 stomachs) according to Whitaker and Cudmore (1988). Haveman (1973) found flies, beetles, other insects, spiders and a little sphagnum moss in the diet of our race, observed in Upper Michigan. Reproduction. In central Wisconsin pygmy shrews, there is no evidence of breeding more than once in the year. The only pregnant female was taken rather late (July), and most females were not pregnant at all. Dr. Philip Wright (personal correspondence) mentioned to me evidence that in Montana one female seemed to be in the process of producing a second litter while nursing an earlier one. Pregnant females carrying 2-7 embryos have been reported from 8 June to as late as 3 August (Jackson 1961, Long 1976, Scott 1939, and Osgood 1938). Hoffmeister (1989) mentioned a Manitoba specimen lactating in September. If breeding regularly commences in June and continues into September, more than one litter per year may be possible, but

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THE WILD MAMMALS OF WISCONSIN

in Wisconsin that would seem infrequent. Possibly obscuring the problem, many females caught may be young-of-the-year, and too young to breed. Feldhamer et al. (1993) examined toothwear to age specimens of Sorex hoyi, considered comparable to shrews of known age of other species. The age was subtracted from the date of capture to estimate birth date. They found southern pygmy shrews breeding in all months of the year with a peak of breeding in late winter. Using their method (but excluding old shrews), I estimate in Wisconsin the pygmy shrews breed from June to September, occasionally later, with peak reproduction in July. Most females I examined were of youngof-the-year shrews. In lower Michigan, none of 18 young-of-the-year pygmy shrews (August 19-23) were sexually active (Baker, 1983). Mortality. House Cats catch pygmy shrews but seldom eat them because of the rank odors from anal and flank glands. Other predators include brook trout, garter snake, and hawks (Cahn 1937, Long 1974). Fleas, mites, a tick (Ixodes), and hymenolepidid tapeworms parasitize pygmy shrews (Buckner and Blasko 1969, Long 1974). Home Range and Density. Long (1974) caught four pygmy shrews in about half an acre in central Wisconsin over a period of several weeks. The collecting was terminated on behalf of the rare shrews. Wrigley et al. (1979) studied the habitats and abundance of Sorex hoyi in Manitoba. The shrew was most abundant in aspen forest and black spruce forest, two taken from tree-line habitats. In central and northern Wisconsin the pygmy shrew is locally more abundant than that in some places, even outnumbering masked shrews. Geographic Variation. Jackson (1925) named pygmy shrews from northern Wisconsin as Microsorex hoyi intervectus. He used the vernacular names “Northwestern Pigmy Shrew” and “Intermediate Pigmy Shrew.” Supposedly it had a broader and higher braincase than the nominate race hoyi. Baird’s

excellent illustrations (1858, for 1857) of his holotype for the nominate race reveal that the description of the nominate race was misconstrued; it agrees closely with that of shrews from northern Wisconsin. I (1972a) placed intervectus in the synonymy of Microsorex hoyi hoyi (= Sorex hoyi hoyi). Specimens examined. Total 49. Adams, Bayfield, Burnett, Clark, Jackson, Juneau, Manitowoc, Portage, Price, Sawyer, Winnebago counties.

The lower anteriormost antemolar tends to be only bicuspidate instead of tetracuspidate, and dorsally the red-brown labial walls are nearly straight.

Blarina brevicauda (Say) Northern Short-tailed Shrew 1823. Sorex brevicaudus Say. In Long. Account of an exped. Rocky Mts., 164. Type from near Blair, Nebraska. 1858. Blarina brevicauda: Baird. Mammals, in Re-

Genus Blarina Gray Short-tailed Shrews The dentition in Blarina resembles that of Sorex in many respects. Large size notwithstanding, the short-tailed shrews are rather typical shrews. The ear is a narrow slit hidden by fur of the head, and in this trait as well as having a relatively short tail Blarina resembles Cryptotis. Doubtless related to its size and strength, the skull of this semi-fossorial predator is robust, broad, with prominent ridges and sharp lateral processes on the braincase for muscle attachment. Such processes are not developed on the papery thin and smooth skulls of smaller shrews. The fifth unicuspate tooth in Blarina is tiny and hidden between the adjacent teeth on either side, but it is pigmented and pointed like the others. There is a crista extending from the apex to the inner cingulum. On the other unicuspate teeth inner pronounced cuspules are present. It is, therefore, slightly inacurrate to refer to these complex upper teeth as unicusps or unicuspids. The third unicusp is smaller than the fourth, extremely compressed as a sulcate disk, i.e., concave posteriorly to accommodate an anterior ridge protruding from the fourth. In this specialization and several others (Table Ins-3), for one the remarkable cuspules on the unicusps, there is some resemblance to Microsorex. The dentary is stout and deep to accommodate exceptionally large molars. There is a post-mandibular foramen.

ports Explor. Survey . Pacific Railway Route. 8(l):42.

The name Blarina, proposed by J. E. Gray in 1838, may refer to Blair, Nebraska, near the type locality. The specific part of the binomen literally means short tail. Because of its extensive burrowing and large size the mammal is often called the “mole shrew” or confused with moles. The burrows may descend half a meter below the soil surface in friable soil (George et al., 1986). Description. The trenchant characters for the short-tailed shrew are given for the genus above. Thorn-like lateral processes on the cranium, one on each side, and large size of the skull identify the skulls of Blarina from those of other shrews. Compared to other Blarina, the northern short-tailed shrew has a larger, stockier body, bigger feet, and a somewhat blunt or truncated nose. Blarina brevicauda has a karyotype of 2N=48 to 50 chromosomes



Skull of Blarina brevicauda. 

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(George et al. 1986). Females have six mammae. In Wisconsin, B. b. brevicauda is typically larger and paler than B. b. kirtlandi. The color of Blarina is slate black or grayish black, often heavily suffused with dull brown. The undersides are similar but paler. Molt occurs at least once (in August and July) and is reported to occur in early winter (Jackson 1961). Northern short-tailed shrews are about four or five inches in length, and the tail is approximately an inch. Weights vary to 30 g. See Table Ins-4. (Cahn 1937, Long 1974). Dental Formula. I 1/1, U 5/2, P 1/0, M 3/3 = 32. Geographic Range. The Northern shorttailed shrew occurs throughout Wisconsin, doubtless in every county. The nominate race is restricted to the Mississippi and the St. Croix drainage basins and the Wisconsin River valley, excluding Dane County and localities southward. Status. The short-tailed shrew is decidedly beneficial to man. It also is important in



food chains of many predators (George et al. 1986, Baker 1983). The animal is common, but contrary to what is often said (e.g., see Jackson 1961), is not the most abundant Wisconsin mammal. Habitats. This ubiquitous shrew is found with varying densities in most terrestrial habitats of Wisconsin. It especially prefers woodlands with open floors, thick leaf litter or wellrotted humus, and an abundance of rotted logs and stumps. Not only in dry woods (e.g., the summit of Mosquito Hill near Green Bay), this species flourishes in wet, black soil of cedartamarack-spruce swamps. The nest is made of various plants, even hair. The tunnels extend either way from the nest and may be directed downward. One tunneled under our garage door and stole pieces of dog food from the nearby food pan, carrying the pieces one by one to a garden hose, then dashing to the burrow entrance. It would tug “mightily” and with surprising strength to pull food pieces from our fingers. Blarina caches foods in its burrow.

Table Ins-4. Populations of Blarina and Cryptotis. Cryptotis were from Wisconsin and Illinois.  Total l.

Tail l.

Hind Foot l.

Greatest l. Skull

Zygomatic breadth

Br. Max. Processes

Cranial Depth

Blarina brevicauda kirtlandi from Portage Country Adult F N=17

115.3±9.7

22.5±2.6

14.44±0.81

23.67±0.48

12.56±0.31

7.93±0.24

6.59±0.25

Adult M N=10

108.4±7.25

19.63±4.7

10.56±2.07

23.57±0.58

12.28±0.35

7.89±0.28

6.52±0.18

Old Ad. F N=3

108 – 101

25 – 22

14 – 14

23.9 23.7 –

12.8 12.5 12.3

7.4 8.6 7.6

6.55 6.45 6.10

Adult F N=33

118.09±9.2

23.48±2.6

14.65±1.2

24.27±0.5

12.77±0.35

8.04±0.28

6.63±0.26

Old Ad. F

116 112-120

23.8 22-25

13.75 13.14

23.7 23.6-22.9

12.75 12.6-12.9

8.03 7.75-8.35

Blarina brevicauda brevicauda from West, Wis., Mississippi Valley

Cryptotis parva #6506 Sauk Co. F. Alc.

63

16

9.7

–

–

–

–

Illinois N=4

60-94

15-19

9-11

16.1

3.4

7.4

–

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THE WILD MAMMALS OF WISCONSIN

One day we found it drowned in the dog’s water pan (Museum specimen no, 5946). Other nest descriptions for Blarina are provided by Shull (1907) and Hamilton (1929). Shull’s nests, ranging from 12-15 cm in diameter, were comprised of tree leaves, grasses, sedges, nettle, goldenrod, and other plants. Hamilton found nests under rotting logs. One nest was of elm leaves and another of maple leaves, 30 cm below the surface. It contained seven young. Foods. Blarina, especially the larger species, prey extensively on small mammals and even small snakes. The saliva is a powerful



Maps showing geographic distribution of Blarina brevicauda in Wisconsin and North America. 

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digestive fluid for insects, and toxic to mice and other small vertebrates (Martin 1981, Pearson 1942, Lawrence 1945, Jeuniaux 1961, and Thomasi 1978). The bite may be considered weakly venomous to humans. Jackson (1961) presents a fascinating account by President Theodore Roosevelt of a shorttailed shrew killing a pine vole and a garter snake. Hamilton (1930) described an attack on a meadow vole lasting 10 minutes. The diet is chiefly insects and other invertebrates (crickets, moths and caterpillars, beetles and grubs, spiders, millipedes and centipedes, sow bugs, snails, worms, and also seeds and other vegetal material (De Byle 1965, Eadie 1949, Hamilton 1930, Ingram 1942). Some insects, such as the larch sawfly, are forest pests. Reproduction. Two or three litters may be produced by a mother Blarina in one growing season (Timm 1975). Seldom does a shrew live over a few months. One lived in captivity 27 months (Baker 1983). Young-of-the-year may breed in the first year (as did Mus. No. 6062, June 15, 5 embryos), and after the long winter only 6 percent of carry-overs live to produce a second litter (Pearson, 1944). I have only two records of pregnancy (each 5 embs). Hoffmeister (1989) only had six records for the southern race (mean number of embryos 5, range 2-7). He suggested that students do not carefully look for embryos. Possibly the females stick close to their burrows when pregnant and are seldom caught. Nowak and Paradiso (1983) report the litter size as usually 5-7 but it may number as high as 10. After a gestation of 21 to 22 days, naked helpless young are born measuring 22 mm and weighing about 0.8 g. After 17 days the furred young move in and out of the nest. They are weaned at 25 days (Blus 1971). Mortality. Although an unpopular food for carnivores owing to odors from the anus and flank glands, the short-tailed shrews are important in the food chains of many predators, including weasels, badgers, foxes, fishers, striped skunks, bobcat and house cat,

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ring-billed gull, five kinds of owls, red-shouldered hawk, water snake, even fishes (brown trout, green sunfish, largemouth bass). The great horned owl is a very important predator feeding on this shrew in Wisconsin (Errington et al., 1940). Doubtless many shrews are killed in winter by deep and enduring frost and consequent food shortage. Spring floods may also take a toll. Fleas, mites, chiggers, and even beetles (Leptinus) are ectoparasites (Jameson 1950, Moore 1949, Timm 1975, Whitaker and Mumford 1972, Scharf and Stewart 1980, and Wrenn 1974). A comprehensive review of parasites is provided by George et al. (1986). Home Range and Density. Especially in thickets and woodlands, throughout Wisconsin, short-tailed shrew densities may be high, leading Burt (1946) and Jackson (1961) to assume the species is the most abundant small mammal in the Midwest. My studies suggest that the meadow voles (Microtus pennsylvanicus) is much more numerous in meadows, weedy and grassy prairies, and marshes, especially in northern counties; and the white-footed mouse (Peromyscus leucopus) is much more abundant in the sandy and shrubby habitats of southern, western and central Wisconsin. Blarina usually ranked second or third in relative abundance with these two species. Jackson and I have two independent tallies of museum specimens from Wisconsin: Blarina. Jackson 393, Long (herein), 376; Sorex cinereus 329, 398; Peromyscus leucopus 537, 1,029; and Microtus pennsylvanicus 567, 548. These ratios, accurate in April 1991, probably have not changed. A Museum Index (Numbers of specimens preserved) is skewed in favor of the less common because one does not prepare all the common specimens. Nevertheless, Blarina is abundant and widespread in Wisconsin. On the Upper Peninsula of Michigan, Manville (1949) found 0.3 to 3.0 short-tailed shrews per acre in May (0.75-75/ha), and 8.5-

11.6 per (21-29/ha) acre in June, in Marquette County. Haveman (1973) found 19 per acre (47/ha) in hardwoods, 7 per acre in spruce swamp, and 5 per acre in bogs. Getz (1961d) found moisture important for any high densities. Nowack (1991) reported the density to vary from 3 to 30 per ha. The home range was 0.2-0.8 ha. Remarks. Specimen No. 5171, from King, Waupaca Co., has a pelage basally light plumbeous gray; distally the hairs become even paler with a buffy, yet silvery-white suffusion. There are some darker undertones showing in the fur of this nickle-colored shrew. The feet and tail were pale grayish tan, and the tip of the nose was black. A specimen (Mus. No. 7816) taken 30 Sept 1994 in Stevens Point seems of the Himalayan (see above) color pattern, as described in Sorex cinereus (see Long and Affeldt-Gehring, 1995). The muzzle is gray all around and including the eye. On either side gray is expressed in small patches above the ear canals. All four feet are gray. The tail is gray and around the base is a grayish tone. The soles of the feet and the lips and nose were pink. Most of the body was pure white. Eight days later, Mr. Dominic Berna, who lives on the same (Stanley) Street, brought in another, so closely resembling the first that surely the two were siblings. The distance between the captures was less than a quarter mile. The first shrew was trapped in a kitchen, with one normal colored Blarina. The second was trapped in a tool shed. Short-tailed shrews do not seem to be cannibalistic on other living Blarina, at least the near neighbors, and often they are found living together. Males probably search females out by smelling anal and body odors. The male has a distinct flank gland (with unknown function) prominent in the breeding season. Agonistic threats are territorial displays, and pulsating calls of high frequency are emitted as the animal searches about (unfortunately for the shrews, it may be heard by owls). These regularly emitted calls may aid in orientation.

Blarina brevicauda brevicauda (Say) For synonomy of the nominate race, see Blarina brevicauda (Say) above.

Range. Western counties in the proximate Mississippi River drainage, and including the lower Wisconsin drainage. See Map. Measurements. See Table Ins-4. Jackson (1961) ascribed larger shrews from western counties to the nominate race, smaller shrews eastward to B. b. kirtlandi. He believed males were larger than females. Measurements are given in Table Ins-4. Specimens examined. Total, 81. Ashland, Barron, Bayfield, Buffalo Co.: Cochrane 1. Burnett, Clark, Douglas, Grant, Iowa, Jackson, Jefferson, La Crosse, Monroe, Price, Richland, Sawyer, St. Croix, Taylor, Trempeleau, Vernon, Washburn counties. Other records. Ashland Co.: Apostle Islands including Madeline, Oak and Stockton isles (Kantak, 1981).

Blarina brevicauda kirtlandi Bole and Moulthrop 1942. Blarina brevicauda kirtlandi Bole and Moulthrop. Sci. Publ. Cleveland Mus. Nat. Hist., 5:99. Type from Holden Arboretum, Kirtland Twsp, Lake Co. Ohio.

Range. Eastern counties outside the proximate Mississippi River drainage, but including part of the Wisconsin River drainage. See Map. Specimens examined. Total, 294. Adams, Ashland, Columbia, Dane, Dodge, Door, Fond du Lac, Forest, Iron, Juneau, Kenosha, Kewaunee, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Marquette, Menominee, Milwaukee, Oconto, Oneida, Outagamie, Portage, Racine, Sheboygan, Vilas, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood counties. TAXONOMIC ACCOUNTS / ORDER INSECTIVORA

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Genus Cryptotis Pomel Least Shrews This diminutive prairie shrew is characterized chiefly by its small size and exceptionally short tail. The short row of unicuspate teeth has only four, the posteriormost being a tiny peglike tooth practically hidden from view. Superficially the antemolar teeth resemble those of Microsorex, because the tiny, disk-like tooth in the Microsorex is difficult to see. Both shrews show three of the teeth, and a posterior fourth is hidden, a small peg. The molars in Cryptotis have high crests in unworn teeth. On the upper unicusps there are prominent cuspules, as in Blarina and to some extent in Microsorex. All the other shrews in Wisconsin have 32 teeth, but Cryptotis has only 30. The ear is hidden in the fur of the head. The lower anteriormost tooth is well developed but never tetracuspidate to my knowledge. The outer rim is nearly straight-sided.

Cryptotis parva (Say) Least Shrew 1823. Sorex parvus Say. In Long, Account... Rocky Mts., 1: 163. Type from Missouri River, Washington Co.: Nebraska. 1842. Brachysorex harlani Duvernoy. Mag. de zool. de Anat. Comp. 25:40. Type from New Harmony, Indiana. 1858. B[larina]. eximius Baird. Mammals. Reports Expl. for a Pacific Railway Route. 8:52. Type from DeKalb Co., Illinois. 1912. Cryptotis parva: G. S. Miller, Jr. Bull. U.S.

whitish or grayish, and the tail bicolored (brown above, paler below). Geographic Range. The three known Wisconsin specimens of Cryptotis are from three southern counties. It should occur in marshes and weedy prairies farther southward. Status. The least shrew is possibly extirpated in Wisconsin. Always rare, no least shrews have been obtained in Wisconsin since 1944. This shrew should be reintroduced in the Wisconsin fauna, into preserved and restored prairies in southern and western Wisconsin. The species, although one of our rarest mammals, is decidedly beneficial to humankind. Habitat. The least shrew prefers grassy prairie or grassy and weedy old fields, broomsedge, briers, cultivated fields, grassy meadows, open woods and, rarely, orchards. Herbaceous ground cover may be more important than soil type (Whitaker 1974). Little information is available on homes for least shrews. Jackson (1961) reports from other studies that the nest is globular, about four or five inches in diameter, composed of dry grass or leaves. There are usually two openings into the nest, which is sited under a rock or log, and sometimes underground at a depth of four or five inches. From Texas, Broadbooks (1952) described a nest found under a sheet of corrugated iron, about 100 m from a cat-tail marsh. About 7 inches in diameter, and 2 inches high, the nest was comprised of old willow leaves. An opening from a short tun-

Nat. Mus., 79:24.

The name Cryptotis parva means a small animal having its ear hidden. Description. Same as given for the genus. From the only Wisconsin skin of Cryptotis available, preserved in alcohol, the color is brownish gray. Illinois shrews are similarly colored. Some least shrews to the southwest have a chestnut dorsum. The belly is

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THE WILD MAMMALS OF WISCONSIN



Skull of Cryptotis parva. 

nel entered the nest from below and a runway connected to it from the side. There was a “toilet area” or latrine at the edge of the nest, where numerous small insects were feeding. This latrine was about 3 inches in diameter. If disturbed, the young, barely haired out, tried to hide in the tunnel or burrow into the leaves. Foods. Hoffmeister (1989) summarized foods in Illinois as lepidopterans, grasshoppers, crickets, chinch bugs, spiders, worms, and unidentified arthropods, and occasionally seeds and flower parts. Hamilton (1944) in



Maps showing geographic distribution of Cryptotis parva Wisconsin and North America. 

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107

Indiana reported insects, earthworms, mollusks, centipedes, and some vegetation in diets of least shrews from eastern states. Reproduction. In Illinois, young of Cryptotis parva are born in spring and fall, with the number of young varying from 4-7 (Hoffmeister, 1989). Whitaker (1974) reported embryo counts as 4.9 (2-7) and litter size as 4.5 (2-7). Gestatation is about three weeks, and the young are haired with opened eyes in two weeks. Newborn weight about a third of a gram (Whitaker 1974). They are “full grown” in a month. Conaway (1958) presents data on growth. Broadbooks (1952) quotes Hamilton, that the young are born blind and naked and grow 0.1 to 0.5 g per day for about 3 weeks. Broadbooks also found an adult male in attendance with the female at the nest. In captivity, the female ate her young. Captive-produced litters averaging 4.56 young (range 19), weaned in 18-19 days. These were sexually mature in about 50 days. Probably least shrews breed from March until November, although October young would find cold nights and frost adverse. They live about 8 months, but as long as 31 months. Mortality. A red fox killed but did not eat a Wisconsin least shrew (Hanson, 1945). Great horned owls ate the other two Wisconsin shrews, subsequently found in their owl pellets. Hawks, owls, snakes and other shrews are likely predators. A flea and several species of mites parasitize least shrews. Home range and Density. Hoffmeister and Mohr (1957) reported populations in Illinois as high as 10-15 per acre, but in some years none. Geographic Variation. There is a single subspecies known from Wisconsin, and central Illinois. Specimens examined. Total, 1. Columbia Co.: Sauk Prairie, 1. Other Records. Total, 2. Jackson (1961): Columbia Co.: E of Prairie du Sac, 1 mi. ESE Dam on Wisconsin River, 1. Dane Co.: Pine Bluff, 1 mi. N Klevenville, 1.

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Order CHIROPTERA BATS “If bats are to remain [on earth].... we must initiate conservation measures.... certain needs are obvious. Some caves harboring important colonies should be protected from undue human disturbance. The trend away from the use of the dangerous residual pesticides must be continued. People who work with bats should try to minimize the disturbance.... Finally, more people should become aware of the many aspects of a bat’s life; such awareness should make people more interested in the protection of these fascinating animals.” — Wayne H. Davis, in Bats of America, by the late Roger W. Barbour and Wayne H. Davis, 1969.

The Order Chiroptera is comprised of the only mammals that fly. Known popularly as bats, these aerial mammals are the only ones with wings, which are modified forelimbs having elongated fingers and elastic webs between them. Distal claws disappeared from the fingers of the hand, except on the functional thumb [and on the index finger in some primitive, tropical bats called flying foxes]. Flight is gliding and thrusting the body through the air, with the capability to ele-



Skeleton of bat. G. Cuvier, Le Règne animal. Woodcut. 1817, 1829. 

vate trajectory. Volant locomotion, seen in several other distantly related mammalian groups, such as flying squirrels, is simply gliding (“volant” actually means flying). Bats, probably descended from primitive insectivores. The molar teeth are formed similarly in W-shaped patterns. Ancient fossilized bats (Jepsen, 1966; Simmons and Geisler, 1998), Icaronycteris index, Archaeonycteris, Palaeochiropteryx, and Hasianycteris are considered insectivorous, some with insects in their stomachs, and they all had advanced wings. These wonderfully preserved fossils from the Eocene epoch give a few clues to the evolution of wings and flight. In addition to toe webbing, there is in bats a flight membrane on either side called a patagium. It is a double-layered membrane of skin extending laterally on each side out to the wrist, to the tip of the fifth digit, and to the ankle or hind foot. Such a lateral membrane has evolved repeatedly in arboreal mammals, probably serving to hide the revealing shadow when the body is flattened against a branch (Spurway 1955) or to break the fall as the animal leaps from a tree. A tail membrane, found only in one other group (Order Dermoptera) stretches between the hind limbs (the uropatigium). Usually in bats the tail vertebrae are comprehended in this membrane. Several characters indicate a gliding origin of flight: bats and gliding mammals are all nocturnal, they fall into flight, bat patagia resemble gliders, and bats’ hind limbs could never leap from the ground. The glider has a great deal of potential energy accumulated by climbing (Long et al. 2003). When bats pull their wings downward and forward, by means of several pairs of relatively large shoulder and chest muscles, the forward edge of the wing is canted downward. Then air is thrust mostly behind, and the hind limbs join in this pumping thrust. Lift is achieved. The wind helps raise the wings to the power stroke position. When bats glide, aerodynamic lift is obtained from pitching the wings against the airstream. The light body is

lifted, although drag greatly increases. As the angle of attack is inclined the bat stalls. If one wing is extended into the airstream while the other is held close to the body, the bat “flits” (Eisentraut 1936). Many echolocating bats hawk insects. They rely on echos from high-pitched calls to “see” in the dark with their ears (Griffin 1958, and others). There are two suborders of bats, the Megachiroptera, or flying foxes, in the Old World tropics and Australia, and the widespread, abundant, and diverse Microchiroptera. The Microchiroptera have specialized wings, in most cases tiny but functional eyes, and have evolved several different patterns of echolocation. Novacek (1985) reports that the oldest known bats (from the Eocene of Wyoming and Germany) possess cranial features suggesting an early function of echolocation. Possibly the orientation sense arose in cavernicolous bats. Other features include the upright rod in the ear (the tragus), the palatal notch separating the premaxillaries (and their incisors), the soft rod attached to the ankle helping to make the uropatagium taut (called the calcar), and the flattened chest.



Big Brown Bats on Ceiling of Twin Bluffs Cave. 1977. 

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Table Chi-1. Incidence of rabies in bats of Michigan* (1965-78) and Illinois (1965-82). Of all bats tested, 5.8 percent were rabid.  MICHIGAN Tested Rabid &%

Species Myotis keenii M. lucifugus L. noctivagans E. fuscus L. borealis L. cinereus N. humeralis Totals

27 75 12 1,093 55 12 1 1,275

0 0 2 48 3 2 0 55

0 0 16 4 5 16 0 4

ILLINOIS Tested Rabid 0 43 4 90 355 378 134 0 1,000

0 4 15 34 20 0

*Figures slightly revised.

Rabies in Bats One of only a few human deaths attributed to rabies transmitted by the overt bite of a bat (species unknown) happened near Blue Mound, Wisconsin (Jackson 1961, Long 1976). A man with no screen on his window was bitten on the ear. He did not seek medical treatment used against rabies virus. He contracted the disease. About 30 years ago I read a report in the local paper by the Portage County Health Officer that all bats were found to harbor the rabies virus. What this really meant was that the bats he sent to the State Hygiene Laboratory in Madison all harbored the virus. After examining the reports, I suspected the number of bats he reported did not exceed four. In Wisconsin tabulations (see Table Intro-2), few bats test positive. In comparison, numbers of dogs, cats, and even cows (bitten by some rabid mammal most likely) that were not inoculated against rabies showed higher incidence (but no longer is this true since implementation of dog immunization). Striped skunks (Mephitis mephitis) showed a high, often epidemic incidence. Constantine et al. (1979) found only 0.025 percent of naturally occurring bats harboring the virus. Other studies have shown about one percent or less (Trimarchi and Debbie, 1977).

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Owing to a national interest in Lasionycteris noctivagans, and its particular strain of rabies virus detected in humans, workers at the Wisconsin Rabies Laboratory must determine which bats are dangerous and which are not. For example, an elderly man attacked by a bat in Texas, with no visible bite marks, contracted rabies and died a couple months later (1997). He and three other Americans died from bat rabies that year, all attributed to a virus of the silver-haired bat, Lasionycteris noctivagans. Two cases are of great interest. A recent Wisconsin death (November 1, 2000) of a man near Reedsburg, associated with silver haired bats by the viral strain, but health authorities blamed bats from his apartment. Those likely would not be silver-haired bats. Silver-haired bats migrate out of Wisconsin southward in October, and do so in large numbers at this time (~ October 14). September 4, 2004, a recovering 15-year old patient, Jeanna Giese, relates catching a “small, black bat” [Lasionycteris is the only black bat in Wisconsin] in a Fond du Lac church. She treated a bite on her hand with peroxide, but developed advanced symptoms of rabies October 15, and was transferred from St. Agnes to Children’s Hospital on October 18. Dr. Rodney Willoughby, infectious diseases and pediatrics, and with the family’s support, attempted an untried treatment, using a drip treatment of the neural protective agent Ketamine, he was able to fine tune the effect of Ketamine with Benzodiazepine. After two days or so he added Ribavirin and even a flu drug Amantidine. The drugs and induced coma protected the Central Nervous System. The immune system fully responded, and the patient progressed steadily. After about 80 days she was returned home, and has progressed daily. Willoughby says enthusiastically that “She will go to college”. This is the premier triumph over rabies. I reiterate, “Don’t pick up sick or wild bats; tell your children to leave helpless bats alone. If one is bitten, take rabies shots.”

In Michigan, Baker (1983) and Kurta (1979) reported of 1,247 bats examined by the Michigan Department of Public Health only 65 (5 percent) had rabies, with only 3 to 11

positive bats in any years. In contrast, 28 percent of 384 skunks were rabid. Both 5% and 28% are overestimates, because any animals captured while sick are more likely to be tested. In nature the percentages would be lower. Trainer (1957) and Long (1976) called for a better study of the bats in Wisconsin. In 1991, I begain identifying bats with the State Laboratory of Hygiene (J. Powell). The UWSP collection was for four years a repository (Tables Chi-2-4) for non-rabid Wisconsin bats.

tional, Austin, Texas, provides a handbook for building and siting bat houses.

Family VESPERTILIONIDAE Gray Evening Bats “The Ordinary Bats (Vespertilio, Cuv. and Geof.) — Have no leaf or other distinctive mark on the muzzle, and the ears separated; four incisors above, of which the middle two ones are apart, and six below, sharpedged and somewhat notched: their tail is comprehended in the membrane.”— Baron Georges Cuvier,

Bats in Houses

in Le Règne Animal, 1817, 1846.

The Bat. It has no feathers, yet has wings, It’s quite

This large and cosmopolitan family contains all the Wisconsin species. See accompanying figures, the key to Wisconsin bats, and the table of characters of Wisconsin bats. Vespertilionid bats in temperate and boreal latitudes, such as those in Wisconsin, show a complex interrelation of microhabitats (microtemperatures), migration, lactation, and growth. Growth rates of young raised in maternity roosts vary with air temperature. In tree dwelling bats, in their cooler roosts, the young and mothers often save energy by entering torpor. Their growth rates seem low. Bats continue growing throughout pre-fledging, pre-migration, and migration until the next season of reproduction. Lasiurus do not seem to lose body mass by lactation and tend to produce twins [even 3-4 young] regularly. They may forage primarily to feed the young, which do fledge at an early (low) percentage of adult body mass (61 percent in Lasiurus cinereus, 55 percent in Eptesicus serotinus, which regularly has twins). The growth rates of the pre-fledged young are lower than those in vespertilionid bats with single young. In all Wisconsin species there are two pectoral mammae, except Lasiurus (with four). In Lasiurus, with such a slow growth rate even in a short growing season, by migration to warm regions, little or no hibernation, and feeding on available insects year round, there seems to be compensation in maintaining energy budgets (Koehler and Barclay, 2000).

inaudible when it sings, It zigzags through the evening air And never lands on ladies’ hair. — Ogden Nash.

In Britain, many people introduced them into their attics where the guano is considered insulation or collected for rich fertilizer. Most Wisconsin people eradicate bats, but especially in older houses, bats may be found in any season, especially in autumn. There is a myth that sprinkling moth crystals will drive bats away, or stringing up an extension light will keep them out. Bats usually leave a house at twilight emitting a few drops of urine. Telltale stains on the eaves may mark the entrances, and tin or aluminum must be used to cover the hole when the bats or their young are not present in the house. Small cracks may be caulked. The best way to remove bats is to put on leather gloves and grab them as they sleep. Sometimes it is practically an impossible task to rid a house of bats. Near the Trees for Tomorrow camp and nature center, in Lincoln County, is a man-made bat shelter that harbors many Myotis lucifugus, an interesting place where adults and children are taken to observe the evening flights. The house is sited about 30 feet high and houses. Many “bat roosts” for the backyard are sold today. Most of them seem ineffective. Bat Conservation Interna-

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It is now possible to identify some bats by their echolocation calls. Ultrasonic bat detectors today (see advertisements in the Journal of Mammalogy) provide detailed information on species identification of flying bats, spatial and temporal bat activity, habitat use and prey selection, and even the physiological processing of echoes (Fenton, 1981; Miller and Andersen, 1984; Thomas and West, 1984; Thomas, Bell and Fenton, 1987; and others). This procedure promises in this century to provide a superb survey of free-ranging bats in Wisconsin and the Upper Peninsula, whereas previously we relied mostly on banding of cave species or by netting to study the diversity and seasonal population changes (see table Chi-5, & Fig.) on seasonal fluctuations and abunance). Bats have an undeserved bad reputation. For some inexplicable but deep emotional feeling, or possibly (some would say probably) it may be taught to people to some extent, there is an apprehension of bats that is often expressed by hatred and disgust. Bats normally do not attempt to get into a woman’s hair. Neither are they usually rabid. Bats are highly beneficial, limiting the populations of harmful insects during the “night shift” when most insectivorous birds are sleeping (E.R. Hall, personal communication; Barbour and Davis, 1969). Bats should be protected, i.e., managed. Some American bats are listed as Endangered Species because they are so scarce and are vulnerable to destruction (in their nursing colonies or hibernacula). Kurta and Teramino (1992) and others also showed the adverse effects of urbanization to bats in Detroit, decreasing their abundance, species diversity and possibly their reproduction success. In suburbs, with numerous shade trees and attics, some species may increase. Barbour and Davis (1969), Kunz (1988), and Nowak and Paradiso (1983) are important references on American Chiroptera.

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Key To The Wisconsin Bats 1

1’

2 2’ 3

3’

4

4’

5

5’ 6

Tail not extending beyond tail membrane (uropatagium) or extending less than 4 mm beyond it ................................... 2 Tail extends distinctly beyond the uropatagium (known from northern Illinois, but unverified for Wisconsin, a possible wanderer) ......... Mexican free-tailed Bat Tadarida brasiliensis A single pair of upper incisors ........... 3 Two pairs of upper incisors ............... 5 Upper surface of uropatagium densely furred, the skin not visible, two pairs of upper premolars, one of which is a minute peg, usually a whitish spot visible on shoulder, dorsal pelage more or less hoary ............................................... 4 Upper surface of uropatagium nearly naked, skin visible and scantily haired proximally, one pair of upper premolars, shoulder spot lacking, dorsal pelage brown .............................. Evening bat Nycticeius humeralis Dorsal pelage maroon brown, washed with hoary whitish or buff, greatest length of skull exceeds 16 mm, forearm greater than 45 mm .................... Hoary bat Lasiurus cinereus Dorsal pelage brick red orange or yellowish orange, thinly washed with hoary buff, greatest length of skull less than 16 mm, forearm less than 45 mm ......... Red bat Lasiurus borealis Dorsal pelage dark brownish or blackish washed with buffy or silvery white ....... ................................. Silver-haired bat Lasionycteris noctivagans Dorsal pelage brownish, reddish or yellowish buff, never washed whitish ..... 6 Dorsal pelage yellowish, tan or pale reddish brown, one large and one minute pair of upper premolars (total of 34 teeth teeth), hairs conspicuously tricolored (brown/ cream/ gray), forearm usually less than 36 .......... Georgian pipistrelle Perimyotis subflavus

6’

7

7’

8

8’

9

Dorsal pelage brown, or yellowish, pale, or reddish brown (faded pelage); normally one large and two minute pairs of upper premolars (total of 38 teeth) or only one large pair (total of 32 teeth); hairs never tricolored; forearm more than 36 mm. ....................................................... 7 Skull more than 18 mm in greatest length, forearm more than 44 mm, premolars 1/2 (total of 32 teeth) .............. .................................... Big brown bat Eptesicus fuscus Skull less than 18 mm in greatest length, forearm less than 40 mm, premolars normally 3/3 (total of 38 teeth). .............. 8 Ear pinna broad and long (16 mm or more from notch), maxillary tooth row more than 5.5 mm, elastic fibers of uropatagium forming a pattern of wide, prominent chevrons numbering approximately 7 (611) ....................... Keen’s or Northern Myotis Myotis keenii Ear pinna narrow, more recurved, and shorter(usually less than 15 mm), maxillary tooth row less than 5.5 mm, elastic fibers of uropatagium forming narrow, indistinct chevrons numbering approximately 12 or more ........................... 9 Dorsal pelage with metallic, brassy or coppery brown glint, never with pinkish or purplish suffusion, calcar not keeled



Vespertilionid bat. W. A. Weber, with Karl Schmidt. 

or slightly keeled, sparse hairs extend beyond toes ................... Little brown bat Myotis lucifugus Dorsal pelage dull brown, dorsal and ventral pelage tinged pinkish or purplish gray over brown, calcar distinctly keeled, sparse hairs usually do not extend beyond toes ..................... Indiana Myotis Myotis sodalis

9’

Bat To his adroit Creator ascribe no less the praise — Beneficient, believe me, his eccentricities. — Emily Dickinson, about 1876

General changes in abundance in Wisconsin’s bats seem profound. Old literature, including Jackson (1961), suggests the red bat was most abundant, the big brown bat uncommon, but the situation is now reversed. Myotis lucifugus, ranging through forests and



Chart of Characters of Wisconsin Bats. Diagnosis to make comparisons easy. Asterisk means unknown in Wisconsin. P = small premolars.  Species P. subflavus M. lucifugus M. keenii M. sodalis M. leibii* N. humeralis L. borealis L. cinereus E. fuscus L. noctivagans Tadarida brasiliensis*

Length forearm

Length tragus

Calcar keeled

No. incisors

32-6 34-8 34-8 34-8 30-34 34-8 36-43 50-8 44-8 39-43 40-5

~½ ear <½ ~½ <½ <½ <½ ~½ ~½ <½ < ½ Short no calcar

— — ?+ + + — + + + — 1

2 2 2 2 2 1 1 1 2 2

Color

Other

Yellow-brown Brass-brown Brass-brown Dull-brown Yellow-brown Ashy-brown Whitish/reddish Whitish/brown Brass-brown Whitish-black Gray

Hair tricolor 1 P >18, elastic fibers 7-12, elastic fibers Black mask Round ears 1 peg P. Round ears 1 peg P. Broad nose No tiny P. Free-tail

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Uropatagium of Myotis lucifugus (left) and M. keenii. Note elastic fiber patterns and long ears. 

and suburbia, was always abundant. Pipistrelles seem to be declining in numbers. Abundance is analyzed in tables Chi 2-5.

Genus Myotis Kaup Mouse-eared Bats Small brown bats having fairly well-developed tragus, a mostly naked uropatagium, and P 1-3/1-3 present in Wisconsin species.

Myotis keenii Merriam Myotis keenii septentrionalis (Trouessart) Keen’s Myotis or Northern Myotis 1895. Vespertilio subulatus keenii Merriam. Amer. Nat., 29: 860. Type from Massett, Graham Island, Queen Charlotte Islands, British Columbia. 1897. [Vespertilio gryphus] var. septentrionalis Trouessart. Cat. Mamm. . Fasc. 1, p. 131. Type from Halifax, Nova Scotia. 1928. Myotis keenii septentrionalis: Miller and Allen. Bull. U.S. Nat. Mus., 144:105. 1985. Myotis septentrionalis Trouessart: Van Zyll de Jong, Handbook on Canadian Mammals, Part 2.

The generic name means mouse-eared. Dr. C. Hart Merriam named the species in honor of J. H. Keen, who collected the holotype.

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Van Zyll de Jong (1985) believed that Myotis keenii found in the Pacific Northwest (and southwestern Canada) is specifically distinct from the wide-ranging eastern bats referred to the same species. Therefore, he elevated the eastern race M. k. septentrionalis to a full species, called M. septentrionalis. The bats are allopatric, and, therefore, the question whether they do or might hybridize is subjective, i.e., it is difficult to demonstrate. Lacking clear-cut evidence, one may emphasize either the resemblance of the two bats or their distinctness. In comparisons of some small samples, there was no overlap (Fitch and Shump 1979), but Miller and G. M. Allen (1928: 109-110) had clearly revealed almost total overlap in lengths of body, tail, skull, and maxillary toothrow, and breadths of zygomata and braincase. In 1994, I examined, with Robert Fisher, several M. keenii from Alaska and southward preserved in the U.S. National Museum (Nat. Hist.). We examined the uropatagia, having found myself an undescribed and subtle difference between keenii and other Myotis in the eastern states (see Fig.). Wide-spaced and parallel elastic fibers in the uropatagium were also observed to be characteristic of the dark, coastal western specimens, as were the elongate ear pinna and tragus. For the aforementioned resemblances and this new character, I retain the name M. keenii, reinforced by his astute judgment of Gerrit Miller, as well as the overlooked overlaps showing close resemblance. Description. The trenchant external characters of Myotis keenii are the large ear conch with a correspondingly elongate pointed tragus within, and the pattern of elastic fibers of the uropatagium widely spaced and nearly parallel, like a music staff, and varying in number usually from 7-12 rows. In Myotis lucifugus the number of fibers, crowded and confused, usually exceeds 18. In subadults and a very few peculiar specimens the fibers are indistinct. In live or fresh bats (only) one can push the ear pinnae for-

ward to see if they extend at least 4 mm beyond the nose. This “book” character does not identify dry museum specimens. The paraboloid shape of the elongate and wide pinna suffices to distinguish keenii from lucifugus, which has shorter, narrower and somewhat recurved pinnae. One questions whether the calcar is or is not keeled (Hoffmeister 1989, Baker 1983), for Wisconsin specimens are slightly keeled. The Myotis keenii skull is approximately 15 mm long by 9 mm across the zygomata. The hind foot measures up to 10 mm, occasionally 11 (see Measurements). The skull is arched above the orbits, rises posteriorly, and is said to rise abruptly. Of diagnostic importance, the arched cranium extends posteriorly with even a slight upward curvature at the lambdoid crest. In consequence, the upper portion of the supraoccipital bulges posteriorly. There is no median sagittal crest. Myotis lucifugus shows less curvature in the rise of the braincase, and less posterior protruberance of the supraoccipital. Myotis sodalis shows a comparable rise, but much less posterior protruberance of the supraoccipital. See accounts of other Wisconsin bats to distinguish them from M. keenii.



Skull of Myotis keenii. 

The pelage of Myotis keenii has a bright sheen, which in bright light is called a “brassy glint.” The basic tone is brown or slightly yellowish brown, but the sheen gives a golden tone to the brown fur. This pelage is usually indistinguishable from Myotis lucifugus, Eptesicus and Nycticeius. The patagia and ear pinnae are slate or brownish gray. The venter (or belly) is grayish or brownish buff, overlain with light buff, cream, or silvery gray. Molt occurs in the summer. Fitch and Shump (1979) provide measurements as follows: forearm length 36.4 (35.9-37.0), ear length 18.6 (18.0-19.0), greatest length of skull 14.8 (14.7-15.0), breadth of braincase 7.0 (6.0-7. 1). Miller and Allen (1928) list skull length and breath of braincase as 14.6-15.5 and 6.8-7.6, respectively. Weights are about 41-43 percent lower in winter. See Table Chi-6. Dental Formula. 1 2/3 C 1/1, P 3/3, M 3/3 = 38 teeth. Geographic Range. Expected throughout the state and the Upper Peninsula. See Map. Status. Keen’s Myotis is often considered rare (e.g., Coggins et al., 1981) in Wisconsin (Jackson, 1961, only documented 26 specimens). This species is actually fairly common during migration in central Wisconsin, and the numbers examined suggest the status throughout the state is improving. The species is decidedly beneficial because it is insectivorous and helps control insect numbers. It can harbor rabies virus, but has weak jaws and probably cannot bite dogs or people (Baker 1983). It is seldom sent to the Wisconsin State Hygiene Laboratory as a rabies suspect. Habitats. Myotis keenii ranges throughout the state in woodlands, usually near lake shores and streams. The species often hangs up in trees, tree cavities, or under loose bark, in the summer. In winter it is often found hanging in caves. During migration this species is likely to show up almost anywhere, even hanging onto brick buildings, and entering them on occasion. Maternity colonies are usually small, containing up to 30 pregnant females, TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

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and are found in barns, behind wooden shingles on old houses, or under loose tree bark. Whereabouts of the males are open forest lands above shrubby understory, or over streams. In winter, Keen’s bats are occasionally found in caves with other cave-dwelling bats, especially in southwest Wisconsin. They seldom exceed 10 animals in a hibernaculum, but might number as many as 300. They prefer cool, moist and quiet areas in a hibernaculum. Hibernation may last for eight to nine months (Fitch and Shump 1979). Foods. Insects and other small invertebrates are eaten. LaVal and LaVal (1980)



Maps showing geographic distribution of Myotis keenii in Wisconsin and also in North America. 

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THE WILD MAMMALS OF WISCONSIN

found Keen’s bats to prefer small moths, caddisflies, stoneflies, homopterans, mayflies, Foods. Insects and other small invertebrates are eaten. LaVal and LaVal (1980) found Keen’s bats to prefer small moths, caddisflies, stoneflies, homopterans, mayflies, beetles, and flies. Rarely mosquitoes are ingested. Reproduction. There seems to be winter sperm storage in Myotis keenii. One young, carried in late May or June, is apparently born in June and rapidly develops (Hoffmeister 1989, Kurta 1980, Clair et al. 1979, Easterla, 1968) until weaning about 32 days later (Kunz 1971). Lactation occurs usually from June to August, but usually not later than July. A juvenile from Sparta, Wisconsin (UWSP7878) was taken 11 May 1995, and an embryo (27 mm) was found 24 June 1980. Keen’s bats are usually considered adults when they show fusion of the epiphyses of the wing, a dubious way to predict sexual maturity (Long and Jones 1966). This method does appear to segregate young which have not attained full growth from old adults that live up to 18 years (Barbour and Davis 1969). Mortality. No information is available on fleas, bugs, ticks, and chiggers parasitize them (in South Dakota). Intestinal and other worms are also reported, by Whitaker and Mumford (1971) and by Coggins et al. (1981) for Wisconsin. Home Range and Density. Little information is available. Hoffmeister (1989) reports that in winter 400 to 800 estimated individuals were congregated in the Black Ball Mine, Illinois. No densities even approaching this number have been seen in Wisconsin. Beer and Greeley (in 1947) banded more than 100 in an iron mine near Hurley, Wisconsin. Geographic variation. There is no geographic variation in this species in Wisconsin and Upper Michigan. The nominate race, in the Pacific Northwest, is darker, the skull shorter, and the ears more recurved (scimitar-shaped).

Additional Natural History. Fitch and Shump (1979) reviewed biology for M. keenii. Specimens examined. Total, 51. Bayfield, Brown, Crawford, Dodge, Grant, Iowa, Iron, Jackson, Lafayette, Monroe, Pierce, Portage, Richland, Washburn counties. Michigan: Big Summer Island, in Green Bay 1.

Myotis lucifugus lucifugus LeConte Little Brown Myotis or Little Brown Bat 1831. V [espertilio]. lucifugus LeConte. In McMurtrie, The Animal Kingdom... 1:431, type from Georgia. 1897. Myotis lucifugus: Miller. N. Amer. Fauna, 13:59.

The generic name means “mouseeared.” The word lucifugus means to hide from the light. Description. The little brown bat is small, with ears neither broad nor elongate, with tragus neither pointed and high nor blunt and short. It lacks a keel on the calcar except rarely, and its elastic fibers of the uropatagium are numerous, crowded together, and usually more than 18 lines (see fig. and account of Myotis keenii). The skull is not flattened, but the rise of the cranium posteriorly is gradual, and the occiput is neither high nor does it bulge much posteriorly. There is no sagittal ridge, and the palate is broad across the molars. Hairs regularly extend beyond the claws of the hind toes. The number of chromosomes is 2N = 44, FN is 50 as in all Myotis (Fenton and Barclay 1980). The little brown bat is dark or slightly yellowish brown, the tips of the hairs with a metallic, brassy sheen, occasionally duller as in M. sodalis, and occasionally (when bleached) almost blond. The venter is gray overlain with pale grayish or brownish tips of the hairs. The ear pinnae and the patagial TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

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membranes are slate gray to nearly black. Walley (1971) found an albino in southwest Wisconsin. Females average a little larger than males. See table Chi-6. Dental Formula. 12/3,C 1/1, P 3/3, M 3/3 = 38. Geographic Range. Found throughout Wisconsin, but usually congregated in suitable caves and mines in the winter. Common in southern latitudes. Clark et al. (1987) found in four summers of netting bats in Iowa a de-



Skull of Myotis lucifugus. 



A skull variant of M. lucifugus. 

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THE WILD MAMMALS OF WISCONSIN

crease from 329 (54.6 percent) in northern counties to 10 (1.7 percent) in southern counties. Across Lake Michigan on the Lower Peninsula, Kurta et al. (1989) showed a drop from 141 (62 percent) in northern counties to only 7 (4 percent) in the southern ones. The big brown bat Eptesicus showed a converse trend. M. lucifugus may be the most abundant bat in Wisconsin. It surely is in the caves and mine tunnels in winter, when some populations may exceed an estimated 10,00020,000 bats. Status. Unlike many of the Wisconsin bats, the little brown bat becomes less common southward Nationally, the numbers of Myotis lucifugus reportedly declined (Fenton and Barclay 1980), probably due to the use of pesticides. There is no obvious decrease in Wisconsin. Habitats. Little browns frequent woodlands, often foraging in riparian habitats or near the mouths of caves. In migration the bats turn up almost anywhere, even entering buildings or hanging onto the exteriors. In winter the bats search out caves hibernacula in which to sleep. Fenton and Barclay (1980) list three kinds of roosts: day, night, and hibernation sites. Day roosts are in buildings, tree cavities, rocks, wood piles, and occasionally caves. Non-reproductive females and males are more solitary. After initial foraging, sometimes bats pack together in confined places for night roosting. Man-made tunnels (mine shafts, storm sewers), old houses, cabins and barns are often used as maternity and temporary roosts. Hibernacula are usually caves or mines to which the bats migrate in autumn. Hibernation may last from early September until mid-May. Torpor patterns were discussed by Kurta (1991). Distances from nursery colonies to hibernacula are as far as several hundred kilometers. Foods. Gould (1959) reports the little brown bat can capture about 500 insects per hour. Whitaker (1972b) found that 16 specimens had eaten mostly moths, caddisflies, flies, leafhoppers, and beetle larvae- usually

small insects less than 10 mm long. Other insects taken include mayflies, wasps, and stone flies (Barbour and Davis 1969, Belwood and Fenton 1976; Freeman 1981, Anthony and Kunz 1977). Fenton and Barclay (1980) report heavy feeding on aquatic insects. Chironomids are a staple food. Effects of pregnancy and lactation on energetics have been discussed by Kurta et al. (1989). Reproduction. In late summer and fall, the little brown bats often congregate in large numbers, a phenomenon called “swarming.” Fenton (1969) found two phases of swarming in



Maps showing the geographic distribution of Myotis lucifugus in Wisconsin and North America. 

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Ontario and Quebec. Sexual activity began following the August phase of swarming, in September. Sperm is stored during hibernation until spring. Copulation may occur in caves when hibernating bats arouse periodically from their sleep. Ovulation and fertilization take place about the time bats leave the hibernacula. A single fetus is carried. Maternity colonies are formed in abandoned farm buildings behind boards and timbers, in hollow trees, and under bark of dead and dying trees. After nearly two months gestation, birth takes place on the Upper Peninsula of Michigan either of the pectoral teats. The eyes and ears open in a few hours. By late July to early August weaning takes place, and the young can fly at this time, about three weeks after birth. Permanent teeth are almost all erupted. Females may become pregnant in their first year. Some little brown bats live 24 years or longer (Griffin and Hitchcock 1965). The longest records are 34 and 35 years (Wayne H. Davis, personal communication). Breeding over many years may compensate for single offspring each year. Adams (1992) studied the osteogenesis of the fetus of the little brown bat, finding that the appendicular long bones ossified earliest of the postcranial skeleton, probably because bats need their wings for flight. Adults are distinguished to some extent by toothwear, and young from older adults by fusion of the epiphyses in the bones of the wing in the latter (see Burnett and Kunz 1982). Mortality. Snakes, raccoons, and house cats feed on little brown bats (Long 1978, Barbour and Davis 1969, Fenton 1970). Birds of prey occasionally take them, as do some opportunistic smaller birds such as red-winged blackbirds and common grackles (Garber 1977, Fenton and Barclay, 1980). Parasites include fleas, chiggers, flukes and tapeworms (Timm 1975, Scharf and Stewart 198, Font 1978). Insecticides may cause significant mortality (Kung et al. 1977, Geluso et al. 1976, Gillete and Kimbroug, 1970). Occasionally a little brown bat har-

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bors the rabies virus. Rabies is not a significant threat to people from this bat. Less than 1 percent of this species harbor rabies, and they seldom transmit it to carnivores (Trimarchi and Debbie 1977, Trimarchi 1978). Home Range and Density. Little information is available for Wisconsin Myotis lucifugus. Jackson (1961) mentions that Beer and Greely (in 1947) observed more than 300 little browns in a mine tunnel near Hurley. Long and Theiss (1996 unpublished) reported many thousands in hibernacula of Upper Michigan and Wisconsin. Although less numerous in large cities, compared to small and medium-sized towns, M. lucifugus was occasionally observed in big cities. It is rarely encountered in the winter, and seems at peak abundance in August. It is, of course, numerous in the hibernacula. Remarks. One specimen (UW-SP # 2749, see Fig.) resembles little browns from nearby sites except the ear pinnae were more recurved and grayer in color. The skull was highly unusual in form, not rising gradually in a low, flattened profile, but rising abruptly as in such forms as Myotis californicus or Myotis austroriparius. Perhaps as a consequence of the abruptly rising cranium, the skull was very short in total length (13.7mm). Such abrupt curvature is seen in other species unknown in Wisconsin. The specimen was sent to Dr. Wayne Davis, an authority on bats, who identified it, unusual features notwithstanding, as M. lucifugus. Two more Wisconsin M. lucifugus, with similarly short and arched skulls were seen in the University of Minnesota (Bell Museum) collection. Geographic Variation. No significant geographic variation was noted. A great deal of individual variation was observed in little brown bats. Specimens examined. Total, 283. Adams, Ashland, Barron, Bayfield, Burnett, Chippewa, Columbia, Crawford, Dane, Dodge, Door, Douglas, Eau Claire, Fond du Lac, Forest, Grant, Green, Green Lake, Iowa, Iron, Jackson, Jefferson, Juneau, La Crosse,



Showing annual curves for abundance of M. lucifugus for 1992-1994. State-wide samples from state Hygiene Laboratory area mainly based on people to bat encounters, and not on bats observed in caves, the usual source. 

Lafayette, Langlade, Lincoln , Manitowoc, Marinette, Marathon, Milwaukee, Oneida, Outagamie, Pepin, Pierce, Price, Portage, Richland, Rock, Shawano, Sheboygan, St. Croix, Taylor, Trempealeau, Vernon, Vilas, Walworth, Washburn, Waukesha, Waupaca, Waushara, Wood counties. Michigan. Delta Co.: Big Summer Island 7. Poverty Island 5. St. Martin’s Island 2.

Myotis sodalis Miller and Allen Indiana Myotis or Indiana Bat 1928. Myotis sodalis Miller and Allen. Bull. U.S. Nat. Mus., 144:130. Type from Wyandotte Cave, Indiana.

The generic name refers to “mouseeared” bats, and the second name suggests the huge communal masses of these bats hanging up in some caves. Karl Koopman (personal corr.) suggested that sodalis means “associated” with M. lucifugus. If he were correct, the other usage seems more meaningful. Description. One reason the species is represented so poorly in mammal collections is the failure to recognize the species. It closely resembles other brownish, medium-sized bats. Field collectors usually do not kill every animal encountered, but collect selectively, and with ecological considerations. There are three cryptic characteristics of the living Myotis so-

dalis that might identify it if one could see them. They are invisible in the darkness or poor light of a cave. The pelage is dull with less of a rnetallic sheen on the fur; the venter is duller also, the fur having a slight purplish suffusion; and some hairs that grow between the toes seldom extend beyond. In the U. S. National Museum collections a few labelled sodalis have hairs extending beyond the toes. Colonies of Myotis sodalis are conspicuous in the southern part of its range. The bats crowd and huddle together, one bat deep, probably to conserve body heat. Such bats are easy to segregate from other closely resembling species, without much examination of subtle characters. An undergraduate research student, Melanie Jones, pointed out to me a new character that distinguishes the little brown bats from the Indiana bat, at least from my few (11) specimens of M. sodalis. The hind toes of M. lucifugus are larger, obviously thicker and with longer claws than in M. sodalis. Generally the toe length failed to attain lengths of 5 mm in sodalis, and usually exceeded 5 mm in lucifugus. If this character is good, then perhaps it will be easier to identify the two species in dark caves. See the aforementioned comments about duller dorsal pelage and purplish suffusion on the venter of Myotis sodalis. The hairs, on very close examination, seem somewhat tricolored (not distinctly so as in pipistrelles) in that the basal portion of each hair is black, becoming gray in the middle, and the hair is tipped with a tiny segment of brown. Myotis sodalis resembles Myotis lucifugus in size. See Table Chi-6. Dental Formula. 1 2/3, C 1/1, P 3/3, M 3/3 = 38. Geographic Range. The known occurrence of Myotis sodalis in Wisconsin is based upon a single specimen taken in a huge hibernaculum called Beetown Mine (or Atkinson’s Diggings). Repeated attempts to collect another specimen from this mine and nearby caves have so far proved fruitless. Netting and searching mines during the summer in southTAXONOMIC ACCOUNTS / ORDER CHIROPTERA

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Skull of Myotis sodalis. 

west Wisconsin for two summers also yielded no specimens (Ainslie 1983). Nevertheless, this species is known in several counties in southern Michigan, in Cook County, Illinois (near southeast Wisconsin), and from Joe Davies County, Illinois (4 specimens), just south of Beetown Cave. The species is rare but present in northeastern Iowa, although no reproductive colonies have been found. The species is an uncommon visitant in Wisconsin but also a possible resident in southern Wisconsin from time to time. So little is known of the maternity roosts (Kurta et al., 1993, 1994) that in Wisconsin they may have been overlooked. Status. The Indiana Myotis is listed as a federal Endangered Species. In some places the numbers of those bats declined as much as 28 percent in 15 years (Thomson, 1982). Because this species hibernates in vulnerable masses that are frequently vandalized by humans visiting caves, this species is also included also on the Illinois State Endangered Species List. It is not included on the Wisconsin list, although rarer in Wisconsin than in most

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of its range, because rare species are not usually mentioned unless their residence is well known. In my opinion, the species should be placed on the Wisconsin Endangered Species List, even if it is peripheral. Habitats. The Indiana bat moves into caves in winter (from November to April). In spring, maternity groups of a few females roost in outlier homes (i.e., temporary shelters away from the main home), behind loose bark, under bridges, in hollow trees, and occasionally in buildings. Humphrey et al. (1977) studied the summer habitats of Myotis sodalis. This species may form nursing colonies in green ash trees (Kurta et al., 1993). Another nursing colony was found in a Michigan sycamore (Kurta et al., 1994). They also occur in oaks (Quercus), elm (Ulmus), and hickories (Carya) (Thompson, 1982). This species often forages over slow-moving creeks and streams lined with trees (Kurta, 1980). Clark et al. (1987) found them in agricultural fields and woodlands (disturbed riparian woods, forested floodplains and upland forests) in Iowa. There are three kinds of roosts. Hibemacula caves are usually found south of Wisconsin. Nursery roosts and outliers are the other homes. There are also temporary outliers in tree hollows and under tree bark (Kurta et al. 1 993). Maternity colonies, up to 28 females but no males, are often found under bark of trees. Foods. Moths seem preferred over small beetles, wasps, bugs, flies, and caddisflies (LaVal and LaVal 1980; Whitaker 1972). About 90 percent of the food of Myotis sodalis is comprised of soft-bodied insects, and there is a preference for moths by lactating females. In fall, diverse insects are eaten. Reproduction. In late summer in the breeding range of Myotis sodalis, breeding swarms assemble in the evening sky, and mating occasionally continues in hibernacula in September and October (Cope and Humphrey 1977, Mumford 1969, Thompson 1982). The female bats hibernate, with fertilization delayed until emergence from

the hibernacula in April (Hall 1962, LaVal and LaVal 1980). As in other vespertilionids, the female contains a gelatinous plug holding the sperm until it dissolves in spring. Ovulation and fertilization seemingly occur at this time. A single fetus is carried by each mother, from May 20 to June 24 (Hall 1962, Easterla and Watkins 1969). Lactation follows parturition from late June to mid-August (Kurta 1980), when the young begin flying about with the adults. Clark et al. (1987) found pregnant females as late as late June in southern Iowa.



Maps showing geographic distribution of Myotis sodalis in Wisconsin and North America. 

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Clark et al. (1987) found no evidence of breeding in northern Iowa, although breeding was common in southern counties. They suggest the flight distance from hibernacula in central Missouri taxes pregnant females moving northward (about 463 km more or less) to establish nursery roosts (the reproductive females taken were netted). Bowles (1975) had taken hibernating males and torpid females in northeastern Iowa, not far from the hibernating Wisconsin specimen. Time might be a factor, for a pregnant female approaching parturition probably cannot postpone it, and after leaving the hibernacula females must seek out opportune nursery sites. Kurta et al. (1993) found reproductive females and young (45 bats) together on green ash trees (Fraxinus pennsylvanica), in southern Michigan. Indiana Bats are aged primarily by closure of the epiphyses of the bones of the wing. Old bats may be recognized by toothwear. One banded bat lived 20 years (Thomson 1982). Mortality. Few predators are known except black snakes Elaphe obsoleta (Barr and Norton 1965), mink and screech owls. Mites, flukes and tapeworms parasitize this species (Whitaker and Mumford 1970; Thomson, 1982). No rabies virus has been reported in M. sodalis. People may kill them when they find the communal clusters in caves. Home Range and Density. The clusters on cave walls, in the coolest parts of the cave, are huge but only one tier deep (Thomson 1982). No information for clusters is available in Wisconsin. Humphrey et al. (1977) found home range to be small. Maternity sites certainly may be expected in Wisconsin, especially if the species ever builds up its numbers. In Iowa it is only 5.6 percent of the total bats netted in summer, and is, as in Wisconsin, quite rare in winter. Additional Natural History. Thomson (1982) reviewed biology of Myotis sodalis. Geographic Variation. There is no evident geographic variation. Specimen examined. Total 1. Grant Co.: Beetown Cave, 1 UI.

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Genus Lasionycteris Peters Lasionycteris noctivagans (Le Conte) Silver-haired Bat 1831. V [espertilio]. noctivagans Le Conte. In McMurtrie. the Animals Kingdom... Baron von Cuvier. 1:431. Type from eastern United States. 1865. Lasionycteris noctivagans: Peters Monatsb. Preuss Akad. Wiss. Berlin, p.648.

Lasionycteris noctivagans noctivagans (Le Conte) The name Lasionycteris means hairy bat, and noctivagans means night wanderer. There is no silver on this bat, but the cream or white wash on such dark fur appears silvery white. Description. This medium-sized bat has fur extending from the back onto the basal part of the uropatiagium, occasionally more than half way to the border. The tragus is exceptionally short (5-9 mm) and blunt, and the calcar is not keeled. The tail is short (less than 40 percent of total length). The skull is flattened (see Fig.). The baculum is large, and the karyotype is distinctive in the family, 2N = 20, FN = 28 (Kunz, 1982). The fur is basically blackish brown, overlain with white- or cream-tipped hairs. This “frosted” effect is why the bat is called “silver-haired.” The ears are black. Older bats may lack the whitish frosted tips of the hairs, and some are even yellowish (Kunz, 1982). Measurements are given in Table Chi-6. Weights vary up to 11 g (Kunz, 1982). Dental Formula. The silver-haired is the only Wisconsin bat with 36 teeth. It has only two pairs of upper premolars; there are three lower premolars on either side. DF = I 2/3, C1/1, P 2/3, M 3/3 = 36. Geographic Range. To be expected in any county throughout the state. This bat seldom winters in Wisconsin (one record, Schmidt, 1931). Furthermore, it has seldom been taken in any parts of Wisconsin except along the forested Lake Michigan western shore. Apparent-

ly in migration they congregate along the shore and wend their way southward. Elsewhere in Wisconsin, the bat and its habits are poorly known, and it seems one of the rarest of our mammals. Approximately 10 percent of bats netted four summers in Iowa were of this species (Clark et al. 1987). In a state-wide sample of bats sent from the Wisconsin Hygiene Laboratory, collected from 1991-1995, this species was also found in northern and western Wisconsin (Long and Theiss, unpublished) (see Map). Dates vary from April 21 to October 19 in this collection. In Iowa it is only 5.6 percent of the total bats netted in summer, and, as in Wisconsin, is quite rare in winter. Status. See Range. This rare and beautiful, silvery bat is now considered dangerous as a rabies threat throughout the United States. Rabies viruses can be identified by antibodies in the victim, and the silver-haired bat has been implicated even when it was unseen, even if its biting was never observed. This implication certainly needs further investigation. Rabies has diminished in some other animals, e.g. dogs and cattle.



Skull of Lasionycteris noctivagans. 

Habitats. The silver-haired bat prefers riparian areas along fast-moving brooks or streams in summer, and often is found hanging up to rest in woodpiles, hiding behind the loose bark of tree or in tree cavities. Schmidt (1931) found one on 6 September, in Clark County, in his basement under the furnace. Long and Thiess (unpublished) record some specimens for Wisconsin in October. Frank Iwen and Scott Craven captured one in Madison on 15 Dec. 1981. Silver-haired bats hibernate in caves and mines in southern Illinois and other states south of Wisconsin. Foods. The diet is comprised chiefly of moths, flies (Freeman, 1981; Kunz, 1982) and emerging aquatic insects. This bat is known as a “moth strategist,” but feeds on several diverse insects. The energy budget per day was on average 4.86 Kcal. Reproduction. Testes enlarge in late July through November (Turner 1974). Very likely sperm storage occurs in females during their hibernation. Kunz (1982) lists a brief gestation of only ten days. Ovulation peaks in April and early May, with implantation delayed about 50 days. Females with one or two embryos were collected in late May and June. One silver-haired bat captured alive gave birth to two offspring on June 20 (Kurta and Stewart 1990). During this birth the female sat upright, the uropatagium curled up like a basket. The first young was born breech, lacking its amnion. The young, a female, pushed against the mother with its hind legs, while the mother constantly licked her. Birth was complete in 23 minutes, and the mother continued to lick the chirping infant. The newborn found its way to the mother’s left nipple. The placenta had not been passed. The second newborn began to emerge breech, about five minutes later. Again, the amnion was already ruptured. This young (a male) did not push against the mother, but it too was licked. In 16 minutes this birth was complete. The mother dragged the chirping male, and this pulled forth its placenta. The other placenta then was extruded. The mother ate them TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

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both; she did not sever the umbilical cords. The young male’s wing was entangled by the cord, and it did not reach a nipple. The cord was stretched but still red in appearance 33 minutes after birth. The mother weighed 11.0 g, and the young 2.5 g each. The baby female was 44.7 mm total length, the male 47.1. Kunz (1982) records weights of naked, newborn young as 1.9-1.8 g. The young are pink, with mostly tan and black wings, the skin naked, the eyes closed. In three weeks the young are capable of flight and of catching insects for themselves. One Wisconsin female (UW-SP 7161) taken on April 21,



Maps showing distributions of Lasionycteris noctivagans in Wisconsin and North America. 

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contained two embryos measuring 7 mm in crown-rump length. Some bats live 12 years. Mortality. Little information is available on the silver-haired bat’s enemies. Sperry (1933) reported striped skunks (Mephitis) preying on them during their hibernation. Owls eat them (Kunz, 1982). Parasites are listed by Kunz (1982) and include mites, bat flies, a flea, two species of Cimicid bat bugs, a nematode, seven trematodes, and three cestodes. Rabies is often reported from this bat, especially in young of the year. In the beginning of these accounts of Chiroptera are remarks on the importance and prevalence of the strain of virus associated with this migratory, woodland bat. Home Range and Density. Seldom are these solitary bats (Kunz 1971, 1982) caught in groups larger than two or three, even in hibernation. Additional Natural History. Kunz (1982) reviewed natural history of Lasionycteris noctivagans. Geographic Variation. No significant geographic variation has been noted in this species. Specimens examined. Total, 24. Adams, Bayfield, Brown, Dane, Door, Kenosha, Manitowoc, Milwaukee, Outagamie, Vernon, Waukesha counties.

Genus Perimyotis Menu Pipistrelle-like Bats Perimyotis subflavus (F. Cuvier) Georgian Pipistrelle 1832. V [espertilio]. subflavus F. Cuvier. Nouv. Ann. Mus. Hist. Nat. Paris, 1: 17. Type locality Le Conte Plantation, Liberty Co., Georgia. 1897. Pipistrellus subflavus: Miller. N. Amer. Fauna, 13:90, published as P. s. obscurus. See also Hall and Dalquest, 1950:600. 1959. Pipistrellus subflavus subflavus: Davis. J. Mamm., 40:521-531. 1984. Perimyotis subflavus: Menu. Mammalia, 48: 410. See Horacek and Hanak, 1985-6.

Perimyotis subflavus subflavus (F. Cuvier) Baker (1983) translated Pipistrellus as “bat”, and because of its diminutive ending I suppose the word meant “little bat.” Since the little bats are no longer regarded as true pipistrelles, neither in the East or West, I resurrect Georgia, for the type locality and former usage. The word subflavus means a little less than yellow, meaning either pale yellow or yellowish. Description. This tiny pipistrelle bat with short ears and blunt tragus has a long tail (about half the total length). The calcar lacks a keel. The skull is tiny, delicate, with broad rostrum and inflated braincase. The braincase is neither flattened nor particularly high in lateral profile. There are sparse hairs along the basal margin of the uropatagium. This blond bat with conspicuous black wings (showing red blood vessels and pink bones in life) is exceptionally beautiful. The dorsal hairs, on close examination, are distinctly tricolored, dark gray basally, buffy subterminally, then brown or reddish brown. (To see this trait, blow on the fur and fan it out in a circular pattern, bare in the center.) The venter or belly is also yellowish brown. The forearm is reddish blond, and the patagial membranes and ears of dried specimens are dusky brown. This tiny bat is significantly smaller even than Myotis lucifugus. See Table Chi-6. Dental Formula. 1 2/3, C 1/1, P 2/2, M 3/3 = 34. Geographic Range. Found normally in southwestern Wisconsin, in the caves of the numerous bluffs there, the Georgian pipistrelle has wandered north as far as Iron County and eastward to southeast Wisconsin. Even in summer the species seems restricted to the hilly country of southwest Wisconsin, and migrates to the caves, mines, and sink holes for hibernation. Status. This tiny pipistrelle is uncommon in southwestern Wisconsin, and is exceptionally rare in most of Wisconsin. Furthermore, TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

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Skull of Perimyotis subflavus. 

its numbers seem to be decreasing in the hibernacula. This bat should be protected immediately especially in caves, possibly secured during hibernation by iron gates. Caves should be set aside to protect it and the peculiar cave faunas associated with bats. The bat is beneficial because of its insectivorous habits, and it is esthetically attractive owing to its tiny size, blond fur, and beautiful black wings. No specimen up to now has been found to harbor rabies virus in Wisconsin, although some have in other states. But these bats probably cannot bite through the skin of humans, dogs, or raccoons, because the jaws are minute and weak. The bat might be regarded as a vector or source of the virus. Habitat. The Georgian pipistrelle is found in deciduous woods generally at the forest edge, along streams and rocky outcroppings, mostly in the hills of southwest Wisconsin. It hibernates in mines and caves. In the Stevens Point collection are numerous specimens from caves, but very few specimens have been taken in summer. J. I. Veilleux (2001) reported that in Vigo County, Indiana, he found re-

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productive females in leafy canopies of deciduous trees, even in groups or colonies. Of 37 roost trees, the pregnant or lactating bats were usually hiding in dead foliage. Since upland oak trees were preferred, the pipistrelles were found often on high ground. Foods. The diet consists chiefly of leafhoppers and tiny insects that inhabit the leafy outer branches of deciduous trees. Moths, bugs, tiny beetles, small wasps, and flying ants are preferred foods (Whitaker 1972; LaVal and LaVal 1980). Reproduction. Males outnumber females in caves, a pattern seen also in other hibernating bats. Copulation seems to precede hibernation; the sperm is stored in the female, and is viable until spring. Mating may also take place in spring according to Baker (1983). Two young are born from mid-June to early July. Usually the young are sheltered in dense tree canopies, bark crevices, tree cavities and probably rock crevices. After approximately 30 days the young are weaned and can fend for themselves. Pipistrelles live at least 10 years (Baker 1983, Davis and Mumford 1962, Davis 1966). Mortality. There is little information on the Georgian pipistrelle’s enemies. A leopard frog ate one (Creel 1963). Owls and other birds feed on summer bats, whereas snakes, raccoons, skunks and other predators occasionally capture adults. People often kill them during hibernation, and even field collectors may decimate the low populations in Wisconsin. Whitaker and Wilson (1971, 1974) report mites, chiggers, and flukes parasitizing pipistrelles. Home Range and Density. In summer, pipistrelles are seldom seen, but may form small groups. Jackson (1961) believed they roosted in shallow rock crevices in summer. No information on Wisconsin summer roosts is available. In southwest Wisconsin Ainslie (1983) netted only seven specimens one summer. In winter hibernacula in Wisconsin and Upper Michigan, pipistrelles are never numerous (Long, personal observations; Stones and Haber 1965; Greeley and Beer 1949).

Additional Natural History. Fujita and Kunz (1984) reviewed biology for this species, as Eastern pipistrelle. Geographic Variation. The four races in P. subflavus vary slightly in size and color.. Wisconsin pipistrelles belong to the nominate race (Davis, 1959), and show no geographic variation. Specimens examined. Total, 73. Crawford, Dodge, Grant, Iowa, Lafayette, Pierce, Richland, Sauk, Vernon counties. Other Records. Upper Mich. Baker (1983): Keweenaw and Ontonagon counties.



Maps showing geographic distribution of Perimyotis subflavus in Wisconsin and North America. 

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Genus Nycticeius Rafinesque Nycticeius humeralis (Rafinesque) Evening Bat 1818. Vespertilio humeralis Rafinesque. Amer. Monthly Mag. 3:446. Type from Kentucky. 1819. N [ycticeius]. humeralis: Rafinesque. J. Phys. Chim., Hist. nat. et Arts, Paris, 88:417. 1883. Scotophilus carolinensis: Strong. Geology of Wisconsin, Survey 1873-1879. P. 436-440.

[Included with brown, silvery, and Georgia Perimyotis (=Pipistrellus) subflavus) bats, all four were given separate names under Scotophilus. The name Vespertilio carolinensis E. Geoffroy-St. Hilaire was to be placed in Eptesicus, not anticipated by Strong, of course, and possibly not even synomynized correctly by Elliot (1907). Hollister (1910) suggested that Strong’s carolinensis was Nycticeius, often known as Scotophilus, later documented from several Illinois specimens taken near Racine. See comments below.]

The evening bat is brown, with ashy-brown sheen on the dorsal fur, but resembles M. lucifugus, M. keeni, and E. fuscus. It has less brassy gleam of the dorsal fur. The grayish venter is tinged creamy buff. The wings and ears are black. Measurements are in Table Chi-6. Dental Formula. Unique among bats in Wisconsin. 1 1/3, C 1/1, P 1/2, M 3/3 = 30. Geographic Range. Ordinarily one would not list a species from Wisconsin without a specimen. Almost all range maps I have seen published for the species shade in southern Wisconsin as part of the probable range. There is one record (see below) from 1883. The species is known (Hoffmeister, 1989) from three separate northern Illinois localities (Winnebago, Lake, and northern Cook counties) bordering Wisconsin. The northern wanderings must extend a little northward of these peripheral localities. The mean of three homing distances for Nycticeius given by Watkins is 96 km (60 miles) and the longest distance homed was 153 km (94 miles). Lack of Wisconsin specimens may be due to the difficulty in distinguishing this bat from little brown bats. In summer, little collecting has been

Nycticeius humeralis humeralis (Rafinesque) Nycticeius means nocturnal. The name humeralis means arms or wings. Watkins (1972) considers the meaning as nocturnal, and pertaining to the humerus. Description. The species closely resembles Little brown and small Big brown bats (which are usually larger). Externally the muzzle of Nycticeius is dark, and the ear tragus is very short and rounded (arcuate). The calcar is not keeled. The skull of the evening bat differs markedly from either of the aforementioned, being shorter, broader, and flattened. There are only 30 teeth, and the single upper incisor on each premaxillary extension is distinctive. It is closely sited next to the canine. Most vespertilionid bats have two upper incisors on each premaxillary bone. The karyotype is 2N = 24, FN = 48 (Watkins 1972), and surprisingly resembles that of the western pallid bat, Antrozous pallidus.

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Skull of Nycticeius humeralis. 

accomplished along the southeast border of Wisconsin. The Nycticeius do not use caves. Not mapped for state. Status. See Geographic Range. Habitats. Nycticeius prefers trees, even lone trees, of green ash and silver maple (Acer saccharhinum) (Kurta 1980). Evening bats find places to hide in human habitations, hollow deciduous trees, and loose bark. S. L. Veilleux (2001) reported reproductive females in Vigo County, Indiana, in the green ash and silver maple, always below the surrounding tree canopy at heights averaging approximately 13 m. Such habitat is more or less continuous from the Chicago-Rockford urban areas into southeast Wisconsin, and even far north and west. Foods. Nycticeius feeds on aerial insects. Reproduction. The sexes congregate in autumn, and two (1-2) young are born from mid-May (in the southern states) to mid-June or even early July. Newborn young develop rapidly, moving to the nipples shortly after birth, the eyes opening in one or two days and hair appearing in five. After 20 days the young reportedly can fly (Jones 1967, Watkins 1972). Wings attain adult length in 30 days. Weaning takes place in six weeks. Growth and development were described by C. Jones (1967).

Mortality. Watkins and Shump (1981) suggest raccoons, domestic cats, and black rat snakes may prey on evening bats, if any fall to the ground. There is little known on enemies. Parasites are mites, bat bugs, roundworms, and tapeworms (Watkins and Wilson, 1974). Home Range and Density. No information is available. In Missouri, nursery colonies harbor 1,000 or fewer, usually much fewer individuals (Watkins, 1972). Additional Natural History. Watkins (1972) reviewed the biology for the evening bat. Documented Record. Strong (1883: 438) reported this bat from extreme southeast Wisconsin under the binomen Scotophilus carolinensis, which odd name obscured the record until I consulted the older literature. See synonymy above.

Genus Eptesicus Rafinesque Eptesicus fuscus (Palisot de Beauvois) Big Brown Bat 1796. Vespertilio fuscus Palisot de Beauvois. Cat. Raisonne du mus. de Mr. C.W. Peale, p 18. Type from Philadelphia. 1900. Eptesicus fuscus: Mehely. Monographia chiropterorum Hungariae, p. 206, 338. 1969. Eptesicus fuscus fuscus: Long and Severson. J. Mamm., 50:621-624.

Eptesicus fuscus fuscus (Palisot de Beauvois)



Map of North American distribution of Nycticeius humeralis. 

Appropriately the name Eptesicus means “flyer in the house. “The name fuscus means dusky. Description. The big brown bat is large with a broad face and rhinarium (nosepad), long forearm, skull elongate and flattened, showing little rise in the curvature of the cranium, and in dorsal outline skull wedge-shaped anteriorly much as in Myotis (which are smaller). There are two pectoral mammae. Upper parts of the big brown bat are dark or yellowish brown, the color of coffee, with TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

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a metallic sheen. Belly coffee-brown or grayish brown, occasionally whitish in pale bats; ears and patagia slate or brownish gray. A few albinos are known (Jackson 1961, and others). The diploid number of chromosomes is 50, PN is 48. Some Wisconsin specimens are bleached (Long and Severson, 1969). Measurements are given in Table Chi-6. The big brown bat is slightly larger than either the red or little brown bats; large individuals are exceeded in size only by hoary bats. Dental Formula. 1 2/3, C 1/1, P 1/2, M 3/3 = 32. Geographic Range. The big brown bat ranges widely throughout the state, and often may be found hibernating in mines and caves, houses, churches and other buildings. The species is more common in the southern and central counties. Most of these, except Iron County, have numerous southern plant communities and town-farmland habitats. The same trend is seen in Lower Michigan (Kurta et al., 1989), where the bat is more common in agricultural and urban habitats. Status. Aside from harboring the rabies virus in a small proportion of big brown bats, this species is a beneficial insect-controlling



Skull of Eptesicus fuscus. 

132

THE WILD MAMMALS OF WISCONSIN

mammal. Owing to utilization of houses, buildings, even church basements, this species has doubtless increased its numbers (but not its popularity). Baker (1983) suggests they have increased “many fold,” and they are on occasion truly pests in human houses. Long and Thiess (1996 unpublished) observed a dramatic rise of Wisconsin Eptesicus. They are most common in towns of 40,000 to 100,000 people, where they are by far the predominant species (Table Chi-3, 4). Curiously, they are less common in the largest city, Milwaukee. They seem to have replaced Lasiurus borealis, which was formerly, in early literature, the most common reported bat of towns and settlements. Whitaker (1995) requested that states and perhaps federal agencies provide protection of these bats and their maternity colonies, because they feed on insect pests (see Foods). Habitats. The typical habitats are deciduous woodlands, as well as urban areas. Big brown bats seek caves and dark buildings in man-made structures and habitations. I have seen them winter, tree cavities and hollows and buildings in summer, and during the year utilize a variety of in summer hanging onto buildings even hiding in crevices of my chimney. Foods. Big Brown Bats select larger prey items than Myotis, especially beetles (Whitaker 1972b, 1955; G. Phillips, 1966, Kunz and Fenton 1973, Hamilton 1971). They also feed on bugs, ants, leafhoppers, moths, crane flies, midges, and other insects (Whitaker 1972, 1995), including several serious beetle pests, and stink bugs. Dipterans, Lepidopterans and other kinds of insects were minor foods. More information on diet is given in Coutts et al. (1973). Foraging begins after sundown, and is usually within 2km of the roost. Big brown bats seldom feed November to March even though they are often seen flying about (Hoffmeister 1989). During lactation the females show a higher metabolic rate and produce more carbon dioxide (Kurta et al. 1990). Data from Juvenile Big Brown Bats from Wisconsin are as follows, including Mus. No., Date of Collection, and Locality:

7195 July 30 Athens, Marathon Co. 7188 Aug. 3 ElkhartLake,Sheboygan Co. 7218 Aug. 17 Oregon, Dane Co. 7095 June 30 Ellsworth, Pierce Co. 7176 July 13 Big Bend, Waukesha Co. 7177 July 13 Eden, Fond du Lac Co. 7183 July 27 Cadott, Chippewa Co. Reproduction. Yearling males and some yearling females may breed. Copulation takes place just before and after entering hibernacula, and continues during arousals in the winter (Beer 1955). Sperm is stored until April, and gestation lasts about 60 days, until late May to mid-June, when one or two, and rarely three,



Maps of distribution of Eptesicus fuscus in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

133

are born. Apparently there is some kind of uterine control resulting in a single young (Birney and Baird 1985). Newborn young are naked, inactive, blind and weigh only about 2-3 g (Barbour and Davis 1969, Davis et al. 1968, Kurta and Baker 1990). Maternity colonies seem surprisingly rare, but apparently a mother leaves her young hanging and searches for them after foraging (Brenner, 1968; Kunz, 1976; Barbour and Davis, 1969). Lactation continues as late as early August. Some details on growth and aging are given by Burnett and Kunz (1982). Big Brown Bats may live 19 years (Goehring 1974, Barbour and Davis 1969). Specimens are aged by toothwear at the tip of the canine. Closure of epiphyseal sutures of the wing distinguishes immature from older bats. Christian (1956) noted steady growth from birth until mid-summer, after which the growth rate diminished. By the seventh summer, canines may be worn down to the occlusal rim of the cingulum. Mortality. Owls, American kestrels, common grackles, opossums, long-tailed weasels, striped skunks and snakes feed on big brown bats (Beer 1953, Black 1976, Dexter 1978, C.F. Long 1971, and Long 1978). Trematodes were reported by Lotz and Font (1983). In summer 1995, a bed bug was found on a dead Eptesicus from Wisconsin. Other parasites include Basilia and Cimex. Acarine parasites include Acanthopthirius and others. Several species of mites also parasitize Eptesicus. Kurta and Baker (1990) summarize hosts of internal parasites. Over 20 helminths infest Eptesicus in Wisconsin alone (Lotz and Fout 1985). Rabies is a problem in Eptesius nationwide. Encephalitus is possibly transmitted. Histoplasmosis may be contracted by this bat or passed in its guano (Bartlet et al. 1982, Hoff and Bigles 1981). Man-made chemicals cause some mortality (Kurta and Baker 1990). Home Range and Density. In spring, female big brown bats congregate in maternity colonies. These are in habitations of people or in oak, beech and other trees. The colony is usually 25-75 adults. In hibernacula males are

134

THE WILD MAMMALS OF WISCONSIN

more numerous (Barbour and Davis, 1969). In Wisconsin at Twin Bluffs, we observed several hundred big brown bats. Usually only a few are found, co-existing with but outnumbered by other bats, especially Myotis lucifugus. Homing may cover 400 km, taking 4 to 6 days. Long and Thiess (1996 unpublished) found the numbers to peak in August and September, and probably they do not diminish much in the caves. They are collected in all months of the year, and probably are more active than other Wisconsin bats in winter. Beer (1955) studied banding records (1940-1953) for 3,871 big brown bats in Wisconsin and Minnesota. They did not make long movements (33-61 miles were the longest), usually less than 10 miles (= 16 km). The mortality rate was approximately 40 percent a year. Additional Natural History. Goehring (1972) made a thorough study of Eptesicus fuscus in Minnesota. Another important reference is Kurta and R. H. Baker (1990). Geographic Variation. Long and Severson (1969) found only a single race in Wisconsin. Many bats along the western border were exceptionally pale and had creamy whitish underparts. Specimens examined. Total, 368. Ashland, Barren , Brown, Buffalo, Burnett, Calumet, Chippewa, Clark, Columbia, Crawford, Dane, Dodge, Door, Douglas, Dunn, Eau Claire, Grant, Green, Green Lake, Iowa, Iron, Jackson, Jefferson, Juneau, Kenosha, La Crosse, Lafayette, Langlade, Manitowoc,



Showing seasonal abundance of big brown bats based on Wisconsin Hygiene Laboratory specimens. Long and Theiss. 



Sketch of big brown bat. Charles and Elizabeth Schwartz, and Univ. Missouri Press. 

Marathon, Marinette, Marquette, Milwaukee, Monroe, Oconto, Outagamie, Pepin, Pierce, Portage, Price, Racine, Richland, Rock, Rusk, Shawano, Taylor, Sheboygan, St. Croix, Trempealeau, Vernon, Vilas, Walworth, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood counties.

Genus Lasiurus Gray Hairy-tailed Bats or Furry-tailed Bats In this genus there is a single upper incisor, on each side, and the skull has such a wide palatal notch the appearance of the skull is crab-like (perhaps “fanged” as in the heads of spiders). The dorsal uropatagium is densely furred, and is nearly concolor with the dorsum. In the specimens I observed of two Wisconsin species, Lasiurus has a tiny peg-like first upper premolar, which is set off line, sited slightly inside the tooth row. Shump and Shump (1982a, 1982b) wrote thorough reviews for Lasiurus borealis and L. cinereus.

Lasiurus borealis (Muller) Red Bat Lasiurus borealis borealis (Muller) 1776. Vespertilio borealis Muller. Des Ritters Carl von Linne... Suppl. 20. Type from New York. 1897. Lasiurus borealis: Miller. N. Amer. Fauna, 13:105.

The name Lasiurus means hairy tailed, and borealis means northern. The name is a misnomer because the bat probably has extended its range northward from southern latitudes, but not very successfully into boreal habitats. Description. This medium-sized, pugnosed bat is easily identified by its reddish furry uropatagium (a portable “sleeping bag”). The skull has the offset premolar in the “crab-like” skull (see description in Genus Lasiurus above). The size is significantly smaller than in L. cinereus (see Measurements). The ear is rounded, nearly circular, and the tragus is short and blunt. The rostrum is exceptionally short, and the canines procumbent. There are two pectoral mammae in females. The karyotype is 2N = 28, FN = 48 (Shump and Shump 1982). The fur is bright brick red-orange in males, and yellowish-orange in the drabber females (there are exceptions to this dichromatism). The young resemble the females in color (Timm 1989). The dorsum is “frosted” or washed with whitish or cream-tipped hairs. A creamy spot is conspicuous on the elbow. The red bat closely resembles L. cinereus but is more reddish and much smaller. Measurements are given in Table Chi-6. Shump and Shump (1982) list average measurements for ten males as follows: total length 108.9, tail length 52.7, hind foot 7.9, ear length from notch 10.5, tragus 7.5, and forearm 40.6 mm. Females averaged eight percent larger. Dental Formula. DF = I 1/3, C 1/1, P 2/2, M 3/3 = 32. Geographic Range. Occur throughout Wisconsin, but red bats are not abundant in northern counties. They migrate southward from Wisconsin for the winter, and seldom use caves. Status. The red bat seems more common in the southern counties (judging from Jackson’s comments, 1961), and all but one of the recently collected (in the past ten years) specimens observed by Long and Thiess (1996 unpublished) were from southeast and south-central Wisconsin. The species had been increasing in numbers northward (Long, TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

135

1976) probably because of the opening of the forests, the planting of deciduous trees, the erection of numerous street lights and other lighting also (which attract nocturnal insects in numbers). One specimen was taken in the Apostle Islands, in Lake Superior. In recent years the numbers of the red bat taken in Wisconsin have declined, judging by their scarcity in large samples tested for rabies (Long and Thiess, 1996 unpublished). The red bat possibly may be replaced by numbers of Eptesicus in human cities and settlements, although direct competition for foods and roost sites seems unlikely. The decline of the red bats may follow tree removal from city streets, due to diseases and construction projects. In early literature in Wisconsin the red bat generally was reported as common, and Eptesicus was uncommon. Habitats. The red bat prefers the open deciduous woodlands and riparian habitats along streams, primarily in the southern and central parts of Wisconsin. The trees they forage in, hang up in, and leave their young in while flying about are elms, box elders, oaks, hackberry, ash, sycamore, and various



Skull of Lasiurus borealis. 

136

THE WILD MAMMALS OF WISCONSIN

shrubs. Only on rare occasions do red bats enter caves or buildings. Leafy branches of ash, elms, sycamore and other deciduous trees are the usual day roosts. Foods. Moths and beetles were observed foods of red bats in Indiana (Whitaker 1972). Crickets are found in their diet (Jackson 1961). Bugs, leafhoppers, wasps and flying ants, flies, and moths are also eaten (Freeman 1981). Some data on juveniles from Wisconsin and Minnesota are as follows, including Age, Date, Measurements, and Locality: Juvenile June 11 58-21-7-8 -tr 2 Chippewa Falls 2 Juveniles June 23 Tiny, umbilicus present, eyes shut, Henney MN Juvenile June 30 64-22-9-9 Tasca State 3.2 g 1 Park, MN (Nursing mother) 3 Juveniles July 14 14-15g Stoddard, WI 4 Juveniles? Aug. 11 31-34 Stillwater, MN

Reproduction. Red bats mate in late summer and fall (Steuwer 1948). Sperm is stored until spring (Barbour and Davis 1969). In April and May the migratory females return to Wisconsin, the males later. The gestation is unknown, but embryos are found as early as late April. Young are born in June or even later. The neonate weighs about 0.5 g. The female may be overloaded with as many as four young. She must carry them in flight, usually 3 (range 1-5). Stains (1965) weighed four young that outweighed the mother (24.4 g, 12.9 g), and yet she mangaged to carry these in flight. Eventually offspring are left hanging in deciduous trees. The young can fly after approximately four weeks and are weaned near this age (Barbour and Davis 1969). A lactating female (UWSP-7877) from Kenosha was taken 29 June 1995, and a mother with young was obtained in Madison on July 7. Mortality. Blue Jays are common predators of red bats with reports in four states (Baker 1983). Hawks, owls, opossums, and striped skunks eat them (Sperry 1933). Echolocation failures apparently cause mortality of several sorts, especially impale-

ment on barbed wire (Van Gelder 1956, Long 1964). Many red bats are killed by cars. In addition to rabies, red bats are plagued by numerous parasites (Shump and Shump 1982). Mumford and Whitaker (1982:193) reported at least four dead red bats drowned by an April storm on Lake Michigan. These were “likely in migration when they encountered the storm.” Timm (1989) found 50 dead red bats in autumn and only two casualties in spring picked up near a Chicago hotel. Home Range and Density. Mostly solitary, red bats often forage in groups. Nichols and Stones (1971) reported red bats in large



Maps showing distribution of Lasiurus borealis in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

137

numbers moving across Lake Superior. Little is known of real density, home range, and migration patterns. Dates of collection in my specimens vary from April 11 to October 18. The species is more likely to be observed in autumn (Long, 1976). Remarks. The red bat harbors rabies virus occasionally, and when infected it presents a problem because it may come into contact with children (Whitaker et al. 1969). This species is most likely to be found sick in one’s yard and, of course, may bite one’s hand if picked up. Warn the children. Geographic Variation. One subspecies occurs in the eastern states, and in Wisconsin. Specimens examined. Total 42. Ashland, Chippewa, Clark, Columbia, Dane, Jefferson, Kenosha, Manitowoc, Menominee, Milwaukee, Portage, Racine, Richland, Rock, Sauk, Shawano, Vernon, Walworth, Washington, Winnebago, and Wood counties. Other Record. Door Co.: Washington Island (Long, 1978).

Lasiurus cinereus (Palisot de Beauvois) Hoary Bat

premolar is set inside the tooth row. The ear pinna is rounded, nearly circular, with a short blunt tragus. There are 28 chromosomes (fundamental number of 48) (Shump and Shump, 1982). There are two pectoral mammae. The fur is brownish, intermixed with blackish and reddish (sometimes yellowish) and frosted with whitish or pale buff. There is a buff spot near the elbow, and the fur of the uropatagium is nearly concolor with the back (often washed with silvery gray). The individual hairs of the back typically have four bands, basally dark, then yellow, then brownish-black, then whitish distally. The overall effect dorsally is brown, red-brown (nearly maroon), or yellowish brown fur frosted with white, which coloration is unique for Wisconsin bats. The ears are brown. Often flying hoary bats may be identified by their swift, direct flight. Measurements are given in Table Chi-6. Dental Formula. I 1/3, C 1/1, P 2/2, M 3/3 = 32. Geographic Range. To be expected throughout the state, particularly during migrations. Formerly thought to reside in the northern coniferous forests, actually the hoary bat

1796. Vespertilio cinereus Palisot de Beauvois. Cat. du mus. de Mr. C.W. Peale, Philadelphia. P. 18. Type from Philadelphia, misspelled as linereus. 1864. Lasiurus cinereus: H. Allen. Smiths. Misc. Coll., 7(165):21.

The scientific names mean hairy-tailed and gray. “Hoary,” as in the phrase “hoar frost,” refers to the whitish tips of the dorsal hairs creating a frosted appearance. Description. The hoary bat is the largest bat in Wisconsin. The wing span occasionally may exceed 15-17 inches. The combination of size, and brownish fur frosted above and extending onto the entire upper uropatagium identifies this species. The forearm usually exceeds 50 mm. The skull is long and broad, “crablike” in form (wide palatal notch). The canine is large and procumbent, a single incisor, and one tiny

138

THE WILD MAMMALS OF WISCONSIN



Skull of Lasiurus cinereus. 

becomes more abundant in the southern counties and on southward. It is never numerous. Status. This solitary species is observed in small groups in summer (they may be family groups). Unlike L. borealis, this larger Lasiurus is rare. In winter it probably leaves the state, so far as it can be determined, and in summer is fairly common in the hilly southwestern counties (Ainslie 1983). Dates of collection in this Museum range from 21 May to 19 November, indicating the active period in Wisconsin. Habitats. Jackson (1961) and Long (1977) mentioned that hoary bats are more likely than



Maps showing distribution of Lasiurus cinereus in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

139

red bats to occur in coniferous forests. This is true if one means the coniferous forests of northern counties, where red bats are seldom found. Hoary bats generally range through much of the conifer forest of the Rockies, but Ainslie (1983) in southwest Wisconsin netted hoary bats in summer in deciduous trees. This species is very seldom seen in caves. Foods. A hoary bat once was seen attacking a Georgian pipistrelle presumably to eat it (Bishop 1947). The primary food source is the community of flying nocturnal insects, such as moths, flies, beetles, and hymenopterans (Black 1972, Freeman 1981, Whitaker 1972). Reproduction. Copulation in hoary bats has not been observed. This probably takes place during the autumn migration either prior to movement, during movement, or upon arrival in the winter range. Males do not seem to accompany the females on their northward migration. By then, the females are, of course, pregnant, likely following a winter period of delayed fertilization. Parturition occurs in May and June (Mumford 1969, Bogan 1972) but these observations were far from Wisconsin. Usually two young are born (1-4) weighing about 4.5 g each. They are initially cradled in the mother’s wings. A mother with two young (one measuring 88 mm in total length) was taken in Madison on July 7. There is a fine silvery-gray hair on the newborn skin, except on the naked venter, and in three weeks



the pelage has grown. The young are left hanging in foliage at night while the mother forages. The young bats enter the population in late July, and fly well at 33 days of age (Bogan, 1972; Shump and Shump 1982). Juvenal males reportedly mate their first year (Druecker 1972). The interrelation of reproduction, migration and growth is discussed under the Vespertilionidae above (Koehler and Barclay, 2000). Mortality. Hawks, owls and snakes probably prey on hoary bats (Church 1967; Wiseman 1963). As in the related red bats, numerous hoary bats become impaled on the barbs of barbed-wire fences (Denys 1972, Hibbard 1963, Iwen 1958, Wisely 1978), and suffer other accidents in flight. Home Range and Density. The hoary bat is rare or uncommon. There is little information on densities. The sexes keep separate in summer, coming together only in the mating season. Remark. The incidence of rabies in the hoary bat is fairly high (Whitaker, 1969). In 1994, only two Lasiurus cinereus were collected at the Wisconsin Rabies Lab, State Hygiene Laboratory, and both had rabies. In wild populations, the incidence is doubtless much lower. Geographic Variation. None is evident in North America. Specimens examined. 22. Dane, Dodge, Grant, Milwaukee, Portage, Sauk, Vernon, Wood counties.

Monthly numbers of bats counted in southwestern Wisconsin caves, 1981. Ainslie. 

140

THE WILD MAMMALS OF WISCONSIN



Table Chi-2 Chi-2. A survey of the species of bats in Wisconsin and their numbers collected by the Wisconsin Hygiene Laboratories, 1991-1994. All specimens are alcoholic specimens in the UW Museum of Natural History, and represent a state-wide survey based on people-to-bat encounters, not collections with mist nets or from caves. Long and Thiess. 

Species

Number

Percent

Eptesicus fuscus Myotis lucifugus Lasionycteris noctivagans Lasiurus borealis Lasiurus cinereus Myotis keenii Other species

230 107 13 7 2 2 0

64 29 4 2 0.5 0.5 0

Totals

361

100



Table Chi-3. By use of the above survey the number of bats were related to population size of the communities (from roadmaps). Milwaukee had the fewest bats relative to human population (and its great ecological disturbance). Bats were often collected in towns and cities, even in towns having nearly or slightly more than 1,000 people, which were the highest frequency sizes of towns. Population size was scaled as logs to base 10. After Long and Thiess. 

Log size

Number towns

Number bats

Bats/log size bats

<2.0 2.1-2.25 2.26-3.0 3.1 3.6-4.0 4.1-4.5 4.6-5.0 5.1-5.5 5.6-6.0

~ 100 48 218 180 65 50 10 2 1

10 14 24 67 51 41 86 38 9

— 6.2 8.0 19.1 12.8 9.1 17.2 6.9 1.6



Table Chi-4. By the same survey of bats above, relative abundance and diversity of bats were determined, related to log population size (base 10) for Wisconsin. Milwaukee has the most people, the greatest diversity of bats, and the fewest of them in relation to population (Table Chi3). Eptesicus and Myotis lucifugus are widely distributed, but uncommon in Milwaukee. The diversity index (D) for the entire state was 0.5. The three lowest ranked sizes were combined to obtain D = 0.583 for 1.7-2.5, which without combining was 0.464. Frequency is given for the species obtained.  Log Eptesicus M. LasioL. L. M. Size lucifugus nycteris borealis cinereus keenii &D <1.7

6

2

2

1.8-2.0

2

1

0

2.1-2.5 & 0.583

6

7

1

2.6-3.0 & 0.464

15

9

0

3.1-3.5 & 0.499

39

27

1

3.6-4.0 & 0.495

32

17

1

1

4.1-4.5 & 0.505

27

10

2

1

1

4.6-5.0 & 0.403

65

13

3

3

0

5.1-5.5 & 0.547

19

17

2

0

>5.6 & 0.717

4

1

1

2

1

215

104

13

7

2

Totals

2

2



Table Chi. 5. Relative abundance (RA) and species diversity of bats netted in southwestern Wisconsin, by habitat. Netting hours per habitat in parentheses. RA = number of bats/ number of hours netting. After Ainslie, 1983.  Northern forest dry-mesic (5.8) RA N Little Brown Bat Red Bat Keen’s Myotia Big Brown Bat Georgian Pipistrelle Hoary Bat Total Species Diversity (H)

129.3 17.2 3.4 20.7 12.1 5.2 187.9 .456

75 10 2 12 7 3 109

Northern forest mesic (6.2) RA N 104.8 11.3 17.7 4.8 0.0 0.0 138.7 .341

65 7 11 3

86

Southern forest xeric (17.5) RA N 109.1 0.6 5.7 1.1 1.1 1.7 119.4 .184

191 1 10 2 2 3 209

Southern Southern Southern forest forest forest lowland (20.8) dry-mesic (14.7) mesic (29.7) RA N RA N RA N 88.0 1.9 2.4 0.0 0.5 1.0 93.8 .089

183 4 5 1 2 195

84.4 0.7 4.8 0.7 0.0 0.0 90.5 .133

124 1 7 1

133

68.0 11.1 3.0 2.7 0.3 0.3 85.5

202 33 9 8 1 1 254 .295

TAXONOMIC ACCOUNTS / ORDER CHIROPTERA

141

142

THE WILD MAMMALS OF WISCONSIN

Lasiurus cinereus

Lasiurus borealis

F’’s & M’s

F F

2

6

M’s

F F F

5

3

M’s

F

7

Perimyotis subflavus 10

M’s

11

Eptesicus fuscus

75 102

90.7 ± .5

79 86 85

79.8 ± 2.8

110.2 ± 6.9

110 ±8

102

91

89 88

86.0 ± 3.16

89.7 ± 4.11

87 89

87.6 ± 3.0

Total length

Grant & Sauk C. 126.7 ±8

Sauk Co. Sauk Co.

Sauk Co.

Beetown C. Limery C. Maiden Rock

Beetown C.

Vic.Stevens Pt.

Brown Co.

F

1

Lasionycteris

“

F2 embs Missouri

F

2

Grant Co.

Nycticeius humeralis 1

M

4

Myotis keenii

“ “

Drummond, Bayfield Co.

Locality

M’s & F’s Indiana

F F

1 1

6

M

8

Sex

Myotis sodalis

Myotis lucifugus

N

57.0 ± 3.2

39 46

42.3 ± 2.8

34 35 35

37.0 ±2.6

40 ± 5.3

44 ± 4.3

42

38

38 40

37.5 ± 3.1

35.17 ± 2.5

33 35

34.6 ± 1.9

Tail length

9.0 ± 1.1

7 6

6.67 ± .8

9 6 10

7.31 ±1.

13 ± 4.6

10.7 ± 2.2

8

10

9 9

9.3 ± .15

9.08 ± .8

10 10

10.14 ± .69

Hindfoot length

15.0 ± 1.26

8 9

8.69 ± .5

11 10 10

10.54 ± .97

16 ± 1.1

14.3 ± 2.1

11

12

16 15

15.0 ±0

–

15 13

14.71 ± .76

Ear length

5

54.17 ± 2.6

37 39

37.3 ± 1.0

34 33 34

33.3 ± 1.

471

45

42

–

37 36

35.5 ± .58

38.0 ± 1.3

37 38

38.1 ± 1.2

FA length

6.83 ± .98

4 3

4.17 ± .98

4 4.5 4

4.38 ±96

62

3

24.7g ± 2.25

8.5 10.5

9.3g ± .9

– – –

6.3 6-6.5

14.4

8 5

–

–

– –

–

6.62 g

– –

–

Weight

3

8

7 7

8.0 ± .8

6.67 ± 1.2

7 7

7.0 ±0

tr. length

17.71 ± .5

– 14.2

13.53 ± .48

12.95 12.6 13.1

13.135 ± .14

19.4 ± .44

19.52 ± .4

16.0

14.1

15.5 15.32

14.88 ± .31

14.37 ± .34

– –

14.93 ± .35

Greatest l. Skull

10.16 ± .23

– 7.9

7.69 ± .15

6.06 ± .26

– 4.9

4.48 ± .3

4.1 4.05 4.15

4.36 ± .22

6.85 ± .1 6.8 6.8 7.0

5.98 ± .14

7.03 ± .14

–

5.1

6.0 5.9

5.59 ±.09

5.31 ± .18

– –

–

Max t-r

10.01 ± .25

10.07 ± .18

7.5

8.3

7.85 7.50

7.48 ± .17

7.33 ± .25

– –

7.59 ± .34

Cranial br.

6.78 ± .99

– 5.7

5.63 ± .1

5.3 5.0 4.76

5.08 ± .34

6.93 ± .14

5.55 ± .24

5.0

5.1

4.7 5.7

4.98 ± .23

4.89 ± .41

– –

5.02 +/- .29

Cranial depth

Table Chi-6. External and cranial measurements for Wisconsin’s species of bats. Means ± standard deviation. Sample size is N, and exponent value is N for some samples. 

Species



Order LAGOMORPHA Pikas, Rabbits, and Hares The ancestry of the lagomorphs is not known for certain; insectivores and primates have been suggested. Owing to their mutual gnawing and destructive habits, the lagomorphs long had been confused with the rodents, until Gidley (1912) separated the two orders, and in some quarters they are confused today by lay people. These two orders of mammals actually have maintained separate lineages at least as early as their first preserved fossils— in the early Eocene Epoch (perhaps late Paleocene, see Meng et al., 1994) for the rodents, and the late Paleocene for the ancient Lagomorphs. Lagomorpha resemble rodents in having two chisel-like upper incisors for gnawing. Unlike rodents, the pikas, rabbits, and hares have a second pair of upper incisors, tiny and peg-like (or spicule-like) sited immediately behind the first pair. The chisel-like incisors and gnawing behavior have evolved in parallel. Modern Lagomorpha are divided into two families, the Holarctic pikas (Ochotonidae) and the cosmopolitan rabbits and hares (Leporidae). A secondarily derived (not primitive) cloaca is seen in the pikas (Long, 1970). There are rabbits and hares in Wisconsin.

Family LEPORIDAE Gray “Naturalists have sought... to distinguish between the Rabbits and the Hares; but although the young of the former are blind and naked when born... and the latter are clothed with hair, and have the eyes open, and in their habits there is this difference, that the Rabbits burrow, whilst the Hares make a “form”... on which they squat.” – G. R. Waterhouse, 1848, Natural History of the Mammalia, Vol. 2.

The Leporidae, or leapers, are characterized by their diminutive second upper incisors, and by elongate hind limbs used for hopping and leaping (saltatorial locomotion). The



Skull of a lagomorph. Anonymous artist. Note skull fenestrae, upper incisors, and diastema of the jaws. 

tail is always short with a conspicuous bunch of fluffy hairs. The hind foot may or may not possess a dew claw (vestigial toe nail), and the other four hind toes (beneath a dense hairy pad) are webbed for support (holding the toes together while leaping). The forefoot has five toes. The testes are extruded into a scrotal sac, but lie under the skin situated a little anterior of the conical penis. There is no baculum as seen in rodents. For its herbivorous diet, the molars are comprised of transverse loph-like crests, and there is a pronounced gap (diastema) between the chewing teeth and the chisel-like incisors extending most of the length of the rostrum and beneath, also of the dentary, i.e., the premaxillaries, maxillaries and nasals. The zygomatic arch projects slightly, both anteriorly and posteriorly, as orbital processes, and a frontal (supraorbital) extension partially enclosing the orbit above has similar anterior and posterior processes. The posterior process may come in close proximity to the braincase (in Sylvilagus). At various places on the skull surface, the bone is exceedingly porous or perforate, and this screen-like structure is termed fenestrate (meaning “with windows”). There is a clavicle, often lacking in leaping animals. The tibia and fibula are fused distally. The skin is very thin and emits water for evaporation by insensitive perspiration. Lagomorphs often reingest their own feces (coprophagy) for more efficient digestion of vegetal carbon compounds. Rabbits differ from jack rabbits and other hares (genus Lepus) in giving birth to naked, blind, helpless (“altricial”) young in a nest made of the TAXONOMIC ACCOUNTS / ORDER LAGOMORPHA

143

mother’s ventral hair. In Lepus there is no nest at all, and the young are born on the ground. Their eyes are open at birth, the body haired, and the active young are said to be “precocial.” In Lepus americanus and L. townsendii the fur usually molts to white in early winter, to brownish in spring and summer.

3

Key to the species of Leporidae in Wisconsin 1.

1’

2.

2’

144

Size small (total length 460 mm or less, hind foot less than 100 mm), orange on nape,skull usually less than 75 mm in length, interparietal distinct from parietal bones posteriorly, postorbital process of frontal bone fused to braincase (to cranial frontal) instead of flaring away from the braincase, jugal of zygoma narrow and hardly tapered, and interpterygoid fossa (depression or cleft between the pterygoids) narrow ........... Eastern cottontail Sylvilagus floridanus Size large, skull elongate, interparietal fused posteriorly, postorbital process of frontal flares away from the braincase, jugal expanded in the middle and tapering at either end, interpterygoid fossa wide ................................................ 2 Summer and winter pelage on the back grizzled grayish to yellowish brown, whitish at hair bases, grayer on cheeks and flanks, nape and feet buffy, tail blackish above, zygomatic arches broad anteriorly, nasals exceptionally wide and exceeding 42 mm in length ..... European hare Lepus capensis (might occur in Wisconsin, introduced onto Upper Peninsula of Michigan). Fur in summer grizzled dark brown or yellowish tan, hairs not whitish basally, nape never orange or yellowish, feet brown or tan, zygomata broader across posterior processes than across the anterior processes, nasals not as broad, though relatively wide in comparison to Sylvilagus, but always less than 42mm in length ........... 3 THE WILD MAMMALS OF WISCONSIN

3’

Feet relatively large for standing on snow, size medium (total length usually exceeds 450 mm, hind foot 110-150 mm), dorsal fur in summer dark or pale grizzled ochraceous and creamy brown without orange rust on the nape, tail dusky above, white below, in winter usually pure white (with pale buffy gray underfur entirely hidden) except for black eyelids and eartips ............................. Snowshoe hare Lepus americanus Feet relatively small but correlated with large size (total length exceeds 550 mm, hind foot about 145-172 mm), dorsal fur in summer buffy or creamy gray and slightly grizzled, no markings on the neck, tail all white, in winter the fur is pure white excepting black ear tips ............. ....................... White-tailed jack rabbit Lepus townsendii

Genus Lepus Linnaeus Jack Rabbits and Hares See account of Order Lagomorpha for distinguishing features of jack rabbits and hares from those of cottontail rabbits.

Lepus townsendii Bachman White-tailed Jack Rabbit Lepus townsendii campanius Hollister 1837. Lepus campestris Bachman. J. Acad. Nat. Sci. Philadelphia, 7:349. Not Lepus cuniculus campestris Meyer, 1790. Type from Saskatchewan, near Carlton House. 1915. Lepus townsendii campanius Hollister. Proc. Biol. Soc. Washington, 28: 70, a renaming of L. campestris.

The name townsendii honors J. K. Townsend, who collected the holotype of the nominate race at Walla Walla, Washington. Lepus means leaper.

Description. The white-tailed jack rabbit is readily identified by large size and white tail, as well as by its prairie surroundings. The skull is less massive than in the European hare L. capensis (see Key above), and the length of the nasals is less than 42 mm. The postorbital and antorbital process flare away from the skull. Chromosomes are 2N = 48 (Hsu and Benirschke, 1971). The color in summer is a creamy or buffy gray intermixed with fine brownish hairs, and the ears are tipped with black. The underparts are white as is the tail. In winter the fur is white, except the black tips of the ears, but the fur and the forefeet are suffused or faintly washed with buff. Occasionally a thin black line is seen on the upper side of the fluffy tail. Young, having fewer guard hairs, show more underfur color (Lim, 1987). The winter molt occurs in November and early December (Lim, 1987). The hind feet and ears grow faster than other body dimensions (Lim, 1987). Lengths vary to 27 inches, and a large hare may weight 10 pounds ( = 4.5 kg). Dental Formula. I 2/ 1, C 0/0, P 3/2, M 3/3 = 28. Geographic Range. Possibly this huge, white-tailed jack rabbit was a rare but natural denizen of southwest prairies in Wisconsin (Corey, 1912), although Jackson (1961) did not think so. Long (1970) listed it as possibly an introduced species. It was widely introduced



Skull of Lepus townsendii. Dorsal, ventral views. 

from Minnesota as a game animal, and persisted for years in widely separated marshes and prairies. The range expanded from 1944 until 1953 (Lemke, 1956) but now has greatly diminished. The species may be eradicated. No one I have consulted in the Department of Natural Resources verifies that any remain. It closely resembles snowshoe hares in winter. I have one specimen, from northern Langlade County. Status. The white-tailed jack rabbit seems to have vanished from Wisconsin, and the reasons are unknown. It quietly disappeared in the last 30 years. None of several reports of its occurrence could be verified. The preferred habitats of open marshland and prairie having wide horizons, i.e., grasslands of vast expanses, are also fast vanishing and almost gone. The last known jack rabbit in central Wisconsin (Buena Vista Marsh) was collected in 1966, by one of my undergraduate students, who donated it to the collection in Madison. William Smith (personal comm.) reported that in the late1960’s a few existed on the Military Ridge prairie country of Grant and Iowa counties (southwest Wisconsin). More than a third of the 19,000 jack rabbits killed in 1951-52, came from Barron, Clark, Eau Claire, Marathon, Portage, Waushara, and Wood counties. There are no such numbers today, although the species is secretive (but often seen, if present, on plowed fields where cover is absent). A few ranchers on the Buena Vista Marsh claim the species is present there, but more likely they see snowshoe hares. Habitats. The white-tailed jack rabbit inhabits open grasslands, prairies or marshes. Occasionally it ranges onto plowed and mowed fields. The jack rabbit may prefer one place on which to rest, called a form, where the vegetation is pressed down. A form is about one by two feet in dimensions. In winter this hare may scratch out a depression in the snow, even digging sometimes a hole for itself in the snow. Foods. Lepus townsendii feeds on green vegetation when available, and buds and bark when greens are not available (Jackson, 1961). TAXONOMIC ACCOUNTS / ORDER LAGOMORPHA

145



Maps showing geographic distribution of Lepus townsendii in Wisconsin and North America. The patchy distribution in Wisconsin after Domke, 1973. Most recent occurrences are shown by dots. 

Reproduction. Breeding commences in April or May, with a gestation of about one month. The precocial young may be brought forth in a form or dropped on the ground. There seems to be a single litter in the year. Litter size is about four (3-6). Weaning may not occur until the young “leveret” is eating green food, at about 4 weeks of age or even later. Mortality. Hawks, owls, and occasionally coyotes kill this jack rabbit, and cars often kill them on the highways. Once thousands were harvested in Wisconsin by hunters (1951-1952, also see Scott, 1947). Lice, fleas, probably ticks, tapeworms, and probably roundworms parasitize this hare. The species can carry tularemia (Jackson, 1961) and some other diseases (Lim, 1987). Home Range and Density. The home range is given by Seton (1953) and Jackson (1961) as 2-3 km in diameter. Jackson (1961) reported the kill of jack rabbits in l951-1952, as l9,383 animals. The populations fluctuated, but today certainly nothing like those numbers of hares remains in Wisconsin, where the species was once abundant. Little is known about density, reported as 3-9 per km2, but

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THE WILD MAMMALS OF WISCONSIN

as high as 71 (Kline, 1963). Usually the jack rabbits assemble in groups of two to four and go hopping over the prairie in the darkness. They are seldom seen in the day time, unless on plowed ground or the roadway. Geographic Variation. None was evident in Wisconsin. Specimens examined. Total, 3. Portage Co.: Buena Vista Marsh (UW20425, 22 March 1969). Langlade Co.: 5 mi. N Antigo, near Bryant (No. 1021), 24 Oct. 1966. Door Co. Approaching Sturgeon Bay Sight record. 1966. Sheboygan Co. Holland 1 UW Wild. Ecol. [Local. not found.]

Lepus americanus Erxleben 1777. [Lepus] americanus Erxleben. Systema regne animalis . . . . 1: 330. Type from Hudson Bay, Canada. “ ... a specimen of the L. americanus ... November, a time in which the fur is undergoing its change from summer to winter colouring. white, with the exception of the head, cheek, back, and chest ... On the back, the coloured hairs are considerably longer than on the

sides of the body, where they are white... a considerable portion of the summer hairs have been shed from the back white hairs... Were the long and scanty coloured hairs to be plucked... it would present the same condition of full winter pelage... the longer and coarser hairs are shed and replaced by equally long, white-pointed hairs... the dense under fur... becomes longer.” — G. B. Waterhouse, 1842, The Natural History of Mammals, Vol. 2.

Lepus americanus phaeonotus J.A. Allen Snowshoe Hare 1899. Lepus americanus phaeonotus J.A. Allen. Bull. Amer. Mus. Nat. Hist., 12:11. Type locality: Hallock, Minnesota.

The scientific name means American leaper or American hare. “Snowshoe” refers to the huge hind feet, which better enable the hare to hop across snow (the chief force of leaping is focused on the hind feet). The hare also was called a snowshoe rabbit, or the varying hare. Description. See Key to the Leporids above. Not so large as Lepus townsendii or L. capensis, and resembling the Eastern Cottontail Sylvilagus except that the ears and especially the hind feet are larger (and heavily padded with bristly hairs). The skull differs from that in Sylvilagus in its flaring postorbital processes, and in partial fusion of the interparietal, and from other Lepus by the rudimentary anterior process on the supraorbital extensions of the frontal. There are six mammae. The summer pelage of this hare on the upper parts is ochraceous brownish gray, often a deep ochraceous brown with intermixture of black (especially in young hares). There is no rusty orange nape patch as in Sylvilagus or domestic Oryctolagus. The underparts are white. The ears are tipped with black. The winter pelage is all white except eyelids and ear tips. Molting individuals, of course, show various patterns of brown and

white. There are two molts per year. Hares in this collection are seen in molt in November and December, and by late April the white is nearly replaced. The Total length usually varies from 1420 inches (360-500 mm); weights vary up to four pounds ( = 1.8 kg). A large male from Langlade and four females from Portage counties are, respectively, as follows: Total length 630, 436±22; length hind foot 145, 135±7;ear length 72, 74.3± 5; greatest length skull 79.1, 77.3± 3.4; zygomatic breadth 39.2, 38.9± 1.1; length of nasals 33.5, 31.8± 2.6; maxillary toothrow 15.4, 15.0± 0.8. Dental Formula. I 2/ 1, C 0/0, P 3/2, M 3/3 = 28. Geographic Distribution. The range of this species has contracted since the turn of the century (Jackson, 1961). The same thing has happened in lower Michigan (Baker, 1983), where the hare occurs chiefly in the northern counties, and throughout the Upper Peninsula (see Maps). Status. Numbers of this hare in Wisconsin have not changed appreciably since Jackson’s (1961) mapping. As a game animal the species is hunted but also managed, or in this case protected at least by hunting season and possession limits. Habitats. The snowshoe hare inhabits the northern boreal communities, conifer swamps where tamaracks and cedars thrive, spruce-fir woodlands, and wetlands such as alder swamps, aspen-birch marshlands, and cat-tail marshes (Grange, 1932; Jackson, 1961; Baker, 1983). Ground cover of vegetation is essential for this hare. It prefers edge habitats. Some prime habitats are thickets of willow Salix, alder Alnus, and aspen saplings Populus (Keith et al., 1993; Keith and Bloomer, 1993). This hare rests in scratched out forms, under sheltering grass, bushes, or a fallen log. Occasionally it burrows under ground or into snow banks, but not often (Baker, 1983). Foods. The snowshoe hare feeds on green vegetation, and winter buds, twigs, bark, TAXONOMIC ACCOUNTS / ORDER LAGOMORPHA

147

and conifer needles. The fecal pellets are often eaten vegetation, and winter buds, twigs, bark, and conifer needles. The fecal pellets are often eaten (coprophagy) to attain maximal food value from complex carbon compounds in plants (Bookout, 1959). Bookout further suggests (1965) the best winter forage is yellow and paper birch, white cedar, sugar maple, trembling aspen, American elm, jack pine, and red pine. Other plants used as forage are white and black spruce, hemlock, which pine, and beaked hazel. Reproduction. The snowshoe hares mate promiscuously. Occasionally the leverets may attempt to breed (Keith and Meslow (1967). Mating begins in March (when hares are supposed to be “mad” because the males may be seen leaping erratically about) and lasts until early September. Gestation is about 35-36 days.



Skull of Lepus americanus. Dorsal and ventral views. Juveniles are compared below, as their different proportions resemble cottontails. 

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THE WILD MAMMALS OF WISCONSIN

Young are born by mid-April (usually 3, 1-7). The young are furred and their eyes open. They weigh up to 25 ounces. Females do not breed the first year. Older females mate repeatedly; they may bear three or four litters per season. Later litters average larger in litter size (Rowan and Keith, 1956). When the population cycle is on the rise, the mean litter size may increase. Each neonate is furred with eyes open, and weighs about 65-80 g. Neonates can crawl about, but rather feebly. By nine days they have doubled in weight and begin to eat green vegetation. By three weeks of age or a little later the leverets are weaned and leave the form. Baker (1983) reports the young “freeze” (that is, remain motionless) in time of danger, and the mother hare “distracts adversaries away from her litter.” The average productivity for Michigan hares is 6.5 young per female (Bookout, 1965). Longevity is 3-4 years, but there is a report of 8 (Crandall, 1964). Mortality. The snowshoe hare is an important forage species in the North Woods, prey for most of the carnivores and birds of prey with which it co-exists. In fact, high frequencies of hares increase the numbers of predators, and lows decrease them. In central Wisconsin, coyotes ate most of the hares radio-collared by Keith et al. Home Range and Density. Home range varies from 5-57 acres (2-22.8 ha). Movements are extensive in summer. Breeding males have larger territories than other hares. In central Wisconsin, in 1990-91, maximum home ranges varied from 1.6 to 0.8 ha in prime habitat of willow, alder and poplar. In patchy environments of willow, alder and poplar, densities varied from 1.0 to 2.7 hares per hectare, and over the total range from 0.3 to 1.3 / ha (Keith et al., 1993; Keith and Bloomer, 1993). Dispersals were most frequently made from small patches. Unless the patch was large (>5 /ha) or the number of snowshoe hares large enough (10 or more) the hares were likely to vanish. The population was declining, and the chief predator was the coyote (Keith et al., 1993; Keith and Bloomer, 1993).

Besides annual fluctuations there are multi-annual population fluctuations, with population peaks every 9-11 years (Keith and Windberg, 1978). The cycle also has been referred to as the 9-10 year cycle and the ten-year cycle. Some high peaks occur every six years and others as seldom as every 13 years. Some relevant studies among a great many include Adams (1959), Adamsic and Keith, 1978, Adamsic et al., 1979, Arnold (1956), Bookout, (1965), Brand and Keith (1979), Brand et al. (1975, 1976), de Vos (1951), Errington et al. (1940), Keith (1974), Keith and Windberg (1978), MacLulich (1937), Meslow and Keith



Maps of distribution of Lepus americanus in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER LAGOMORPHA

149



Table Lag-1. Suspected Fluctuations in Multi-annual Cycles in Mammals that occur in Wisconsin. After Dymond (1947), with Pitymys ochrogaster added as a possibly cyclic mammal. 

Species Cycle (Yrs.) and Range (Yrs.) Lepus americanus 9-10 (=10) (8-11)* Lynx canadensis 9-10 (=10) (7-12) Sciurus carolinensis approx. 5*** Jackson (1961) Microtus pennsylvanicus 2-4** (1-4) Pitymys ochrogaster ?2-4 May be irregular Ondatra zibethicus 9-10 (8-12)*** Vulpes vulpes 9-10 (8-13)*** Martes pennanti 9-10 (8-11)*** Neovison vison 9-10 (6-12)*** * Range revised to 6-13, see account of Lepus americanus. ** Cycle is often 2-3 years, or 4-5, often irregular, and has been recorded 4-5. *** All workers I consulted knew of no regular cycles in these mammals in Wisconsin.

(1968), Pettingill (1976), Todd et al. (1981), Windberg and Keith (1976), and Wood and Monroe (1977). In Michigan, the kill by hunters varies approximately from 150,000 to 750,000 hares per year (Baker, 1983). The numbers of this species throughout Canada regularlyfluctuate in 10-11 year cycles of abundance (see works of Lloyd Keith, of the University of Wisconsin—Madison, and his many associates), but this hare shows irregular fluctuation in Wisconsin. Perhaps the coincidental effects of predator-prey interactions and seasonality cycles of vegetation abundance are affected by Wisconsin hunting harvests. W.E. Scott (1952) summarized Wisconsin harvests (see Jackson, 1961) from 19311949. From 1950 until 1982, the harvest numbers are listed by Wise (1989) as follows: Year Harvest Year Harvest 1950 154,428 1980 392,800 1960 61,629 1981 232,900 1972 101,700 1982 163,766 1979 404,000 In the winter of 1999-2000, the harvest of snowshoes was estimated as 61,858, mostly from Price, Oneida, and Rusk counties (Dhuey, 2000). Remark. Once, in early summer, I observed a young snowshoe hare deep in the

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THE WILD MAMMALS OF WISCONSIN

Jordan Swamp, central Wisconsin. After it hopped up to me fearlessly, I picked it up and petted it. After I put it down, it went hopping away without showing any concern. Additional Natural History. Bittner and Rongstad (1982) wrote an excellent review of biology for Lepus americanus. Geographic Variation. None has been observed in Wisconsin. Hares on Isle Royale in Lake Superior have been referred to L. a americanus (Baker, 1983). Specimens examined. Total, 43. Ashland, Bayfield, Burnett, Chippewa, Door, Florence, Forest, Iron, Jackson, Juneau, Langlade, Lincoln, Marathon, Marinette, Oconto, Oneida, Portage, Price, Rusk, Taylor, Washburn, Waushara counties.

Genus Sylvilagus Gray Cottontails See Description under Sylvilagus floridanus. “Bred and born in a briar patch! And with that he skipped away as lively as a cricket in the embers.” — Brer Rabbit to Brer Fox (by J. C. Harris, Stories of Uncle Remus)

Sylvilagus floridanus (J.A. Allen) Eastern Cottontail 1890. Lepus sylvaticus floridanus J. A. Allen. Bull. Amer. Mus. Nat. Hist., 3:160.

Sylvilagus floridanus mearnsii (J. A. Allen) 1894. Lepus sylvaticus mearnsii J.A. Allen. Bull. Amer. Mus. Nat. Hist., 6:171. Type from Fort Snelling, Minnesota. 1904. Sylvilagus (Sylvilagus) floridanus mearnsi: Lyon. Smith. Misc. Coll., 45:336.

Sylvilagus floridanus means the Florida wood rabbit. Eastern cottontails occur mostly in the eastern United States.

Description. The cottontail is the smallest of Wisconsin leporids (total length 460 mm or less, hind foot less than 100 mm, skull usually less than 75 mm in total length), with skull narrow, nasals tapered anteriorly, interparietal distinct from adjacent bones, fenestrae lacking on rostrum, anterior processes of supraorbital extension of frontal rudimentary, posterior process fused to braincase, hind foot small, jugal of zygoma slender. There are four pairs of mammae. Diploid chromosomes are 42. The eastern cottontail shows grizzled brown upper parts in all seasons, rusty orange or reddish brown patch on nape of neck, underparts whitish or grayish, tail short, brownish gray above and conspicuous white fluff below. Guard hairs are coarse, variably



Skull of Sylvilagus floridanus. Adult. Dorsal and ventral views. 



Skull of Sylvilagus floridanus. Juvenile. Dorsal and ventral views. Juveniles differ in proportion from adults, resembling snowshoe hares. 

black, brown, and buff, and underfur charcoal gray. The throat and legs are reddish brown. Although there is no seasonal color change to winter white, as in Wisconsin Lepus, the cottontail molts twice a year, one molt before winter and another in the spring. Each eye is ringed with a bold white circle. In spring and early summer eastern cottontails in central Wisconsin, half-grown or older, show high frequencies of an undescribed and fairly conspicuous white stripe pattern in the grizzled fur. The band or stripe commences above the hind limb and extends forward approximately 100-150 mm on either side. The width of the band is approximately 10-20 mm. This pattern seems possibly associated with molt because the dorsum is fresh brown, and ventrally the belly fur is gray. The grayish white stripe interrupts the grizzled brown by a short grayish extension isolating on each flank a small patch of grizzled brown fur. The stripe also may be related to the folding of skin, where the limb bulges from the body wall. It is not a physical consequence of bulging, and it extends too far forward to be thus explained. The stripe is hardly apparent in autumn. The cottontail varies in total length from 16-18 inches (400-460 mm), and weighs up to 4 pounds ( = 1.8 kg). Females are larger than males. Some measurements of eight males from Portage County are as follows: Total length 427± 55; hind foot 99.6± 6.5; length ear 60.32± 5.6; greatest length of skull 74.2± 1.5; zygomatic breadth 36.7± 1.5; length nasals 32.6± 1; maxillary toothrow 15.0± 0.7. Dental Formula. I 2/1, C 0/0, P 3/2, M 3/3 = 28. Geographic Range. Cottontails are widespread and abundant throughout Wisconsin and the Upper Peninsula of Michigan. Found on some islands as well (see Map). Status. In many years the eastern cottontail is very abundant, concentrations occurring in proximity to farms, residential areas, and even urban areas. The species is an important smallgame animal, a fur species (but of poor quality), TAXONOMIC ACCOUNTS / ORDER LAGOMORPHA

151

a meat animal, and a prey species for carnivores, raptors, snakes, and other predators. It can be a pest in our fields, gardens, orchards, lawns, and cemeteries. Its presence is often made known by chewed saplings, gnawed naked of bark up to a height of 2-3 feet. This species followed the clearing of forests and settlements of the early settlers northward into the forests. Jackson (1961) reported that the species occurred as far north as Green Lake County in 1846 (Muir, 1913: 181). Nelson (1909) documents the arrival of cottontails in Douglas County in 1907, but it



Maps showing geographic distribution of Sylvilagus floridanus in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

was reportedly common just south of there. Jackson (1961) found them in the Apostle Islands in 1919. Long (1978) observed them on Washington Island, in lawns and fields, never in the forests or swamps. Habitats. Cottontails are found at the edge of woods and fields, in lawns, shrubby areas, brush piles, brambles and briars, thickets and hedges, usually in or near stands of deciduous trees. Low shrubs with dense branches and thorny hedge are good cover types for rabbits. Also they are seen in grassy fields and savannas, roadsides, disturbed areas, and cut-over forest. They are not so common in corn and soybean fields. They are replaced northward in boreal and wet habitats by snowshoe hares. The eastern cottontail rabbit uses burrows in which to hide or stay warm, especially in winter. It often appropriates burrows made by woodchucks and badgers. It also finds shelter in thawed and grassy openings in snow banks, in dense thickets and junipers, woodpiles, and in brushpiles. In the breeding season the female’s nest is a small pit probably excavated, lined with fur plucked from her breast, and covered over with grass, leaves, or pine needles. Foods. In Wisconsin, green vegetation, seeds, flowers, bark of shrubs, oak and other saplings, even blackberry, fruit trees and fruits, buds and twigs, herbs, grasses, clover, and cultivated crops (Allen, 1939; Hickie, 1940; Haugen, 1942; personal observations) are eaten. In the caecum, a sac at the junction of the small and large intestines, where microorganisms are prolific, complex carbohydrates are fermented and formed into soft, green fecal pellets. The large, green pellets are passed and re-ingested for further nutrition, a behaviorism called “coprophagy” (Geis, 1957; Kirkpatrick, 1960; Bailey, 1969). Reproduction. The male cottontail’s testes enlarge in Michigan from late February to mid-March, and breeding continues until September. Lemke (1957) found one pregnant female on 21 November. The male gambols about in a courtship dance, head-to-head en-

counters followed by jumping, and a variety of postures likely associated with sexual odors (Chapman et al., 1980). Gestation lasts 29-30 days. Rongstad (1969) described prenatal development. The female builds the nest (see Home above), and the number born average about 5 (range 4-7) in Michigan, in Illinois 46. One in central Wisconsin had nine (see below). A female may produce 20-25 young in a season. Furthermore, the young born early in the season are 12-23 percent of all cottontails present in the fall. Young of the year also breed. A life table by Lord (1958) began with a theoretical population of 1,000, which peaked at 5,688 adults and young by August. The blind, naked young weigh about 30 g each, and are suckled twice a day. The eyes open about the sixth day. In two weeks the furred young are out of the nest, although the mother offers them milk for some days. Some 25 years ago, on the south side of Stevens Point, I observed two or three small cottontails out of their nest reaching up to nurse at their mother’s breast. On 25 May 2003. Claudine Long observed in late afternoon in Stevens Point, an odd “pyramid-appearance” resembling a rabbit. When she approached to approximately 8 m (measured later) a large cottontail bolted away. What caused the pyramid shape was a litter of young (each approximately 120 mm in length). The young had been standing simultaneously at the mother’s breast trying to nurse. When she left them, they crouched flat on the ground, bodies crowded together randomly, in a space about 0.6 m2. All were watching, but none moved. She counted nine young. When she bent down they scattered. Eye lens weights of the eastern cottontail vary with increasing age. Lord (1959) plotted out these weights (maximum wt 200 mg). After one year of growth the curve levels off. Hoffmeister and Zimmerman (1967) found that at 5.5 months cottontails attain maximal size. Petrides (1951) described fusion of the epiphyses of the radius and ulna between 7 and 18 months. TAXONOMIC ACCOUNTS / ORDER LAGOMORPHA

153

Mortality. In Michigan Hickie (1940) estimated that in 1938, more than 300,000 hunters bagged 2,000,000 cottontails. In 1974, some 410,000 hunters killed an estimated 2.25 million, and in 1975, the take was 2.47 million (Baker, 1983). In Wisconsin, the numbers are comparable. In 1932 (2,474,125), 1942 (1,397,308), and 1954 (1,311,392) the results compare closely. Low years dropped to only 382,186, which is still a phenomenal number for game animals. In 1999-2000, the harvest of cottontails was estimated at 250,727, mostly from Grant, Dodge and Sheboygan counties (Dhuey, 2000). The list of natural predators is lengthy (Jackson, 1961, Baker, 1983, Chapman et al., 1980) for this important forage species, including coyotes, foxes, domestic dogs, wolves, bears, probably raccoons and probably opossums, mustelids except otter, bobcat, domestic cats, hawks and owls, crows, red squirrel, great blue heron, and several species of snakes. Even small predators can kill baby cottontails. Cottontail rabbits harbor several deadly diseases of humans such as tularemia, Pasteurella tularensis, transmitted from rabbit blood (during cleaning of the rabbit for food). More than 10 human cases a year are contracted in Wisconsin. It may be passed from rabbit to human or rabbit to rabbit by numerous arthropods, including ticks, flies, mites, fleas, even mosquitoes. Yellow specks on the liver and spleen indicate the presence of tularemia in a rabbit. The rabbit also has trouble moving about and develops lesions. Eradication of huge populations of rabbits often occurs in nature by this disease. Salmonella (Youatt and Fay, 1968), Q fever, Rocky Mountain spotted fever, and equine encephalitus also have been reported in cottontails. Sickness from the raccoon round worm affects some rabbits. Some rabbits suffer from Herpes (Schmidt et al., 1992; and others). Parasites include bot warbles, ticks, especially in Wisconsin the rabbit tick (C. F. Long, personal observation), many species of fleas, mites, a fluke, numerous kinds of tapeworms,

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THE WILD MAMMALS OF WISCONSIN

and at least nine kinds of roundworms (Jackson, 1961; Chapman et al., 1980). Young rabbits often drown or chill and die in the nest. They are killed by automobiles and cats. One may add to natural mortality the game harvest, for this is the most commonly killed animal taken by hunters, throughout the United States. Home Range and Density. Trent and Rongstad (1974) radio-tagged cottontails, finding the males to wander in home ranges about 10 acres (4 ha), diminishing to 4 acres in the late summer (after breeding). Adult females averaged 4.3 acres (1.7 ha) in spring and 21 acres in late summer. Other findings on populations of cottontails have been obtained by Hickie (1940), McCabe (1943), and Lord (1963). The turnover rate of cottontails is 80 percent. There is evidence for and against regular periodic cycles, but certainly there are highs and lows of abundance. At my home in central Wisconsin, in jack pine-oak savanna, when the populations of cottontails were high (winter, 1991) my wife and I removed 41 cottontails from one acre without any apparent effect on their numbers. Other cottontails moved into the area to replace those removed. In three years (1997-1999) not a single cottontail was observed on this acre. In spring (2002-2003) we have seen several, but again in winters 2000-2003 not one. Because of the behavior of the rabbits in the summer of 1999, and five found dead, we assumed the population had suffered a tularemia epidemic (see Mortality above). Also, urban deer removed much of the cover, e.g., dense thickets of blackberries. Keith and Bloomer (1993) found cottontails on snow to suffer much higher mortality from predation than did Lepus americanus (89% to 18% vs 84% to 63%). Their central Wisconsin study suggests that predation (primarily coyote predation) may eradicate some cottontail populations in northern forests where snow cover is usually heavy. Additional Natural History. Chapman et al. (1980) is an excellent reference source for the eastern cottontail.



Eastern cottontail. Charles Schwartz. 

Geographic Variation. There is a single subspecies in Wisconsin and the Upper Peninsula of Michigan. Specimens examined. Total, 109. Adams, Columbia, Crawford, Dane, Dodge, Door, Green, Green Lake, Iron, Kenosha, Kewaunee, Juneau, Lincoln, Manitowoc, Marathon, Marinette, Milwaukee, Oconto, Oneida, Outagamie, Ozaukee, Polk, Portage, Racine, Rusk, Sauk, Sheboygan, Trempealeau, Washington, Waukesha, Waupaca, Winnebago, Wood counties.

ORDER RODENTIA Gnawing Mammals Almost half of the species of mammals in the World (approximately 2,000 of 4,600 mammalian species) belong to the Rodentia. About a third of the approximately 1,000 mammalian genera of the world are rodents. Not only are there many species, but a great number have amazing fecundity. Not surprisingly, they show high relative abundance in most terrestrial habitats. Rodents first evolved in the late Paleocene Epoch and showed spectacular success by the Eocene. Although those ancestral short-legged gnawers are extinct, there are some still with us (e.g., mountain beavers Aplodontia) that have evolved very little in most of their characters, i.e., retaining many primitive features. The marmots Marmota, from North America and eastern Eurasia, including Wisconsin’s woodchuck (Marmota monax), have progressed little beyond the

ancient mountain beavers. Tree squirrels (Sciurus sp.) have specialized for arboreal habits, but their teeth seem primitive (Black, 1963). The Norway rat (Rattus norvegicus) was important in decimating the human populations of Europe in Medieval times by spreading, with the aid of flea parasites, the “black plague.” This pestilence persists today even in America. These rats and the house mouse (Mus musculus) may transmit directly or indirectly the plague, tularemia, Rocky Mountain spotted fever, salmonella, Lyme disease, Hantavirus, and other diseases. They also destroy stored food, documents, books, and other property in our homes. In Wisconsin, rodents, along with cottontails and nuisance deer, are among the most injurious of mammals (causing over $1,000,000 damage annually). The muskrat Ondatra [historically the most captured fur animal] is probably the most beneficial furbearer in the world. What animals are more endearing than gray and fox squirrels (Sciurus), the beautiful striped and alert little chipmunks (Tamias and Eutamias), and the other squirrels for that matter? The graceful and elegant forest deer mouse (Peromyscus maniculatus maniculatus) is a lovely and gentle little mammal. Consider the industry of the “busy beaver” (Castor canadensis), and its tremendous impact on American destiny and history by virtue of its valuable fur luring westward (and into Wisconsin) those early explorers and settlers from the eastern colonies. Many rodents are beneficial to man: eating weed seeds and insects, making soil (see below), and planting forest trees (by burying seeds). Not fully appreciated is their absolutely essential role as “prey species.” Most Carnivores, beneficial snakes, and birds of prey depend on rodents for food, in one season or another, in one place or another, so that our ecosystems are rich not only in nutrients and potential energy, but providing many species with an array of food sources. The vole Microtus pennsylvanicus may make up to 40 percent or more of the animal TAXONOMIC ACCOUNTS / ORDER RODENTIA

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biomass in the marsh, where it causes little harm to humankind. In these communities, it may comprise 90 % of the mammal biomass. Golley (1960b) showed the importance of this vole in funneling sun energy caught in plants to the carnivores that feed on the voles. The voles consumed 1.6 % of available plant energy, and weasels consumed 31 percent of energy stored in the voles. The abundance of this vole may allow raptors and Carnivores to attain high densities. Rodents differ from lagomorphs in possessing only a single pair of upper incisors. There is a diastema and loss of canines, comparable to that in lagomorphs. Some premolars are retained in most rodents, but in many mice there are none. The radius and ulna are not fused distally in Wisconsin rodents as in rabbits. There is usually a large caecum to facilitate digestion of plant carbohydrates. The rodents tend to be small, although the beaver sometimes exceeds 90 pounds. In the evolution of gnawing and chewing, several peculiar patterns of muscle attachment appeared leading to success of some kinds of rodents and to one means of classifying suborders of rodents. Without delving into the controversial taxonomy of higher categories of rodents, there are several fundamental patterns necessary and used to broadly classify Wisconsin rodents. These patterns are “sciuromorph”, “myomorph”, and “hystricomorph”. The most primitive of our rodents belong to the Sciuromorpha, characterized by the simple attachment of the masseter (which muscle lifts the lower jaw) to the sturdy zygomatic arch (zygoma). This is the typical attachment seen in mammals besides sciuromorphs, for example, in cats, dogs, and many mammals. The marmot has an expansive bony plate anterior to the zygoma that is somewhat sulcate and to which muscle attaches. In this respect, the marmot hardly differs from the beaver, which has no deeper sulcation proportionally, although often that condition is believed true, and of course the beaver is highly specialized for chewing bark and

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trees. Other rodents, which are not too dissimilar from squirrels in muscle pattern, include pocket gophers Geomys bursarius. The Myomorpha include the mice and rats that feature a slip of the masseter muscle extending through the infraorbital canal, finding a new “origin” on the rostrum of the skull well anterior to the zygomatic arch. That specialization and generally small size must have been adaptive, because no other mammals have prospered as has this group. Myomorpha is a dominant form of mammalian life, if one measures dominance by abundance and relative abundance. In Wisconsin, the harvest mouse Reithrodontomys, deer mice Peromyscus, voles, bog lemming, and muskrat all show the myomorph pattern. The hystricomorph rodents have the infraorbital (= antorbital) canal greatly enlarged as a passage for an extensive portion of the masseter muscle. In Wisconsin the porcupine is the sole member of this group, which apparently arose in South America. Hystricomorphs on that continent are diverse in number of families and genera. The Wisconsin zapodid (“jumping”) mice also have an enlarged infraorbital canal, and resemble Hystricomorpha in this character. In Wisconsin there are ten species of squirrels (Sciuridae), the beaver (Castoridae), pocket gopher (Geomyidae), harvest mouse and deer mice, four voles, the bog lemming, muskrat, non-native house mouse and Norway rat (all in the Muridae), two species of jumping mice (Zapodidae), and the hystricomorph porcupine (Erethizontidae).

Family SCIURIDAE Gray Squirrels Squirrels, bright-eyed rodents of diurnal habits (excepting the nocturnal and crepuscular flying squirrels Glaucomys), have well-haired or bushy tails, a bow-legged stance useful for climbing the trunks of trees, and a prominent clawed thumb (e.g., Spermophilus) or small thumbnail. Wisconsin squirrels include the

woodchuck (= groundhog), two ground squirrels, two chipmunks, three tree squirrels, and two flying squirrels. There is incredible species stacking and niche partitioning of habitat in Wisconsin. For example, in Portage County all ten squirrels occur, and on an acre by McDill Pond, seven species co-existed (Table Rod-1).

3'

4 Key to genera and species of Squirrels in Wisconsin 1.

1'

2

2' 3

Lateral gliding membrane extends between forelimb and hindlimb, tail dorsoventrally. flattened Flying squirrels ..... ........................................ Glaucomys 1a Skull or hind foot 37 mm in length or more, whitish ventral hair grayish at bases, venter dusky, even on the throat ...... Northern Flying Squirrel Glaucomys sabrinus 1b Skull or hind foot less than 37 mm length, ventral hair usually pure white, especially on the throat ...... .............. Southern Flying Squirrel Glaucomys volans Lateral membrane absent, extending between forelimb and hind limb, tail when fluffed not remarkably flattened ......... 2 Antorbital (= infraorbital) canal not developed, the foramen piercing a zygomatic plate of bone, head with prominent stripes ....................... Chipmunks 2A Dorsal stripes to base of tail, a spicule premolar anterior to P4/ ...... ......................... Least Chipmunk Eutamias minimus 2B. Dorsal stripes extend to brownish rump patch and not to base of tail, P3/ lacking ..... Eastern Chipmunk Tamias striatus Antorbital canal well developed, head never striped .................................... 3 Zygomatic breadth greater than 48 mm, anterior lower premolar having paraconulid, zygomatic plate sulcate as in bea-

4' 5

5'

vers, distinct interorbital notches anterior to prominent postorbital processes ....... ................ Woodchuck (= Groundhog) Marmota monax Zygomatic breadth less than 58 mm, anterior lower premolar lacks paraconulid, zygomatic plate never sulcate, interobital notches and postorbital processes minute or absent .............................. 4 Zygomata converging anteriorly, pelage conspicuously spotted, i.e., dappled with obscure spots ............ Ground squirrels Spermophilus 4A Dorsal fur boldly marked with distinct lines and rows of spots, hind foot 41 mm length or less, greatest length of skull 46 mm length or less 13-lined Ground Squirrel ............. Spermophilus tridecemlineatus 4B Dorsal fur dappled with pale spots on tan color, head gray, hind foot or skull exceeds 50 mm length ..... ........... Franklin’s Ground Squirrel Spermophilus franklinii Zygomata nearly parallel, tail long and well-haired, pelage never spotted ...... 5 Greatest length of skull never exceeds 50 mm, venter pure white, dorsal pelage brown or chestnut brown, baculum spicule-like ........................... Red squirrel Tamiasciurus hudsonicus Greatest length of skull in adults more than 50, venter ochraceous or whitish tinged with brown or gray, baculum discoid except its base .......... Sciurus 5’A 5’A Much orange in fur, especially on venter and tail, tiny spicule (= P 3/) never present ............ Fox squirrel Sciurus niger 5’A’ No orange in tail or dorsal fur, usually whitish but brownish or even ochraceous may occur on venter, tail hairs show many white guard hairs, many squirrels are melanistic, usually a spicule (P3/ ) in each upper cheek toothrow ........ Gray squirrel Sciurus carolinensis

TAXONOMIC ACCOUNTS / ORDER RODENTIA

157



Table Rod-1. Squirrel food resources in central Wisconsin. All herbivores or herbivore-omnivores, in season they eat plant buds, insects, fruits, and fungi in season. All reproduced in the study area, but Sciurus niger, an edge species, was observed only once. 

Species/niche

Staples

Oddities

Habitat

Woodchuck* Grazer-browser E. chipmunk* Granivorefrugivore Red squirrel* Conivoregranivore Gray squirrel* Granivoreomnivore S. flying squirrel* Granivore 13-lined ground squirrel Grazer-omnivore

Leaves, shoots Acorns, hazelnuts, fruits Pine cones, seeds

Oak leaves Thornapple, greenbriar

Edge, open woods Edge, woods

Eggs, fruits

Conifers, hardwoods

Mushrooms

Woods

Birds, eggs

Oaks

Fledgling

Dry grassland

Acorns, nuts, seeds Acorns Seeds, shoots, insects, berries

* May feed in trees



Lateral view of woodchuck skull. Flower & Lydekker, 1891. 

Genus Marmota Blumenbach Woodchuck and Marmots The marmots are the largest of the squirrels, attaining weights in some forms up to 16 pounds (7.5 kg). The genus is exceptionally primitive among rodents, as are the ancient aplodontids (mountain beavers). Marmots have five toes on each foot, except in the Siberian species the thumbnail is lacking. The thumbnail is a small hoof or nail, functional more in standing on rocks or holding food than in excavation (Long and Captain, 1974, 1977). Therefore, it is misleading to refer to these fossorial but ancient squirrels as ground squirrels, except in the sense that the name definition may refer to habits and not relationships. Also primitive is the stance, which is sub-digitigrade approaching plantigrade, more so than usual in the other bow-legged and digitigrade Sciuridae. The skull is flattened and broad, as in the aplodontids, but postorbital processes are prominent. There is a primitive pattern of premolars, namely p 2/1, and the upper ones are not vestigial or lacking (as in more advanced squirrels). Anal glands are present. The coarse fur and fossorial habits confuse some people into mistaking woodchucks for badgers. The burrows are often taken over by badgers, foxes, skunks, and cottontails (in winter).

Marmota monax (Linnaeus) Woodchuck or Groundhog 1758. [Mus] monax Linnaeus. Systema naturae, ed. 10. 1:60, Type locality Maryland. 1904. [Marmota] monax: Trouessart. Catalog. Mamm., Suppl., p. 344.



Woodchuck at burrow. By A. R. Dunmoor. 1900. 

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THE WILD MAMMALS OF WISCONSIN

The name Marmota from Latin means mountain rat (mar = rat), and monax reportedly was derived from an Indian name; this was the the scientific name used by Linnaeus. Woodchuck comes from the Cree Indian word otcheck. The woodchuck is also called

groundhog, Siffleur (French-Canadian), whistle pig, and marmot. Groundhog’s Day, celebrated 2 February annually (especially in Pennsylvania) probably was based on European myths about hedgehogs or Eurasian badgers, and coincided with Candelmas, an ancient religious celebration linking a sunny day with a cold spring. The groundhog supposedly emerges to check the weather. If it sees its shadow, there will be six more weeks of winter. If cloudy, spring comes early. In Wisconsin, spring never comes early. Description. The woodchuck is a stout, short-legged squirrel of medium size (large for the squirrel family, about two feet in length) with coarse grizzled fur and a long, fairly bushy tail. The skull is broad and flattened, with wide zygomata and wide mastoid breadth. There is a low sagittal crest and usually in adult woodchucks a prominent lambdoid crest. In younger woodchucks the sagittal crest is undeveloped and instead parallel sagittal ridges approach one another at the midline of the skull. The occiput curves upward to the lambdoid crests, and the rostrum curves downward anteriorly. The incisors are robust. The postorbital processes of the frontals are prominent, projecting laterally, whereas the postorbital processes of the jugal bones are low and arcuate. The interorbital breath is rather narrow. The paroccipital processes are elongate. The two upper premolars are fairly well developed, the milk teeth (present in young-of-the-year)

smaller, especially the deciduous third upper premolars (dP3/ ). The broad molars above and below are rather high crowned with deep basins in the lower teeth. A prominent reentrant angle invades each of the molars on the labial surfaces, the angle in each of the upper molars enclosed by a V-shaped loph. There is usually a low loph anterior to each V. There are rudimentary internal cheek pouches. Chromosomes are 2N = 38, FN = 62; the Y chromosome being small and acrocentric (Hoffman and Nadler, 1968). The baculum is broad basally and tapers to a variable tip (in females there is a small os clitoridis). The eight mammae are in two pectoral, one abdominal, and one inguinal pairs. The upper parts are dark grayish or reddish brown, grizzled by pale buff tips on the hairs. Basally the hairs are dark blackish or gray-brown, subterminally or terminally the hair is chestnut or ochraceous, and a conspicuous buff tip is often present. The crown of the head is black, often faded, and scatterings of whitish buff hairs may be found around the nosepad, extending onto the cheeks. A little whitish may be seen over each eye. The feet are all blackish or dark drown, and the bushy tail is nearly black. The black soles of the feet are naked. The venter is variable in tone, color and pattern. Usually it is somewhat blackish but overlain with a tawny red and sometimes ochraceous or even buffy ochraceous. Perhaps in the south there is less





Skull of Marmota monax. Dorsal, ventral views. 

Burrow of woodchuck. Missouri Conservation 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

159

black in the ventral fur. There is a single molt beginning in June lasting until August. Some melanistic woodchucks may be expected in Wisconsin (Jackson, 1961). Males are slightly larger than females in woodchucks (Jackson, 1961; Snyder et al., 1961) and the animals continue growing for several years. Some Wisconsin measurements are listed in the subspecies accounts. The following observed ranges in adults (in millimeters and kg) were given by Lee and Funderburg (1982) for woodchucks from North



Maps showing geographic distribution of Marmota monax in Wisconsin and North America. The subspecies boundary follows Jackson, 1961. 

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THE WILD MAMMALS OF WISCONSIN

America: Total length, 418-665; tail length, 100-155; hind foot length, 66-88; body weight, 2.3-5.4. Dental Formula. I 1/1, C 0/0, P 2/1, M 3/3= 22. Geographic Range. Found in suitable habitats throughout Wisconsin except on islands in Lake Superior and Lake Michigan . This species prefers hills or embankments at the forest edge. Status. Woodchucks are injurious when their den is near a vegetable garden, and they occasionally damage a dike or embankment with their burrows. Personally, I do not ascribe to control methods mentioned by Jackson (1961). One may ask is gassing a rodent worse than shooting it? If one has enjoyed this affectionate little rodent as a pet (Long and Long, 1965), then one will object also to shooting it, like shooting a dog, and a lap dog at that. In any case, the woodchuck presently enjoys protection in Wisconsin. If judged a nuisance the woodchuck may be trapped or killed. If one is a pest, despite its aesthetic value, it can be easily caught in a live trap and transported, hopefully into a suitable habitat. Under legal protection it seems that the woodchuck is improving its status in the southern counties and increasing also in the north. Although it is known to have become scarce in some areas due to hunting pressure, it is not certain that the woodchuck was ever as widespread in Wisconsin as Jackson (1961) assumed. In Illinois, Hoffmeister (1989) believed that when the settlers cleared the deciduous forests it made habitats more suitable for the woodchuck. Habitat. Almost fossorial, the burrowbuilding woodchuck chooses for its den welldrained, sandy soils. The den is sited usually in open woods or the forest edge, where woodland meets meadow, usually on a sunny hillside or embankment, but occasionally near buildings, woodpiles, rocky outcrops, and fencerows. Woodchucks require available succulent vegetation, visibility, and sunshine. The burrow is excavated by tearing with the foreclaws and teeth, and kicking the soil

farther behind with the back feet. Usually a mound of dirt is found in front of the burrow’s entrance. If the animal opens a “plunge hole” or escape hole from within the burrow, there is no dirt pile there and the entrance to it is seldom used. The main entrance is about 6-7 inches high by 7-8 inches wide (Jackson, 1961), sometimes larger. Usually there are at least two (sometimes three or four) entrances, and the burrow length may be 15-50 feet in length. The burrow usually is about two feet underground (1-5 feet), and there are often tunnel branchings and a nesting chamber. There is little vegetal material placed in the nest, and one blind chamber may be used as a latrine (covered over fecal scats and dried urine). This home may be used, improved and enlarged by successive generations of woodchucks. The hibernaculum is similar to the nest chamber, but the burrow is plugged with soil while the woodchuck sleeps. Occasionally a skunk or rabbit may share the burrow system, possibly unaware of its sleeping neighbor. Some diagrams of woodchuck burrows are depicted in books by Fisher, Jackson, and Cory. A third type of home is more or less temporary, visited by mother and young, the kind of subsidiary den called an “outlier” by Long and Killingley (1983) and called “auxiliary” by Kenneth Armitage (an expert on marmot behavior, and an alumnus of the University of Wisconsin). Foods. Except for many cultivated plants from vegetable gardens, little is known about woodchuck foods. Pets I have raised loved to eat clover and dandelions, as well as a wide variety of foods we ate ourselves. Leaves from a sassafrass tree stuffed one wild woodchuck’s stomach, and I have seen them in trees in the spring eating oak leaves. Probably they are exceptionally hungry after a winter fast. One had a full stomach of June beetles (Gianini, 1925), and another was attracted to pond vegetation in Ontario (Fraser, 1979). Grizzell (1955) examined 32 stomachs from individuals in the spring, and found red clover, white TAXONOMIC ACCOUNTS / ORDER RODENTIA

161

clover, grasses, chickweed, and alfalfa as frequently eaten foods. Reproduction. Hoyt and Hoyt (1950) described copulation; a yearling male mounted a female, after “boxing” a few seconds with her. The female tucked her nose down and held her tail up, while the male held her dorsal fur with his teeth. The male copulated for 8 minutes, then remounted for 5 minutes, then again for 3. Males and females seem to form pair bonds during the time of breeding, from late February through March in Maryland, but in Missouri breeding begins a little earlier (Twitchell, 1939). As the time of parturition, which has not been observed, the female drives the male from her den. Gestation lasts about four weeks (Hamilton, 1934), perhaps as long as 31-33 days (Grizzell, 1955; Hoyt and Hoyt, 1950). Birth occurs in the period from early April into May. There are usually 4-6 young, occasionally as many as nine. On average the number slightly exceeds 4 young. Eleven newborn woodchucks yielded 27.2 g average weight. They were nearly naked, toothless, blind and helpless. In a week the eyes opened, and the average weight for each young at that time was 45-62 g (Grizzell, 1955). Davis (1964) observed young emerging from the burrows about 15 May, each weighing about 300-450 g. By July the young begin to disperse, usually to abandoned dens. They cannot be readily distinguished by sight from the adults; their pelage is paler, muzzle narrow, and their incisors lack brown pigmentation. Juveniles differ from adults in small skulls, milk teeth, narrow rostrum, and smaller eye lens (Davis, 1964). Lactation retards laying on of hibernation fat until weaning. There is one litter born each year. Woodchucks live between 4-10 years (Crandall, 1964; Lee and Funderburg, 1982). Mortality. Even though the woodchuck is protected in Wisconsin, the animal is often shot or trapped because of its forays to the garden. Some are eliminated because the den is placed where people do not want it to be, although seeing the young playing on one’s

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THE WILD MAMMALS OF WISCONSIN

property would seem desirable to me. Dogs and automobiles are also major causes of mortality, and if hunting of woodchucks were legal the woodchuck probably could not hold its own. Most road kills seem to occur after emergence from hibernation. Numerous young are killed by cars in late March, April and May. Some youngsters die in winter, and others die if the burrow is flooded. Predation seems of little importance in limiting woodchucks. Foxes, coyotes, black bears, and badgers occasionally eat them (Grizzell, 1955; Beule, 1949; Long and Killingley, 1983). Large snakes, hawks and owls occasionally eat small woodchucks (Lee and Funderburg, 1982). Social stress reportedly can cause loss of offspring (Grizzell, 1955). Occasionally woodchucks suffer parasitism, especially from arthropods such as ticks, fleas, mites, and dipterans. A woodchuck may die from the infestation or from bacteria transmitted by the vectors (plague, perhaps spotted fever, tularemia). The roundworm Obeliscoides cuniculi has been reported from woodchucks (Lee and Funderburg, 1982). Home Range and Density. Unlike most marmots, Marmota monax is less likely to mingle together in colonies. On occasion 2-4 may be found sharing a den. Woodward (1990) found high densities (up to 5.36 per ha in fall) at highway interchanges (on the man-made grassy roadsides). The roads effected linear shapes to the home ranges. The home range seems considerably less than an acre in central Wisconsin, although erratic wanderings have not been studied, and territoriality is not evident except around the animal’s den. Movements are seldom over 100 m, and woodchucks from three dens I observed were not observed to wander over 50 m away. The smallest home range was of a yearling, killed two months after emergence by an automobile about 40 feet from the den. This observed area was between standing water and the road. Hamilton (1934) noted 30 occupied dens in less than 3 acres. In New York Manville

(1966) found 1/46 acres (18.4 ha), and Twitchell (1939) found 1/36 acres (14.4 ha) in summer in Missouri. Grizzell (1955) counted 18/100 acres (40 ha). Laundre (1975) estimated 30- 40/640 acres (256 / ha) on the Upper Peninsula of Michigan. Remarks. Woodchucks are diurnal, although soon after emerging from hibernation the hungry animals reportedly occasionally continue their activities into the night. Nocturnal activity is seldom observed (Grizzell, 1955). They are true hibernators, which subsist on their stored fat leading to decreasing body weight during hibernation of 30-33 percent (Grizzell, 1955). The body weights fluctuate throughout the year, increasing during the growing season (for approximately six months) and decreasing during hibernation. In southern states woodchucks begin hibernation in early November, but they probably hibernate earlier in Wisconsin. Older and larger individuals hibernate earlier and emerge earlier (Grizzell, 1955). Aside from one record in March and one woodchuck killed 20 December 1961 in Portage County, Wisconsin, specimens were collected April through September. The woodchuck, with long incisors and thick fur, can often protect itself from predators. They have been observed to chase dogs away. They snap their teeth rapidly, emit anal scent when angry or afraid, and do seem to express those emotions. Woodchucks are more intelligent than some would suspect, considering their low encephalization ratio (log brain to log body weight). Judging from the behavior of one young-of-the-year, a pampered house pet belonging to my wife and me (Long and Long, 1965), we give the woodchuck credit. This young male was affectionate, playful, and on occasion tried to imitate our behaviour even more so in some respects than a smart dog will do. After observing human use of the toilet seat, without any coaxing, it sat with its posterior hanging in the waste can adjacent to the stool, where he defecated and urinated, then climbed down and scurried away.

Additional natural history. Swiecinski (1998) reviewed the woodchuck’s natural history. Geographic Variation. According to Jackson (1961) the southern woodchucks are larger and less reddish tawny on the underparts. In the small sampling of Wisconsin skins in this collection, I saw none of the color differences described by Jackson (1961). There was no paler color evident in the south except in older specimens showing some bleaching of the fur. The crown of the head tends to be black with white scatterings of hairs around the nose in my northern specimens, but they were few and small. The venter showed no significant difference in color, either tone or pattern, and certainly was never whitish in the southern skins. There is slightly more black suffused in the ventral fur to the northward, but the character appears sporadically in the south. It was impossible to draw a subspecific boundary on the basis of color, but it is reasonable to follow his perception because there is probably a wide zone of intergradation between the two races in Wisconsin. Size differences do not define the races. I follow Jackson (1961) in the following classification.

Marmota monax monax (Linnaeus) 1758. [Mus] monax Linnaeus. Systema naturae, ed. 10. Type locality, Maryland. 1780. Arctomys monax: Schreber. Die Saugethiere..., pl. 208. Type locality, Maryland. 1904. [Marmota] monax: Trouessart. Catalogus mammalium... Suppl., p. 344.

The nominate race of the woodchuck has been ascribed to adjacent Illinois southward (Hoffmeister, 1989). Inasmuch as the race is characterized by larger size, I include here some measurements listed by Hoffmeister. All specimens were females from central Illinois and SW Ohio. Total length, 600.3 ±49.7 (540-660); tail length, 134.4 ±21.7 (93-165); TAXONOMIC ACCOUNTS / ORDER RODENTIA

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hind foot length, 86.3 ±4.3 (78-90); greatest length skull 93.4 ± 2.8 (90.3-97.4); zygomatic breadth, 63.1 ±3.3 (59.2-68.0); least interorbital constriction 25.4 ± 2.0 (23.2-28.7); nasal length 38.5 + 2.2 (35.6-41.1), maxillary tooth-row 22.1 ± 0.82 (20.6-23.1). Specimens examined. Total, 3. Dane Co.: Black Earth, 1. Dodge Co.: Taylor Road, 1 mi.S Pond Road, 1. Waukesha Co.: Douseman’s Ditch, 1.

Marmota monax rufescens A.H. Howell. 1914. Marmota monax rufescens A. H. Howell. Proc. Biol. Soc. Washington, 27:13. Type from Elk River, Sherbume Co., Minnesota.

Measurements comparable to those given for M. m. monax for M. m. rufescens from several northern counties are as follows, Total Length (N = 5), 525.6 ± 44.5 (471578); length of tail, 4, 152.3 ± 47(120-221); hind foot length 5, 69.8 ± 10.5 (53-80); greatest length of skull 7, 83.5 ± 2.84 (80.4 -89.2); zygomatic breadth 8, 54.9 ±2.27 (51.558.0); least interorbital breadth 8, 21.6 ± 1.69 (19.7-24.0); length of nasals 7, 34.3 ± 1.50 (32.1-36.3); maxillary tooth-row 8, 20.5 ± 1.01 (19.4-22.0). Remark. One adult from central Wisconsin (No. 7144) has milk premolars (dP3/ ) retained. Specimens examined. Total, 18. Buffalo Co.: 0.5 mi. SW Mondovi 1. Calumet Co.: 3 mi. W Kiel 1. Juneau Co.: 8 mi. N Necedah 1. Kewaunee Co.: T23N, R24E, sect. 20, 1. Manitowoc Co.: Sect. 20, T18N, R21E 1. 1 mi. N St. Nazianz, on Hwy 131, 1. Marathon Co.: 7 mi. from Marathon City 1. Oconto Co.: Jct. Hwys T and 64, 1. Oneida Co.: Rhinelander 1.— 22 March, early record. Polk Co.: Clear Lake 1. U. Mn. Portage Co.: 12 mi. E Stevens Point 1. Long’s home on McDill Pond (no specimen preserved). No specific locality 2. Rusk Co.: Hawkins 1. Trempealeau Co.: 2 mi. SE Galesville, Sect. 10, T18N, R10W, 1.

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Waupaca Co.: Hwy 110, E Waupaca 1. Wood Co.: Pittsville, Twn Richfield, Sect. 32, 1. Central Wisconsin 1 (not plotted).

Genus Spermophilus F. Cuvier Ground Squirrels The ground squirrels are probably best arranged following the marmots, because the thumb is primitive, usually clawed. The forefoot differs in that the thumb is functional, the index finger longer than the fourth, the fifth is small, and digit III is longest of all (Long and Captain, 1974). Black (1963) also arranged the ground squirrels as a separate and primitive group. The name Spermophilus and the common name “spermophile” were established in mammalogy until A. H. Howell synonymized the name, preferring the older name Citellus Oken. With few exceptions Oken’s names are invalid, i.e., non-Linnaean. After a period when both names were popular, the American Society of Mammalogists followed its committee on nomenclature and the International Commission on Zoological Nomenclature and considered Citellus invalid (Carter et al., 1968).

Spermophilus tridecemlineatus (Mitchill) 13-lined Ground Squirrel 1821. Sciurus tridecem-lineatus Mitchill. Med. Repos. (n.s.), 6(21): 248. Type from central Minnesota (see J. A. Allen, Bull. Amer. Mus. Nat. Hist., 7: 338, 1895). 1849. Spermophilus tridecemlineatus: Audubon and Bachman. The viviparous Quadrupeds of North America. 1: 294. 1908. Citellus tridecemlineatus: Jackson. A preliminary list of Wisconsin mammals. Bull. Nat. Hist. Soc., 6(1-2): 13-14. Also, 1961. Mammals of Wisconsin, p.130.

The generic name Spermophilus means a lover of seeds. The tridecemlineatus means 13-lined, which is an appropriate name for



Spermophilus tridecemlineatus. Phillip Grossenheider. 

this striped and spotted squirrel. The thirteenlined ground squirrel is known locally in Wisconsin as a gopher or striped gopher, and has been called “picket pin”. Mitchill, an early mammalogist working in Wisconsin and Minnesota, gave this squirrel its name and suggested it be called the Federal Ground Squirrel because of thirteen stripes and the thirteen American colonies. Description. The thirteen-lined ground squirrel is a small squirrel with a mediumlength tail, large eyes but small ears, and a conspicuous pattern of stripes and dotted lines that run lengthwise down the back and sides. The hand or manus has five toes, and the thumb is short with a distinct claw. The middle or third digit is longest of the five. The skull is narrow, lightly built, and the molar rows converge somewhat posteriorly. The molars are rather low cusped, not high cusped as in S. franklinii. The metaloph of the P4/



Skull of Spermophilus tridecemlineatus. Dorsal and ventral views. 

is broken, not continuous. The braincase is quite arched, especially in comparison to S. franklinii. Therefore, the foramen magnum is much more ventral in position. The baculum is ctenoid distally (Burt, 1960). There are 10 mammae on the female. Approximately 13 longitudinal stripes alternate dark brown and light tan or buff. Within and set off by the dark stripes are the longitudinal rows of almost square light tan spots. Either anteriorly or posteriorly some of these spots and rows become confluent. The lateral dark stripes contain rows of spots not as regular and definite in pattern and even the light stripes may be broken up into spots so as to resemble the other rows of spots. Approaching the belly, the lower sides are nearly concolor with the tan or rusty and tawny venter. The feet are light tan or buff, with nearly black claws. The underside of the tail may tend toward ochraceous but the tail is bordered with brownish and distally buffy color due to the buff tips and subterminal banding of dark brown. The upper side of the tail is blackish, rusty or dark ochraceous, with buff intermixed. The flanks are often buffy or rusty ochraceous brown. The large eyes are nearly black, and the postauricular area is often grayish or pale tan. The eyelids are conspicuously pale. The forehead is irregularly and finely spotted but toward the nose the fur becomes light tan. In some specimens the cheeks are pale buff, and in others the throat and cheeks are orange tawny. Some venters are pale buff whereas others are a lovely golden brown. The dark stripes vary from black to rich chocolate or dark brown, and the pale stripes vary from tan to nearly white. There are two annual molts, the summer coat (attained by June) is more brown and less grayish than the winter (attained in September). Albinistic individuals have been reported by Hoffmeister and Hensley (1949), but the spotted pattern was evident on the whitish dorsum. Kent D. Hall kept an albino, also with pattern discernible, born in captivity from a mother from central Wisconsin, TAXONOMIC ACCOUNTS / ORDER RODENTIA

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from 1972-1976. Melanistic individuals have been noted, but none is in the Wisconsin university collections. Males may be a little larger than females. Occasionally a specimen may weigh a little over 200 g. See Table Rod-2. Dental formula. I 1/1, C 0/0, P 2/1, M 3/3 = 22. Geographic Range. The distribution dispersion of this ground squirrel has closely followed that of the fox squirrel (Sciurus niger) discussed beyond. Before the turn of the 20th century the 13-lined ground squirrel inhabit-



Maps of distribution of Spermophilus tridecemlinatus in Wisconsin and North America. 

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ed the short-grass prairies of southern and western Wisconsin, extending northward as far as Pepin, Portage, and Brown counties. By 1961, the species expanded its range northward through Wisconsin into Upper Michigan, but was unknown in Forest, Vilas, and Florence counties. It was unknown north of the canal at Sturgeon Bay on the Door Peninsula. Burt (1948) recorded the species in the extreme southeastern part of the Upper Peninsula, and Baker (1983) had records for Dickinson, Marquette, Iron, and Menominee counties on the Upper Peninsula. The species now occurs above Sturgeon Bay on the Door Peninsula. Evans (1951) suggested that Wisconsin ground squirrels extended their range northward in the hedges and thickets associated with oldfields. Status. This 13-lined ground squirrel thrives throughout most of its range because Americans create short-grass fields and lawns. Golf courses, cemeteries, mown lawns and parks, roadsides, campuses, and all such places are prime habitat for this species, even though humankind wages war against them relentlessly. Their excavations are not appreciated by those who like lawns and mown grassland. These squirrels frequently foray into the garden to eat vegetables and strawberries, occasionally they eat bulbs and dig in the flower beds, and that is about the extent of their damage. In my wife’s gardens they do less damage than chipmunks, and being rarer they are not banned from the premises. Not all people are so tolerant. I have kept them as pets, raised from the time of their



emergence, on melted ice cream or milk-egg mixtures. A lover of sunshine, the beautifully patterned 13-lined ground squirrel is a wonderful neighbor scampering about the yard. This species is widely used as a lab animal for hibernation studies. Kent Hall, emeritus professor of this University, usually kept many in animal care laboratories for his studies. Philemus R. Hoy, about 1888, in a letter quoted by Jackson (1961: 137) mentioned “beneficial” habits of the thirteen-lined ground squirrel feeding on both meadow voles and insects, over a period of 30 years.” Fitzpatrick (1925) concluded this short-grass prairie squirrel is beneficial because of the many insects consumed. Habitat. As mentioned above, the 13lined ground squirrel prefers short-grass prairie, but may be found in other weedy or grassy communities. Most of the day it forages for food. Mown areas, such as cemeteries, are popular habitats and provide easy hunting for insects. The grass may be exceptionally short, or the soil may be entirely bare. Soils are usually sandy or sandy loam, common sites in the prairies and savannas of Wisconsin. The ground must be well drained for dry burrows. On my property in central Wisconsin they range into the hedgerow to co-exist with the eastern chipmunks (Table Rod-1), and also into dense grassy areas while dispersing. Open ground with wide visibility is as important as food sources in the ecology of this species. Burrows of the 13-lined ground squirrel are often small outliers, but the main burrow has numerous branchings. Kent Hall (personal

Two burrows and an outlier of the 13-lined ground squirrel. After Rongstad, 1965.  TAXONOMIC ACCOUNTS / ORDER RODENTIA

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comm.) often found male-female pairs together in the burrows during the breeding season. This squirrel may have multiple entrances to its burrow. At night some ground squirrels plug their burrow entrances with soil or grass. The nest is usually an accumulation of grass. Rongstad (1965) studied and discussed burrow systems in Wisconsin. Foods. The 13-lined ground squirrel feeds on vegetal foods such as peas, beans, berries, and underground tubers or roots (such as those of beets and dandelion), but up to 70 % of the diet may be insects (Streubel and Fitzgerald, 1978). Many kinds of seeds are eaten, often stuffed into the mouth, which opens into paired internal cheek pouches, for transport of food to the burrow. Some plants used in this way include sunflower, ragweed, dandelion, vetch, grasses, and knotweed. The animal foods include insects, such as grasshoppers, crickets, ants, beetles and their grubs, stoneflies, and true bugs. Worms and millipedes also are eaten. Opportunistically, the young of birds (as well as eggs of ground nesters), small lizards or snakes, and even small mammals are eaten. In late June (2002), Joseph Graceffa, in Stevens Point, Wisconsin, observed a 13-lined ground squirrel leap from the ground to capture by the neck a young (feathered-out) house sparrow (Passer domesticus) as it attempted to leap into flight. It ate the brain at the site of capture and left the bird’s carcass on the ground. This ground squirrel also feeds on carrion, even carcasses of its own kind (Bailey, 1893; Howell, 1936; Whitaker, 1972a; Yeager, 1937; B. Bailey, 1923; Brigwater and Penney, 1966). Reproduction. Males are reproductively active when they emerge from winter hibernation. Females are viable a few days later. Ovulation seems induced (Streubel and Fitzpatrick, 1978). Multiple paternity has been noted (Hanken and Sherman, 1981). Parturition begins in mid-April and continues until early May in Wisconsin; there is a single litter per year (Rongstad, 1965). There are a few cases of second matings, perhaps when the

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first litter is lost or the female fails to conceive. Perhaps that explains one juvenile specimen (UWSP 3718, external measurements 177-64-31-6) taken 4 August in Wood County, and a remarkable record (UWSP 2995, measuring 178-53-30-6) from Taylor County taken on 25 September 1971. Late litters are probably unsuccessful through severe winters of Wisconsin. Long ago as a boy in springtime, in Crawford County, Kansas, I recall that young “13lined spermophiles” emerged from their burrows in June. In Wisconsin, at least in central Wisconsin, they emerge in early July. In southern Wisconsin emergence of young was observed 20-23 June, and the young begin to disperse eight days later. One (UWSP 1910) was taken near Stevens Point 12 June. Kulpa and Hall (1983) isolated 28 pregnant females from Wisconsin Rapids, and they gave birth from 25 May to 1 June. Gestation lasts from 27 to 28 days, and the young are born naked, blind and helpless (Streubel and Fitzpatrick, 1978). Usually there are about 8 offspring, but there can be as many as 13 (Zimny, 1965). Rongstad (1965) found 8.7 ± 0.03 litter size in Wisconsin. Newborn young weigh only 6-7 grams. By 12 days the pattern of spots and stripes is visible on the now darkened skin and the hair is beginning to grow out. Soft trilling calls are made. By 20 days the incisors emerge and the young crawl about. By 26 days the eyes open. Weaning was complete after 5 to 7 weeks. Only a third-grown, the young venture from their burrows and search for plant and possibly insect foods. They soon dig their own burrows, small and shallow at first. By the time for hibernation, although they delay it a few weeks, the young are only 3/4 grown. Bridgwater (1966) discussed growth and development in this species. Longevity is approximately 7-8 years (Crandall, 1964). Mortality. Aside from humans, who trap and poison this species in lawns and fields, and kill thousands with automobiles along the highways, the badger is an important preda-

tor (Leedy, 1947; Long and Killingley, 1983). Weasels, domestic cats, dogs, foxes and coyotes, and various hawks eat them. Even shrikes crows, and prairie snakes eat them on occasion (Craighead and Craighead, 1956; Linduska, 1950; Dearborn, 1932; Jackson, 1961; Fitzpatrick, 1925; Schofield, 1960). Parasites include blood protozoans, cestodes, nematodes, spiny-headed worms, botfly larvae, mites, ticks, lice and fleas (Jackson, 1961; Scharf and Stewart, 1980; Whitaker, 1972; Streubel and Fitzpatrick, 1978). Home Range and Density. Gunderson (1976) in Minnesota reports home range for males up to 11.7 acres, and 3.4 acres for females. Distributions of 13-lined ground squirrels are patchy, because short-grass prairie is patchy. McCarley (1966) found one reason autumn populations are limited is that young of the year disperse in late summer. Adults ranged from one per three to one per 4.5 acres. After weaned young appeared above ground, the number increased to 2 per acre. Evans (1951) found in one summer 3035 ground squirrels in a 15-acre field. In Ohio, Lishak (1977) observed as many as 12 adults and juveniles per acre. There are some favorable habitats, such as in cemeteries and golf courses, where Wisconsin 13-lined gound squirrels are more abundant than 2 per acre. Jackson (1961) suggests as many as 20 per acre in some habitats. Rongstad (1965) found annual mortality high, 81 percent. Remarks on Hibernation. Although the 13-lined ground squirrel is not the only hibernator in Wisconsin, it was studied earliest and has been studied most intensively. P. R. Hoy (1875) discussed it first. G. E. Johnson and his students made many early studies, and Johnson and Hanawalt (1930) wrote a timeless classic on the subject. Other early papers were by Wade (1927, 1930). A more recent work is by Fisher and Mrosovsku (1970). This species exhibits a circannual rhythm involving hibernation, and also fluctuations of metabolism, reproduction (in spring), weight gain (in summer), and other physiological chang-

es. In late September the fat adults (especially adult males) begin to stay underground, and those not so fat may continue feeding another month before entering hibernation. Kulpa and Hall (1983) reported that males attain greater body weights than females but enter hibernation about the same time. Streeter and Hall (1983) found in weaned squirrels that various diets led to varying peak weights, but for each of these a hypophagic period of diminished body weight followed, leading to hibernation. In young-of-the-year the onset of hibernation was in late September, even in juveniles treated with the appetite depressant naloxone. However, I observed one foraging for food as late as 16 October 2002. Sex, diet, and maximum weight seemed to have no trigger effect on hibernation, but after peak weights were attained followed by the hypophagic phase, hibernation soon followed. Curled into a ball, in a nest of grasses, the squirrel falls into a deep dormancy and its metabolism falls. Such winter sleep is defined as hibernation when, and only when, the temperature fluctuates markedly with the ambient temperature. In S. tridecemlineatus the body temperature may drop, so long as the environmental temperature drops, to about 3o C, which is a few degrees above freezing of water. The heart rate drops from 50-350 beats per minute to a bradycardia of only 5 per minute. Breathing rates drop from 50 to 4 times per minute. Because the metabolism is so much reduced, the hibernation fat is consumed very slowly. The squirrel remains alert to physical stimuli such as touching or stretching, but otherwise it seems asleep. There seems to be only one ground squirrel per hibernaculum burrow. Sometimes the ground squirrels arouse from deep sleep, even to awake and emerge above ground in southern latitudes. This is unknown in Wisconsin, where winters are severe. Beer (1962) reported that they emerge in Minnesota as early as 26 March. Males emerge before females, and are immediately ready for courtship and breeding. They were TAXONOMIC ACCOUNTS / ORDER RODENTIA

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prepared for reproduction even while in their burrows, but the females do not enter estrus until emergence. Wade (1950) suggests that the ground squirrels cannot emerge until the ground thaws, but since chipmunks of similar size and form may emerge through blacktop roads and sometimes clamber about on deep snow in Wisconsin, I must question this suggestion, especially in southern parts of Wisconsin and in sandy soils of central Wisconsin. Obviously the return to normal metabolism requires a great expenditure of energy, which relates to considerable weight loss, sometimes almost half the weight in August. The body weights are lowest, in adults, during spring reproduction (following soon after hibernation). Hibernation seems a great strategy for a mammal of warm habitats to invade the northern regions, such as Wisconsin prairies (which are frost bound to depths of down to five feet in winters of little snow). It is therefore odd that this species hoards stores of seeds but hibernates so much of the year (almost six



months). The metabolism is so low in the Wisconsin squirrels it seems doubtful that they eat, especially without water available. Geographic variation. Because the race is the nominate race, probably little attention has been paid to its geographic variation. There is a great deal of microgeographic variation from place to place in pallor and venter colors in Wisconsin, but no significant speciation. Probably many of the northern populations emigrated from southern ones, so it seems unlikely that in recent times any differentiation would have occurred. Some populations are quite pale, whereas others are dark brown. Some individuals show reddish brown and the venter may be variably buff or golden tan. Specimens examined. Total, 80. Adams, Bayfield, Columbia, Dane, Dodge, Door, Douglas, Dunn, Green, Iron, Jefferson, Juneau, La Crosse, Lincoln, Manitowoc, Marathon, Marinette, Monroe, Oconto, Oneida, Pepin, Portage, Price, St. Croix,Taylor, Walworth, Waukesha, Waushara, Wood counties.

Table Rod-2. Some external and cranial measurements of adult Spermophilus in Wisconsin.  Spermophilus tridecemlineatus

Sex and N Total length Tail length Hind foot Ear length Greatest length of skull Zygomatic br. Interorb. Br. Length nasals Maxillary toothrow

M, 8 F, 6 247.4±19 246.5±16 83.3±10.6 89.5±10 34.3±1.8 32.0±2.8 6.83±1.4 6.6±2.1 40.1* – 23.9* – 7.6* – 12.4* – 7.13* –

5 4 264.8±18 241.3±32 95.4±4.3 87.5±7 36.4±1.3 36.0±1.6 10.8±2.2 9.75±0.5 40.75±2.3 40.73±0.95 22.6±1.8 22.7±0.6 7.4±0.5 7.58±0.4 12.67±0.97 12.1±0.8 7.56±0.5 7.89±0.4

*N = 4

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3 1 284 286 93 98 38.7 39 6 5 40.5 42.5 23.4 24.6 7.9 8.3 13.2 13.9 7.5 7.4

S. franklinii 2 – 245, 286 – 65, 74 – 34, 33 – 11, 9 – 38.6, 39.2 – 22.9, 21.6 – 7.2, 7.4 – 12.7, 10.3 – 7.0, 7.0 –

F, 4 – 360.3±37 – 124.7±31.2 – 51.5±2.4 – 12.0±1.15 – 52.8±0.15 – 29.5±0.48 – 10.44±0.39 – 18.75±0.14 – 9.9±0.28

The great anatomist F. Cuvier in 1825, not his famous brother Georges Cuvier, established the generic name Spermophilus. This word means seed-lover. The naturalist Sabine named this squirrel in honor of the famous British explorer of the Arctic, Sir John Franklin, who was lost in the Canadian Arctic in 1846. See status of Oken’s name Citellus in account of Spermophilus tridecemlineatus. Description. In the western states there are many diverse ground squirrels that share with this species a typical coat pattern of light brown, tan or buff upperparts dappled with small spots of whitish or buff. Such a pattern is cryptic coloration in grassy habitats, where sunshine is filtered by the grasses or sage, and the ground is dappled with sunlight. This species is the only ground squirrel in Wisconsin exhibiting such a pattern, and the flecking is never mentioned in most descriptions.

Franklin’s ground squirrel is larger, longer-bodied and much longer-tailed than the 13lined ground squirrel S. tridecemlineatus. The tail is bushy and almost half the body length. The skull is long and narrow, especially the nasals and rostrum. The braincase is more flattened than in S. tridecemlineatus, and the width between the orbits is wider. The teeth (especially the lower molars) have higher cusps and cuspids than in S. tridecemlineatus, probably for eating flesh. The ears are low and rounded, unlike that of the gray squirrel (which has a similar whitish but even bushier long tail). The claws of the forefeet are short and robust. There is a claw on the pollex rather than a nail or “hoof,” seen in tree squirrels, but five toes are on each foot. There are large internal cheek pouches, 10 mammae, and the chromosome pattern is 2N = 42 (Nadler, 1966). The skull of Spermophilus franklinii is much larger than the skull of the 13-lined ground squirrel, but similar. Dorsally, the postorbital processes flare away from the cranium and are quite long. The jugal extends noticeably behind the zygoma, more so than in the 13-lined ground squirrel, and the lambdoid crest is higher in mature animals. The ventral aspects of the skull are very similar, except the teeth, which are more massive in S. franklinii. From the side, the skull is more flattened, not nearly so arched as in the 13-lined ground squirrel. The rostrum is relatively longer and





Spermophilus franklinii (Sabine) Franklin’s Ground Squirrel 1822. Arctomys franklinii Sabine. Trans. Linnaean Soc. London, 13:537. Type from Carlton House, Saskatchewan. 1827. Spermophilus Franklinii: Lesson. Manuel de Mammalogie ... p. 244. 1938. Citellus franklinii: A.H. Howell. N. Amer. Fauna 56:57.

Drawing of Spermophilus franklinii. V. Hogg, Univ. Kansas (in E. R. Hall). 

Skull of Spermophilus franklinii. Dorsal and ventral views.  TAXONOMIC ACCOUNTS / ORDER RODENTIA

171

the zygomata angled posteriorly more acutely than in Sciurus, resulting in a narrower, triangular anterior plate for origin of the masseter, instead of a nearly four-sided plate in Sciurus. When the skull rests on its dorsal surface, the foramen magnum opens upward in Sciurus but opens posteriorly in S. franklinii. The baculum is toothed distally, as in the 13-lined ground squirrel. The upper parts are brownish gray intermixed with a suffusion of yellowish and black, dappled lightly with tiny specks of dingy white. The eyelids, cheeks, throat, and inner legs are buffy. The tail is whitish intermixed with buffy gray but with a pale creamy suffusion visible. The head and adjacent neck is a pronounced silvery gray, the hairs lightly tipped with white. There is a single molt in early summer, and winter pelage is bleached. Observed weights range from 450-460 g. Measurements are given in Table Rod-2. Dental Formula. I 1/1, C 0/0, P 2/1, M 3/3 = 22. Geographic Range. Franklin’s ground squirrel inhabits marshes and wet meadows in the western and southern prairie counties, but is not known in the extreme southwestern corner, nor in most counties along Lake Michigan. It ranges as far northwest as Polk County and in the center to Clark and Portage counties. The species probably occurs in Marathon County (Mead Wildlife Area). Status. Never abundant, this unusual squirrel is on the Special Concern list of Wisconsin species, and might be diminishing in numbers. Sowls (1948) reported that this ground squirrel accounted for 19 % destruction of duck nests studied in Manitoba. In central Wisconsin I know that no such predation on this scale exists. Based on my observations, the snapping turtle (Chelydra serpentina), common crow (Corvus brachyrhynchos), and mink would kill many more ducklings and eat more eggs robbed from the nests than S. franklinii. This ground squirrel is never abundant in Wisconsin. Although not entirely beneficial because of its predation on

172

THE WILD MAMMALS OF WISCONSIN

song birds and duck nests, this species is harmless insofar as crops and gardens are concerned. Since it avoids mown, grazed, and well-drained pastures it does not come into contact much with humanity. It is seldom abundant, but occasionally is found in loose breeding colonies of four to eight individuals. At the margin of its range, in Central Wisconsin, mostly in Portage and Wood counties, one or two of these squirrels were taken every one or two years from 1967-1972. None has been collected since 1972. Recently Lewis and Rongstad (1992) reviewed the status of this squirrel in Illinois and Wisconsin. Habitats. Franklin’s ground squirrel prefers marshes and tall-grass prairie, especially alongside wooded areas, railroad rights-of-way, and weedy fields. Mowing prairie is adverse to this species, which is found in tall weeds, grasses and forbs, including clover, dock, big bluestem, other grasses, thistles, goldenrod, dandelion, strawberry, cocklebur, wheat, and so forth. Standing water is often nearby. The species has been taken near sand dunes, especially on railroad embankments, where it often makes its burrow system, and on weedy roadsides (Mumford, 1969; Jackson, 1961; and others). The burrow system has been described by Kennicott (1858 or 1859) and Ellis (1982), as longer and deeper than that of the 13-lined ground squirrel, often sited on a bank in weedy cover, and often having the entrances plugged with loose dirt. The diameter of the tunnels averaged 8-10 cm. Foods. A variety of grasses, herbs, berries, and seeds is eaten. Plants include sow thistle, chokecherries, elderberries, beach pea, and clover (Sowls, 1948; Seton, 1953; Long, 1967). About 1/3 of the diet is animal matter. Numerous insects such as beetles, grubs, caterpillars, grasshoppers, crickets, ants and their eggs are eaten (Bailey, 1893). Seton (1953) noted feeding on flesh: deer mice, young cottontails, and chickens. I have observed them in Kansas feeding on young dickcissels and their eggs, and once in Illinois (near Urbana) on a road-killed pheasant (Long,

1986b). Sowls (1948) discussed their predation on duck eggs and ducklings in Manitoba. Reproduction. Gestation is about 26-28 days, following April courtship, which takes place as the squirrels emerge from hibernation. The young are born in May or June, and lactation commences then continuing until weaning some 40 days later. The single litter size varies, from 5-11 young. The young are born naked and blind; hairs appear on their bodies in 10 days. The eyes open in 20 days. They begin to “whistle” in 20 days and emerge from the burrow in approximately 30 days. Weaning is a few days thereaf-



Maps showing geographic distribution of Spermophilus franklinii in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

173



Sketch of Eutamias minimus by E. T. Seton. 

ter. One Franklin’s ground squirrel lived 7 years and two months (Crandall, 1964). Mortality. The Red-tailed Hawk is the primary enemy, according to Seton (1953). Foxes, coyotes, striped skunks, mink, weasels, and an occasional hawk or owl catches them (Baker, 1983). The badger, of course, is a specialist in ground squirrel predation (Long and Killingley, 1983). Large snakes may eat them. Jackson (1961) mentions lice, fleas, protozoans, tapeworms and roundworms. Many are killed by cars. Insecticides and weed killers may have caused the species to decline. Home Range and Density. There is nothing reported to my knowledge on home range. The Franklin’s ground squirrel is colonial or at least forms “loose communities” for rearing the young (Hall, 1955; Gunderson and Beer, 1953). Populations peak perhaps every four to six years with as many as 30 animals per acre (Schwartz and Schwartz, 1981). Sowls reported 14 shot in less than an hour at a locality in Manitoba. Banfield suggests 48 per acre (1974) is common. Remarks on Habits. Diurnal, secretive, except when calling back and forth to one another or chasing one another in breeding, the Franklin’s Ground Squirrel has a low, musical trill which signals its presence. It hibernates in winter, and spends much of the summer underground as well. Prior to hibernation fat is deposited on the body, which lasts the animal until it emerges in April. Af-

174

THE WILD MAMMALS OF WISCONSIN

ter breeding they are seldom seen, apparently beginning hibernation as early as late September. Dates on my specimens, indicating summer activity, range from 12 May, with lactation on 15 July, two specimens in late September, and one as late as 15 October. Hibernation, therefore, may not last seven months as reported by Hoffmeister (1989) in Illinois. Hibernation reportedly lasts from September to April, the males appearing above ground a week before the females. Geographic Variation. None is evident in Wisconsin. Specimens Examined. Total 8. Dane Co. Grove W. Area 1 UW Wild. Ecol. Portage Co. Sect. 2, T23N, R7E, 2. 1 mi. W Hwy; N, 1. 1/2 mi. W Junction City, 1. 2 mi. S Junction City, 1. Jordan Swamp, 1. Wood Co. 3/ 4 mi. SE Arpin 1.

Genus Eutamias Trouessart Western Chipmunks I have studied the arguments presented for arranging all the chipmunks of North America in the genus Tamias Illiger and am unconvinced. Hoffmeister (1989) and Baker (1983) also choose to retain the name Eutamias for the western chipmunks. I am most persuaded by the argument of John White (1953). Taken together with his other works at that time it comprises a scholarly and intelligent classifica-

tion of chipmunks in relation to the other Sciuridae. White carefully weighed the usefulness of characters, which in squirrels are notoriously polyphyletic and convergent in their evolution, choosing those in which he held the strongest confidence. Some of these had been disparaged owing to “non-functional” persistence (upper third premolars) but he found them functional (showing tooth wear). Loss of the P3/ in Tamias may have evolved in response to root competition of the adjacent premolars. That process has adaptive significance. It is important that Tamias has as its type species the eastern Tamias striatus, so that the taxonomy of the North American Eutamias differs geographically from that of Tamias. White listed ten characters, including for Tamias the elongated head of the malleus, sharp angle between lamina and manubrium of malleus, ventral keel on tip of baculum (resembling Spermophilus), unfused hypohyal and ceratohyal bones, rounded tendon of digastric muscles, absent upper P3/, lingual anterior root of P4/ , short tail (as in Spermophilus), medial white stripes twice as wide as the others, lateral pairs of white stripes all short. Some of these characters are consequential of one another. They persuade me to retain both the name Eutamias and the name Tamias. Recently, Ellis and Maxson (1979) obtained immunological evidence to support this thesis. Burt (1960) said there is no evidence from bacular form that Eutamias and Tamias are one genus.

Eutamias minimus (Bachman) Least Chipmunk

least, referring to small body size. This squirrel is the smallest of Wisconsin’s Sciuridae. There is a single subspecies in Wisconsin, which Jackson referred to Eutamias minimus jacksoni (A.H. Howell) without comment. Other authors followed suit. The name that should be applied to this race is Eutamias minimus neglectus (J.A. Allen). Allen examined specimens from Upper Michigan (near Escanaba), northern Minnesota, and the northeast shore of Lake Superior referring them to a bright colored race from the Lake Superior region. The last locality mentioned became the type locality (see below). Subsequently, Howell drew a line between the bright chipmunks of the Lake Superior region and a northern race Eutamias minimus borealis, so that the type locality of neglectus fell in the range he ascribed to borealis. Therefore, each worker had a different opinion on the identity of the chipmunks of the northeast shore. Howell assigned all the chipmunks examined from the north shore to the bright race. Since he excluded the type locality of neglectus from the range thus delineated for the bright chipmunks, neglectus became a synonym of borealis. He then renamed the bright chipmunks jacksoni. The concept of borealis at that time was broader than now, for example it extended into Wyoming. Anderson (1946) drew the line between the bright chipmunks and borealis much farther northward, and that explains better the presence of bright chipmunks all through the woodlands north of Lake Superior (even as Howell admitted), which some of my specimens confirm (see below). Therefore, the name jacksoni is a synonym of neglectus.

1839. Tamias minimus Bachman. J. Acad. Nat. Sci. Philadelphia, 8:71.

Eutamias minimus neglectus (J.A. Allen) The Chipmunk. He moves with flickering indecision Like strange stripes across the television. — Ogden Nash.

The name Eutamias means a true hoarder of stores (or foods), and minimus of course means

1890. Eutamias quadrivittatus neglectus J.A. Allen. Bull. Amer. Mus. Nat. Hist., 3:106. Type from Mouth of the Montreal River, Ontario. 1922. Eutamias minimus neglectus A.H. Howell. J. Mamm., 3:184. TAXONOMIC ACCOUNTS / ORDER RODENTIA

175

1925. Eutamias minimus jacksoni A.H. Howell. J. Mamm., 6:53. Type from Crescent Lake, Oneida Co., Wisconsin. 1944. Eutamias minimus neglectus: Anderson and Rand, Candian Field-Nat., 57:134. Also Anderson, Nat. Mus. Canada Bull., 102:114, 1946.

Description. The skull generally resembles that of Tamias, narrow but broad across the interorbital constriction. The presence of a tiny upper third premolar on each side distinguishes this tiny squirrel from Tamias. Bright stripes, small body size and a relatively long tail also identify this quick and brighteyed chipmunk. The median dorsal black stripe is the longest extending from the brownish nape or crown along the back onto the base of the tail. Adjacent to the median stripe is a narrow strip of pelage brownish or grayish and this fur is bordered laterally by a bright white (occasionally buffy or creamy) stripe which is enclosed above and below by conspicuous black stripes. Lateral to these on the sides of the chipmunk is beautiful ochraceous or cinnamon buff pelage, which is bordered below by the pure white venter. The dorsal stripes, even the lateral ones, are elongate, extending to the base of the tail. A rusty chestnut or brown patch at the base of the elongate tail present in Tamias is lacking in Eutamias. Chipmunks have stripes on the head, and often in Eutamias minimus the stripes are conspicuous. The white of the eyelids below and above the eye extend anteriorly to the nose, and posteriorly almost to the ear. Post-auricular patches of gray are evident. The tail is grizzled grayish brown or brownish gray above, and bright ochraceous brown or ochraceous below. The feet are similar to the brown or gray dorsal pelage, that strip which is not involved with striping. The bacular tip has a tiny dorsal keel, and the form of it is slender. There are eight (two pectoral, four abdominal, and two inguinal) mammae. Internal cheek pouches are large in this species. Winter pelage is more grayish, as is the juvenile pelage.

176

THE WILD MAMMALS OF WISCONSIN

The total length is about 200 mm. The tail is relatively longer than in Tamias, 40 percent or more of total length. Weights vary up to 50 g. See Table Rod-3. Dental Formula. Note tiny upper third premolars; the formula is I 1/1, C 0/0, P 2/ 1, M 3/3 = 22. Geographic Range. The least chipmunk is found in suitable habitats in forested northern counties, extending southward as far as Juneau, with recent occurrence in Sheboygan County. Status. Jackson (1961) considered the least chipmunk as abundant as the eastern chipmunk. He was wrong, I have looked in the wrong habitats, or Eutamias has dramatically declined. The species seems to have vanished in some of the southern parts of its range, possibly in competition with Tamias striatus, even though Reilly (1970) found no competition between these species on the nearby Upper Peninsula of Michigan. Some suspect competition between the two chipmunks because Tamias becomes so abundant in proximity to man’s habitations. Another competitor might be the red squirrel. On the Upper Peninsula clear cutting in the forests seems to be benefiting the least chipmunk, according to Verme and Ozoga (1981). The animal is a decided asset for the Wisconsin fauna, being one of the most colorful, cutest, and friendliest denizens of campsites in the North Woods. The damage in some cabin or to some garden or crop is hardly significant. In Wisconsin it has no financial impact. To obtain a measure of general abundance one might compare the specimens preserved in this collection (about 200 Tamias to 48 Eutamias). Habitat. Often reported from conifers, and rocky lakeshores, the least chipmunk is most likely to be found in northern counties in wetlands, such as conifer swamps and riparian habitats of willows and alders. It is often found, with Tamias, at the forest edge, where visibility is good, soil black, and natural foods available. If there is ecological sepa-

ration between Eutamias and Tamias, in Wisconsin or the Upper Peninsula, the least chipmunk is found in wetter habitats. In Alger and Schoolcraft counties, upper Michigan, Ozoga and Verme (1968) found numerous Eutamias in conifer swamp, and only a single Tamias was taken with them. Tamias prefers higher, dryer home sites. Both species occupy hardwoods, conifers, and forest edge together, especially in rocky places. Don Follen, in October 1967, collected least chipmunks in oak-maple hardwoods mixed with some aspen near Alvin in Forest County. One was trapped in a grassy marsh nearby. I observed them on several occasions on granite outcrops of lakeshores, with jack pine, blueberries, mosses, lichens and sparse grasses. Usually there were spruce and aspen also. In western North America, at various elevations, least chipmunks often inhabit moraines, sage covered gullys, and even flat desert places, as well as the montane forest habitats. In Wisconsin and the Upper Peninsula there are no habitats resembling those warm, dry and exposed soils, even though Eutamias is, since the Pleistocene epoch, an invader from the far west. There is rocky till on Rib Mountain and its nearby hills, resembling talus in the mountains of the Rockies. Eutamias once occurred there, but probably the little chipmunks had ranged along the Rib River (at the foot of the mountain) where the species still occurs upstream near Athens.



Skull of Eutamias minimus. 

Ground cover would seem less significant in dashes by this quick-moving chipmunk over stony habitat, except for scatterings of bracken fern, blueberries and raspberries, with stunted jack pines often present. Some brush and other cover are probably necessary for foods and security. The chipmunk excavates its burrow and the opening is often plugged, while a new main entrance is inconspicuous. The burrow may be worked between and among rocks. Nests may be constructed in the burrows, or hollow trees, woodpecker cavities, and stumps, or beneath fallen logs, in rock piles, and perhaps on occasion as accumulations of grass and leaves in trees. Orr (1930) found one such summer nest 18 feet above ground in a black spruce. Winter nests are often constructed above hoarded foods, at one observed depth about 3 feet beneath the ground surface. These nests are comprised of shredded bark, grasses, catkin fibers, and even mammal hair and feathers. Foods. Little is known about foods of least chipmunks. Probably they eat the same kind of foods the other chipmunks eat, namely seeds, grasses, fruits, insects, perhaps an occasional egg (Criddle, 1943; Vaughan, 1974; Forbes, 1966). Blueberry seeds (befitting wet habitats), smartweed and timothy seeds have been found in cheek pouches (Banfield, 1974), and a cache for winter contained hundreds of acorns and thousands of cherry pits. Hazard (1982) reported that they ate strawberries. They often eat raspberries. These berries often grow in seral or edge habitats. Reproduction. Following their long winter sleeping, least chipmunks breed while chasing each other above ground. In early May, pregnant females construct nursery dens with nests of grass; after an estimated 31-day gestation period 5 or 6 (2-7) young are born, usually in early June. They are naked, the eyes and ears closed. Each neonate weighs about 2.3 grams. The eyes open in about 28 days, and the young are well haired by 40 days. In less than two months the young are weaned. Usually a single litter is born; late litters probably result from TAXONOMIC ACCOUNTS / ORDER RODENTIA

177

loss of an earlier one (Skryja, 1974). Young-ofthe-year apparently do not breed. Mortality. Little is known of predation on least chipmunks, especially in Wisconsin. The usual hawks, owls, perhaps crows and ravens, possibly large fishes, snakes, and Carnivores must be important predators. Weasels and martens are suspected to kill them. Seton pictured such a “wanton” killing of a chipmunk family by a weasel. Probably many fail to emerge after a long winter, if cached food was in short supply. Forest fires doubtless destroy many, although burnt over forest land



Maps showing geographic distribution of Eutamias minimus in Wisconsin and North America. 

178

THE WILD MAMMALS OF WISCONSIN

features the reappearance and abundance of Eutamias after a few years. Parasites include internal nematodes (Jackson, 1961) and arthropods such as fleas, ticks, mites, and lice (Jackson, 1961; Manville, 1949; Timm, 1975). Home Range and Density. Little is known about these parameters in least chipmunks. Jackson (1961) speculated 30 or more per acre in suitable habitats. I have never seen them more numerous than 5-8 in an acre, and quite localized within that acre while absent in adjoining habitats. Reilly (1983) suggests 5-15 per acre as more usual values. Reilly (1970) and Manville (1949) found from less than one to 5.6 per acre on the Upper Peninsula. Individuals wander over home ranges of less than an acre to 4.3 acres. Remarks on Behavior. Diurnal, the least chipmunk vocalizes with sharp calls for danger and growling among themselves. Usually when they call they jerk their tails. Not as territorial as Tamias, the adults nevertheless seem to maintain spatial separation (Reilly, 1970). The winter is passed in winter sleep (sometimes regarded as torpor, because they are often active above snow and underground). The animals disappear underground from October until March. Additional Natural History. Forbes (1966) studied least chipmunks in northern Minnesota. Geographic Variation. There is no apparent geographic variation in Wisconsin and the Upper Peninsula of Michigan. Further, specimens from the north shore of Lake Superior are no different, except that a series of five from 25-30 miles northwest of Kenora, Ontario were a little grayish. Fresh pelage observed on chipmunks from Horseshoe Lake, Manitoba, was bright. These and all other least chipmunks on the Upper Peninsula are referred to Eutamias minimus neglectus (J.A. Allen) because of their characters and on geographic grounds. See argument above. Specimens examined. Total, 48. From Upper Michigan, 4. Wisconsin. Ashland,

Bayfield, Douglas, Florence, Forest, Iron, Juneau, Langlade, Marathon, Oconto, Oneida, Sheboygan, Taylor, Vilas counties. Michigan. Delta and Schoolcraft counties.

Genus Tamias Illiger Eastern Chipmunk The characters distinguishing Tamias from Eutamias were discussed in the account of Eutamias. The eastern chipmunk is larger, less brightly colored, and the dorsal stripes do not extend to the relatively shorter tail. The upper P3/ is lacking, there is a chestnut or rusty brown patch on the rump, and the tip of the baculum has a minute ventral keel.



Eastern Chipmunk. Sketch by anonymous student, Wildlife Society Newsletter, UW-Stevens Point. 



Skull of Tamias striatus. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

179

Other traits are included below in the account of the Wisconsin subspecies. There is a single species in this genus. Perineal, anal, and oral glands were discussed by Snyder (1982). The baculum (Burt, 1960) averages about 4.15 mm in length, and there is an os clitoridis. The skeleton and musculature are described by Bryant (1945). The feet are pentadactyl except the thumb is vestigial and bears a small nail. The tail is short, about 30-38 percent of the total length. There are four pairs of mammae.

proached me, jumped up and tried to snatch it.” — William Brewster, quoted in E. T. Seton’s Lives of Northern Animals, 1909; 1953, II, p. 201.

Tamias striatus (Linnaeus) 1758. [Sciurus] striatus Linnaeus. Systema naturae, 10th ed. 1:64. Type locality fixed by A.H. Howell, N. Amer. Fauna, 52:14, 1929, Upper Savannah River, South Carolina. 1857. Tamias striatus: Baird. 11 th Ann. Report, Smithsonian Inst., p. 55.

[The Eastern chipmunk] When (1888) the famous Cambridge naturalist William Brewster shot and broke the wing of a wood thrush and it

1891. Tamias striatus griseus Mearns. Bull. Amer. Mus. Nat. Hist., 3(2): 231. Type from Fort Snelling, Minnesota.

went fluttering along the ground, a Chipmunk pursued and caught it. “The Chipmunk killed the bird and had eaten most of the brains... As I

1932. Tamias striatus lysteri: Komarek. J. Mammal., 13: 207. Also Barger, Wisconsin Cons. Dept., Publ. 351, p. 11, 1951.

held the bird dangling, the Chipmunk ap-

Table Rod-3. Standard external and cranial measurements of Wisconsin chipmunks Tamias striatus and Eutamias minimus. There are no significant differences among the populations of Tamias striatus. Locality

N

Sex

Bayfield Co.

9

M

2

F

Portage Co.

5

M

Vernon Co.

6 3

F M

Grant Co. Dodge Co.

5

M M

TL

Tail Hind foot

Ear

Gr. l. Zygo. br.

Int. br. l. nasals Max. t-r

Tamias striatus

3 Racine Co.

F M

248 +12.5 235 248 250 +15.0 236 268 245 230 265 242.5 +21.7 221 266

96.4 +11.9 83 90 92.6 +7.8 86.67 83 102 97 102 87.5 +17.0 90.7 84

37.22 +2.1 34 36 35.25 +1.26 33.17 33 30 31 36 33.75 +2.0 35.3 34

17.11 +2.6 19 19 21.2 +6.7 16.17 17 18 14 16 15.25 +1.5 17.3 12

40.7 +1.1 39.95 41.5 4.94 +0.39 40.33 42.65

22.6 +0.67 23.06 22.9 22.64 +0.42 22.03 23.4

9.98 +0.36 10.69 11.55 10.14 +0.63 9.79 10.35

13.09 +0.58 12.13 12.89 13.79 +0.82 12.31 13.65

6.16 +0.53 6.14 6.10 6.20 +0.21 5.95 5.89

41.32 41.4

23.0 23.0

10.62 9.91

13.14 12.9

6.1 5.96

40.47 41.9

22.0 22.8

9.54 10.2

13.05 13.4

5.94 5.6

— —

23.5 22.6

— —

— 13.9

6.6 6.6

31.29 +0.96 31.8 31.3

17.79 +0.57 17.8 17.65

6.82 +0.18 7.05 6.8

9.41 +0.86 9.45 9.76

4.9 +0.23 4.7 4.94

Tamias striatus doorsiensis (after Long 1971) Door Co.

5 8

Adults sub-adults

Forest Co.

6

M

2

F

259 —

95 —

198.0 +8.0 198 197

85.4 +7.7 82 80

36 —

20 —

Eutamias minimus

180

THE WILD MAMMALS OF WISCONSIN

29.0 +1.58 28 28

13.8 +1.6 12 13

The name Tamias means a hoarder and steward of stores (or foods) and striatus means striped. The names griseus and doorsiensis refer, respectively, to gray and to the land of Door. Description. Same as set forth above for the genus. The skull is broad across the interorbital constriction in both Wisconsin races, and exceeds that of chipmunks in lower Michigan. The two races in Wisconsin do not differ much from one another in this respect. The chromosomes number 2N = 38, with a dot-like Y chromosome (Snyder, 1982). Other Wisconsin squirrels of comparably small size, including the Spermophilus, are never striped on the head, except Eutamias, which chipmunk is similar. The dorsal, longitudinal stripes in Eutamias extend to the base of the tail. Tamias features a mid-dorsal stripe of dark brown dividing the dorsal grizzled pelage (grayish, brownish or even ochraceous in tone). Laterally are two narrow brown stripes enclosing a whitish or buffy white stripe. This pattern is seen on either side. The rump is brownish or tan. The ochraceous brown sides merge gradually to a whitish ventral fur. Pale facial stripes about the eye, above and below, set off the prominent, bright black eye. The dorsoventrally flattened tail, well-haired but not bushy, is brown above with pale grayish border and is dark chestnut or ochraceous bright below. There seems one molt per year (in the growing season) (Snyder, 1982). In 40 years, I have examined three live melanistic chipmunks in Stevens Point, Wisconsin. All were released on my property, but never seen again. James Woller caught a melanistic male on 17 June 1995, in Stevens Point, which the author prepared (UW-SP 8,016). Since there are thousands of eastern chipmunks in this community, the incidence of melanism is certainly low. Measurements are given in Table Rod-3. Dental Formula. The dental formula is I 1/1, C 0/0, P 1/1, M 3/3 = 20. Permanent dentition erupts by 3 months, and yearlings have worn check teeth (Snyder, 1982).

Geographic Range. This species is one of the commonest mammals in Wisconsin, occurring in every county and in a wide range of habitats. It is even abundant in human settlements. It is not found on the Apostle Islands or on the Grand Traverse islands (including Washington, Rock and other isles in Door County). It also avoids especially wet and prairie habitats, and is seldom seen in the “goat prairie” region of western Wisconsin. See Map. Status. This colorful, lively little squirrel is abundant and maintains high densities in suitable habitats. It thrives even in the proximity of humankind. It may become a pest on garden fruits and vegetables, feeding also on flower garden bulbs, and caving in lawns. After spending quite a sum on an asphalt driveway, three chipmunks burrowed under it and caused deep snake-like depressions as their burrows caved in. Twice in early spring, the chipmunks burrowed up through the asphalt road in front of our house. It seems callous to me, who is enchanted by chipmunk charm, but I have known one man and another (as a youth) who each shot 200 chipmunks in and about their garden and lawn for the sport of shooting, justified by garden damage. I also knew of the Olsons in Amherst Junction, who cut a hole in their kitchen door to allow one of these delightful creatures to share meals. Although nowhere in danger of extirpation, the subspecies population of Tamias striatus doorsiensis is vulnerable because it is found only on the Door Peninsula of Door County. Habitat. Eastern chipmunks are found in rocky places, such as bluffs or gullys, or on exposed outcrops and ledges. They also thrive in hardwoods (oak, maple, hickory, and beech), and in conifers especially in uplands where red and white pines grow in open forest. Along lakeshores, rivers, and at the edge of marshes and swamps they may be found, and in jack pine savannahs and brushy hillsides they are often abundant. They thrive in TAXONOMIC ACCOUNTS / ORDER RODENTIA

181

human neighborhoods where trees and brush are present to provide food. Stumps, deadfalls, stone fences, and woodpiles provide perching places for them to defend feeding territories. They need soil depth because they must dig burrows to survive the winters. Being so well adapted to mature deciduous forests and to forest edge, Mahan and Yahner (1998) compared the demography of this species in continuous forests and mangaged clear-cut forest sectors. They found no differences in reproduction, body weight, time remaining on the study plots, or diet. When



Maps showing geographic distribution of Tamias striatus in Wisconsin and North America. 

182

THE WILD MAMMALS OF WISCONSIN

mast was scarce, both populations suffered (i.e., the eastern chipmunks weighed less). In a related study (1996) burrow sites selected on high ground, where logs and stumps seemed essential, were important as a “critical” resource for these chipmunks. Surprisingly, an overstory of trees, even oaks and other mast producing species, was not so important, because foods were varied. Such findings bode well for the eastern chipmunk; they suggest that in clear-cut forest and suburbia, so long as den sites are available, chipmunks may thrive. Factors such as slope, stumps, perch sites, and diverse foods allow the chipmunks to select suitable den sites (Henderson et al., 1985). Chipmunks do not always dig burrows, but may live in nests in woodpiles and rocky crevices. Burrows may be short or long and complex, probably depending on their age and usefulness. Descriptions of burrows are given by Panuska and Wade (1956). Much digging is carried out in winter, so that those burrows are usually complex. In spring short burrows are built and often abandoned, as the chipmunks fiercely fight and drive the losers out of the area. Weaned young soon fight for space. Foods. Eastern chipmunks feed on plants primarily, mostly acorns (mast) and maple seeds gleaned from the forest floor or procured by climbing into the trees to harvest. Very likely beech nuts are also eaten in beech forests in eastern Wisconsin. Other parts of the plants are also eaten, buds, even the flowers (Aldous, 1941) but not so much as fruits, nuts and seeds. In May, eastern chipmunks ate mostly roots, according to Wrazen and Svendson (1978). Insects, bird eggs, invertebrates, even mice and snakes may be eaten (Torres, 1937; Harriot, 1940; Mumford and Whitaker, 1982). Fruits are eaten on the spot, their seeds dropped on the ground, and seeds and acorns are the most important foods cached underground for winter. Chipmunks, then, are very important in planting forests and ground cover (e.g., greenbriar). Pyare et al. (1993) found eastern chipmunks in New

York to prefer small acorns of white oak (Quercus alba) over red oak acorns (Q. rubra). Activity patterns of harvesting white oak acorns seemed to influence the success and development of the forest. They detect ripe and edible hazelnuts and cast off the husks to eat them. It is essential a chipmunk hoards up seeds and acorns to last the winter, because the winter sleep lasts only short periods of days and then the chipmunk emerges from its torpor and feeds. Snow lay deep in Stevens Point, several inches at my bird feeder (25, 27 November 1985), where an eastern chipmunk scrapped with winter birds for seeds. A larger chipmunk was seen foraging on snow nearby (24 November). I have seen them sunning on the snow-step of the burrow in early spring. In mild winters, such as 2000, they emerge in central Wisconsin by 1 March; another was seen in Milwaukee the same date. In Virginia, Wolff (1996) found high mast production to increase survival of Peromyscus and chipmunks. This agrees with my observations, but an abundance of chipmunks in fall is often followed by scarcity in spring. Reproduction. The eastern chipmunk regularly produces two litters per summer. Matings are frequent in late spring and late summer. Testes regress in winter. The young-of-the-year probably do not breed, but they are observed trying at a tender age. Some tiny youngsters are seen playing about in late summer. Judging from their size they likely will never store up sufficient food for the winter. After some winters, probably due to a shortage of acorns stored during the previous autumn, hardly any eastern chipmunks emerge from winter sleep. Those that do, produce litters as early as late March. Males are reproductive even in February, and occasionally come out to sun near their entrances in the snow cover. They probably occasionally breed at this time. The females have two estrus cycles, in the spring and summer (Banfield, 1974). The gestation period is about 31 days, and the TAXONOMIC ACCOUNTS / ORDER RODENTIA

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young are born blind and naked, in the old winter burrow as a rule. By 18 days, hair is evident on the skin. By a month their eyes have opened and they resemble small adults. They then emerge from the burrow (after 5-6 weeks) and play together. By five or six weeks the mother recommences breeding. Her young are gone when the second litter arrives a month later. Late-in-the-season litters, even emerging from their burrows in early October, have only approximately a month to cache foods, but occasionally all the chipmunks have gone underground by then. The litter size is variable, usually 3 or 4 young, 4-5 according to Snyder (1982). The observed range is 1-8. There are eight mammae. To my knowledge, the young never suckle above ground, and possibly weaning forces them to emerge from the burrows. Tamias lives up to 4-7 years (Crandall, 1964). Mortality. The diurnal eastern chipmunk is seldom taken by owls. Hawks regularly take them. I have seen a sharp-shinned hawk pick one up and carry the poor little fellow away. There are records of great blue herons and ravens feeding on them (Harlow et al., 1975; Connor, 1971; Porter, 1951; Burt, 1941). Wild and domestic carnivores catch them, my own little beagle-terrier caught several in my yard. Raccoon, red fox, bobcat, lynx, coyote, red squirrel, Norway rat, large snakes, and especially weasels and martens have killed them (Allen, 1938; Toner, 1956; Wood, 1922; Banfield, 1974). Botflies (their larval warbles) infect chipmunks (Ozoga and Phillips, 1964; Domey, 1965). They always seem to be scratching. Fleas, lice, ticks and a variety of worms infest these squirrels (Allen, 1938; Scharf and Stewart, 1980; Timm, 1975; Snyder, 1982; and Jackson, 1961). The La Crosse encephalitus virus was identified in Wisconsin chipmunks (Berry et al., 1975). Home Range and Density. Home range for eastern chipmunks varies from 100 m2 to >10,000 m2 (Snyder, 1982). Males wander farther than females, and may range within

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approximately two acres. Often they do not move about this much, depending on food resources, densities of the chipmunks, etc. Use-frequency is highest near the burrow, which is central in most home ranges. Getty (1981) found that chipmunks avoid one another allowing overlap of home ranges and spatial time-sharing. While winter hoards are collected, more time is spent fighting and underground. This “space-time” analysis defines home range as time spent wandering, separate from other activities. I can confirm (see Jackson, 1961) that chipmunks may attain densities of 20 per acre, for they do that on my property regularly not even counting the newly emerged young. Burt (1940) reported about four per acre (10/ ha). Remarks on Behavior. This small sciurid is diurnal, active from March (sometimes late February) to October, when it enters winter sleep. Torpor varies during the winter with frequent arousals, but Snyder (1982) says some remain dormant all winter. There is no heavy deposition of fat in autumn (see Brenner, 1975; Scott and Fisher, 1972; Panuska and Wade, 1956; Maclean, 1981). Panuska (1959) shows the effect of warm temperature on “hibernation” in Tamias, i.e., there is weight gain in cool burrows and significant weight loss in a warm environment. Rectal temperatures fall (from 38.50 C) with ambient temperature; as torpidity is assumed, the rectal temperature approaches (to 30 C) the ambient temberature (30 C) (Maclean, 1981). Snyder (1982) reviews other physiological information. The animals are solitary and highly territorial except when a male and female are chasing about breeding. I have observed chases even in trees at elevations well over 60 feet. Twice I saw chipmunk in McDill Pond, swimming across the channel to our island (Maribell Isle), once making use of a submerged log to get partly across the expanse before entering the water. Geographic Variation. The race T. s. griseus differs from the peninsular race T. s. doorsiensis in darker color, of the non-white

stripes and dorsal fur, of the feet, and of the underside of the tail. Jackson (1961) recognized a race in southern Wisconsin, referred to T. s. ohionensis. He wrote that the chipmunks in southern Wisconsin, from Buffalo County in the west to Washington County in the east were darker, more brownish, and smaller, but I noted no important distinctions. In Illinois, just to the south, Hoffmeister (1989) assigned northern specimens to the race T. s. griseus, and did not recognize T. s. ohionensis Bole and Moulthrop at all. Jackson (1961) believed the pale chipmunks on the Door belonged to the race T. s. peninsulae Hooper, from Lower Michigan, but Door chipmunks differ from that pale race in wider cranial breadth, smaller skulls, and other features mentioned by Long (1974). In cranial characters the Wisconsin chipmunks are all similar, suggesting the Door County chipmunks became pale evolving locally on the pale limey soils and pale gray and buff limestone outcrops of the Niagara escarpment. Genes for pale pelage may have been distributed widely, on the other hand, to be swamped out by the invasion from the south of darker T. s. griseus. The alleles may have persisted on the Door Peninsula, where the substrate favors retention of the pale pelage. That would account for the close resemblance of the skulls of the Wisconsin races, and the marked size difference with small skulls from chipmunks to the eastward across Lake Michigan and beyond. The short time since the glacial ice had covered the Door and filled Lake Michigan, less than 10,000 years ago, does not allow much time for either the evolution of T. s. doorsiensis responding to natural selection for pale camouflage, or even the other possibility, of immigration. Long (1965) reported similar post-Pleistocene differentiation of color and pallor of chipmunks and other sciurids in Wyoming in the same span of time, which may be comparable to what happened in Wisconsin. Probably the genes for pale pelage were present in populations on both sides of Lake Michigan, and were rapidly selected for where

the substrates reduced predation on those chipmunks having them. Some pale color in chipmunks of the Upper Peninsula ascribed to intergradation between T. s. peninsulae of Lower Michigan and T. s. griseus may be ascribed to long ago introgression from populations leading to speciation of doorsiensis. Or it may result from polymorphism in alleles for pallor, but strictly selected for, in their respective environments in both Michigan’s eastern peninsulae and Wisconsin’s doorsiensis. There may be a slight clinal darkening in mainland Wisconsin chipmunks southward, but to follow Jackson (1961) assigning southern specimens to an Ohio race on such subtle, gradual variation may add to confusion. Specimens from northern Illinois were assigned by Hoffmeister (1989) to griseus. I recognize no significant speciation in southern Wisconsin.

Tamias striatus doorsiensis Long 1961. Tamias striatus peninsulae Hooper, see Jackson, Mammals of Wisconsin, p. 149. 1971. Tamias striatus doorsiensis Long. Proc. Biol. Soc. Washington, 84:201-202. Type from Peninsula State Park, Door County, Wisconsin.

Description. This chipmunk is pale, not only its feet, cheeks, and dorsal pelage, but also the underside of the tail. The rump patch is tawny and less rusty chestnut. The skull is similar to that of T. s. griseus. Compared to T. s. peninsulae Hooper, from lower Michigan and some of the Beaver Islands, a race which is comparatively as pale, doorsiensis has much brighter, more conspicuous post-auricular patches, more grayish dorsal pelage adjacent to the dark and white stripes, the tail is more frosted with white, more heavily intermixed with black, and longer. The underside of the tail is a shade paler than in peninsulae. The feet and cheeks are more ochraceous. The skull is more robust, with wider nasals, zygomata, and rostrum. The teeth are more masTAXONOMIC ACCOUNTS / ORDER RODENTIA

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sive, as in T. s. griseus. See account of the significantly darker Tamias striatus griseus. Specimens examined. Total, 22. Door Co.: Peninsula State Park 9 or more (USNM). 6 mi. W Sturgeon Bay 4. Sturgeon Bay 3. 2 mi. N Jackson Port, near Wayside 2. Near Fish Creek 1. 3 mi. N Bailey Harbor on Hwy 57, 1. .5 mi. SE Peninsula Center 1. 1.5 mi. W Kangaroo Lake, on Hwy A, 1.

Tamias striatus griseus Mearns 1891. Tamias striatus griseus Mearns. Bull. Amer. Mus. Nat. Hist., 3:231. Type from Fort Snelling, Hennepin Co., Minnesota. 1942. Tamias striatus ohionensis Bole and Moulthrop. Sci. Publ., Cleveland Mus. Nat. Hist., 5(6):135. Type from Cincinatti, Ohio. Referring to synonomy only Wisconsin specimens, but likely the race is invalid.

Description. Tamias striatus griseus is a small sciurid having striped pelage above and white below, thin whitish stripes on the eyelids extending anteriorly to the nose and posteriorly almost to the ear pinna. The median dorsal stripe extends from the nape of the neck posteriorly onto the rump, but is not continued to the base of the tail, the lateral stripes are likewise short, especially the lateral ones. Adjacent to the mid- dorsal stripe are narrow strips of brownish or grayish pelage, bordered below with black, then comes white or creamy white, then black, then brown-ochraceous or grayish ochraceous. The feet are cinnamon brown, the tail grizzled grayish brown above and dark brownish orange below. Pale postauricular patches are behind the ear pinnae. The rump is rusty brown to dark chestnut. For comparison with the least chipmunk Eutamias, see account of that species. Compared to the pale race on the Door Peninsula, T. s. griseus has darker underside of tail, feet, cheeks, and the rump patch, and the upper side of the tail is less frosted with white. The cranium is similar.

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Specimens examined. Total, 73. Upper Michigan 9. Wisconsin. Adams, Burnett, Bayfield, Brown, Chippewa, Clark, Columbia, Dane, Dodge, Douglas, Dunn, Forest, Grant, Iowa, Iron, Jefferson, Juneau, Kenosha, Kewaunee, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Menominee, Milwaukee, Oconto, Oneida, Ozaukee, Pierce, Portage, Racine, Rock, Rusk, Sauk, Sawyer, Shawano, Sheboygan, Taylor, Trempealeau, Vernon, Vilas, Washburn, Washington, Waupaca, Waushara, Winnebago, Wood counties. Michigan Schoolcraft County. Genus Tamiasciurus Trouessart Douglas Squirrel, Chickaree or Red Squirrel “In the North, the red squirrels are... dependent on the seeds of various conifers... the refuse [from “feasts” at “feeding sites”] may form sizable midden heaps... The red squirrel is partial to mushrooms and stores great numbers [and] seems immune [even] to the toxic qualities of the amanitas, eaten in some quantity, as this writer has had opportunity to observe”. — W. J. Hamilton, Jr. American Mammals. Just a tawny glimmer, a dash of red and gray, Was it a flitting shadow, or a sunbeam gone astray ! I hear a mocking chuckle, then wrathful, he grows bold, And stays his pressing business, to scold. — Anna B. Comstock



Red squirrel. Lloyd Sanford, with Hamilton, 1939. 

Tamiasciurus hudsonicus (Erxleben) Red Squirrel 1777. [Sciurus vulgaris] hudsonicus Erxleben. Systema regni animalis..., 1:416. Hudson Bay. Type locality fixed by A. H. Howell at Mouth Severn River, Ontario, Proc. Biol. Soc. Washington, 49: 134, 1936. 1923. Tamiasciurus hudsonicus: Pocock. Proc. Zool. Soc. London, p. 213.

The name Tamiasciurus uses the Latinized and Greek words meaning steward and shade-tail and was doubtless intended by Pocock, with usage as late and as enlightened as 1923, to point out the hybrid-like similarities of this little tree squirrel to the other two genera. Hudson Bay was the meaning of hudsonicus. The early naturalist Pennant described red squirrels from Hudson Bay. Description. Aside from its reddish color (see below) the red squirrel, which superficially resembles the Sciurus, has distinctive forefeet and genitalia and is smaller in size. The forefeet, adapted both to spending much time on the ground and to leaping about in the tree canopies (mostly horizontal branches) have inner toes (III, IV) nearly equal in length, and those adjacent (II, V) also are subequal (Long and Captain, 1974). The thumb (I) possesses a minute nail as in Sciurus. Some have referred to the even arrangement in Tamiasciurus and Eutamias as artiodactyl, which is somewhat misleading because there are, of course, an odd number of toes (five). The genitalia are unusual in both sexes compared to those in Sciurus. In males there are minute Cowper’s glands, no bulbar gland, a true urethral diverticulum, a long filiform penis, and a minute os penis. The seminiferous vesicles are huge. In the female the vagina is unusually long and coiled during estrus. Anal scent glands are present (Mossman et al., 1932; Layne 1954, in New York squirrels). The tail is about half the length of the body, the ears are somewhat pointed and tufted (especially in winter). The zygomata are

not bowed outward much, but are nearly parallel to the skull. There are eight mammae (one pair pectoral, two pairs abdominal, one pair inguinal). The color is typically reddish, with more or less golden tawny or grayish brown tones intermixed. The dorsal fur is lightly flecked with black. In summer there is usually a bold, black line laterally and immediately above the white underparts, extending from the shoulder to the flank. This lateral stripe is obscure in winter. The head is darker than the dorsum, and around the eye is a conspicuous white ring. The tail is bright reddish above, with the tips of the hair tawny and having subterminal black bands. The tail below is gray and buff intermixed. The feet are tawny gray or brownish gray with gray soles somewhat overlain with silvery hairs. The underparts are white or pale creamy buff. This reddish color, so much like the coloration of the red fox Vulpes, may cause intimidation of the other tree squirrels, which are often set upon by even the young red squirrels. In most of the western subspecies of this squirrel, the dorsal fur is dark tawny brown or even gray-brown, the tail tipped with conspicuous silver-tipped hairs as in the gray squirrel. For this reason, westerners are not likely to call the squirrel a red squirrel, and often use the name chickaree (Long, 1965; Hall and Kelson, 1959: 399). The coloration of red squirrels in Wisconsin boggles the mind at times, because the variation in one place may include some particularly brown, others having reddish middorsal bands, and others being quite rufescent. When the mid-dorsal band is present, the sides are buffy or cinnamon brown. This marked variation is seasonal, and usually relates to the molt. The molt apparently begins, especially in young-of-the-year, in the tail with a sketchy extension of red developing along the back. This molt takes place in fall, and by November the mid-dorsal band is common in the squirrels with sides and feet pale golden brown or cinnamon gray. The winter pelage TAXONOMIC ACCOUNTS / ORDER RODENTIA

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is much brighter red than in summer, although the feet are often grayish in winter. The molt seems to progress forward from the tail (November) and subsequently spreads laterally and onto the shoulders and head. The bright hairs seem to fade, not molt, after April, when the fur is worn and more brownish. See Table Rod-4 for measurements for the two sexes. The size is significantly smaller than in Sciurus. Dental formula. I 1/1, C 0/0, P 1-2/1, m 3/3 = 20-22. The anterior (third) premolar of each upper jaw is usually absent, and if present minute, and partially covered by the large fourth premolar. Geographic Distribution. Widely distributed in Wisconsin, except in the southwestern part of the state. Surprisingly it is absent southward of the Wisconsin River from Columbia County, westward to the Mississippi. There are no records in northwest Illinois, although the area is ascribed to the probable range of this species by Hoffmeister (1989). This squirrel is another example of a Jackson-Hoffmeister pattern (see Plan of this Book, Plan-1), but the zoogeography is indeed more interesting than that simplistic taxonomy implies. Apparently the Minnesota race has worked its way into Wisconsin from the west and northwest, consistent with a pattern of other forest mammals of western origins. There it intergrades with the eastern race T. h. loquax (Bangs).



Skull of Tamiasciurus hudsonicus. 

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Status. The red squirrel is holding its own within its distributional area, especially in coniferous forests, but not so well in urbanized areas or other areas of hardwoods densely populated by gray squirrels (Reichard, 1976; Riege, 1990). It avoids treeless grasslands and marshes, but is a conspicuous denizen of the northern fir, cedar and pine forests. It has lost ground in the extreme southeastern part of Wisconsin and in adjacent counties of Illinois (Hoffmeister 1989). Red squirrels in the United States are seldom hunted or harvested for fur. Indians used them for food (Cleland 1966), and some people in central Wisconsin eat them together with gray squirrels. In Canada 25,000 skins are sold annually (Banfield 1974) to fur traders and subsequently shipped to Europe. They have a value of only two or three dollars each. Red squirrels are not protected by game laws. They are responsible for some tree damage by gnawing, eat thousands of pine seeds, kill young birds, and eat the eggs of songbirds on occasion. Some mistaken squirrel hunters have the belief that their fighting with (and the supposed castration of) the larger Sciurus is bad for squirrel hunting. Red squirrels have endearing aesthetic qualities, being such a beautiful and conspicuous member of the North Woods. Fishing with my two sons some years back, on a Canadian lake, we recall red squirrels as memorable as the loon by the boat, the bald eagle that soared overhead, the osprey, and the lines of mergansers fleeing and pattering over the water. It seems now more remarkable than any of the fish we caught. Where the red pines grew tall on high granite outcroppings towering over the shoreline, red squirrels were leaping about some 150 feet (50 m) above our boat. The squirrels seemed so small at that distance, and leaped so far from tree to tree that they seemed like little birds. They never once fell. I have not seen any such “frolicking” in tree canopies in Wisconsin. Habitat. This squirrel is found commonly in northern forests (Hatt 1929, Layne

1954), usually in pines, balsam fir, spruce, hemlock, cedar, and mixed hardwood-conifer forest (with beech and maples). The species may be found on occasion where the conifers are introduced and the typical trees are hardwoods (oak, hickory). In southeast Minnesota red squirrels are found in several towns. On the campus of St. Olaf College, in Northfield, Minnesota, the habitat is hardly coniferous, but a few red squirrels range around the edge of the campus. The red squirrels in Iowa live in pure deciduous tree stands near rivers and lakes (Lynch and Folk 1968). Sometimes in Wisconsin the red squirrel is



Maps showing geographic distribution of the red squirrel in Wisconsin and North America. 

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found in jack-pine-red oak savanna or in red pine and spruce Christmas tree plantations. They are abundant in parks where white pines are predominant. In beech-maple, with some hemlock or pine intermixed, either red squirrels or grays are predominant. This is true also in lower Michigan, where fox squirrels prefer the oak and hickory (Beckwith 1954). One can say the same for southwestern Wisconsin, where ecological preference may at least back up the factor of the river barrier maintaining reds north of the Wisconsin River and excluding them southward. In these river bottoms, sycamore, hickory, even walnut trees forest the area. Hemlock, pine, spruce and fir are not common, and there is little of the preferred habitat for Tamiasciurus. I found huge stands of jack pines. Since red squirrels are active in winter, it seems they would readily cross the ice wherever the Wisconsin River is narrow and the current not swift. Possibly red squirrels only recently approached the river, and are not really common in river bottoms, which may, along with the river itself, act as an effective barrier. On islands in Lake Superior and Lake Michigan, red squirrels are more often found than any other squirrel, usually exclusive of any other kind of squirrel. On these islands maples and cedars are abundant, and there are some oaks, pines and fir trees. On Stockton Island, in Lake Superior, William McKee (field notes) collected them in mixed forest (white and yellow birch, maple, cedar, hemlock, and balsam fir). On Washington Island, in Lake Michigan, red squirrels are seldom seen far from balsam and hemlock. In the southern parts of the range, red squirrels occur in quaking aspen, jack pine, white birch, hazelnut, and red maple. This habitat was north of New Lisbon (field notes, L. Wargowski). The denning of Tamiasciurus is fitting for its hybridized name, for they den in tree cavities and leaf nests in trees as the Sciurus do, and they den at ground level even in burrows (Yahner 1980), and also in woodpiles and in jumbles of rock, as chipmunks do (Fan-

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cy 1980, Layne 1954, Doutt et al., 1966). A tree nest is usually the approximate size of a basketball, with twigs outside a layer of leaves. Inside is the nest material of fine vegetation, usually grasses. I have noticed a mother and her young carrying grasses into a hollow oak tree formerly occupied by white-breasted nuthatches. In the cedar siding of my porch, there was no nest material at all for the young squirrels, suggesting that this den was temporary. It was used at least twice, and at least for two days (Long, 1993). The mother accompanies her young regularly from den to den, and some dens contain more nest materials than others. When young are discovered or threatened the mother presents an intense distraction display and afterward carries the young, one at a time, by its ventral skin, away to a safer den (Long, 1993). Temporary dens for young have been called “outliers” following the lore of the European badger (Long and Killingley 1983), these differing in their permanence, occupancy by other members of the social group, etc. There is similarity between movements of young to several outliers in these two quite different species: the arboreal or semi-arboreal red squirrel, generally being rather solitary, and the fossorial European badger, famous for its complex burrow systems and social clans. In eastern states, red squirrel territories defended by adult male or female were not common as observed in this species in western states (Riege, 1990; Layne, 1989; and others). Red squirrels often defend against conspecifics (Hazard, 1960). Where the gray squirrels are abundant (Riege, 1991), even though the red squirrels are aggressive, they are usually not predominant. In late summer there may be competition for tree cavities (Long, 1993). Foods. In central Wisconsin, red squirrels were observed feeding on jack-pine cones of both sexes, flicker eggs, fruit-heads of sweet fern Comptonia sp, and hazel nuts. The red squirrel may feed on any seeds or fruits in

season. These include acorns, conifer seeds, nuts (Hatt 192, fungi and cambium bark (Smith 1968, 1981), buds, flowers and maple seeds (Reichard 1976) and sap of trees, raspberries, insects, young birds and small mammals (Klugh 1927, Hamilton 1939, Hatfield 1937, Kilhain 1958, Banfield 1974). Smith (1981) measured food consumption as about 117 kcal per day, for a lactating female 323 kcal per day. See Table Rod-1. In late summer and fall the red squirrels begin to cache food for winter, mostly seeds, nuts, and acorns. In some places the food stores are cached in “middens” where hundreds of food items are stored. Most characteristic in middens I have observed are stores of conifer cones. These may be buried, or laid on the ground at the foot of a tree. Reportedly, the tree as “prey” and the squirrel as “seed predator” have co-evolved with mutual benefit (Smith 1970, Elliot 1974). In spring, when chasing or calling, the red squirrels occasionally fed on cached cones. In summer, in central Wisconsin, I saw them simultaneously calling from tree canopies and feeding on jack-pine cones. During May-June red squirrels foraged chiefly on red maple seeds, according to Riege (1991). Where and when available, red squirrels feed on maple seeds in Wisconsin. Mortality. Humans are an important enemy, shooting red squirrels and killing them by automobiles. Forest fires cause mortality. The marten is a famous predator (Seton 1953). The incredible climbing abilities of the red squirrels certainly lessen predation by arboreal pursuers. Predators on red squirrels include badger, bobcat, red fox, screech, barred, and barn owls, great horned owl, redshouldered hawk, Cooper’s hawk, broadwinged hawk, coyote, mink, long-tailed weasel, lynx, kestrel, and snakes (see Baker 1983). Parasites include fleas, 11 species of fleas in New York alone (Layne 1954), and two in Michigan (Monopsyllus and Orchopeas, Scharf and Stewart 1980). Lice, ticks, mites and chiggers are reported from red squirrels.

Internal parasites include tapeworms, flukes, roundworms, bot fly warbles, and coccidea (Dorney 1965, Baker 1983). Reproduction. Breeding begins February and March and re-commences in June and July. A female from Jackson County was lactating as late as October 10. Several males may attempt to mate one female. Layne (I954) believed that there were attempts at monogamous mating, when a male included a female in its home range and defended the area to keep other males out. There are soft coughing calls and chasing of the female prior to copulation in a tree or on the ground. Reported gestation periods range from 34 to 45 days (Ferron and Prescott, 1977; Lair, 1985). Litter size is about 5 (4-7). The young are born hairless with eyes and ears closed. They are about 70 mm in length, and weigh about 6.5 grams each. Hair develops by 10 days, and the eyes open in about four to five weeks. The young venture from the nest by 38 days, and are weaned by 7 or 8 weeks (Ferron 1980, Layne 1954, Svihla 1930). The young accompany the mother learning, playing, finding things to eat; they may stay with the mother all winter on occasion. This maternal behavior suggests that usually only a single litter is brought forth in a season, but there are usually two litters. Young do not breed in their first year. One squirrel lived three years in the wild, and they may live 10 in captivity (Banfield 1974). Home Range and Density. Riege (1991) found evidence of a “spring shuffle” when red squirrels move about freely and their home ranges overlap. In winter red squirrels avoid the hardwoods and their home ranges diminish. Density is difficult to measure as the squirrels move about so much. Layne (1954) found the density to vary with the habitat quality. For his study, one for five acres was low (1 / 2 ha), and two per acre (10 / 2 ha) high. Food concentrations and family gatherings may raise density to 12 per acre, according to Jackson (1961). I have seen as many as seven per acre in jack pine savanna, but five TAXONOMIC ACCOUNTS / ORDER RODENTIA

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were offspring of one female. The males usually come and go, ranging out of the oneacre study area. I have seen red squirrels actively chasing one another in late August on Washington Island, doubtless territorially claiming some foraging area for winter food supply. Rusch and Reeder (1978) felt that territorial behavior regulates red squirrel density near pine cone sources. Smith (1968) suggests that red squirrel males expand their feeding territories in spring to include females, while chasing off other males. Riege (1991) found greatest densities are in autumn. Linduska (1950) found 50 percent turnover in red squirrels. Remarks. Long (1993) recorded several interesting behaviors of the red squirrel. Used as a nest-site distraction display, and on occasion (but with less intensity) in territorial and interspecific threats, a complex call involving two or more vocalizations practically at once is emitted in a conspicuous display by a mother red squirrel near young. This call involves, with the harsh chattering, a “piping” or squeaking component resembling young. Along with the mother’s leading of the observer or predator from tree to tree, it distracts attention away from the young hidden in a nearby nest. The same call was often given at dawn by the mother, sited a short distance away from an outlier nest from which the young quietly emerged. There is a ventriloquistic quality to the call, which probably confuses the observer about the call’s direction and source. The summer movements of the mother and her young from one outlier to another in the family’s wandering and feeding, sometimes changing dens from night to night, are quite interesting. Additional natural history. Steele (1998) reviewed the biology of the red squirrel. Geographic variation. There are two subspecies of red squirrels ascribed to Wisconsin. Throughout most of the state and in Upper Michigan as well, the race is T. h. minnesota. Interbreeding in southeastern Wisconsin, the southeasternrnmost specimens are ascribed to T. h. loquax, which ranges south-

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ward into Illinois and eastward into Indiana. Without specimens from southeast Wisconsin to examine, except one from Germantown, this assignment is purely on geographic grounds, a line drawn subjectively between to distinctive samples. From Table Rod-4, I judge Hoffmeister (1989) was correct in saying T. h. loquax has larger feet. Jackson’s comment (1961) that minnesota had larger feet, by 10 %, is in error, although some individuals may be large. The geography is set forth below.

Tamiasciurus hudsonicus loquax (Bangs) 1896. Sciurus hudsonicus loquax Bangs. Proc. Biol. Soc. Washington 10:161, type from Liberty Hill, Conneticut. 1936. Tamiasciurus hudsonicus loquax: A. H. Howell. Occas. Papers Mus Zool., Univ. Michigan. 338:1. Specimens examined. None. Hoffmeister’s assignment, based on Cory (1912:124).

Tamiasciurus hudsonicus minnesota (J. A. Allen) 1899. Sciurus hudsonicus J. A. Allen Amer. Nat., 33:640, type from Fort Snelling; Hennepin Co., Minnesota. 1940. Tamiasciurus hudsonicus minnesota: Hayman and Holt. In Ellermann, The families and genera of living rodents. British Mus., 1:346. 1943. Tamiasciurus hudsonicus murii A. H. Howell. Proc. Biol. Soc. Washington 56: 67, type from Morehead, Clay Co., Minnesota.

Specimens examined. Total, 143. Adams, Ashland, Bayfield, Brown, Calument, Chippewa, Clark, Door, Florence, Forest, Iron, Jackson, Kewaunee, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Oconto, Oneida, Outagamie, Portage, Price, Sauk, Sawyer, Sheboygan, Taylor, Vilas, Washburn, Washington, Waukesha, Waupaca, Waushara, Wood counties.



Table Rod-4 Rod-4. Measurements of 14 males and 6 females of Tamiasciurus from Portage County, Wisconsin. 

Males Females

Males Females

TL

Tail

Hind foot

Ear

308.8±10.8 317±21

125.6±5 125.2±8.5

44.9±1 43.0±5

19.4±3 19.3±4

Greatest Length

Zygomatic breadth

Interorb. breadth

Max. t-r

45.8±1 45.4±0.6

26.2±0.8 26.1±1.1

13.9±.5 14.1±0.6

7.5 ±.26 7.8±0.3

Genus Sciurus Linnaeus Tree Squirrels Medium-sized (see Table Rod-5) diurnal squirrels with long, bushy tails, prominent ears (usually tufted in winter, in Wisconsin), tiny pollex bearing a minute nail or hoof distally, upper third premolar vestigial or absent, digits IV and V elongate, upper molars showing prominent transverse crests confluent on lingual border, and often terminating in distinct cusps. Braincase depressed posteriorly (i.e., cranium arched), palate broad, zygomata broaden posterior to the upper toothrows, occiput extends posterior to exoccipital condyles, often with a median and minute projection in adults.



Sketch of a gray squirrel Sciurus carolinensis. Courtesy Dan Metz. Scratchboard. 

Sciurus carolinensis Gmelin Gray Squirrel 1788. [Sciurus] carolinensis Gmelin. Systema naturae, ed. 13. 1: 148. Type locality, “Carolina.”

Sciurus carolinensis pennsylvanicus Ord 1815. Sciurus Pennsylvanicus Ord. In Guthrie, A new geog., hist., coml. grammar... Philadelphia, 2: 292. Type from Pennsylvania, west of the Allegheny Mountains. 1894. Sciurus carolinensis pennsylvanicus: Rhoads. Appendix of a reprint by Ord, on page 19. 1961. Sciurus carolinensis hypophaeus Merriam: Also Jackson (1961). Wisconsin. 1948. Sciurus carolinensis hypophaeus Merriam: Burt (1948). Upper Michigan. 1912. Sciurus leucotis: Cory. Field Museum Nat. Hist., Zoology, Vol. XI, p. 116. Also Snyder, Bull. Wis. Nat. Hist. Soc., 1902.

The name Sciurus means shade-tail in Greek, but it came to mean squirrel, which is how Linnaeus used the term. The specific name of the binomen, of course, refers to the type locality Carolina, and pennsylvanicus refers to the type locality of this wideranging geographic race. Description. Generally the description is the same as given for the genus above, but in comparison with the fox and red squirrels, more trenchant characters are listed. The gray squirrel resembles the slightly larger fox squirrel, but is larger than the red squirrels (see measurements). The skull differs in smaller size from that of the fox squirrel. Almost always there is a small peg upper third incisor present. In some states about 1% lack the peg incisor, but Jackson (1961) observed no specimens and I have only a few (for examples, UW-SP 134, 4963). The absences were observed only in subadults (having the fourth upper premolar not fully erupted). The baculum is small, disk-like with a thorny projection (Burt, 1960). Chromosomes number 2N = 40 (Nadler and Sutton, 1967). There TAXONOMIC ACCOUNTS / ORDER RODENTIA

193

are eight mammae (four pectoral, two abdominal and two inguinal). The red squirrels and gray squirrels are the only Wisconsin tree squirrels with long whitish hairs in the tail, but there is no trace of rufous in the fur of S. carolinensis, so characteristic of the dorsal fur of the red. The belly of the gray squirrel may be whitish, as in the red squirrel, but it is never whitish in the fox squirrel. The light-colored venter in the gray squirrel may vary, to be rusty, cinnamon, or even brown. Often the belly is marked with creamy or rusty blotches or a mid-ventral line of brown-tinged gray. The gray squirrel has grizzled dorsal fur, but the predominant tone of it is gray. Often in winter the dorsum is more or less frosted white. On the flanks there is generally a brownish tone, and in winter and early spring the ears are somewhat tufted with orange and white patches. This feature seems for the most part to have been overlooked; I have never seen tufts on the ears, even in winter, on gray squirrels from central Illinois or at Northfield, Minnesota. Tufts are variable in frequency in grays from southern Wisconsin. Melanism (e.g., UW-SP 4042, 988-9, 6968, 895, 3585) is common in the Wisconsin populations (see below), and I have seen a live albino on Washington Island. In Stevens Point, which is incorporated on both sides of the Wisconsin River, there is a creamy or yellowish mutant squirrel, the tail nearly lemon



Skull of gray squirrel Sciurus carolinensis. 

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THE WILD MAMMALS OF WISCONSIN

yellow and the head nearly white (UW-SP 6970, 1111). Over a third of a century I have observed one to a few yellow mutant gray squirrels in nearly every year. These mutants occur in an area about 7 by 3 miles, on the east side of the River. Some squirrels showing intermediate dorsal color seem heterozygous for yellow and normal, and some of these supposed “hybrids” are nearly gray with yellowish tails. In 1997, Professor Mark Boyce told me he saw a yellow mutant on the west side of the River, the first such report. In December 1999, my wife and I observed three yellows together chasing one another at the cemetery on Patch Street, near McDill Pond. In late January and February, staying until middle May, a mixed yellow (the tail certainly yellow) was resident on our acreage, with one black and eight normals. In the melanistic squirrels there are ear tufts present in winter, but they are obscure, concolor with the dorsal fur. If there is an iron-gray brownish tone on the face, throat and chest of a gray, it also tinges the tufts. The ear tufts are conspicuously white on the yellow squirrels. The molt commences in late spring, and ear tufts disappear then (by late May). Molt continues into summer (Brown and Yeager, 1945). The molt proceeds from the top of the head and mid-dorsum, and proceeds in all directions especially posteriorly and ventrally until complete. A second molt appears on the flanks in July-September and proceeds dorsally and anteriorly. This primary molt probably and almost cryptically begins in July (Flyger and Gates, 1982). Students often are confused by identification of gray squirrels because many specimens are not the ashy or silvery gray so common in late autumn and winter. This time is peak abundance of squirrels, the time they are hunted, and the time when leaves are down making it easier to see the squirrels. If gray at all in summer, the dorsum is somewhat rusty iron gray above, and often the belly is rusty, almost chestnut brown. In most specimens the belly is pure

white, although the throat and upper chest may be yellowish tawny or rusty brown. From Washington Island one specimen had a rusty brown belly, and some venters observed from various localities in Wisconsin were more or less brownish or ochraceousbrown in other parts of Wisconsin too. The feet are often rusty and bright, and rusty brown hairs are found intermixed in the tail. New fur is short and brownish, about the same color as a snowshoe hare, and such a color does not fit expectations when persons are more familiar with the ashy gray. The long,



Maps showing geographic distribution of Sciurus carolinensis in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

195

whitish hairs intermixed with gray and brown in the tail is important in identifying brownish gray squirrels, especially in summer. These are concentrated laterally in the tail, almost as whitish outer bands. The ashy color of the dorsal fur is a whitish tipping of the shorter brownish fur becoming intermixed with long black ones as they grow out. The dark hairs appear on the flanks and shoulders, and become confluent laterally and sometimes above a persisting band or stripe of brownish gray. Eventually new ashy fur spreads upward and toward head and tail. In summer, the short fur on the face is quite brown, and this color persists in some squirrels all year. The ear tufts grow out in late fall and winter. Measurements and weights are given in Table Rod-5. The grays are smaller than fox squirrels averaging 18-21 inches in length (457-553 mm) in total length, and up to 28 ounces. Dental formula: I 1/1, C 0/0, P 2/1, M 3/3 = 22. Geographic range. Populations of gray squirrels occasionally increase into the thousands, forcing them in low mast years into starvation or mass emigrations. These phenomena of high density and emigration were observed often in early Wisconsin history (Schorger, 1949), prior to game magagement. The numbers of gray squirrels rose and fell cyclically, perhaps approximately every five years (Jackson, 1961), and they varied then and do now considerably from place to place and year to year. The number of acorns produced probably play a role in these local fluctuations (Nixon et al., 1975). Gray squirrels, to cache food, hide acorns in holes dug in the ground, usually one per hole, never more than a few. Therefore, the squirrels plant their own forests and create their own habitat. Grays return to their caches, apparently by smelling, reportedly finding as many as 85 percent of the hidden acorns (Thompson and Thompson, 1980). The surplus obviously remains as seed; the gray squirrels are beneficial to the forestry in Wisconsin. There is immense aesthetic value of this beautiful squir-

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THE WILD MAMMALS OF WISCONSIN

rel. The great appreciation for this cute active, intelligent and pretty mammal scampering about in our lawns, parks, and natural areas cannot be measured. It is often hunted for sport for its delicious flesh, not so much for its fur. The gray squirrel occasionally kills young song birds or eats their eggs, raids an occasional garden or gnaws down saplings and small fruit trees, and gnaws on houses (one caused several hundred dollars damage to my deck drawn to the wood probably by the presence of sap in the cedar). Grays are so clever at robbing bird feeders some frustrated bird lovers are unhappy. [My wife hangs an empty plastic milk bottle (appropriately trimmed) around the post, and it seems to always keep the squirrels away, so long as they cannot jump onto the feeder from above. Therefore, they forage at the base of the feeder becoming fat and almost square in form.] One of the most curious mysteries, now attributed to the gray squirrel, was the disappearance of the tiny American flags put out in an Osh Kosh cemetery over the Memorial Day and July 4th holidays. For two years a thief was suspected of stealing flags. When a strong wind knocked down a big tree, shredded flags were found within gray squirrel nests. The positives greatly outweigh the negatives, regarding the status of the gray squirrel, and being such a beautiful object of nature study and photography we are happy to have it here. Habitats. In a word, the habitat of the gray squirrel is “hardwoods”. The oaks and maples are essential not only for seeds and security from predators, but for the tree hollows that often shelter the squirrels in winter and provide security in the care of young. The habitat is often called the forest edge, or open hardwoods, overlapping the similar habitat of Marmota and Sciurus niger. In Illinois forests, elective logging depressed breeding in old adults temporarily, but squirrels returned more abundant than ever (Nixon et al., 1980). Riege (1991) found that availability of foods and habitat affected densities of gray squir-

rels more than interspecific competition with red squirrels in the forests. Gray squirrels attained their highest densities in oak-maple forests, whereas red squirrels concentrated, for the most part, in fir-cedar communities or pines, when they were producing cones. Clear cutting and clearing of trees improve habitats for grays (and other squirrels). When nest cavities are in short supply two or several gray squirrels occupy the same tree cavity. Leaf nests are also constructed, in oaks and other high trees, occasionally in pines. One may evaluate habitat suitability in the gray squirrel by reference to trees especially those with acorns and other hard mast. In Wisconsin there are two chief cover types, namely deciduous forests (wetlands, highlands and urban parklands) and mixed deciduous-conifer forest (mostly in northern counties). Especially in winter there must be hard mast, hoarded by gray squirrels and also used by their competitors: chipmunks, whitefooted mice, and others. For survival of the gray squirrels, there must be adequate cover and trees for security, for nesting in season, and for reproduction. Forests of large diameter trees having dense overstory and numerous tree cavities, and including some oaks provide optimal habitat. Canopy closure varies from about half to 75 percent, and understory should vary from 20-30 %. There are two major requirements necessary for squirrels, and they may considered one. Oak trees, maples, or other food trees are necessary, and if winter is severe the available mast food cached mostly in the ground must keep the squirrels alive until spring. Therefore, bird feeders and other alternate food sources benefit squirrels in urban areas, especially those having some mature hardwoods. Hoffmeister (1989) found two mature oaks on the University of Illinois campus to provide for about five gray squirrels, and the numbers varied from year to year. On my property, in central Wisconsin, about an acre bordered by lakeshore and

roadway, the numbers vary from six to at least 22. There are seven or eight old red oaks, a few small white oaks and two large ones, a grove of hazelnuts, and there are numerous maples present. There are also four other kinds of squirrels commonly present, and three of these also feed on acorns and maple seeds. When squirrels are numerous, there are movements of at least one, sometimes several squirrels, to and from other neighborhoods. In a normal year, after a mild winter, I counted as many as seven squirrels chasing one another in a tree in April, with two others on the ground. Such chasing in similar numbers was also seen in mid-February. Some squirrels, known by tail damage or mutant color, wander at least a kilometer away. There is a British word for squirrel nest, the “drey”, used for their “grey squirrel”. Wisconsin gray squirrels often build nests of sticks and leaves high in the tree canopies. They also carry vegetation into tree cavities. I suppose the word drey applies to both kinds of squirrel nests. The nest for the first litter and for most adult grays, when hollows are available to them, is usually placed in a tree cavity or some hollow structure similar to it. The nest often is lined with shredded bark and plant fibers. Later in the year, the nests constructed in cavities may be bundles of shredded leaves. Nest construction likely is somewhat opportunistic in site selection and nest materials. Young squirrels and those not finding hollows are often forced to build leaf nests, in the tree branches. These are made clumsily by the beginners. In the best ball-like squirrel nests, the intertwining of branches and leaves makes a rain-proof chamber (entered by the squirrel from an obscure opening at one side) (Jackson, 1961). Sometimes these leaf nests are used for a couple years, and tree hollows perhaps as long as opportunity exists. Leaf nests are usually sited about 25 feet above the ground in hardwood trees, but occasionally are built lower. Rarely gray squirrel nests are found in conifers. OccaTAXONOMIC ACCOUNTS / ORDER RODENTIA

197

sionally the nest is built on an older squirrel nest or on a bird’s nest. Foods. Jackson’s (1961) list of foods is in close agreement with foods that I have seen or heard that gray squirrels use, as follows: many nuts including acorns, seeds, fruits, especially seedy fruits of maple, elm, hornbeam, hackberry, arrowwood and other species of Viburnum, cherry, mulberry, thornapple, wild grapes, buds of elm and oak, inner bark and sap (maple, elm), corn (the germ only), insects, and occasionally bird eggs (Dambach, 1942; Korschgen, 1981; Nichols, 1958; Montgomery et al.1975; Sanderson et al, 1980). The gray squirrel occasionally preys on small birds and mammals, even an eastern chipmunk. Squirrels gnaw on bones for the minerals. I have seen them eating mushrooms and suet. In winter and spring, gray squirrels make numerous excavations in the snow and ground in search of buried acorns, usually carrying a wet acorn into a nearby tree to eat. I found them to feed on oak buds in spring, hazelnuts in summer, and apples in fall. Some buried acorns are eaten after the snow melts, and I suspect that many acorns are hoarded and eaten in tree hollows. When grays are fighting in winter they may be competing for females, but also defending tree hollows used as homes and food caches. Territoriality may be defense of area, the female mate (as in deer), or a cache of acorns. C. Smith (1978) suggests “spreading out food by scatter-hoarding avoids an effective, aggressive defense of a stored food site from one’s conspecific competitors.” Gray squirrels may scatter hoard nuts to reduce site territoriality, whereas red squirrels that both scatter hoard and hoard seeds in larders may not successfully defend their caches from gray squirrels, making the commoner gray squirrel a kind of parasite (parasitoid?) on the red squirrel. Reproduction. Some mother gray squirrels have two litters per year. They usually cannot breed until their second winter. The

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THE WILD MAMMALS OF WISCONSIN

breeding commences in January and February, with young appearing after a gestation of some 44 days. In 1968, when the snow was piled high around my house some naked young fell out of a gray squirrel’s nest (sited in a jack-pine) in darkness right onto the ice, and with a great commotion the mother carried them away somewhere in the darkness. First litters are usually born by early April, and breeding continues into July or later for second litters. In September 1994, I saw tiny young that emerged from the nest, in a bur oak on the University campus. As many as eight young may be born, but usually the number is two to four. Only the mother cares for the young, and they may be moved if the nest is disturbed (Nixon et al., 1968). Weighing about 15 grams at birth, the young slowly grow and fur out, opening their eyes at approximately 30-35 days. In this museum collection there are several adults marked as lactating when collected, in early April, and one (UW-SP 912) as early as 29 March. Weaning begins after about 50 days when the active young are about half grown. By then the mother is ready for her second litter. These may stay with the mother into winter. One small male (UW-SP 5) taken April 29, is juvenile. Its greatest length of skull was only 45.3 mm. The only teeth erupted were the incisors and the deciduous fourth premolars. In a season a mother usually produces at least six young in the two litters, and in Longley’s study (1963) almost half the young survived through one winter until the next autumn. Females are reproductive for about six years, and males for about eight. Mortality. By hunting and removing habitat, humans are enemies of gray squirrels, and automobiles kill them in Wisconsin doubtless in many thousands. Add to humancaused mortality many squirrels killed by dogs, cats, and electric wires. Nevertheless, the species is holding its own today, especially in suburban habitats. By conserving old mast trees in lawns and parks, where hunting is seldom, humans are not adverse to

gray squirrels. In nature bobcats (if present), weasels, martens (when present), wolves (if present), red and gray foxes, and birds of prey kill them. They are not easily taken as prey. Ravens, snakes, and owls occasionally kill them. Once in Stevens Point, in winter, I watched a gray squirrel on the side of a tree directly facing a goshawk, which made an occasional pass, usually sitting on a nearby branch within two feet of the bold squirrel, but it could not catch it. The squirrel always escaped by darting behind the tree. In early November (2003) a small Cooper’s hawk alighted on a tree branch above a gray, cutting off its escape, to force it to leap down to the open ground. The gray immediately ascended and bit at the hawk, driving it away. In 25 years at our home, we have seen three gray squirrels with bobbed tails (from fighting?). Some works on predation include Schofield (1960), Pettingill (1976), Harlow et al. (1975), and Baker (1983). Parasites include mange mites, fleas of many species, lice, small ticks, and viruses which may cause tumors. A disease called squirrel pox was reported in Michigan (Stuht and Harte, 1973). Botflies occasionally leave their warbles in gray squirrels. Internal parasites include blood protozoans, roundworms, microfilaria, flukes, tapeworms, and spiny-headed worms (Kilham, 1959; Jackson, 1961; Scharf and Stewart, 1980; Clark, 1959; Parker and Holiman, 1971; Koprowski 1949a). Home Range and Density. In Kansas, the home range for gray squirrels was calculated as circular areas about 1.5/ha for females, and 3/ha for males (Armitage and Harris, 1982). Riege (1991) found that home ranges overlapped considerably. The average minimal-area polygon for 11 squirrels was 1.5±0.8 hectares. In my experience some squirrels stay on my acreage (2 ha) all winter, fattening themselves at my bird feeders; but some squirrels come and go, being observed as far away as half a mile, and on rare occasions returning to our property. Koprowski (1994a) mentioned home ranges as 0.5 ha to somewhat

less than 20 ha. Males had somewhat larger home range than females. The home range varied inversely with squirrel density. Territoriality was not evident. Madson (1978) reported that 21 grays in Sauk County, Wisconsin, wandered approximately 2 acres (0.8 ha). Dispersal was noted from August to January, but in some years it began as early as March. Where oaks were producing the fewest acorns gray squirrels there had their lowest densities. Longley (1963) found home range (foraging) to extend as far as 5 miles (8 km). Live-trapped squirrels returned home from distances of about 3 miles (= 4.8 km) (Schwartz and Schwartz, 1981). In large forest tracts grays seldom exceed two per acre. Densities varied from one per acre in September to only 0.65 (1 per 5 ha) in winter. Baker (1983) reported 5/ha as general. The high densities found years ago, when 20 could be shot in a single tree, cannot exist in the diversity of habitats today, according to Baker (1983), but on islands either in Lake Michigan (Long and Long, 1986) or urban islands in large cities it is not uncommon to see overpopulations of grays. Gray squirrels are famous in mammalogy as examples of mammals where numbers build up and the population, at least in part, moves away from one area to another, even crossing rivers to escape population pressure. In early American history these movements were often documented in the eastern United States. In Michigan, Seton (1920) quotes from the Bay City Tribune of February 17, 1907, that a population was observed in 1866, along a two-mile stretch of road to number 1,400 squirrels. Hundreds of black phase grays and normal grays crossed the Raisin River (Wood, 1922). Banfield (1974) mentioned a 19th century crossing of the Niagra River, and Fryxell (1926) mentioned grays crossing the Mississippi into Iowa in 1905 and 1925. Jackson (1921) mentioned squirrels crossing into southern Minnesota. Many squirrels drowned in these movements. He also mentioned a horde of grays encountering Lake Chetek, TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Barron County, while on the march, and a dozen squirrels were observed swimming (one at a time). About 20 were found drowned in bays and inlets. This emigration occurred in late September and ended before October. Long and Long (1986) reported a build up of squirrels on Washington Island, resulting in an exodus of grays swimming off into Lake Michigan. Some (about a dozen) were observed in Ellersen Bay and others seemed to leave the east side, more than 90 washing up on the beach of Rock Island (where no gray squirrels occur). Apparently several hundred grays participated in this exodus. Shorger (1949) studied the historical literature finding that gray emigrations resulted in the early 19th century about every 1-5 years. There are no such emigrations occurring in recent years, except the Washington Island irruption. Irruptions may be more common on islands where populations fluctuate anyhow. The population numbers and their crashes seem related chiefly to the availability of mast as food for the squirrels. Remarks. Dominance in fighting and chasing does not seem to depend much on color in the gray squirrel. Both mutant yellow and melanistic color phases described above have been observed in some years to run away from normal grays, and in other years either a yellow or black squirrel was observed to chase the grays. Oddly, the little red squirrel Tamiasciurus even half grown will put a gray to flight. I hypothesize that this may be because of their color, which resembles that of the red fox. Sciurus, although generally asocial, sometimes nest communally, especially in winter. Koprowski (1996) noted “kin clusters” in gray squirrel mothers with adult young, but no fox squirrels remained in their “natal areas” (philopatric). Unrelated adults nested together in both species, but adult female fox squirrels rarely nested together. Related gray squirrel females showed no aggression toward one another; there was observed aggression among unrelated females. Geographic Variation. The JacksonHoffmeister pattern (Table Plan-1) is seen in

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the taxonomy of the gray squirrel in Wisconsin. The large subspecies in Minnesota, if it is a valid subspecies, is S. c. hypophaeus, described by C. Hart Merriam. Wisconsin and the state of Illinois have been ascribed to two separate races by Jackson and Hoffmeister, respectively. On what basis should one recognize hypophaeus, of Minnesota, as a valid race, and where should the boundary between it and the southern S. c. carolinensis be drawn? Hall and Kelson (1959) and Hall (1981) followed Swanson in restricting hypophaeus to northern Minnesota, with its eastward border the St. Croix River. This arrangement left both Wisconsin and Illinois to S. c. pennsylvanicus. Some have stated that the northern S. c. hypophaeus (including in this concept Minnesota, Manitoba, Wisconsin, and Upper Michigan) has a high frequency of melanistic squirrels. Speculatively, such a high number of black individuals could be attributed to the charred tree stumps and logs of northern forests after forest fires, or the ordinary explanation of Gloger’s Rule, that dark forms inhabit shadows of forests and well-watered regions (where the wet soils are dark). Black fur absorbs heat, not insignificant in squirrels enduring the winters of the North Woods. In any case, melanistic squirrels are seen locally throughout the state of Wisconsin, extending southward into Illinois in relatively high frequencies (Hoffmeister, 1989) and throughout the Upper Peninsula of Michigan. Hoffmeister (1989) found the highest Illinois frequencies of melanistic squirrels in Jo Daviess, Carroll, Cook, Lake, and Adams counties, where most of these are found in the northeast and northwest corners near Minnesota and Wisconsin. All the squirrels shot in 1857, near the Rock River, about 50 in number, were black (Kennicott). That is (was) a significant frequency, unless they were shot selectively. Hoffmeister reports that today the highest frequencies are along Lake Michigan from Evanston to Zion in Illinois. Schorger (1949) believed the blacks were rare

south of Reedsburg and Baraboo in his day, and uncommon northward except where locally abundant. Such places are Waupaca and the zoo area in Wisconsin Rapids. I usually have one or two on my property in Stevens Point, although for the first ten years there was none. I suspect in Wisconsin less than 5 % are black, except in some local populations. Another northern characteristic is the presence of conspicuous but hitherto unnoticed winter ear tufts. Although not so large as in tassel-eared squirrels, they are indeed prominent. Contrasting white and ochraceous hairs suggest some visual communication, and perhaps the tufts are used in species recognition and courtship, since tufts begin in late winter and occasionally last occasionally until early June. The function of warming of the thin and prominent ears is obvious. I have never seen the tufts when I lived in Champaign-Urbana, in central Illinois (three years), nor even when I was looking for them in the winter of 1991, at St. Olaf College, in southeastern Minnesota (where I was Visiting Professor). On Washington Island, where some or all the grays may have been introduced, most winter squirrels have tufts. In the southwestern Wisconsin counties and in southern counties, in some populations at least, no tufts were seen. This Museum’s collection contains some squirrels from southern Wisconsin having tufts. Tufted squirrels were observed from Kenosha Co.; Janesville, Rock Co.; Monroe Co.; Vernon Co.; Marquette Co.; Dodge Co.; Jefferson Co.; and Waukesha Co. No tufts were seen in winter on specimens from Richland Co. ( 2 ); Dane Co.; Washburn Co.; Columbia Co.; and Milwaukee Co. A border specimen from Illinois had tufts (McHenry Co.) but one from Jo Daviess Co. (Stockton) did not. Hoffmeister (1989) studied size in gray squirrels, for S. c. hypophaeus is supposed to be large, and he assigned all Illinois squirrels to the southern race S. c. pennsylvanicus (although his map mistakenly refers all squirrels in Illinois to the race S. c. carolinensis). He reported slight clinal variation in

size from north to south. I found none in Wisconsin (see Table Rod-5). Jackson (1961) studied grays in Wisconsin and Minnesota, and looked for other, more important (than melanism) characters. He mentioned the dark venters as more common in northwest Wisconsin rather in the southeast part. He reported “distinctive color differences” in both winter and summer pelages. Not appreciated or overlooked were the generally darker upper parts of hypophaeus; the darker tail, particularly noticeable in the shorter white tips to the individual hairs and thus producing a much less frosted tail; the base of tail hairs much more grayish and less tawny or cinnamon; the brown tinge on the flanks darker and less ochraceous, the cheeks, temporal region, and ears brownish gray, often in winter distinctly iron gray, never yellowish ferruginous or ochraceous as in S. c pennsylvanicus. I could not confirm any of these differences as significant. Havera and Nixon (1978) studied the cranial dimensions (size) of squirrel skulls from central Wisconsin, northwest Illinois, north central Illinois and in the Illinois River Valley in northeast Illinois, extending a fair distance southward. They also compared with discriminant function analysis gray squirrels from the remainder of Illinois with these northern populations. They noted a break in a cline between the northern populations and the Illinois River squirrels. These were intermediate between the northern squirrels and those southward. They concluded the northern populations were in a northern race (which they called pennsylvanicus instead of hypophaeus) and that the southern squirrels of smaller size were referable to S. c. carolinensis. Hoffmeister (1989) rejected this classification. The race S. c. carolinensis has extremely small individuals, and the dorsum is more or less washed with tawny or tan brown. Any assignment of Illinois squirrels to this race was obviously incorrect. Assignment of most Illinois squirrels to S. c. pennsylvanicus is reasonable. An assignment of the squirrels in TAXONOMIC ACCOUNTS / ORDER RODENTIA

201



Table Rod-5 Rod-5. Cranial measurements of some gray squirrels in Wisconsin and northern Illinois. There is no significant geographic variation evident in these and several other measurement. Sexes are combined. Generally the localities are north to south. Mean ± standard deviation and observed range. Illinois data are from Hoffmeister, 1989.  Locality (Counties)

N

Greatest L.

Zygomatic Br.

Cranial Br.

Int. Br.

L. Nasals

Max. toothrow

P4-P4 Br.

Postorbital Br.

Lincoln & Marathon

3

63.4 62.3-64

35.2 34.9-35.5

25.3 25.8-26.6

19.5 18.2-22.6

21.1 18.8-22.6

11.3 11-11.7

13.4 13.3-13.5

19.4 18.9-19.8

Portage

12

63.1±1.49 59.9-64.6

34.8±0.7 33.6-36.2

25.9±2.15 19.51±1.04 21.04±0.55 11.52±0.35 13.18±0.45 19.57±0.9 19.3-27.2 17.3-21.2 20.1-21.7 11.1-12.03 12.5-13.9 17.9-21.2

Waupaca & Waushara

10

63.2±0.94 34.92±0.92 25.7±0.68 62.2-65.1 33.7-35.9 25.6-27.4

19.4±0.85 18.1-21.0

Sauk

4

63.6±1.6 62-65.9

35.6±0.61 35-36.1

29.95±0.4 26.9-27.4

19.93±1.0 21.25±0.24 11.08±0.33 13.35±0.41 19.8±0.63 18.6-21.0 21-21.5 10.7-11.4 12.9-13.7 19.3-19.9

Marquette

3

62.7 61.5-63.7

34.5 33.5-35.2

26.1 25.1-26.8

20.3 19.8-20.9

Racine, Milwaukee & Kenosha

6

61.6-±0.8 31.46±0.69 25.38±0.33 18.73±1.6 60.6-62.6 33.8-35.6 25.1-25.9 16.7-21.3

20.2±1.16 11.36±0.49 13.13±0.54 19.25±0.56 18.7-21.0 10.7-12.1 12.5-14.0 18.7-20.2

Richland & Vernon

2

63.7 62.6-65.8

35.1 33.4-36.8

26.2 25.3-28.0

18.8 17.8-19.8

20.6 19.9-21.3

10.9 10.8-11.0

13.4 12.9-13.8

19.4 19.2-19.6

McHenry Co., 1 Illinois

61.5

35.0

26.5

18.2

19.4

11.2

13.2

18.8

NW Illinois

62.4

35.0

24.4*

–

20.3

11.3

–

19.4

18-22

20.3±0.50 11.65±0.50 13.28±0.10 19.3±0.63 19.5-21.4 11-12.3 13-13.7 18-20.7

20.3 19.6-21.8

11.0 10.9-11.1

13.2 12.9-13.5

19.8 19.2-20.1

* A low value.

northern Illinois counties to S. c. hypophaeus might have been made by Havera and Nixon. Cory (1912) showed little regard for hypophaeus, saying it might be on average a little larger than typical squirrels from Wisconsin. He ascribed the Wisconsin and northern Illinois squirrels to a northern race (S. c. leucotis (Gapper)). I cannot separate Wisconsin squirrels from Illinois populations in size (Table Rod-5) or other characters. One should understand that the discriminant function analysis, used by Havera and Nixon, which did separate northern populations of Illinois from central and southern samples, will combine and weight characters in such a way that a distinction can be made. Illinois and Wisconsin squirrels are similar.

202

THE WILD MAMMALS OF WISCONSIN

The traits of the northern gray squirrel populations are interesting microgeographic variation, but not constant enough for subspecific recognition. Specimens examined. Total, 112. Adams, Ashland, Burnett, Chippewa, Clark, Columbia, Dane, Dodge, Door, Forest, Green, Jackson, Jefferson, Juneau, Kenosha, Lincoln, Marathon, Marquette, Menominee, Monroe, Oneida, Outagamie, Ozaukee, Pepin, Portage, Price, Racine, Rock, Sawyer, Sauk, Sheboygan, Trempealeau, Vernon, Vilas, Washburn, Washington, Waupaca, Waushara, Waukesha, Wood counties. Illinois. Jo Daviess Co.: Stockton 1. McHenry Co.: No specific locality 1.

Sciurus niger Linnaeus Fox Squirrel Sciurus niger rufiventer Geoffroy St.-Hilaire 1803. Sciurus rufiventer E. Geoffroy St.-Hilaire. Catalogue des mammiferes du Museum National d’Histoire Naturelle, Paris. Page 176. Type locality, Mississippi Valley. 1851. Sciurus sayii Audubon and Bachman. The viviparous quadrupeds of North America. 2: plate 89 and page274. Type from river bottomlands of Wabash River in Illinois, or from the Missouri River, or possibly Michigan. 1852. Sciurus Vulpinus Lapham. A systematic catalogue..., Fourth Rept. Regents, p. 44. 1902. Sciurus ludovicianus Snyder. A list, with brief notes, of the mammals of Dodge Co., Bull. Wisc. Nat. Hist. Soc., 2:118. 1907. Sciurus niger: Osgood. Proc. Biol. Soc. Washington, 20: 44. 1908. Sciurus niger rufiventer: Jackson. A preliminary list of Wisconsin mammals. Bull. Wisc. Nat. Hist. Soc., 6: 16.



Sketch of fox squirrel Sciurus niger. By Francis L. Jaques. In Cahalane, 1961. 

The name Sciurus means shade-tail, referring to its size and bushy quality, and the word niger means black. Fox squirrels are seldom black. The subspecific name rufiventer, means reddish belly, an apt description, except the color tends more to orange than red. As in other Sciurus, there is a small nail on the pollex, the third and fourth digits are elongate to encompass part of the circumference of a tree, and the eyes are large (giving a cute appearance and an alert expression). The bow-legged stance, adaptive for climbing, leads to the term scampering for running about on the ground, which this species does more than S. carolinensis. The skull closely resembles that of the gray squirrel, but averages larger. The infraorbital canal is smaller (less than 5 mm length), and the upper premolar 3 is absent. The cusps and cuspids of the molars are more rounded or bunodont than the flat-worn cheek teeth of gray squirrels. The chromosomes number is 40 (Nadler and Sutton, 1967). The baculum resembles that of S. carolinensis. The bones of the skeleton usually show a reddishorange or “pinkish” tint (Levin and Flyger, 1971; Flyger and Levin, 1977). Does the pink in the bone relate to the red color of the blood? Haeme production, the source of the red, depends on the action of uroporphyringogen UI, chiefly in erythropoietic (i.e., blood-forming) tissues in bone marrow. Too much of UI results from insufficient enzyme uroporphyrinogen III co-synthetase (or enzyme-UIII). Apparently the chemistry and titres in the fox squirrel resemble those in congenitally sick cattle and humans, who suffer “erythropoietic porphyria.” Overproduction of UI apparently is normal in fox squirrels, but some Wisconsin fox squirrel bones are not pinkish. The dorsal color of the pelage is ochracaeous gray, with a strong intermixture of black dorsally, concentrated on the forehead above the cheeks and eyes, and medially in the long tail. The toenails are conspicuously black against the bright orange feet, and the vibrissae are long and black. The cheeks are TAXONOMIC ACCOUNTS / ORDER RODENTIA

203

more or less orange, often dusky with suffused black, and the prominent ear tufts grown in winter and spring are bright orange. The venter is a rich ochraceous orange, paling to rose-orange, almost pinkish orange in some specimens. The tail is bright orange, almost tawny orange intermixed with black or brown, which is more visible dorsally than on the underside. Distally the tail has long hairs tipped with pale ochraceous beyond the bands of black-orange-black hairs. Melanistic squirrels have been reported, but usually the black squirrels in Wisconsin are gray squirrels. A mutant pattern observed in Dane County, southwest Wisconsin (La Crosse, also 2 mi. W Viola No. 4160), nearby Iowa (1 mi. SW Rossville), and reported by Kennicott (1857) in northern Illinois has black beginning on the cheeks and extending on the entire venter, and onto the lower legs. The Iowan specimen has black on the cheeks, intermixed on the crown a little, and extends even partially onto the feet. The face and body of this pattern with orange set against dark black is striking to say the least. It might function in display, in intimidation. Molt lasts about a month, beginning in spring. New hair appears on the head and often a distinct molt line can be seen belting the body. Even young of the year molt and grow a dense winter coat (with ear tufts). Some squirrels molt twice or late (e.g., Sept. 28, UW-SP 7131, Vernon Co.)(also see Koprowski, 1994b). There are eight blackish mam-



Skull of Sciurus niger. 

204

THE WILD MAMMALS OF WISCONSIN

mae (Flyger and Gates, 1982). Measurements are in Table Rod-6. Dental Formula. Upper third premolars absent. I 1/1, C 0/0, P 1/1, M 3/3 = 20. Geographic Distribution. The distribution of Sciurus niger, a tree squirrel preferring forest edge habitats, is dynamic, as ever changing as the clearing of woodlands and the growth of hardwoods. Additionally, there is the possible displacement by competition with Tamias and S. carolinensis, perhaps some competition with other woodland mammals (deer mice, flying squirrels, etc.). For example, at my home in Portage County, basically an oak-jack pine savanna habitat overlooking a lake, gray squirrels are predominant among eight squirrel species present, but only one fox squirrel has visited the place in 23 years (staying only a day). Fox squirrels are found here and there in Portage County, but gray squirrels are the abundant tree squirrels in deciduous woodland habitats or park areas. The only occurrence for this savanna area that I have observed in Portage County, was in woodlots or hedges adjacent to cultivated fields, mostly toward Junction City and westward, and tamarack-cedar swamps east of Stevens Point. Cleland (1966) reported fox squirrels in archaeological sites in a broad region from Ontario to Michigan, but Jackson (1961) found the species confined to southern counties of Wisconsin before the turn of the 20th century. In oak and hickory woods they were abundant, occurring along the Mississippi to the St. Croix, extending into Dunn County, ranging southward as far as southern Juneau County, and along Lake Michigan as far as the Door Peninsula (even northward of Sturgeon Bay). Up to 1961, kill records were highest in this same oak-hickory and oak savanna region, but squirrels were killed even in northern counties (in low frequencies). No sign of them was in Iron, Vilas, and Florence counties. The observed expansion of range northward since 1961, was thought to result from cutting into the continuous northern forests,

formerly inhabited only by grays and reds. Coincidentally, fox squirrels swept northward in Lower Michigan, fastest along the lake shore counties, and by “introductions” colonized the Upper Peninsula in the easternmost counties (Baker, 1983). Fox squirrels reached the Upper Peninsula by way of Wisconsin after publication of Burt’s work (in 1948). Baker (1983) reported that most of the forested Upper Peninsula is “still not fox squirrel range.” Jackson (1961) reported a specimen from Brown County near Green Bay, approximately 40 miles (= 64.4 km) from the Michigan boundary. Long



Maps showing distribution of Sciurus niger in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

205

(1974) reported them from both Marinette and Florence counties extending the range to the Michigan border. In Michigan, in the early 1970’s, fox squirrels were noticed in the southwestern quarter of Iron County and southwestern corner of Dickinson County. In 1977, a fox squirrel was found dead on a road in Baraga County, and another was found later in Menominee County (Baker, 1983). Status. Fox squirrels have delicious flesh, and were eaten in greater numbers than grays by pioneers (Schorger, 1949b). Today it is a game mammal throughout Wisconsin and locally in the Upper Peninsula. Sport hunting is its chief economic value. In natural woodlands the fox squirrel is not so secretive as the gray, and forages later in the day. In the southern counties where hunters seek bobwhite, partridge, and especially the wild turkey (in oakhickory and bass-maple forests near forest edge, on sunny, rocky hillsides, and in cleared and disturbed habitats), many fox squirrels are shot as game. Some hunters seek them out specifically, sitting in the woods where tree nests are conspicuous, waiting until one scampers out in the sunshine, and shooting them with rifles equipped with scopes. In most counties the rarer fox squirrel is taken less frequently than grays. The fur is of little value, and is not saved in Wisconsin. Once the tails decorated car antennae, before the advent of Green Bay Packer-mania and the use of Packer flags. The fox squirrel causes some economic damage by gnawing to human habitations, and some fruit trees are ravaged. In corn-growing areas, which seemingly encourage fox squirrels to move into adjacent fencerows and wood lots, fox squirrels may eat enough corn to cause significant damage. Aesthetically, the fox squirrel is a beautiful mammal with its orange ear tufts prominent in winter, orange coloration and long, lovely tail. Few can fail to appreciate its beauty either as it gracefully climbs about in a tree or sits erect, neck outstretched, standing on its hind limbs on the ground. Squirrels are second only to songbirds as objects of photography (Koprowski, 1994b).

206

THE WILD MAMMALS OF WISCONSIN

Habitat. In a word, the fox squirrel prefers “forest-edge.” Therefore, it is a mammal of savanna, preferring open woods where it scampers about on the ground. A large forest certainly is not required, and a hedgerow or fencerow with a few mature oaks is quite suitable. As one might expect, fox squirrels also dwell in oak thickets, deciduous forested wetlands with sunny openings, and other open deciduous woods. The dry, forest uplands of southwest Wisconsin, and the deciduous woods in southeastern Wisconsin, where oaks, walnuts and hickories are found, are favorite haunts of the fox squirrel. Where gray and fox squirrels occur together, fox squirrels may chase grays away, but usually the grays defend the nest cavities in trees, constructing relatively few leafy nests, and the fox squirrels must utilize leafy nests in the sunny tree canopies. This sympatry is common in the woodlands of west-central and southwest Wisconsin. Hazard (1982) reported neither species dominates the other by fighting and chasing. Steele and Weigl (1992) discussed energetics and patch use of the habitat. In woodlands, especially continuous hardwoods, the grays usually win out in Wisconsin. In fir-cedar and pines the reds usually win out. Either or both Sciurus may thrive in a town, but usually in Wisconsin the grays are established in urban areas. One may evaluate habitat suitability in the fox squirrel by reference to canopy of trees, including those with food sources, especially oaks, and to nearby cultivated grain crops. These plants provide essential winter foods. Understory must be present for cover and reproduction. Fox squirrels’ nesting habits require fewer nest cavities, but the fox squirrel will use them. Closure of canopy may range from approximately 22-60 %. Shrubby understory is of little use to this species if it exceeds 30 percent. Tree nests are quite often constructed in branches of trees about 30 feet or higher above ground, and are made of shredded leaves, bark cut from twigs, and branches. Hoffmeister

(1989) states that in the tree cavity the nest of a fox squirrel is usually made of leaves. Foods. Foods in Wisconsin are similar to those of grays, including primarily the mast of the hardwood forests. Acorns, maple seeds, buds of elm and oaks, cambium bark and sap (like the gray squirrels, the fox squirrels often gnaw on the cambium layer of trees and eat sap in spring and winter), mushrooms, arthropods, and such foods are often eaten. Fruit from trees, corn and many kinds of nuts and seeds are also eaten. Allen (1943) lists important mast bearing trees for Michigan, which also occur in Wisconsin: white, red, bur and black oaks. Allen (1943) and Reichard (1976) mention such diverse foods as flower buds of maples and bur oaks, maple sap, catkins of willow, cottonwood, flowers of beech, elm, hackberry and basswood, beetles, tubers, bulbs, roots, nest eggs and young of song birds, and seasonal strawberries, serviceberries, haws, plums, raspberries, blackberries, greenbriar, cherries, ash, dogwood, elderberries, and others. Acorns, nuts, seeds, and corn are also preferred fare. Fungi, grapes, wild rose, and bittersweet are eaten now and then. Many food items are listed by Koprowski (1994b). Reproduction. Fox squirrels have two litters each year (Allen, 1943; Brown and Yeager, 1945; Koprowski 1994b). The first season of breeding begins in January and gestation lasts 44 or 45 days following mating. The second season begins in June and lasts sometimes into October. A specimen from near Nichols, in Outagamie County, was lactating on October 28. Yearling females usually breed only once. Breeding is diminished by low food supplies and bad weather. Breeding is enhanced by previous removal of adults, especially females (Hansen and Nixon, 1985), which are the most stable and territorial of the population. Litter size varies up to 7 (one specimen had 7 fetuses, Hoover, 1954). Averages have been reported between 3 and 4 in central Illinois (Hoffmeister, 1989), but over its range the mode is usually 2 or 3 (Koprows-

ki, 1994b). The young are born in nest cavities of trees and occasionally in tree nests (Allen, 1942). The newborn young weigh about 15 grams, and are blind and naked. In a week hair appears on the back, and the weight doubles. By 35 days the young are active, eyes open, and the body hair is almost furred out. Allen (1943) mentions that the eyes open by the fifth week. By 55 days the young emerge from the nest, about 100 days after conception. Weaning follows three months after birth. Pregnant females drive away their young, but second litters may accompany the mother several weeks longer than usual. Annual production is about 6 young per adult female, less in yearling females, which comprise about 60 per cent of females in Michigan (Allen, 1943). Fox squirrels survive more than 6 years (Fouch, 1958), up to 9 in captivity (Crandall, 1964). Mortality. Few predators can catch tree squirrels regularly. Probably on rare occasions a sick, old or very young individual is caught by raptors (hawks, occasionally owls, once an osprey) and Carnivores (especially foxes) (Jackson, 1961; Allen, 1943). Domestic dogs and cats kill them, but the greatest mortality today is from automobiles and hunters. Jackson (1961) lists many parasites including lice Enderleinellus and Neohaematopinus, mites Euhaemogamasus and especially Sarcoptes scabei (for the mange), flea Orchopeas, chigger Trombicula, and ticks Haemolaelaps and Dermacentor. A variety of internal parasites include blood protozoans, spiny headed worm, 10 species of round worms (including Bohmiella, Enterobias, Helig-modendrium, Physaloptera, and Trichostrongylus that occur in Wisconsin squirrels). Sometimes the incisors do not occlude, and grow in curls, even penetrating the squirrel’s brain. Koprowski (1994b) lists predators, parasites, viruses, and pesticide problems in great detail. They often work in combination to kill off populations. Allen (1943) discussed how winter and food scarcity related to predation and scabies TAXONOMIC ACCOUNTS / ORDER RODENTIA

207

on weakened squirrels would increasingly affect fox squirrels, which are southern mammals dispersing northward into the North Woods. A severe winter (1935-6) was related to a decline in fox squirrels in Michigan. Scabies (sarcoptic mange), an obvious factor, followed a winter of low oak mast. Much more research is needed on the competitive interactions of several kinds of squirrels and other mast eaters in Wisconsin. Periodic mast scarcity is in itself a great problem for S. niger and other squirrels. Allen (1943) discusses this thoroughly, and some of his ideas are included here. “In 1939 there was the greatest abundance of mast occurring in five years, and in 1940 the population probably reached a high for the same period. But the complete failure of the 1940 acorn crop precipitated a crisis in the ensuing winter. Among fox squirrels there were many signs of malnutrition and weakness; 16 individuals were found dead in natural dens, and wood duck and raccoon nest boxes. Five more were found on the ground. In addition, a gray squirrel and two flying squirrels were recorded as mortalities. Mange was wide-spread and those autopsied were 3 to 8 ounces (87-232 g) under the average weight for late winter the year before.” Other details of starvation, emaciation, and convulsions are described by Allen. Scabies and shock were considered extremely dangerous to squirrels. In addition to direct mortality, “food scarcity further reduced the population by preventing breeding.” Extreme winter weather works adversely with food scarcity against fox squirrels. Allen (1943) mentions the weakness of emaciated squirrels caused by mast failure, and additionally the ice and snowcover that buried nuts so deeply they are “less available.” The general weakening also makes squirrels more susceptible to predation by dogs, hawks, or owls. Home range and Density. Jackson (1961) gives home range as about 3 or 4 acres, occasionally exceeding 20 acres (80 ha). Wise (1986) reports that fox squirrels wander in larger home ranges than do gray

208

THE WILD MAMMALS OF WISCONSIN

squirrels. Koprowski (1994b) mentions home ranges for this species from 0.85-17.2 ha (240 acres) for females and from 0.54 to 42.8 ha (1-100 acres) for males. C. E. Adams (1976) presented some characteristics of home range for the fox squirrel. Home ranges overlap extensively, and territoriality of areas is not evident. Fighting over females is another kind of territoriality. Juveniles disperse from home areas to new homes. Males dominate females, and adults intimidate juveniles. Remarks on Behavior. Hazard (1982) doubts that interspecific fighting in squirrels results in one species’ dominance. In the fox squirrel population, adult females are the most stable in their home ranges or territories (see below). Either in courtship chases or territorial battles, or even in displacement during food competition, two adults begin with tail flicking, as in grays. Purrs, barks, and other scolding sounds are emitted during courtship, performed with various approaches, probably scent emission, and even courtship grooming (McClosky and Shaw, 1977). Jackson (1961) reports that the fox squirrel scold is more guttural and lower in pitch than that of the gray, ending in a drawn out “qwa-a-a-aa.” Although the species is said to not be strongly territorial (for example, Baker,1983) the female den sites are evenly spaced (about 50 m apart). Nevertheless, the squirrels forage in overlapping home ranges, and in winter several may sleep together in their nests. The orange winter tufts in most Wisconsin fox squirrels, for one thing, are for warmth, and even the pinnae of the ears may be furred (Flyger and Gates, 1982). As in the gray squirrel, S. carolinensis, the prominent tufts, which are even longer than in the gray squirrel, may be related to some overt or positive visual communication. My brother David Long and I raised Kansan fox squirrels for pets. One that escaped from him bit my mother in the face. Another pet fox squirrel bit Hartley Jackson (1961) in the face. A person should not expect docility from an adult fox squirrel. But one I had was



Table Rod-6 Rod-6. Some measurements of Sciurus niger from Vernon and Manitowoc counties, Wisconsin (3 males). 

TL

Tail

Hindfoot

Ear

Gr. L

Zygomat. br

591 702 592

290 265 271

66 75 65

22 26 24

66.7 — —

36.8 — —

excellent, in the University of Kansas graduate student dorms where I lived. It would carry items my wife was ironing up to the top of the bedroom drapes. Fox squirrels, consistent with their preference for the forest edge, spend a great deal of time foraging or scatter hoarding nuts on the ground. Reportedly they run from enemies over the ground longer than grays, eventually taking to the trees to escape. For communal nesting and philopatry, see Koprowski (1996). Geographic Variation. In Wisconsin there is no significant geographic variation in the fox squirrel, and none would be expected in populations descended from southern populations dispersing northward in historic times. No significant sexual variation was noted. Specimens examined. Total, 61. Adams, Brown, Burnett, Crawford, Dane, Dodge, Green, Green Lake, Jackson, Juneau, Kewaunee, La Crosse, Langlade, Manitowoc, Marquette, Marathon, Menominee, Monroe, Outagamie, Pierce, Portage, Richland, Sauk, Vernon, Vilas, Waupaca, Waushara, Washington, Winnebago, Wood counties.



Gliding Flying Squirrel. Walter Weber, in K. Schmidt. 

Genus Glaucomys Thomas North American Flying Squirrels These softly colored, pug-nosed but lovely squirrels are characterized by a lateral fold of loose skin, which stretches between wrist and ankle. Some workers call it a “plagiopatagium.” Resembling the calcar of the uropatagium of bats, there is a process (Baker, 1983) that helps to make the membrane taut. Discovered by Muul (1968), as far as I can determine, the unnamed wrist structure might be called a carpar analogous to the bat’s calcar. The presence of a flight membrane, used to glide from high elevations, as in several other mammalian groups, was considered sufficiently divergent to arrange these squirrels in a separate subfamily (Petauristinae). Because of this membrane, the crepuscular or nocturnal habits instead of diurnal behavior, and by the consequentially enlarged eyes and flattened tail, Long and Captain (1974) and Black (1963) proposed that the flying squirrels, known from North America and Asia, were directly derived from tree squirrels (such as Sciurus). Therefore, Glaucomys and the Oriental gliders are not assigned to a separate subfamily. The skull in Glaucomys is small with delicate postorbital processes and downturned



Glaucomys sabrinus. By Susan E. Smith. 1992. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

209

nasals. A tiny upper third premolar is present, as in the tree squirrels. The fur, exceptionally soft and fleecy in the North American Glaucomys, is furred in such a way the hairs comprise an air foil for gliding locomotion.

Glaucomys sabrinus (Shaw) Northern Flying Squirrel 1801. Sciurus sabrinus Shaw. General Zool., 2:157.

Glaucomys sabrinus macrotis (Mearns) 1898. Sciuropterus sabrinus macrotis Mearns. Proc. U. S. Nat. Mus., 21: 353. Type from Hunter Mtn., 3300 ft., Catskills, Greene Co., New York. 1915. G [laucomys]. s[abrinus. macrotis: A. H. Howell. Proc. Biol. Soc. Washington, 28: 111.

The name Glaucomys means gray mouse, and sabrinus may mean something like Severn, which is the type locality (mouth of Severn River, Ontario). The namer Shaw did not say, but Baker (1983) suggests the old Latin name for an English River changed from the Roman to English Severn probably indicates the Canadian Severn River. The race name macrotis means large ear. Description. The northern, and also the southern flying squirrels, are readily distinguished from other sciurids by the lateral membrane used to glide, by enormous eyes for nocturnal vision, and by large mouselike ear pinnae. The northern flying squirrel is significantly larger than the southern. The ventral hairs are more grayish at their bases, so that the venter is more often mottled with grayish, even on the throat. The baculum is short and slightly twisted, and relatively stouter than in G. volans. It measures only 6.3-7.3 mm (Burt, 1960). There are four pairs of mammae in the female. The two species of flying squirrels are proportionately similar, as has been often noted. I submit two characters which seem to distinguish them in Wisconsin. First, the small,

210

THE WILD MAMMALS OF WISCONSIN

arched skull of G. volans has a proportionally larger orbit, due in part to the narrower jugal which is developed less anteriorly than that in G. sabrinus. Superficially it would seem from examining the skull that G. sabrinus would have more difficulty seeing forward. A conspicuous difference is in the color of the tail, which dorsally is not brighter and reddish as is the dorsum, but dark, dull walnut brown. Occasionally the reddish of the dorsum extends onto the base of the tail, but not far. In comparison, the tail of G. volans is brighter than its dorsum, a pale tawny gray. The underside color of the tail in volans is in contrast to the soft, tawny gray color above, instead a lovely ochraceous or gray-orange. In G. sabrinus the underside is brownish gray, ranging from almost black to a dirty white. The skull has a small, downturned rostrum, with the braincase twisted ventrally, so that in lateral profile the rostrum and cranium seem flattened and short. The remainder of the skull is massive. The postorbital processes are attenuate, flaring away from the cranium. The nasals and maxillary extensions are aligned with the zygomatic plates, anterior to the zygomata. The zygoma (especially the jugal bone) is relatively thick. These cranial characters usefully distinguish the species from other sciurids, except not so much from G. volans. The dorsal pelage in Glaucomys sabrinus is grayish overlain with cinnamon-ochraceous color, even chestnut in bright, new pelage. The pelage is darker in fresh molt, where the cinnamon brown tips are not grown out, and in worn pelage where the tips seem to be worn off. The brightest chestnut colors are seen in July pelages, and in one specimen taken in early September. In September-November specimens the fur is significantly darker plumbeous or blackish gray in tone, from the underlying dark color. The tail resembles the dorsal fur above, but may be more ochraceous. On the neck the ochraceous also may be brighter. The cheeks may be grayish. The ventral fur is a dirty white due to the gray bases of the hairs. The neck area is more

nearly whitish, but even here gray is evident. The dorsal pelage is brighter and more reddish than in the drab, soft-colored G. volans. Additional remarks on color are given in the account of G. volans. An annual molt occurs in late summer and early fall. Measurements and weights are given in Table Rod-7. The measurements of the skull and other bones are significantly larger than in G. volans, but proportionally there seems no way to distinguish the two species (except in the form of the baculum) from one another. Dental Formula. I 1/1, C 0/0, P 2/1, M 3/3 = 22. The anteriormost premolar is minute. Geographic Distribution. The scarce northern flying squirrel is found in boreal woodlands northward of a boundary extending from Burnett County southeastward into Portage County, possibly northern Juneau County, thence into Outagamie County and probably not continuously throughout Door County (apparently restricted to the forests north of the canal at Sturgeon Bay). Not found on any Wisconsin islands in Lake Superior (which is surprising to me) or Lake Michigan (which is likewise surprising, because the islands are close together, the species is the boreal one, and the squirrels do not hibernate). Status. The geographic range today is about as it was in the years preceding Jackson’s work. The slight extension of range southward is likely that of known range. In-



Skull of Glaucomys sabrinus. 

deed, the distribution of Glaucomys sabrinus is more likely receding and the numbers probably diminishing. This problem is very possibly developing because (a) the related southern flying squirrel, G. volans, is extending its actual range northward into the range of G. sabrinus, and (b) there is direct competition between the two species, for example, nesting cavities (tree cavities), usually taken over by the earlier breeding G. volans (Muul, 1968). In Central Wisconsin, there are evidences that volans adapt better to the spreading human settlements. The proper management and conservation of this remarkably lovely, interesting, and harmless sciurid, then, promises to be a real challenge. The northern flying squirrel must not only adapt to the activities of humankind, but it is contested by a near relative, which may eradicate this rarer, boreal species. Possibly some nesting-house design may prove beneficial, and in remote and continuous woodlands bolster the fecundity of G. sabrinus. The species should be placed on a list of threatened mammals in Michigan and Wisconsin (Long, 1974). Judging by museum collections, in which never are there more than a few of these animals represented from any locality, the total number of animals preserved is much lower than is the number of southern flying squirrels (G. volans). In Portage County, where both species now are found sympatrically, G. volans is much more abundant. This may to some extent reflect the greater abundance of volans near man’s habitations, and doubtless reflects the localization of G. sabrinus in conifer communities and wet forests north of Stevens Point. There are estimates that the number of G. sabrinus has been reduced in Wisconsin (Jackson, 1961) and in Michigan (Muul, 1968) from earlier days. I have found no evidence to the contrary, and I do have evidence that the southern species is moving northward. Habitat. According to Jackson (1961) the habitat preferred in Wisconsin is mixed hardTAXONOMIC ACCOUNTS / ORDER RODENTIA

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wood and conifer, usually a wet forest, seldom a pure hardwood stand, usually forests where decayed logs lie on the forest floor. The trees are usually hemlock-maple or hemlock-gray birch, and occasionally cedars. In Michigan, this squirrel has been reported in conifer swamps (Green, 1925) and in jackpines, cutover hardwoods, and mixed conifer-hardwood forest (Manville, 1948). There are two kinds of homes. The cavity is used almost any time of the year, in live or dead trees, hollow stumps, the tops of snags or telephone poles, and nooks in the attics of



Maps showing geographic distribution of Glaucomys sabrinus in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

old houses. The cavities may be natural, or remodeled woodpecker holes. Nests are found in the tree cavities, for newborn litters. The stick nest (comprised of twigs, lichens, mosses, and shredded bark, Howell, 1918; Cowan, 1936) is made in spring and summer, usually in evergreens high above the ground. The nest of another squirrel or a crow may be used. An opening facing the trunk is usually made for rapid exit in the dreys. In winter, up to nine squirrels have been found in one tree cavity (Jackson, 1961). Foods. As in other tree squirrels it is very important for G. sabrinus to cache seeds, conifers seeds (usually in the cones), and acorns in large quantities for lasting the winter. Foods are actively procured even on cold nights, taken from boreal trees (such as spruce seeds) and supplemented by buds, arthropods, especially moths and beetles, and dripping maple sap in season. Bird eggs and young are reportedly eaten, and certain edible fungi are often eaten when available. Where beech trees are found the seeds are stored for winter in hollow trees and in stumps. Occasionally pine cones are piled on the ground. If G. sabrinus finds the cache of another species of squirrel it raids it (Brink and Dean, 1966; Smith and Aldous, 1947; Wrigley, 1969; and Seton, 1953). Reproduction. G. sabrinus usually has a single litter in late spring, but some females bring forth a second litter in late summer. If there is a second, perhaps the first was lost (Banfield, 1974, Doutt et al., 1966). The specimens in this University’s collection show no records of pregnancy, and few adult records before mid-July. Lactating females have eight teats, suggesting about four embryos more or less. Muul (1969) reports the number is about 3 (2-6). Lactating females were observed 14 May, 2 September, and 13 October (which date is surprisingly late for such a boreal mammal). Courtship begins in March, probably even before the thaws set in, and continues until late May. The male stomps its feet and emits high, pulsed calls. During copulation females purr and males whine. Ap-

parently breeding re-commences in summer. Gestation lasts about 37 days according to Muul (1969). Specimens taken from a litter of six, from Woman Lake, Cass Co., Minnesota, were tiny on May 20, 1950. Respectively, Univ. Minn. 2901, 2900, had these standard measurements and weights: 151, 151; 64, 63; 26, 25; 26 g, 26.2 g. After three weeks in captivity at reportedly 43 days of age, a third specimen was 183, 82, 28, 32.7 g. Newborn young are about 70 mm in length, weighing about 5.8 g. They are naked with eyes and ears closed, but the patagial membrane is evident (Muul, 1969). In six days vibrissae are evident, and in 18 days the pink bodies are furred. The eyes open in 31 days, and the flattened tail is prominent. After 40 days the young emerge from the nest, and weaning seems complete by 60 days. The young glide about after about 90 days, and leave the parents at this time. Squirrels in this collection were most numerous in October, including young-of-the-year. Mortality. The barred and great gray owls (Seton, 1953; Corace et al., 2007), gray wolf (Voight et al., 1976), bobcat (Pollack, 1951), and domestic cats (Toner, 1956) prey on G. sabrinus. Large fish may occasionally eat one that falls into the water (Seton, 1953; see Baker, 1983). Other owls and nocturnal furbearers doubtless take them, and many predators conceivably eat the young. A forest fire might kill these squirrels. Rarely while gliding some are impaled by sharp objects. Fleas (Manville, 1949), lice, mites, chiggers, tapeworms and roundworms may parasitize these squirrels. Inasmuch as the northern and southern flying squirrels occasionally are sympatric in northern and central Wisconsin, and the kinds of parasites are so similar, cross-infectivity is a possible danger to one or the other. J. N. Pauli, S. Dubay, E. Anderson, and S. J. Taft (personal communication) appraised the incidence of the parasite Strongyloides robustus in fecal samples of live-trapped Glaucomys volans and G. sabrinus in an area of sympatry (Schmeekle Reserve, Univ. WisconTAXONOMIC ACCOUNTS / ORDER RODENTIA

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sin—Stevens Point) hoping to document a detrimental effect on sabrinus that might limit its distribution southward. However, about half of G. volans was infected, whereas only 11 percent of sabrinus was. This work may be published more detail and fails to support the hypothesis that one squirrel replaces the other with the help of the parasite [as both squirrels have been sympatric in this area for many years]. Home Range and Density. Hardly anything is known of the northern flying squirrel’s wanderings, in Wisconsin. In far off North Carolina and Pennsylvania, where home range was determined by radio tracking, it was estimated to vary from 8 to 32 acres (3.2 / 12.8 ha). Manville (1944) estimated that G. sabrinus numbered 1/14 acres (1 / 5.6 ha) on two study areas in the Huron Mountains. Remarks. The flying squirrels are nocturnal and glide or voloplane dextrously from high to lower elevations as a means of locomotion, besides climbing with agility in trees. The northern flying squirrel spends more time on the ground than the southern. Additional Natural History. Wells-Gosling and Heany (1984) reviewed the natural history of Glaucomys sabrinus. Geographic Variation. None was detected in Wisconsin. The northern flying squirrels in Wisconsin have been referred to the race G. s. macrotis, an eastern race with type from New York, by Hartley Jackson (1961). A. H. Howell (1918) drew a boundary line between macrotis and the nominate subspecies in northwest Wisconsin. There is no mention ever discussed by Jackson as to where to draw that boundary. The racial boundary probably lies northwest of Wisconsin. Jackson found no differences between northwestern specimens and specimens from Door County. The nominate race is probably larger and darker in color of pelage than seen in Wisconsin flying squirrels. Skull measurements for Wisconsin specimens are listed in Table Rod-7. Specimens examined. Total, 24. Bayfield, Clark, Door, Douglas, Forest, Lang-

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THE WILD MAMMALS OF WISCONSIN

lade, Lincoln, Oconto, Oneida, Portage, Rusk counties. Michigan Records. Schoolcraft Co., 4 mi. N Manistique. Houghton Co. (Crider, 1979, unpublished study on the Sturgeon River). Marquette Co. (Haveman and Robinson, 1976). Menominee Co.: (Burt, 1946). See also Stormer and Sloan (1976). Other records. See Jackson, 1961; McCabe 1981: Forest Co., Sea Lion Lake; Florence Co. Lost Lake. Sight records, questionable, of squirrels reported to me from Juneau and Monroe counties.

Glaucomys volans (Linnaeus) Southern Flying Squirrel Glaucomys volans volans (Linnaeus) 1758. [Mus] volans Linnaeus. Syst. naturae, 10th ed. 1: 63. Type locality fixed by Elliot (Field Columb. Mus. Zool. Ser., 2: 109: 1901) in Virginia. 1915. [Glaucomys] volans: A. H. Howell. Proc. Biol. Soc. Washington, 28: 109.

The name Glaucomys means gray mouse; volans means to fly. Description. This small, pug-nosed, arboreal squirrel is characterized by a lateral fold of skin covered with fur, with which the squirrel glides as one means of locomotion. Closely resembling G. sabrinus (above) especially in cranial proportions, G. volans is significantly smaller. The hind foot is less than 33 mm, the skull less than 37 mm; and the maxillary toothrow is less than 7 mm. The skull is not only smaller, but the orbit relatively large owing to a slender jugal bone developed less at the anterior end. There are eight ventrally arranged mammae (in four pairs). There are 48 chromosomes, according to Hoffmeister (1989). The baculum is slender, and slightly twisted. Although G. volans is smaller than G. sabrinus the baculum is longer (12.1-12.8 mm) (Burt 1960).

In Wisconsin, there are apart from size differences, significant differences in color. See the account above of G. sabrinus, particularly the comments on the color of the venter and tail. Dorsally, the color in G. volans is paler, more of a cinnamon pecan or pecan color, whereas in G. sabrinus the color is richer chestnut or ochraceous and in worn pelages darker, walnut brown. Ventrally, the color of G. sabrinus is splotched grayish because the bases of the hairs are plumbeous gray. In G. volans, the color is more whitish, seldom is there an intermixture of gray, and especially on the throat the hairs are pure white. The underside of the tail tends more to pinkish cinnamon, or ochraceous, less washed with blackish. It is a lovely color scheme. Molt seems to begin in late summer in the old adults, but there is little known about molting in G. volans, especially in Wisconsin. The southern flying squirrel is one of the smallest of the Wisconsin sciurids. The external meaurements are approximately 220-253, 80-120, 28-33, which are smaller than in G. sabrinus (260-360, 115-170, 34-45). Measurements are in Table Rod-7. Dental Formula. As in G. sabrinus, the formula is as follows: I 1/1, C 0/0, P 2/1, M 3/3 = 22. The anteriormost premolar is a tiny spicule.



Glaucomys volans in a bird box Roger Tory Peterson. Courtesy of Virginia Peterson, Houghton Mifflin. 

Geographic Range. At present the southern flying squirrel is to be expected in any county in Wisconsin, and is eventually spreading its geographic range throughout much of the Upper Peninsula of Michigan. Previously known only in southern Wisconsin, the species has been dispersing northward possibly at least in part at the expense of G. sabrinus. See Map. So far the species is restricted from the Door Peninsula and some heavily forested northern counties, and from all the islands investigated in Lake Michigan and Lake Superior. The record from Burt (1948) in southeastern Upper Michigan suggests that formerly there was a connection between that population and the Wisconsin southern flying squirrels southward and southwestward, or possibly with populations spreading along Lake Michigan from Lower Michigan ranging southwestward to the Wisconsin border. Status. The southern flying squirrel seems abundant locally, especially in the southern counties and near human habitations. The species is spreading its range northward, invading the forest counties previously occupied only by G. sabrinus. No protection is deemed necessary, inasmuch as the common Southern flying squirrel may be increasing at the expense of the northern. The species seems harmless to man, although sometimes in winter raising our concerns by sleeping and gathering in people’s attics. There is some predation on birds in nestboxes. There is no eco-



Skull of Glaucomys volans. 

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215

nomic value for fur or food, but aesthetically flying squirrels are beautiful and fascinating. Habitats. A denizen of the hardwood forests, especially those in southern Wisconsin (hickory, maple, oak) the geographic range differs dramatically from G. sabrinus in being largely congruent with the prairies. This is true not only in southern and western Wisconsin, but also in the prairies along Lake Michigan extending into Michigan. This pattern seems odd because the squirrel is arboreal. Some adverse ecological factors that hypothetically may be involved with the prai-



Maps showing geographic distribution of Glaucomys volans in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

rie distribution are the prior occupation of G. sabrinus in the northern woodlands in the absence of G. volans; pine-maple instead of oak-maple forests in the north; recent invasions of prairie country in Wisconsin following the riparian woods and deciduous forest edges; and dispersal following planted trees of farms extending the range northward primarily in the cultivated prairie regions farm by farm. Mapping the geographic range from a collection of specimens documents the squirrel primarily from populated areas (non-continuous forest). In Illinois, second growth hardwoods are preferred, although not required for this squirrel. Brush seems essential (Hoffmeister, 1989; and others). Both flying squirrels occur together in white pine-tamarack-maple woodlands and marshes just north of Stevens Point. On the Schmeekle Nature Preserve; G. volans is more abundant, and is distributed throughout most of Portage County as well. In winter, the southern flying squirrel may be somewhat communal and is often found in groups in bird houses, tree cavities, and attics. I have heard of numbers approaching 30 for attics in Portage County and one house somewhere in northern Wisconsin. Jackson (1961) reported as many as 22. During torpor the body temperature drops for short periods (Muul, 1968), but the squirrels are not



Shredded wood nest of Glaucomys volans. 

actually hibernating and are often active on cold nights. Nests for bringing forth young, in birdhouses, woodpecker cavities, and natural tree cavities, even in the dreys of other squirrels (doubtless abandoned), are usually made of leaves and shredded materials, such as the inner bark of trees. One nest (see Fig.) found in a bird house and preserved in the UW-SP collection is about 7 inches in diameter rolled up around the edge and depressed in the middle, comprised of shredded inner bark (May 7). Two others (in May and on Aug 7) were made of the same material. A fourth found 26 May in a bird house abandoned by chickadees incorporated their moss nest with shredded bark added from above, which eventually became well mixed at the bottom of the nest by the nestlings. A fifth was in a box appropriated from chickadees (broken eggs), for on July 25, a mother squirrel was found in the mossy nest with five newborn young. Young squirrels are often moved to new nests (Madden, 1974), but in every case I observed, the mother is attentive when her nest is disturbed, never over 2-3 m away, and she always returned to it. Foods. As in most arboreal squirrels, the chief food is acorns, supplemented with hickory nuts, maple seeds, fungi, berries, invertebrates, and bird eggs and young. When food is scarce buds and bark are eaten (Seton, 1953; Dolan and Carter, 1977; Banfield, 1974; Muul, 1968). The squirrels harvest and cache in systematic procedures (Avenoso, 1968; Muul, 1968). In late May, 1999, when my wife and I discovered the mother flying squirrel with young in a birdhouse formerly occupied by chickadees, and their mosses were incorporated with the squirrels’ shredded wood and bark, the question arose, was the house appropriated or abandoned by the birds? That same week there was predation in a nearby birdhouse occupied by tree swallows (Tachycineta bicolor) where six newly hatched young had been fed by the parents. Inside the box, one dead parent was found partially eaten. TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Six young lanquished and died, and there was no sign of the other parent. The opening of the box was so small that only a southern flying squirrel or a small weasel could enter, and the latter is not only rare in this area but would have a difficult time ascending the 1"- wide metal pole. There were telltale gnawings at the entrance. The putrid carcasses may have been the reason no squirrels nested in this box. The next day, the nestbox housing another family of black-capped chickadees (Parus atricapillus) was also emptied, with some crushed eggshells present. The evidence suggests the southern flying squirrels destroyed two and perhaps three nesting families of birds. About three weeks later the box contained a mother squirrel with five newborn young (see Homes above). In June, 2000, another birdhouse was taken over from tree swallows with young, and the mother swallow had been killed. Reproduction. Hardly any information is available from Wisconsin, and my specimens do not add much. My son John, his children, my wife and I observed a litter of three alert furred-out young as early as May 7, 2005. Two lactating females were collected on 14 May and 19 June. Young, or at least small specimens thought to be young-of-the-year, were taken in October and November. In Oconto County a small squirrel was taken 19 July, and in Juneau County as early as 1 March. A nest was also observed 19 March 1991. Courtship begins early, earlier than in G. sabrinus, in February. There seem to be second litters. One lived 7 years (Crandall, 1964). On my property in central Wisconsin, I have seen naked young in nests in September and others haired out in October (capable of “flight”) and likewise in late April, early May, and late July. One observed litter of two males, naked and blind, were subsequently reared by the mother in a bird house (with gnawed entrance). The two were seen first 16 April, the lengths about 50 mm. The mother did not move the young and usually watched us from a nearby oak sapling as we checked

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the young. By May 1, the young were haired out, eyes open, and the tiny ribbon like tails were twined about one’s finger. They watched us closely as we handled them. This handling was repeated until 6 May. On May 7 the family had departed, after some three weeks under observation. Ants had invaded the nest. Another nest found by my wife and me, on 25 May 1999, contained two young nearly as large as the mother, and they bobbed their heads up through the shredded bark to watch us, then ducked in again, while the mother leaped to the fence, about a meter away, watching us with her huge eyes, with the sun glowing through her eight translucent, elongated, pink teats. Another nest found 25 July, contained slightly furred young, with naked patagia resembling bats, about 55 mm in length, and with tail long and nearly round. One day later the tail seemed slightly flattened. The naked patagia extended forward of the forelimbs onto the neck and posteriorly a few mm behind the thighs, approaching the tail. The eyes were shut. One young squeaked noisily when handled. The mother returned to the nest in less than five minutes after we left. Since one nestbox was appropriated from chickadees, it was interesting that on 15 August, three black-capped chickadees (Parus atricapillis) approached the mother partially hiding in a jack pine crevice, about 2 m away, coming within 1 m, 1.5 m, and 2 m distance all making the distraction display call, without the usual display (see Long, 1982a). In a couple minutes they left, and the female returned to her nest. The young were probably capable of gliding away from the box.. Mortality. Nocturnal predators such as great horned owls (Errington et al., 1940), house cats (Jackson, 1961; Hoffmeister, 1989) and other owls and carnivores (Dolan and Carter, 1977) prey upon G. volans. They are occasionally injured by impaling themselves on sharp objects while gliding. Snakes may enter tree hollows and eat them. Timber cutting and forest fires locally eradicate these squirrels.



Table Rod-7. Some external and cranial measuremenrs of Wisconsin Glaucomys. 

Counties

Sex

TL

Tail

Hind Foot

Ear

Gr. L

Zygo br

Max. t-r

Glaucomys sabrinus Clark Forest Forest Portage Portage Portage Oneida Oneida Oneida

F M F M M F M M F

298 265 273 294 260 276 250 240 ?217

112 113 112 118 111 112 120 100 ?50

32 32 34 36 39 36 35 40 35

21 23 23 21 21 22 18 20 22

37.2 36.3 38.0 37.2 – 38.0 35.7 35.6 37.6

21.7 20.6 22.4 22.1 – 22.2 21.2 – –

7.04 6.7 6.6 6.9 6.8 6.84 – 6.74 6.85

Glaucomys volans Portage Portage

6M 7F

212±26 204±40

92±4 95.1±6.7

28.8±2.6 30.3±3.8

16.0±3 16.0±2.3

33.8±1.7 35.0±0.8

20.4±0.7 20.6±0.9

5.86±0.2 6.18±0.23

Ectoparasites include six species of fleas, mites, and lice (Day and Benton, 1980; Dolan and Carter, 1977; Scharf and Stewart, 1980). Endoparasites include protozoa, acanthocephalan worms, roundworms, and tapeworms (Dolan and Carter, 1977). Likely a rare incidence, rabies and a type of malaria have been reported (Venters, 1962; Dasgupta and Chattergee, 1967). See account of G. sabrinus. Home Range and Density. There is little information on populations of G. volans in Wisconsin, and for nearby states the information is confusing and speculative, both for movements and density. For one thing, the young of second litters join the adults and earlier young in autumn to make the densities higher. In both species of flying squirrels, judging by my museum specimens, the numbers of young in September, October, and November were nearly triple the usual numbers per month. On my 1.2 acres of woods overlooking McDill Pond in Portage County, there have been occasional visits by one or two adult squirrels to feed on acorns. Numerous females have brought forth litters in the bird houses, but never more than two females at once, and the numbers of young were mentioned under Reproduction. Remarks. Nocturnal gliders, the small G. volans can glide rapidly for distances up to

about 100 feet, and usually they run around the trunk of a tree immediately after alighting on it. This may allow the squirrel to escape a following owl. There is a communal torpor of irregular periods, but no true hibernation, and these squirrels are active year round. Additional Natural History. Dolan and Carter (1977) is an excellent source for G. volans. Hatt (1931) noted habits. Geographic Variation. None was observed in G. volans. Specimens examined. Total, 42. Adams Co, Chippewa, Dane, Douglas, Dunn, Juneau, Monroe, Oconto, Polk, Portage, Vilas, Waupaca, Wood counties.



Wisconsin Beaver. By C. A. Long. 

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Family CASTORIDAE Gray Genus Castor Linnaeus Beavers Holarctic, large, aquatic rodents having dorsoventrally flattened, nearly naked and scaly tails, webbed hind feet and a sulcate zygomatic plate anterior to the zygoma. The primary food, at least in winter, is the inner bark (cambium and phloem layers) of trees, which are felled and gnawed, and often incorporated piece by piece, summer and fall, in dams and lodges. The family is ancient, arising in the Oligocene Epoch. The aquatic genus Castor is known only through the Pleistocene and Recent.

Castor canadensis Kuhl North American Beaver “The Beaver of Canada... surpasses the Badger in size, and is the most industrious animal in fabricating its dwelling... Large glandular pouches, which terminate on the prepuce, secrete a pommade of very pungent odour, which is employed in Medicine... Castoreum.” — G. Cuvier, in Regne Animal, 1846. 1820. Castor canadensis Kuhl. Beitr. z. Zool. und vergleich. Anat.1: 64. Type locality from Hudson Bay, Canada. 1912. Castor subauratus Taylor. Univ. California Publ. Zool., Vol. 10, p. 167. Type from Grayson, Stanislaus Co., California. 1913. Castor caecator Bangs. Bull. Mus. Comp. Zool., Vol. 54, p. 513. Type from Bay of St. George, Newfoundland.

The name Castor comes from Greek kastor, meaning beaver, and canadensis refers to the country where the type was collected. Beaver is an old English word “beofor” meaning brown. There is no rule about the plural of beaver, interchanged more or less. Mention of particular animals usually is

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THE WILD MAMMALS OF WISCONSIN

“beavers” and as a kind of animal “beaver”, e.g., “three beavers were on the bank”, or “some beaver burrow in stream banks.” Description. Beavers are large (dog-sized) rodents with brown or tawny brown color. There is a dorsoventrally flattened tail, oval in dorsal outline, usually scaly and mostly hairless, but furred proximally. It varies in size from 20 cm (8 inches) X 10 cm (4 inches) to 32.5 (13 inches) X 20 cm. The tail functions for fat storage for winter, communication by slapping the water surface, heat exchange, balancing while walking on land, and, of course, as a rudder in swimming. The hind feet are large with webs between the toes (see fig.), having the first and especially the second digit with a divided claw (for grooming the fur). All feet are pentadactyl, the forefeet dextrous and used to handle foods, carry young beavers (“kits”), and transport building materials to construct the dams and lodges. The underfur is gray and dense, the brownish guard hairs coarse and long. The skull is large with formidable rootless incisors (chestnut on the anterior surfaces) and rootless hypsodont cheek teeth (having transverse lophs). A diastema is present in each tooth-row. In dorsal aspect, the paired nasals, taken together, are oval, widest in the middle. There is a small sagittal crest in older specimens, and the zygomata are stout and very deep at the postorbital process. The zygomatic plate where the masseter muscle attaches is deeply sulcate. The dentary shows a deep angular process projecting ventrally, and below the lower incisor the dentary may project ventrally somewhat as in sabre-tooth cats. The basioccipital is dished, and the zygomatic arches flare away from the skull. The cheek teeth were described in Regne Animal as “grinders, four in number above and below, with flat crowns. They appear as if formed of a doubled bony fillet, exhibiting one deep indentation on their internal borders, and three on the outer edge above, and the reverse below” (G. Cuvier, 1846, 1863). There is a club-shaped baculum in males tapering to a blunt or rounded distal tip, and there

are four pectoral mammae in females. There are 40 chromosomes (Lavrov and Orlov, 1973). Other aquatic adaptations include a nictitating membrane used when swimming, and the closure of nostrils and ear canals under water. By bradycardia and other physiological adaptations beaver can submerge up to 15 minutes. Anal scent and castorium (one of the earliest scents used in perfumes) glands are present in both sexes. These latter glands near the groin empty with the urine to scent-mark piles of vegetation and mud (castors) or other sites. The anal glands are paired. The lips close behind the incisors, probably an aquatic adaptation. Probably also adaptive to aquatic life is the cloaca, a pouch that accommodates the scent glands, the urogenital openings and rectum (this cloaca is not to be confused with any reptilian cloaca). It is difficult to identify the sexes because of the cloaca. Other characters are listed by Jenkins and Busher (1979) and Hill (in Chapman and Feldhamer, 1982).



Skull of Castor canadensis. 



Webbed hind foot of beaver. 

The color is brown, but the tone may be chestnut, reddish brown, tawny or drab walnut, even black. The tail is nearly black but it pales with age to gray. The color is nearly the same overall, brighter above, and usually lacking splotches of other colors. However, Lovallo and Suzuki (1993) reported a family-related phenotype of splotched white feet in two beavers. The underfur is dense, and there is a molt beginning in summer. Prime fur develops for winter. The total length varies from about 1,000 to 1,200 mm (39-46.6 in), tail length 258440, tail width, 90-200, hind foot length, 156-205, and ear length, 23-29. Cranial measurements range up to 146 mm greatest length, 108 zygomatic breadth. The weights range usually to about 30 to 40 pounds but occasionally in Wisconsin exceed 100 pounds (= 45 kg). Schorger (1953) reported large Wisconsin beavers weighing 39.4, 36.5, and 35.6 kg. Some measurements are listed in Table Rod-8. Recently Ucker (1994) submitted a photo of a carefully weighed beaver from the Peshtigo River, near Crivitz, weighing 120 pounds (54.5 kg), a new weight record. Walter Klukas was the trapper. The total length is nearly as long as the height of the man shown with the beaver. Dental Formula. I 1/1, C 0/0, P 1/1, M 3/3 = 20. Geographic Distribution. Before 1800, beavers occurred throughout what is now Wisconsin and the Upper Peninsula of Michigan. Native Americans used them for food (Baker, 1983). The Caucasion Americans almost eradicated them in this region. Since 1901, the wildlife conservation agencies in Wisconsin and surrounding states protected surviving beavers. The species made a remarkable recovery, not only in Upper Michigan and Wisconsin, but throughout most of the United States. The beaver is uncommon in the prairie counties of western Wisconsin, and does not seem to be a permanent resident on most islands in Lake Superior or Lake Michigan. It is TAXONOMIC ACCOUNTS / ORDER RODENTIA

221

abundant on Outer Island, in the Apostles. Beavers may visit islands from time to time, and may take up residence on some of the larger ones. From the 1970’s until the present the beaver has been regaining lost territory, except in urban areas, and may occur in all the western, southwestern, central, and northern counties. It lives near people, if left alone, so long as food and water are available. Status. Beavers build lodges and dams, modifying local environments in Wisconsin marshes, swamps, and stream valleys. Of-



Maps of geographic distribution for Castor c. canadensis and C. c. michiganensis (north of west-east line above Green Bay) in Wisconsin and North America. 

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ten this distinctive habitat is called a “beaver dam community.” It often affects the distribution of many organisms, including waterfowl, trout and many wetland species (Knudsen, 1962). Certain fishes, amphibians, birds, mammals, and some invertebrates and plants lived in the beaver dam communities, which changed from impoundment to meadow as beavers felled aspens, willows, and other deciduous trees before moving on to new habitat, leaving the dams to decay and drain. Beaver also lodge in lakes and dig bank burrows in river banks. During the 1700’s-1800’s in European and American markets, beaver fur became stylish, especially beaver hats, and the demand for North American beaver pelts led to the early exploration and exploitation of the American West, as well as many of our states, provinces, and territories eastward. By 1900, along with land-use by the invading Caucasians, the demand for fur and overtrapping led to the extirpation of beavers in many vast regions of America. Beavers were thinned out in southern Wisconsin, but beavers were present in Wisconsin and upper Michigan. The beaver inhabited the Northwoods for centuries. Not only are beaver bones most abundant of mammalian remains at most archaeological sites, a burial with copper implements contained a beaver robe



Lodge of beaver. Where dikes and waterways are damaged, culverts dammed up and roads flooded, thousands of nuisance beaver are transported to wilder places (if they are unoccupied by other beaver, and budget and time allow). C. Long, The World Book. 

(Greenman, 1966). Legal protection began in 1901, and was practiced more stringently by 1905 (Jackson, 1961). About 1919, a study on the status of beaver made by Hartley Jackson and George Wagner determined that beaver were an asset to Wisconsin, despite some flooding of some roads and agricultural land and cutting of desirable trees. Transplanting began in the early 1920’s. Some beaver from Wisconsin and Upper Michigan were sent to Pennsylvania and New York. In 1936, beaver occurred in 50 counties, and by 1954 in 56 counties. Trapping was permitted since 1936 in some counties. Today the declining value in fur results in higher numbers of living beavers, and the activities of people cause many of them to consider beavers as nuisances. Over 3,000 trappers annually trap an estimated 60,545 beaver, mostly in Conibear traps (Dhuey, 1995). Benefits to humankind (Hill, 1987) include water storage (much more important in the arid West, but of some Wisconsin use in flood control), erosion control of local gully formation, the fur (depending on the styles and demand), and even as a food (for some people). Beaver are prey for wolves and some other predators, and the beaver dam community benefits many other animals and plants. Aesthetic appreciation for nature observers is important. Formerly castorium was used in perfume making and as a medicine. Jackson (1961) discussed the formation by beavers of humus soils and many low prairies (or at least meadows) in Wisconsin. Over long periods of time, silt accumulates in impoundments of small valleys in the highland, established successively by beavers working their way toward the valley floor. These beaver meadows in sum have helped produce much rich farm land in valleys of wooded regions across the entire northern half of North America (Ruedemann and Schonmaker, 1938). On the negative side, beavers cut down ornamental trees, nibble on shrubs, burrow TAXONOMIC ACCOUNTS / ORDER RODENTIA

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in dikes, and cave off stream banks. They occasionally follow a row of corn in a field eating the shoots. Their extensive flooding of low cultivated areas by dams that are sometimes huge and complex may cause considerable damage. Long famous for its fur and its importance in the exploration of America, scientific and popular literature are replete with articles on the beaver. Only the white-tailed deer may rival the beaver in literary volume. In Canada, the beaver is a famous symbol found in some endearing movies, books and articles, and on coins and seals. Habitats. Being aquatic, the beaver inhabits various bodies of water: lakes, rivers, ponds, streams, dammed up brooks and ditches, marshes, swamps, and impoundments. Dams constructed are often large and complex, and impound water over wide areas (a few ponds exceed 10 acres). They are deep enough to provide security to the beaver colony. Thus, wild areas may be altered by the activities of beavers, usually changing the land to a wetland. Food trees are necessary in beaver habitat. When used up the beavers depart, leading to another ecological change, from the beaver dam community to that of a sedge or grassy meadow. Not only do many animals and plants associate with the beaver in its manufactured environments, but several kinds even have used their lodges for their homes, including water shrews, wolves, and bobcats (see accounts of those species). From August to September the beaver colony works on lodge building and damming of water. The sound of flowing water reportedly is a stimulus to build dams. The behavior is seen in juveniles, but they may not do construction the first year. Downed trees, branches, mud, stones, and other available material, even corn stalks (Robert Henderson, personal correspondence) are used. The beaver digs, pushes and shovels (lifts) mud and other materials into place, building a dome-shaped roof over a large

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room with its floor several inches above the water level. The beavers do not work in groups, each tends to work alone (Novak, 1987). At least two entrances are below water. Beavers also dig burrows into riverbanks, occasionally combining one kind of dwelling with the other. To swim freely from one pond to another, beavers occasionally dig canals (not over 6 m in my experience), some in Upper Michigan were mentioned by Agassiz (1913). Jackson (1961) gave the length of some as 300 feet. (I suggest that water flow helped ditch such a long trench.) In northern lakes where the water is surrounded by granitic and steep banks, where no burrow could be dug, and the water is too deep for a lodge sited out in the water, the lodge may be constructed on a steep rock ledge at the water’s edge, and not be separated from the shore. If there are no stream banks, a lodge must be constructed. Water may be impounded by one or more dams. These may be small or taller than a man’s height. Alexander Agassiz, the famous naturalist son of the great naturalist Louis Agassiz, studied beaver for two years in Upper Michigan. He was also busy developing a copper mine. He wrote to another scholar on beavers, Lewis H. Morgan, about his “repeated opportunities” in Upper Michigan, to study beavers collecting chips, observing habits, dams, and even canals [italics mine]. He estimated some colonies were over 900 years old, that some ponds exceeded 40 acres in area, that the associated beaver meadows were up to two mile-sections in area, and that beavers were active all winter, often wandering far from the lodge, with many tracks going “in all directions”. In Ashland County a dam was constructed 12 feet high and 40 rods long (Barber 1919). Here a giant lodge was built 16 feet high. The lodge may be as low as one meter but is usually up to two meters high. As many as eight to ten beavers may occupy a large lodge. As it is built, over a single room, the

surrounding mud is excavated, so that the water near the lodge deepens as the lodge grows higher. The temperature inside on cold winter nights is warmer than outside, and the lodge temperature is not so extreme as the air temperature outside. The kits are born inside the lodge or bank burrow. Foods. The primary and essential foods are inner bark of aspens (Johnson, 1983), paper birch or willow. Aspen is much preferred. Other species of trees (at least tree parts) are eaten. Various water plants, buds, and other terrestrial plants are eaten on occasion, such as water lilies (personal observation) and even poison ivy, sedges, tubers and roots, corn, and acorns. Conifers regularly are eaten, especially young white pines in winter and spring (personal observation, over 20 years). Novak (1987) mentions that conifers are not essential, but beavers may girdle small pines and eat the pitch. Coprophagy has been observed. Small trees are easily cut down and hauled to the water, where the beaver eats in relative security. Trees about 3-5 inches in diameter are often hung up by other trees, and much of their food is unused (Johnson, 1983). Trees larger than that usually fall to the ground and may be used. Trees leaning over the water will fall into it when cut, and are readily used for food or construction. Beavers may wander 100 feet or so from water looking for food. Food may be transported through canals. In autumn and winter, the Wisconsin beavers cache branches under water for food in the season when the pond or stream is locked in ice. Reproduction. Beavers tend to be monogamous, and to maintain offspring of several ages in the lodge. Usually a single female in the lodge conceives. She breeds generally in January or February, into March. Beaver often copulate in water. Castors (i.e., scent mounds) are made at this time for territorial reasons. The gestation lasts about 107 days, with birth occurring in May or June, and sometimes later. The mean litter size is

between 3 and 4, occasionally with more kits, sometimes 6, reportedly 10. (With only four mammae probably about 6 is the maximum number of young). Longley and Moyle (1963) found litter size in Wisconsin as 5.3 embryos. The more food available the higher is the litter size. Population density affects fecundity (Payne, 1984, Boyce 1974). Large mothers tend to have large litters. The young beavers are born completely furred out, in various shades of color much as in the adults, with eyes partly open and teeth partially erupted. They require care but seem rather precocial compared to most rodents. They leave the lodge with the mother in 14 days, and males may bring in leaves for them to eat in 14 days. The infants range in size from 340-630 g, with members of small litters tending to weigh more. Some southern populations tend to have small litters, but there seems to be no evidence proving a relation to temperature or latitude (Payne, 1975; Osborn, 1949; Hill, 1987). Beaver often live up to 13 years, occasionally to 24 (Nowak, 1991). The young are weaned at about 8 weeks of age, some, perhaps, by three months, but they feed readily on plant material after about one month, and some, reportedly, as early as 4 days. The young are suckled about nine times a day. The young fondle the mammae as they drink during 5-10 minute periods. Young-of- the- year (i.e., kits) apparently do not breed their first winter, but some yearlings may be active the second winter. Breeding is listed as 21 months for both sexes (Novak, 1987). Young are usually not driven out of the lodge in autumn, but many depart before then to establish lodges of their own. Mortality. Humans cause much mortality from trapping, 13-80 percent (Novak, 1987), and transplant some beaver to new habitats (Boyce, 1974; Payne, 1975). Floods and hunger kill some beavers naturally. About the only natural predators are wolves, which prey often on beavers in summer, especially when deer are scarce (Hill, 1987). Jackson TAXONOMIC ACCOUNTS / ORDER RODENTIA

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(1961) lists the great-horned owl and goshawk as predators. Occasional predators are river otters, even mink, coyotes, red foxes, bears, bobcats, and lynx. Black bears preyed on beavers in the Apostle Islands (Smith et al. 1994). (See account of the black bear). Tularemia is a disease of beaver, which also affects humans; it is apparently water borne and also transmitted by ectoparasites and direct contact. It is caused by the bacterium Francisella tularensis (= Bacterium tularense). Tularemia sometimes causes important epidemics in beavers. A variety of protozoans and worms are internal parasites (Jackson, 1961). External parasites are scarce but include ticks (Ixodes, and peculiar beetles (Platypsyllus and Leptinillus). Occasionally, beavers are killed by falling trees they have cut themselves. Jackson (1961) mentions one such casualty, and I have a photograph of another. Beavers often fight, especially males, and seem to attack the rump and tail. Although wounds are common, mortality may not be much affected. Home Range and Density. Movements have been as extensive as 238 km, but averaged only 7.4 km in 472 translocated beavers that were recaptured (Knudsen and Hale, 1965). Dispersal reduces density of beaver colonies, but the main controlling factor is trapping (Boyce, 1974). As lowered food quality may deplete beaver densities, depleted food caches may cause starvation and wandering in winter and spring, leading to greater mortality by predation. Density is usually expressed as colonies per given area, say 10 km2 square, or a given length of stream (i.e., 1 per 10 km of stream). Colonies are located in the fall by the presence of food caches. Data published outside Wisconsin vary from about 0.3 colonies per 10 km2, sometimes three times that in good habitat, and along streams about the same. Remarks. A relative of Castor canadensis that formerly lived in Wisconsin was the giant beaver Casteroides, mentioned in the account of prehistoric mammals earlier. The sex ratio varies from place to place, from about even numbers, from 95 males to

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100 females, or to a greater proportion of females (Gunson, 1970; Payne 1975; Woodward 1977). Apparently there is a preponderance of males in subadults but more females in adults. Briefly, this curious and historically important mammal, with such a complex family life and clan territory, may be said to be crepuscular and nocturnal. It is often seen in Wisconsin in the daytime. The young live with the adults, and sometimes other young are also there, during the winter months. Movements (Hill, 1987) include colony activities, wandering by some adults not really understood but ascribed to those beaver that lost mates, and regular dispersal of 2-3 year olds from a colony to form new colonies elsewhere. A colony is a group of beaver consisting of the adult pair, yearlings, and kits. They use and defend a common food source and a common water supply, and often a common system of dams. The territory is marked at least in some areas by scent mounds called “castors”, small piles of mud, vegetation, and secretions of castorium from the castorium glands and probably scent of the anal glands. This scent is known to cause disturbance in a colony when emitted by foreign beavers. Warning sounds are made by slapping the tail on the water surface, but vocalizations are few, consisting of low whines, whistles, or whimpers. The young learn to slap their tails in the water at about 2-3 weeks of age. The beaver tries to run from enemies like any other terrestrial mammal, but it can walk erect using the tail as a counterbalance, carrying mud and other objects in the forepaws. It swims both at the surface and below it, usually kicking alternately with a hind foot. It is active all year, but often confines its activities in winter to the lodge, and to the food cache. On warm nights it may be out on the banks. They seldom attack and bite, but they often hiss and threaten. The behavior observed within a lodge is highly interesting. Prior to birth of young the entire family was observed to clean the lodge

and spread leaves and herbs over the floor. In this endeavor the family works as a group. The family observed the birth, and the large male and another beaver formed a triangle with the mother to enclose and warm the kits. The mother ate the placentas. Juveniles and adults lick the rather precocial neonates, and carry them away from water. Juveniles clean the lodge, bringing in new vegetation. The mortality of kits is surprisingly low in most studies, even of young-of-the-year. Few beaver live to ages as old as 10 years, but occasionally to 20 (see Novak 1987). Additional Natural History. Jenkins and Busher (1979) reviewed biology for the beaver. A classic study was made by Warren (1927) on the beaver in Yellowstone Park. Geographic variation. Two geographic races occur in Wisconsin. They differ significantly in color, but not much by size or proportion. From my observations, and by use of the literature, I conclude that the dark Michigan beaver is of medium size, whereas the beavers in most of Wisconsin are medium to large. Probably southern beavers average larger, but possibly have lived longer. That being the case, one can assume the physiological and reproductive traits of the two kinds hardly differ. There is little evidence that either kind has been altered racially by transplantation and introductions in the last 70 years. Certainly some of the beavers in Wisconsin are large, even huge, but the size differences are really not distinctive in the variable family groups. Dr. Al Gardner, recalling his field work in Seney National Wildlife Sanctuary in Upper Michigan, told Robert Fisher and me, “they [beavers] are not only dark, but to me they looked black.” Across the Upper Peninsula, and ranging into northern Wisconsin (where all the beavers examined by Jackson, 1961, had been trapped) the beavers are dark in color, a soft almost black tone varying from otter brown to a charcoal black (not glossy black, as in skunks or bears). Convinced of the validity of the northern geographic race,

at least on the character of coloration, it became necessary as a taxonomist to draw some kind of boundary between this race and beavers observed in central Wisconsin. Including some beavers mounted long ago, I have seen only tawny brown beavers in central Wisconsin. They occasionally attain great size (exceeding 100 pounds). I cannot follow Jackson (1961) in assigning all Wisconsin beavers to the Michigan race. That judgement gives credence to Hoffmeister’s (1989) provisional classification, and removes an HoffmeisterJackson example from along the Illinois state boundary (Table Plan-1). Most specimens examined, unfortunately, are skulls (the pelts were sold), and the few skins do not allow any definition of subspecies boundary. Not many skins are available in the Smithsonian collection either, and that is probably why Jackson (1961) ascribed the entire state of Wisconsin to the dark race. That Upper Peninsula beavers are dark brown, nearly black, is well known in the fur business. It is a common saying there that Iron County beavers are the same as Upper Peninsula beavers. John Olson, a DNR fur specialist at Park Falls, believes some there are nearly black, some “light”, and most brown. Mr. Russ Kilker, the Gruenwald Fur Company, believes most beavers in Wisconsin are brown, but become lighter or “reddish” nearing the Illinois boundary. Kelly Thiel, a beaver trapper for U. S. Department of Agriculture (damage control), traps beavers that are nuisances and those often found along trout streams. He has reportedly handled 1,200 beavers yearly since 1988, in northern Wisconsin. He has a rational perception of beaver variation based on much experience. Although he has seen no beavers from Iron County, he observed beavers black, almost black, and occasionally dark brown in Bayfield, Douglas, and Vilas counties. Some are blackish in Ashland County. Between Rhinelander and Merrill he believes a line could be drawn, south of which in Lincoln and Marathon counties beavers TAXONOMIC ACCOUNTS / ORDER RODENTIA

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are usually brown, and lighter (golden brown), occasionally an odd color of reddish-brown. Based on his impression, which agrees with that of Olson, and is consistent with my few observations, I draw a provisional boundary across the state, noting that individual variation and family variation broaden the perceived zone of intergradation between the races. The line separates a distinctive northern dark race from southern and western beaver populations. Marked variation evident in four pelts in the Madison collection show these traits: Portage Co. Dark reddish brown; Dane Co. pale golden tan; Grant Co. in molt (March) with worn golden brown pelage and dark reddish brown new fur; and Green Co. very dark, almost blackish, but head golden brown.

Castor canadensis canadensis Kuhl See above synonymy of the nominate race given for the species. Type Hudson Bay. Description. The critical trait for identification is color, nearly always bright chestnutgolden brown, and seldom a dark walnut brown. See geographic variation above. Remark. In some other states, introduced beavers of subspecies differing from the one extirpated there has led to some hesitation in using geographic races at all for beavers Specimens examined. Total, 31. Buffalo, Dane, Grant, Green, Lincoln, Marathon, Portage, Price, Taylor, Waupaca, Wood counties.

Castor canadensis michiganensis V. Bailey 1913. Castor canadensis michiganesis V. Bailey. Proc. biol. Soc. Washington, 26: 192. Type from Tahquamenaw River, 5 mi. above falls, Luce Co., Upper Michigan.

Geographic Distribution. Northern Wisconsin and Upper Michigan. See Map.

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THE WILD MAMMALS OF WISCONSIN

Description. A dark colored, mediumsized beaver closely resembling the nominate race. See Geographic Variation above. Specimens examined. Total, Wisconsin 5. Bayfield, Vilas counties. Other records. Bayfield Co.:Taylor’s Creek (Jackson 1961). Douglas Co.: Lovallo and Suzuki (1993). Upper Michigan (USNM specimens). Luce, Alger, Chippewa counties.



Table Rod-8. External measurements and some weights for beavers in Upper Michigan and northern Wisconsin.  Total tail hind foot lengths

US 170561 Taquahmenaw River 58 lbs US 247288 Chicogan Lake 1015 US 243780 Michigamme 1055 US 243788 Michigamme 1030 US 247287 Salmon Trout Cr. 960 US 236596 Grandview, WI 1050 US 236595 Grandview, WI 965 US 247318 Gresham Lake 1025

300 350 290 300 350 365 390

175 175 175 170 180 170 170

— 32, 40 lbs 35, 30 lbs —, 30 lbs 35, — 30, 35 lbs —, 40 lbs



Table Rod-9. Fur harvest data of aquatic furbearers in Wisconsin. After Dhuey, 1994, 1995, 2000, and personal communication. 

Species

Year

Harvest

Average Price

$ Pelt Value

Muskrat Muskrat Muskrat Muskrat Muskrat Mink Mink Mink Mink Mink Beaver Beaver Beaver Beaver Beaver Otter Otter Otter Otter Otter

1999-2000 1996-1997 1995-1996 1994-1995 1993-1994 1999-2000 1996-1997 1995-1996 1994-1995 1993-1994 1999-2000 1996-1997 1995-1996 1994-1995 1993-1994 1999-2000 1996-1997 1995-1996 1994-1995 1993-1994

286,212 160,747 108,046 325,396 304,741 16,921 21,333 8,545 32,500 22,086 — 30,184 25,012 86,574* 61,339 2,794 1,233 1,233 4,615 3,412

— 4.15 2.35 2.21 1.86 — 20.50 12.08 11.84 16.15 — 20.44 16.46 14.45 15.23 — 44.66 44.47 48.76 57.30

— $667,100 $253,908 $719,125 $566,818 — $437,326 $103,223 $384,800 $356,689 — $616,960 $411,697 $1,250,994 $934,193 — $62,462 $54,837 $225,027 $195,507

*6,201 beaver taken in supplementary harvest.

Family GEOMYIDAE Gill Pocket Gophers

Genus Geomys Rafinesque Eastern Pocket Gophers

The fossorial pocket gophers are sciuromorph rodents that have, with their closest relatives, the Heteromyidae, evolved paired furlined cheek pouches with openings outside the mouth. This adaptation for hoarding food in the burrow was different from internal cheek pouches of deer mice, chipmunks, ground squirrels, hamsters and other rodents in having the external openings. By some macroevolutionary and probably embryological change (Long 1977) the new kind of cheek pouch was immediately adaptive, because the seeds transported and cached in the burrow were dry whereas the internal cheek pouch brings all the seeds into contact with saliva in the mouth. This loss of saliva to the seeds is a water loss, and in deserts small mammals cannot afford to lose water. The change in foraging from stuffing the seeds in the mouth instead into the nearby fur-lined pouch (in fact, into the extended and inverted corner of the mouth) permitted the “wrong side out” pockets to persist and improve in form. No alternative microevolutionary scenario makes any sense.

The North American rodents Geomys are represented in Wisconsin by one species.



Figure showing cheek pouches, large forefeet and grooved incisors of Plains Pocket Gopher. 

Geomys bursarius (Shaw) Plains Pocket Gopher Geomys bursarius bursarius (Shaw) 1800. Mus bursarius Shaw. Trans. Linnaean Soc. London, 5:227. Type from Upper Mississippi Valley. 1817. Diplostoma fusca and D. alba Rafinesque. Amer. Monthly Mag., 2:44. Types from Missouri River Region. 1825. Ascomys canadensis Lichtenstein. Abb. k. Akad. Wiss. Berlin, for 1822: 20. Type from “Canada”. 1829. Geomys bursarius: Richardson. Fauna Bor.Amer., 1:203. 1957. Geomys bursarius wisconsinensis Jackson. Proc. Biol. Soc. Washington, 70: 33, type from Lone Rock, Wisconsin.

The name Geomys means mouse of the earth. The specific part of the binomen bursarius means pocketed. Thus, the two characteristics, fossorial behavior and external cheek pouches are described by this Latinized name. The common name is plains pocket gopher, or merely pocket gopher or gopher. The word “gopher” is used in the vernacular way, for in much of the Midwest it is a term used for the 13-lined ground squirrel Sper-



Figure of Geomys bursarius. C. Hart Merriam. 

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mophilus tridecemlineatus. In central Wisconsin, where no pocket gophers are to be found, the people use the word gopher for ground squirrels, without knowledge of the common name 13-lined ground squirrel or the former name “13-lined spermophile.” Description. In Geomys, unlike other pocket gophers, there are two grooves on the anterior surface of each upper incisor. The median groove is deeper. A shallower but distinct outer groove is parallel to the median one. In some of my specimens there are three grooves, although the third is faint. Hoffmeister (1989) found the same pattern in some specimens in Illinois. There is a diastema on each side of the dentition, but there are upper premolars present, each comprised of two joined columns. The molars are almost lophodont with transverse enamel loopings. The rostrum is long, with the nasals extending posteriorly to the level of the zygomata. The zygomata are wider in their transverse breadth anteriorly than behind, and the tympanic and lambdoid expansions broaden the posterior part of the skull (the occiput is nearly straight across). Thus, the skull is rather angular, and the profile in lateral view is of a quite flattened braincase. Most of these specializations are fossorial adaptations, general ones of all digging mammals, or unique ones seen only in pocket gophers (such as the slender tail which is a tactile organ as the gopher backs up in its burrow).



Skull of Geomys bursarius. 

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The dorsal color is drab reddish brown to light chestnut brown. There may be white on the tip of the tail. There are at least two molts annually, and two may be taking place simultaneously. The pelage is short, smooth and has a brassy sheen in sunshine. There is white-spotting on nose and throat on numerous specimens (including seven from this collection) from the Brule region (Jackson, 1961). The penis bone is a simple rod with tip expanded slightly laterally. The length is 1012 mm (Burt, 1960). There are eight mammae. In mothers the pubic symphysis is enlarged (Hisaw, 1925). The chromosomes number 2N = 72, with a fundamental number of 72 with 68 acrocentrics (Hart 1978). The males are 10-15 percent larger than females, and reportedly at least 20-25 percent heavier. See tables Rod-10-11. Dental Formula. 1/1, C 0/0. P 1/1, M 3/3 = 20. Geographic Range. The range of the pocket gopher is confined to the western third of Wisconsin and unknown on the Upper Peninsula. If a straight line were drawn from Ashland in Bayfield County to Lone Rock and Gotham in southern Richland County, only the record from southern Price County would lie east of that line. There are no records south of the Wisconsin River in southwestern Wisconsin, for the River apparently has halted the southward dispersion. Far to the southward extending across central Illinois into Indiana, is a large, black pocket gopher G. b. illinoensis. Apparently the Mississippi River prevented the species from invading Illinois along much of its length, but in southwest Illinois the crossing was made and the bridgehead expanded across the state with marked differentiations occurring in color and larger size. The pocket gophers of western Wisconsin likewise seem to have crossed the Mississippi (and St. Croix) rivers somehow. They occupied the sandy loam valleys extending their range eastward along the river courses, but were barred from Grant and Iowa coun-

ties, and other counties in the southwest region, by the wide Wisconsin River. At Gotham the habitat changes abruptly to jack pine savanna and across the river southward are deciduous and sycamore bottomlands which have not been invaded by Geomys, nor by red squirrels for that matter (see account of Tamiasciurus). The Wisconsin pocket gophers are tan-brown and, although some are as large as muskrats, the Wisconsin races are smaller in size than the Illinois race. The dissimilarity suggests two separate invasions, different evolutionary histories, and long separation of the two eastern stocks.



Maps showing geographic distribution of Geomys bursarius in Wisconsin and North America. 

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231

Status. The Wisconsin pocket gopher is not common but in no peril of eradication. Something of a nuisance, its mounds and burrows tear up agricultural fields, and there is some eating of truck crops and shocked grain. It tends to dwell in friable soils on well-drained ridges or embankments, and in grassy or weedy open areas. There the soils are sandy, with little clay or “gumbo” soil present. Pocket gophers prefer soils where tubers and succulent leafy plants such as clover and dandelions are available for food. Living in extensive burrow systems, it is no surprise they avoid flood plains and marshy areas where the burrows are subject to flooding. Heavy farming of the land, or the presence of a badger can eradicate a population of pocket gophers. Rather peripheral to the farmer’s sphere of activity, they are not often harmed. Gopher traps are available in hardware stores for local problems. Jackson (1961) states that pocket gophers inhabit “waste ground,” and therefore cannot be called a menace (i.e., a pest). In such situations it often does more good than harm by turning over the soil and mixing vegetable matter with it. Habitat. The plains pocket gopher dwells in friable well-drained soils, usually sandy loam, in open meadows, pastures, roadsides, railroad rights-of-way, old fields, cultivated fields especially clover and alfalfa, cutover or burned over land, and occasionally in lawns or gardens. In Wisconsin, the gophers are usually in fairly close proximity to streams, because that is where the sandy soils that the gophers use as immigration routes into the hilly countryside. In sandy areas, the proximity of water also permits the establishment of forbs and legumes, dandelions, clover, alfalfa, and other succulent plants on which gophers feed. Gophers are not found in the wet or clay soils, or in dense root masses in wetlands or along streams, and according to Jackson (1961) they cannot swim. Their external cheek pouches are not only adaptive in hoarding foods into their tunnels, but are an aridenvironment adaptation restricting the loss of

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saliva on thousands or hundreds of hoarded seeds and stem parts (Long, 1977). The pocket gopher lives most of its life, actively in winter or summer, either night or day, in elaborated tunnel systems. The burrow is not especially deep, except in winter when the frost enters the ground. The tunnels may descend below three feet depth. Even then, the pocket gopher tunnels to the surface, burrows under the snow, and leaves evident above ground, in warmer seasons, the cores of plug materials for meters in length. They were deposited inside tunnels but were eventually exposed by the thawing ice and snow. The tunnel system usually follows a main linear tunnel, with numerous extensions to either side that are usually plugged with light soils. The behavior to plug a side tunnel opening leads to their capture by gopher traps. These are set into the main tunnels beneath a large and usually sandy mound, with sand thrown more toward one side. Opening the tunnel by use of a shovel soon results in a response by the gopher to plug the opening and push the trap out. The gopher sets off the trap when it contacts the trigger. In some side tunnels, which may be plugged with soil, the food cache is stored. The gopher may extend its head outside a tunnel to the surface to tear off leaves and stems, which are cut into suitable lengths to transport into the food tunnels. Roots and tubers are eaten below ground. The main burrow over a long time period may have required removal of some seventy cubic feet of earth. Obviously burrow systems vary with terrain, time of excavation, soil composition, and the individual whims of the fossorial homebuilder (Smith 1948, Downhower and Hall 1966). McLaughlin (1951) reported a system 125 feet long with at least 57 mounds. No studies have been made on tunnel systems in Wisconsin. Apparently the usual times that tunnels are shared are when young are with the mother or two gophers are mating. The nest is reportedly a mass of cut stems, observed at a depth of 2 feet, measur-

ing about 7 X 3 1/2 X 6 1/2 inches. The cut stems are about one and a half inches in length, comprised of common grasses in the area (Smith 1948). McLaughlin (1951) also described a nest and a food cache. Foods. Hardly anything is known of food habits of Geomys in Wisconsin. They doubtless eat alfalfa, clover, and dandelions. Other foods of similar nature are probably eaten, and grasses and tree roots may be eaten. Bones were gnawed in the nest of a gopher studied by Smith (1948). Reproduction. According to Jackson (1961), who cites no studies, mating takes place in the spring, sometimes by late March, but usually during April or May. The male may tunnel into a female’s burrow or travel over the surface of the ground in search of a female. A specimen from nearby Allamakee Co. Iowa was pregnant (3 embryos) on 8 April 1969. The embryos were 11 mm in crownrump length. Females taken in April, east of



Burrow system of Geomys bursarius. Courtesy E. Raymond Hall. 

the Mississippi and St. Croix rivers in Wisconsin, contained no embryos. On 7 May a female (UW-SP 7699) was lactating and contained 5 embryos 8-12 m in crown rump length. Another (UW-SP 7700) contained 2 embryos 10 mm long. A third female contained no embryos. There are usually three or four neonates (young) in a litter, but the number varies from 2-6. The newborn young are blind and naked, about two inches in length and weighing six or seven grams. The skin is pinkish. There are two furrows or grooves (Anlagen) for the future external pockets at the corner of the mouth. Each furrow is about 5 mm in length. The young may emit squeaks after birth. They are nursed at least 10 days, perhaps until two-thirds grown, at which time they may poke their heads from holes to forage. Eventually they tunnel away to make new burrows on their own. There is a single litter each year, and young-of-the-year cannot breed. McLauglin (1951) found male and female cohabiting a burrow system on February 9, in Illinois, of a different subspecies of Geomys bursarius. Bailey (1929) reported embryos between April 12 and May 22 in Minnesota. Hoffmeister (1989) gives the gestation as about one month, but a Kansan gopher in captivity gave birth 51 days after capture (Sudman et al. 1986). In Wisconsin, judging from my few records, it lasts about a month (late April to late May). Mortality. Little is known about the enemies of Geomys in Wisconsin. A young or above-ground gopher may be caught by any carnivore, hawk, or owl. Owls frequently regurgitate remains of Geomys in owl pellets. Jackson (1961) suggests that weasels catch them, and in nearby Minnesota the pocket gopher is the primary prey of the badger (Lampe 1976). It is odd Jackson made no mention of the badger as a predator, probably due to a paucity of evidence. Bull snakes prey on them (Hisaw and Gloyd 1926). Farmers often rid their fields of pocket gophers.

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233

Home Range and Density. The home range is approximately the same size as the burrow system, because the pocket gopher seldom leaves the system for ordinary wanderings. Extensions of burrows result in dispersal movements. Jackson (1961) thought those might be “many miles” but this distance seems doubtful. There may be male-female occupancy in a burrow in February or March. A solitary mother will occupy a burrow with her young until they are weaned. Usually males outnumber females and likely wander more. In the UW-SP collection the percent of females is 60 percent (N=25). There is little information available about home range and density in Geomys in Wisconsin. In mild winters mounds are pushed up near Osseo until Christmas. Fresh mounds are evident in late March and early May. I have seen one core of dirt left by melting snow, about 3 m in length at 3 mi. W Mondovi, April 20, 1996, and another April 24, 1997, at the same place. One core was 2 m in length. Remarks. The excavation-function was described long ago by Merriam (1895) as picking and excavating with the incisors while the forefeet both dig and shove loose dirt under the body. The hind feet also move the dirt posteriorly, and if the gopher does not succeed in moving beyond the accumulation it turns in the burrow and with both wrists joined together under the chin, pushes the dirt back with the palms of the hands while moving with the hind feet. Thus, the dirt is discharged from the nearest opening forming a “little hillock”. This hillock is called a gopher mound. Gopher mounds usually reveal the presence of the secretive gophers. The mounds are not usually circular, as are mole hills, because the gopher throws the dirt to one side. They are more likely comprised of sand. It is odd that this species is so asocial, when some other burrowing rodents find such benefit in communal living. Geographic Variation. Even though isolated in the western counties of Wisconsin by

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THE WILD MAMMALS OF WISCONSIN

the Mississippi and St. Croix rivers, the pocket gophers in Wisconsin have not differentiated much. They do not approach the distinctness of the isolated population in central Illinois, which is predominantly black. Pocket gophers are highly variable from place to place, leading to the naming of many populations as geographic races. In Wisconsin specimens I have examined there is marked variation with age and males are larger than females. The northernmost gophers do not cross the Brule River northward, but range along its southeastern shore. They have extended their range across the divide of the Mississippi and Superior drainage in Bayfield County, but not by much. According to Jackson (1957) these northern gophers differ from southern populations in several cranial characters: The premaxillary bones reportedly are wider and less concave posteriorly, almost flattened or even slightly convex. The rostrum is reportedly wider also, and the edge of the premaxillary bone is nearly straight anterior to the zygomatic arch. A narrower distance separates the posterior ends of the nasals and the



Table Rod-10 Rod-10. External measurements of Geomys bursarius. All specimens judged adult, but some are old adults. Males supposedly exceed females in size,, but some observed females were exceptionally large. Measurements from Jackson (1961) are marked with an asterisk. The northern specimens precede the southern.  Locality

Sex&N Total L.

NW Wisconsin* Douglas Co. &Drummond

M2

Hind Foot Wts g

F1 F1 F1

85 (75-95) 68, 85 73.3 (66-80) 70 (70-70) 87.5 (80-92) 67 69 90

35.5 310 (34-37) (270-350) 31, 34 — 33.8 — (33-35) — 33 — (32-34) — 37.8 — (34-37) — 36 — 31 183 35 —

F1 F2

255 260,260

66 63,73

31 31,31

F2 M4 F2

3 W Strum Bell Center Cochrane Osseo 1/2 N Chippewa Falls 2 S Galesville 1 E Gotham

Tail

292 (260-325) 230, 279 260 (249-269) 259 (249-270) 313 (277-375) 242 224 283

M4

— 260.6 g



Table Rod-11 Rod-11. Some cranial measurements of Geomys bursarius, males from Gordon, Strum, Bell Center, and Lone Rock, and females from Chippewa Falls and Lone Rock.  Greatest L

Zygomatic br

Cranial br

Max. t-r

52.3 52.7 53.0 52.6, 54.1* 54.4 42.5-44.5*

31.2 33.5 33.3 31.2, 31.7 33.8 25.4-26.2

26.5 28.8 29.4 — — 29.6 —

8.9 8.8 9.7 — — 8.9 —

*Occasionally the nasals extend farther than the incisors, and occasionally the supraoccipital extends farther posteriorly than the condyles.

adjacent frontal bones are likewise narrower. This distance is only about one-half as broad as it is long, instead of noticeably wider. However, the characters did not work in my specimens (Table Rod-11), and if they did the difference would be trivial. Jackson mentioned the color is not “appreciably” different, but my southern specimens are slightly paler. No significant geographic variation was observed. Specimens examined, Total 42. Bayfield, Buffalo, Burnett, Chippewa, Crawford, Douglas, Dunn, Eau Claire, Jackson, Monroe, Richland, Trempealeau counties.

Subfamily Murinae Gray “What[ever] moss is to the reindeer, what[ever] grass is to the buffalo, the Mouse millions of the North are to all the northern carnivores, from Bear to Blarina. When we shall have fully worked out the life history of each of these species, I believe we shall learn that the whole of that vast, beautiful, important, and specialized production that we call “carnivora,” rests on a broad simple basis of Muridae, that in turn rests on the grass, that rests on the earth. We shall for each of these flesh-eaters write, “It sometimes eats this and sometimes eats that, but by far the greatest bulk of its food is Mice.” — Ernest Thompson Seton, Food of the Marten, in “Furbearers”

Myomorph rodents (i.e., those with a small infraorbital canal traversed by a slip of the masseter muscle) are those lacking premolars, and as defined here consist of mice and rats (species of Peromyscus, Reithrodontomys, Microtus, and allies all formerly called cricetids), as well as the introduced house mouse Mus musculus and Norway rat Rattus norvegicus, which have sparsely haired, scaly tails. and hard palates extending posteriorly behind the last molars.

Family MURIDAE Gray Rats and Mice, Some are Quite Nice These are myomorph rodents (see remarks under Rodentia) and include herein the common North American mice known previously as Cricetidae (the genus Cricetus is not native to North America). Some workers use Sigmodontidae, which excludes Mus and Rattus. Our Peromyscus and Microtus are the commonest mammals in Wisconsin, and are wide-spread.



Skulls of Peromyscus leucopus, P. maniculatus (dorsal and ventral views, note pinched rostrum), Reithrodontomys megalotis (dorsal and ventral, note grooved incisors), and the vole Pitymys ochrogaster (3 views a, b, c, note zig-zag molars). After E. R. Hall and D. Hoffmeister.  TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Genus Reithrodontomys Giglioli Harvest Mice

Reithrodontomys megalotis (Baird) Western Harvest Mouse

Often found in sheaves, haystacks, and round bales of hay associated with harvest, the mice give credence to their name by bending grass stems over to cut off the heads of seeds. These tiny mice are delicate in form, brownish above, clean white below, bright-eyed, and their upper incisors are each grooved on the anterior face for the length of the crown and much of the root (see figure above left). The skull is rounded and smooth, and has slender zygomata. The incisive foramina are large and hardly separated by a thin septum. The outer wall of the infraorbital canal is a broad, delicate sheet of bone. The tail is thinly haired, distinctly bicolored, and usually elongate in relation to the total length. The feet are exceptionally small, smaller even than those of Peromyscus maniculatus bairdii (see Measurements). Of 18 species recognized in North America, there is but one in Wisconsin, and it is confined to the southern half of the state.

1858. Reithrodon megalotis Baird. Mammals, in Reports Expl. Surv... 8(l): 451. Type locality between Janos, Chihuahua and San Luis Springs, New Mexico 1893. Reithrodontomys megalotis: J.A. Allen. Bull. Amer. Mus. Nat. Hist., 5:79.

Reithrodontomys megalotis dychei J. A. Allen 1895. Reithrodontomys dychei J.A. Allen. Bull. Amer. Mus. Nat. Hist., 7:120. Type from Lawrence, Douglas Co., Kansas. 1914. Reithrodontomys megalotis dychei: A.H. Howell. N. Amer. Fauna, 36:30. 1944. Reithrodontomys megalotis pectoralis Hanson. Field Mus. Publs., 564, Zool. Ser., 29205. Type from Westpoint, Columbia Co., Wisconsin. Hoffmeister and Warnock, Trans. Illinois Acad. Sci., 47-162, 1955, and other taxonomists have regarded the Wisconsin mice as inseparable from R. m. dychei. The difference, a pectoral spot, is inconstant in Wisconsin harvest mice.



Harvest mouse. By F.B.S. in Anthony. 

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THE WILD MAMMALS OF WISCONSIN

Reithrodontomys translates as “groovedtooth mouse”, which is meaningful. The specific part of the binomen megalotis means big ear, which is less meaningful (although the ear is prominent). The subspecific part of the trinomen, dychei, honors L. R. Dyche, the founder of the University of Kansas Museum of Natural History, and the collector of the holotype. Description. See account of the genus above. This small, clean-appearing mouse, with grooved incisors and tiny feet, can be identified by several cranial characters and small body. The skull, described above in characters for the genus, has total length less than 22 mm. The baculum is a minute rod. The penis and baculum resemble those larger structures in Peromyscus. There are six mammae (one

pair pectoral, two pairs inguinal). Unlike 48 chromosomes seen in all Peromyscus, the harvest mouse has 2N=42 (Shellhammer 1967; Webster and Jones 1982). Extra chromosomes (up to four tiny chromosomes) are reported in some specimens. Grooved incisors resemble those in the pocket mouse Perognathus (found in Minnesota, but unknown in Wisconsin) and jumping mice (Zapodidae). For comparison with long-tailed Zapus, Mus musculus, which resembles a dirty-colored harvest mouse, and Peromyscus maniculatus bairdii, see accounts of those species. Some external and available cranial measurements of Wisconsin specimens are as follows: Portage Co.: Female 127-61-16-15; greatest length 19.9, zygomatic br. 10.3, int. br. 3.25, maxillary tooth row 3.7, length nasals 7.5, wt. —; F 141.5-63-19-14; —; M 139-6812-13-10.0 g. Waupaca Co.: 127-50-18-14; —; Trempealeau Co.: 120.5 (112-130), 57(5060), 15.8 (15-17), 12(12-12), N = 4; 19.6, 10.1, 3.2, 3.4, 7.1 (N = 1). Monroe Co.: Fort McCoy 129-60-16-11, 9.0g.; 21.1, 10.6, 3.3, 3.2, 7.0. A pregnant female from Sauk Prairie measured 120-51-14-X and weighed 10.3 g. Dental Formula= I 1/1, C 0/0, P 0/0, M 3/3=16. Geographic Distribution. The harvest mouse occurs in grazed fields, stubble, alfal-



Family and nest of harvest mice. Lloyd Sanford. 

fa, sandy prairies, and grassy edges of marshes (hayfields) so far only in the southern half of the state. See Map. Status. The harvest mouse is rare in Wisconsin. Nowhere is it common. The prairies on which it lived in southern and southwestern Wisconsin were themselves greatly disturbed, although some mice have established themselves in what remains and in old fields, pastures, and savannas. This mouse may have invaded the state from the west, from Minnesota, or the south or southwest, Illinois or Iowa, about the turn of the 19th century. The mouse had extended its range deeply into central Wisconsin (Long 1970), but no specimens have been taken recently (in spite of some diligent efforts) for over 20 years. The threat of land use destroying prairies and even old field habitats is great in southern Wisconsin (e.g., Dane County). This beautiful and harmless mouse should be monitored by state authorities, and transplants of harvest mice into some of the newly established prairies would be interesting. Birkenholz (1967) suggests the harvest mouse occupies seral, open habitats. That might explain why some populations decline over time. Land use might also explain the declines, as might unknown causes such as long-term climate change. Conservationists will study these problems. Habitat. The harvest mouse is found in grassy areas with or without brush or trees present, seral or disturbed fields, grazed pastures, marsh lands, hayfields, and sandy ridges. Grasses may include brome, bluegrass, bluestem, foxtail, Panicum, as well as various forbs such as goldenrod and smartweed (Birkenholz 1967; Hanson, 1945). Birkenholz found that they preferred habitats with grasses about 18 inches in height, whereas Hoffmeister (in an overgrown orchard with blackberries) found them in vegetation as high as five feet. Webster and Jones (1982) mention grassy and weedy habitats such as pastures, meadows, fence-rows, fallow fields, and borders of fields. In southern Wisconsin, SvTAXONOMIC ACCOUNTS / ORDER RODENTIA

237

endsen (1970) caught this mouse in fair abundance in 1967-1968, in old field habitats, especially in autumn, in Phlelum, Agropyron, and Panicum grasses, the legumes Lespedeza and Trifolium, the forbes Aster, Asclepias, Aplopappas and Solidago (comprising 72 percent of the total plant species). The grasses Andropogon, Elumus and Setarus, the blackberry Eubatus, and the composites Tragopogon and Taraxacum made up 23 per cent of the plants. A few woody plants and grasses made the remainder.



Maps showing geographic distribution of Reithrodontomys megalotis in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

The nests are balls of grass stems and leaves set in a field above ground. They are occasionally placed in an abandoned bird’s nest. They may be sited two feet above the ground. The nests are often lined with milkweed or thistle down (Schwartz and Schwartz 1981). Small openings are found at the base of the nest. Harvest mice also live in burrows (Birkenholz 1967), especially in winter. Foods. No food studies have been made on Wisconsin harvest mice. Elsewhere the diet is primarily seeds, many of which are cached for winter. Much herbaceous vegetation is also consumed. Insects (as much as 22% Lepidopteran larvae) are eaten (Whitaker and Mumford 1972). Hall (1959) quotes Henry Fitch stating that this mouse consumed seeds of foxtail, switchgrass, Indian grass, false redtop grass, brome, and side-oats grama. Harvest mice climb weeds, legumes and grasses day and night to harvest seeds. Reproduction. A single pregnant female collected in the Sauk Prairie contained 4 embryos. The mice breed only during the growing season. Some data are summarized in Webster and Jones (1982) and Jackson (1961). The gestation period is 23-24 days, possibly longer. Newborn are naked, blind, and helpless. They weigh only about one gram each. The eyes open in less than two weeks. Fur grows out in about one week. The young are weaned in about 24 days. The litter size is about four (2-6 or 7). In Indiana, Mumford and Whitaker (1982) found 30 pregnant females to average 3.8 embryos (2-6). There are rarely as many as 8 or 9 embryos (Long, 1962). Adult size is reached in five weeks. The young mice may mate by six weeks. A second litter may be produced 24 days after the first, according to E. R. Hall. The life span may be 18 months. Mortality. Nothing is known about predation on harvest mice in Wisconsin. I saw what I think was a harvest mouse “treed” on a tall weed by a large snake. Prairie carnivores and raptors take them when possible.

Remains are often identified in owl pellets. Parasites include Trypanosoma, a cestode, acanthocephalan, nematodes, fleas, chiggers, mites and lice (Webster and Jones, 1982). Some parasites are mentioned by Jackson (1961). Mumford and Whitaker (1985) list parasites from Indiana. Home Range and Density. Schwartz and Schwartz (1981) and Kaye (1961) report the home range of two females as one half to a little larger than one and one half acres. In Illinois over a three year span, Birkenholz (1967) found the density to fluctuate normally from 4-12 per acre. In central and western Wisconsin, seldom can even two be taken at the same locality. Svendsen (1970) found the population density much higher in southern Wisconsin, in 1967-1968, reported as 18 mice per acre (45 / ha) during the fall seasons. He reports this amounts to 0.046 animals per trap night. In spring only 0.012 animals per trap night were taken. There were four times as many mice in autumn. Hansen (1945) found a maximum density of 2.4 per acre in foxtail-smartweed cover. Remarks. Information on this little mouse is so scarce, I failed to find a petite vignette from some famous naturalist to charm the reader, to make it known this is no common mouse. The old masters had so little information they could seldom identify any species of harvest mouse. Some failed to note the grooved upper incisors, and one said they never ate insects. Cory (1912) had no specimens from either Wisconsin or Illinois. Emmet T. Hooper was an authority on murid mice, including Central American harvest mice, but said nothing for my purpose. Hall (1955) mentioned that they could travel many yards through the high stems of grasses without coming to the ground, and described the feet as efficient for seizing and grasping grass stems because the toes of the forefeet flex against the palms making a grasping hand. I offer my own vignette: The harvest mice seem to be mice of the grasslands, indeed living in unity and harmony with the community of TAXONOMIC ACCOUNTS / ORDER RODENTIA

239

grasses themselves. Regarding this ecologically integrated relationship of grass and harvest mouse, the poet Walt Whitman might have agreed, perhaps, in his Leaves of Grass, singing the grassland was “as the father to bosom held his son.” Harvest mice travel through the tops of the tall grasses, make nests of the fine grass stems, line the nests with the softest fibers available from milkweeds and thistles, eat grass seeds, prey on grasshoppers, and make or use runways extending through grass. One pet I had for a while made its nest from a ball of cotton fibers, and like my captive Peromyscus spent much time grooming itself and playing about in the cage. The pelage is a pale brownish gray, the belly and feet purest white (dusky at the hair bases). The dainty form seemed especially charming, but there was no petting this pet. When opening the door to clean the cage one had to be careful. The sprightly mite leaped suddenly onto an arm, out the door, up the curtains, and then a “merry chase” ensued. Hall and Kelson (1959) mentioned that of the harvest mice the plains species is the most widespread. Likewise, this Wisconsin subspecies has extended its range deep into this state. The nominate race R. m. megalotis occupied the vast range of basins and high prairies west of the Rockies, and the Great Plains race R. m. dychei occupied the vast prairies east of the mountains from Alberta in Canada to eastern Arkansas. Crossing the Mississippi River only with one salient, the race may have invaded northwest Illinois and did find southwest Wisconsin. Eventually it found its way into central Wisconsin. Additional Natural History. Webster and Jones (1982) studied the plains harvest mouse. Geographic Variation. One race dispersed northward or northeastward into Wisconsin. Specimens examined. Total 37. Columbia Co.: Portage 1. Dane Co.: York Twsp. 1. Various localities 20 UW. Monroe Co.: Fort McCoy, Tl7N, R3W, Sec. 20, 1. Fort McCoy 2 UW. Portage Co.: 5 1/2 mi. N Stevens Point 1. 5-5 1/2 mi. E Stevens Point 2. Jor-

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THE WILD MAMMALS OF WISCONSIN

dan Swamp 2. T21N, R8E, Sect. 4, 1. Sauk Co.: Sauk Prairie 1 UW Wild. Ecol. Trempealeau Co.: 2 mi. N Gaylesville 4. Waupaca Co.: 1 mi. N Iola 1.

Genus Peromyscus Gloger The American deer mice, formerly called “white-footed mice” (a name now used for Peromyscus leucopus) inhabit most of North America, often with two or more co-existing (i.e., sympatric) species. They are usually abundant and are among the most abundant of mammals in the ecosystems of America. Such abundance is true in Wisconsin, where three interacting Peromyscus are found. Owing to their manifold life-activities and high population densities, even their great biomass as forage for predators, they are indeed biologically important. William Henry Burt (1948), famous mammalogist, mentioned that the forest deer mouse was exceptionally beautiful. That mouse occurs in northern Wisconsin, and the other two Wisconsin deer mice are also beautiful. The three mice resemble one another and are not easily identified without reference to several cryptic but diagnostic characters (see below). This genus in the past was known as Hesperomys Waterhouse or Sitomys Fitzinger. The type species for Peromyscus is Peromyscus arboreus, a synonym of Peromyscus leucopus noveboracensis. The deer mice resemble murine rodents such as Mus by having long tails (as long as a third or even more than half of the total length). There are minute scaly annulations of the tail clothed over with fur. The ears are mostly naked and prominent. Internal cheek pouches are more or less developed. The relatively large eyes, thin-walled cranium lacking conspicuous ridges, small infraorbital canal, roughly triangular and bounded by a bony plate of the anterior part of the zygoma, all characterize these mice. The dentary is elongate with short coronoid process, molars are low crowned and

tuberculate (when unworn), and the upper incisors are smooth.

Key to the species of Peromyscus 1

1’

2

2’

Hind foot usually 17-18 mm, to 19 mm, tail short, usually less than 64 mm in length, upper parts brown darkening dorsally nearly to black ....................... ....... Peromyscus maniculatus bairdii Hindfoot usually 20-22 mm in length, tail longer than 64 mm, dorsal fur brown without much mid-dorsal dark tone, but wuth reddish chestnut brown or dusky fawn (yellowish tan-brown) ................ 2 Ears 17 mm or longer, tail about 80-83 mm in length and pencillate (tufted), whiskers long (the upper vibrissae may be extended behind the ear pinna, the lower vibrissae are nearly as long and white), dorsal fur yellowish in tone or brown ..... ... Peromyscus maniculatus maniculatus Ears less than 16 mm in length, tail less than 77 mm, never pencillate, and seldom well-haired, whiskers “normal” length (some upper vibrissae may be extended even behind the ear pinna, but lower vibrissae obscure), dorsal fur often slightly reddish or brown ..................... ........................ Peromyscus leucopus

Blair (l940) provided a classic of population dynamics for Peromyscus in southern Michigan. King (1968) reviewed biology for this genus. Wolff (1989) described social behavior in Peromyscus in Kirkland and Layne’s (1989) review of biology. Wolff (1985) discussed ecology in Peromyscus. The prairie deer mouse P. m. bairdii is small, with a short, thick tail. The fur is dark mid-dorsally; the short tail (< 65mm) and hind foot (usually 17-18 mm) easily identifies this mouse in the field. Young mice, in gray pelage, have a less attenuate tail than seen in the other long-tailed species. In the laboratory the short skulls identify adult P. m. bairdii.

The two long-tailed Peromyscus resemble one another, and often are in similar habitats. The juveniles are not identifiable in such situations, although they soon attain adult characters (e.g., large ears in P. maniculatus). See the Key above for general traits. Long and Long (1993) used bivariate and discriminant analysis of adult mice in northern and central Wisconsin, and on islands in Lake Superior and Lake Michigan. They found geographic variation in P. maniculatus suggesting that the name gracilis in Wisconsin seems inappropriate (see account beyond of P. maniculatus). In their analyses the best characters were ear length, length of rostrum, and length of tail. Other characters varied from place to place, but incisive foramina length, cranial depth and breadth (previously given high weight by taxonomists) were least reliable.

Peromyscus leucopus (Rafinesque) 1818. Musculops leucopus Rafinesque. Amer. Monthly Mag. 3: 446. Type from Kentucky Pine Barrens. 1895. Peromyscus leucopus: Thomas. Ann. Mag. Nat. Hist., series 6, 15: 192.

Although Hoffmeister (1989) uses the name of the nominate race P. l. leucopus for Illinois white-footed mice, I follow Osgood (1909) and numerous other workers in recognition of the race P. 1. noveboracensis (Fischer). Hoffmeister’s rationale was that some Illinois variants were similar in size to Kentucky mice. Cory (1912) ascribed southern Illinois mice to the nominate race, but most Illinois mice to the race noveboracensis. Cory mentioned larger size, longer fur, and paler upper parts in noveboracensis. The venters are purer white. He also referred the Wisconsin white-footed mice to this race. Osgood (1909) had analyzed over 300 mice from the nominate race, restricted by him to the “Lower Austral” life zone (p. 118), and over 2,000 of noveboracensis. Hoffmeister’s TAXONOMIC ACCOUNTS / ORDER RODENTIA

241

observation that mice in northern Illinois are not readily distinguishable from the southern mice may be understood by Osgood’s comment that ideally the holotype of leucopus would have been selected from Louisiana and for noveboracensis from the middle of New England. Intergradation confuses comparisons from Kentucky, Illinois [and Wisconsin]. Osgood describes well the geographic variation in white-footed mice from this WisconsinMichigan region, and the northern Illinois mice are noveboracensis.

Peromyscus leucopus noveboracensis (Fischer) White-footed Mouse 1829. [Mus sylvaticus] noveboracensis Fischer. Synopsis mammalium. P. 318. Type from New York. 1830. Cricetus myoides Gapper. Zool. J. 5: 204. Type from a place between NewYork and Lake Simcoe, Ontario. 1842. Mus michiganensis Audubon and Bachman. J. Acad. Nat. Sci. Philadelphia. P. 304. Type from Erie Co.: Ohio. This name was applied to Peromyscus maniculatus bairdii, and probably to Mus musculus. See their synonymies. 1901. Peromyscus leucopus minnesotae Mearns. Proc. Biol. Soc. Washington, 14: 154. Type from Fort Snelling, Hennepin Co., Minnesota.

The name Peromyscus means “little mouse” but the meaning of the prefix Pero is unknown. The name leucopus is Greek for “white foot.” The name noveboracensis is Latinized, intended to mean “from New York,” based by Fischer on Pennant’s New York “variety.” Eboracum refers to the English area now called York, Eboracum to the Romans, later changed to the name of a Viking warrior Jorvik, which eventually became Yorwik, and finally York. The word novum means new and “ensis” means from this place. Description. A long-tailed deer mouse having medium length whiskers and ear pinnae (not short as in the voles and bog lem-

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THE WILD MAMMALS OF WISCONSIN

mings, nor as long as in long-tailed P. maniculatus) and a dusky brown or chestnut brown dorsum with pure whitish underparts (often tinged buff or cream). The tail may be “distinctly bicolored” (dark brown above and whitish below) or in many specimens sparsely and thinly haired, so as to appear “indistinctly bicolored”. The contrasting colors more or less merge when they meet. This latter character was not original with Burt (e.g., Audubon and Bachman, 1842), but Burt made it famous in his field guide (Burt and Grossenheider, 1952) and it does not always work. When the tail is indistinctly bicolored, which is often the case, that color pattern identifies P. leucopus. From P. m. maniculatus, which P. leucopus resembles closely, the white-footed mouse has a shorter tail (65-78 mm), shorter whiskers (vibrissae), the lower ones are never white, and shorter rostrum of the cranium with an anteriorly pinched pair of incisive foramina. The ear pinnae are shorter (smaller) than in the race maniculatus, and are similar but larger than in the short-tailed P. maniculatus bairdii. The tail lacks a pencillate tuft of hairs and as a rule is more sparsely haired than in P. m. maniculatus. In lateral profile the skull is short and shows an arched cranium. Adult P. leucopus differ from the small P. m. bairdii in having larger feet (19-21 mm length, which are also wider or thicker. In comparison to the house mouse Mus musculus, P. leucopus lacks a buffy or brownish



Photo of mother white-footed mouse suckling young. 1900. By Dugmoor. 

belly (a whitish belly is seen in some Mus), and the eyes are less protruberant and not set forward. P. leucopus differs from the harvest mouse Reithrodontomys megalotis in having smooth (lacking grooves) upper incisors, and it is decidedly larger in body dimensions. The baculum is a simple rod slightly curved (Hooper, 1958). The number of mammae is six, with at least four pectoral teats functional. The chromosome number is 48 (Singh et al., 1966). In more detail than mentioned above, the color of juveniles is gray above, whitish be-



Maps showing geographic distribution of Peromyscus leucopus in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Overlap and movements of long-tailed Peromyscus Fine line is margin for P. m. maniculatus; it receded and has relict populations in the south. Heavy dashed line shows extensions of range for P. leucopus. The dotted line shows range for leucopus mapped by Jackson (1961). Long (1996). 

low, as in other juvenal Peromyscus. The adults of all Peromyscus are indistinguishable in color of the ear pinnae (being slate gray) and eyes (shiny black). The dorsum varies depending on the fresh or worn condition of the pelage; worn pelage is dark brown (the plumbeous or lead gray basal parts of the hairs show through and the bright tips are worn away) whereas fresh pelage (as soon as the bright tips grow out) is nearly russet or chestnut. Rarely is such reddish pelage seen in P. maniculatus, never in P. m. bairdii (which is olivaceous walnut brown or even grayish brown, and darker along the mid-dorsum). The feet are whitish. The adults molt annually, in summer. See Key for measurements and comparisons with other long-tailed deer mice. Accompanying figures show weights in males and females. Dental Formula. DF = 1/1, C 0/0, P 0/ 0, M 3/3 = 16. Geographic Distribution. See Map. This species may be expected in suitable habitats throughout the state and on the Upper Pen-

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insula of Michigan, anywhere in forest edge, mature deciduous forest, and brushy habitats. This species is not confined to such habitats, has been steadily dispersing northward from southern Wisconsin, but is excluded from many of the dense northern coniferous and mixed hardwood-conifer forests. It is excluded from some habitats in prairies, swamps, and marshes. Centuries ago this mouse invaded deeply into Wisconsin (Jackson 1961). Jackson (1961) reported the geographic range as approximately the southern threefourths of the state, with the marginal records then mapped at the tip of the Door Peninsula, and from southern Oconto, Price, and Washburn counties. He believed that the species had not followed the land use by humankind as aggressively as some species had (e.g., Spermophilus tridecemlineatus or P. maniculatus bairdii). Burt (1948) had listed only one county record from the Upper Peninsula (in Menominee Co.). As can be seen from the map, the white-footed mouse has greatly expanded its range since 1961, even invading Washington Island (Long and Long 1993; Long, 1996), and several far northern counties, and also has increased its range on the Upper Peninsula of Michigan (see Baker, 1983). Agricultural fields and roadsides are important dispersal routes (Cummings and Vessey, 1994). Peromyscus leucopus is aggressive, adapting to human land use and dispersing northward, as is evident from the mapping of past (Jackson, 1961; Burt, 1948) and present records. Northward dispersion also was evident on the Lower Peninsula of Michigan (Hooper, 1942) and in New York and Connecticut (Miller,1893). There seems to be competition between long-tailed P. maniculatus and P. leucopus, or perhaps the land use is becoming more favorable to leucopus. That P. leucopus ecologically replaced the long-tailed maniculatus along a zone of contact in Wisconsin and Michigan, roughly along the so-called Tension Zone” ecotone, is based on zoogeography (Long,

1996). Particularly useful are relicts of “gracilis” (= P. m. maniculatus) in the south, and the pattern in Door County, where P. leucopus occupies the Peninsula and longtailed P. maniculatus occurs on numerous offshore islands. Either replacement occurred on the Peninsula, or P. maniculatus invaded all the islands and missed the Peninsula. In Clark County, at the northwestern margin of known range, the two species maintain separate but similar habitats in the west and are sympatric in the east. On Washington Island, P. leucopus invaded in 1987 (Long and Long, 1993) and soon increased in numbers (Long, 1996), while P. maniculatus decreased dramatically in the forest habitats (see Fig.). Since then the two species fluctuated irregularly (Long, 1996). Other studies show P. maniculatus is better adapted to severe cold (Wolff, 1986; Wolff and Hurlbutt, 1980; Pierce and Vogt, 1993). Since the observed competition ensued on Washington Island, in the past six relatively mild winters, neither species seems dominant. No significant differences were seen in diet, parasites, or effects of predation. Status. This mouse may be the most abundant wild mammal in Wisconsin. It occurs in most counties. In the forests and savannas it seldom does any damage to humankind, and indeed is a valuable member of predator food chains. In agricultural settings it occasionally



Graph showing frequencies before and after P. leucopus invaded the home of P. maniculatus, Washington Island. After Long (1996). 

eats grain and garden products, but also is beneficial in eating insects and weed seeds. The white-footed mouse doubtless competes with other granivores and nut-eaters. By burying acorns it aids forestation, but may replace P. m. maniculatus when they occur sympatrically. It may invade the rural habitations of people and cause a little damage. One po-



Scatter plots for long-tailed Peromyscus groups Above bivariate for ear and tail lengths. Below Canonical variates of discriminant functions. Long and Long, 1993. 2’s = central Wisconsin P. leucopus.  TAXONOMIC ACCOUNTS / ORDER RODENTIA

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tential problem is the possible transmission of disease either directly or by its ectoparasite hosts (ticks, fleas). These include plague, Lyme disease, Rocky Mountain spotted fever, and rarely the recently discovered Hantavirus. Habitat. See general comments above in the section on Geographic Distribution. The white-footed mouse is a forest-edge species, but is also found in many diverse forest and woodland habitats (beech-maple, oak-maple, oak-hazelnut, jack pine, oak-sycamore). Mice thrive especially in the deciduous woodlands and brushy areas (Getz, 1961; Long and Long, 1993; Long, 1978). In fields, the mouse prefers the brushy thickets, invades the grasslands as brush and saplings ecologically supplant other prairie species, and thrives in brambles, vines and thickets so long as they are not too wet. The species ranges into riparian woodlands where Clethrionomys and its stump-deadfall habitat are found, onto floodplains (where the white-footed mice may thrive, or seem absent even when the species is abundant nearby), on sand barrens and savannas, in hedgerows, barn lots and pastures, weedy prairies, disturbed farmlands, even in cultivated fields. Also it is found at wooded rocky outcrops and ravines where creeks may or may not be present. These refugia protect them from deep frost (Long, 1973). Getz (1961) is the only worker I know of who found them ranging into grass-sedge marshes, although I have taken them at the edge of marshes where different habitats are nearby. In winter the open, wind-swept fields, where the snow is thin, is death for white-footed mice, which survive in tree cavities, bird houses or similar protected places in their winter nests. They may seek shelter in barns and houses, basements, and garages. I twice observed hoards of acorns on the engines of cars. On Washington Island, where now this species is found with P. m. maniculatus, the white-footed mouse tends to occupy higher, dryer woods and to congregate in the vicinity of oaks (which are not common trees there). The P. maniculatus climb better and persist

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on the northern and northwestern lakeshore bluffs. Stah (1978;1980), Wolff and Durrand (1986) and Wolff and Hurlbutt (1982) report that the two co-exist in the same woodlots, and that P. maniculatus dwells more often in the trees. In such a place, P. leucopus likely would eventually win out, with its better base for ground foraging. It is more likely to use ground dens. In cold, snowy and boreal forests (spruce, fir, tamarack, etc.) the long tailed Peromyscus maniculatus seem dominant (Pierce and Vogt, 1993; Wolff and Durr 1986; Long, 1996; and others). See account of P. maniculatus (Table Rod-12). Occasionally found in burrows or ground crevices, this scansorial mouse usually nests on or above ground and sometimes in trees (Horner, 1954; Stah, 1980). The nests are constructed of fine plant fibers, downy or fibrous material, feathers and cloth, and even rabbit fur on occasion, sited in a mass of sticks, weed stems, leaves and grasses. The nest is made in abandoned bird nests, hollow logs, or branches of trees, crevices in rocks and stumps, and studs of man-made walls (Nicholson, 1941; Jackson 1961). Eisenberg (1968) described the stereotyped behavior of nest building. The nest measures as much as 10 inches (= 254 mm) in diameter, with a depth of about 7 inches, and having an entrance hole on the side. Male and female may jointly build the nest. Feces and especially a gooey strong urine in winter may foul the nest and necessitate making another one. Foods. The chief foods of white-footed mice are seeds of forbs and grasses, nuts, pine seeds, and insects. In spring and often at other times berries seem to color the finely minced stomach contents. White-footed mice hoard caches of seeds or nuts both below and above ground in summer and autumn (Heithaus, 1981). Whitaker (1963) and Grahame (1929) listed insects as foods, larvae of moths, beetles and even butterflies, as well as sawflies, wasps, and hornets. Sometimes these mice eat carpenter ants, both the adults and the eggs (Long, 1996). Grass and weed seeds, clover, and fruits

such as grapes or cherries are eaten (not hoarded), as well as some fungi (Gosling, 1977; Getz, 1961; Whitaker, 1967). Reproduction. In central Wisconsin the carry-over mice from the winter produce two successive litters usually and most of the adults perish. In late summer and autumn the young of the year produce one or two litters. The litter size (N=31) in central Wisconsin is approximately 4.77±0.18 (range 3-7) so that a female is capable of reproducing nearly 20 offspring if she lives a full year, approximately 9.5 in each year. Observed frequencies of numbers of embryos was as follows: 3 embryos, 4 females; 4, 7; 5, 13 (mode); 6, 0; and 7, 1. Counts of placental scars were comparable. The testes of the male enlarge in spring and produce viable sperm. Long (1973) showed that even the carry-over males tend to perish after breeding in the spring. Long (1973a) explained the so-called “unimodal” peak of summer reproduction seen in northern populations of white-footed mice combined two subsets— the carry-overs and young-of-the-year mice. These are basically the same population subsets breeding in the bimodal pattern farther south (Stickel and Warbach, 1960, Long, 1968, and others). The two periods of breeding are compressed together in the northern latitudes because the season is shorter (the cold season is longer). From one subset through the second subset, both testis function and lactation continue through the breeding season, but the number of births declines in mid-summer (see fig.).



Figure showing subsets of unimodal frequency distribution for body weights in Peromyscus leucopus. Y = young of the year, n above bars. Long, 1968. 

The bimodal pattern may be more apparent in southern Wisconsin, and is seen in southern Michigan (Burt, 1940) and central Illinois (Long, 1968). Another example of a bimodal curve is given by Svendson (1964) for northern Kansas. In the southern latitudes there are more exceptions to the rule that carry-overs perish, and indeed breeding occurs in every month of the year. But the basic pattern is bimodal, with a cessation of breeding in mid-summer. When winter’s deep frost is deep in the ground, as it is in central Wisconsin when snow cover is thin (occasionally the frost drops to 2 m depth), then most breeding is by youngof-the-year in the next late summer and fall. With so many mice dying before spring and early summer, the few young that are produced may thrive in the open habitats. This is an example of seasonality and reproductive adaptation. When snow cover (17-18 inches, deeper in snowdrifts and in the North) prevents deep penetration of killing frost, the breeding peaks in spring, but hardly any breeding adults survive through summer. Juvenile frequencies are likewise bimodal, with highs appearing in late summer and again in early fall. Long (1973) also found that the central Wisconsin mice fall into a cline of decreasing litter size southward, providing an example of Lord’s Ecological Rule (1960), describing larger litters of northern, non-hibernating small mammals. In northern latitudes P. leucopus shows increased mean litter size, although the number of litters may be fewer. No good reason has been found to explain this rule, because selection for large litters apparently necessary in northern latitudes, indeed, would as likely increase survival also in the south (where no reason can be found for the litters to be smaller). Large litters may be unfit to some extent, if they cause any mortality or problems for the reproductive females. Thus, theoretically any adverse effect of mortality of mothers, may balance with the adverse effect of small litter size, so that the latter is confounded in the north and the TAXONOMIC ACCOUNTS / ORDER RODENTIA

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former in the south (Spencer and Steinhoff, 1968). (But why would hypothesized mortality in southern females having large litters not be adverse also in the north?) In birds the time spent foraging is longer in northern populations because the photoperiod is longer in summer there (Lack, 1968). The food gathered will support a larger brood size, whereas in southern latitudes the time for foraging limits brood size. There might be a parallel cause for this gradient, and photoperiod may well be the cause. But nocturnal parent mice do not forage for food in the longer day in the north. Long (1973) hypothesized the time spent nursing and caring for the litters in the nests during long daytime periods might support larger litters in the north, whereas shorter photoperiods limit them in the south. Obviously some correlate with latitude makes sense because the litter size changes so regularly southward in the same race (Long, 1973). One bothersome question, does the time spent nursing during the day also last longer at higher elevations (where again we find litter size is larger)? Considerations of the elevation factor suggest seasonality, for mouse populations. If a seasonality hypothesis (Lindstet and Boyce, 1985; and others) is correct explanation, at least in part, then reduced density dependent competition, following a winter of starvation and high mortality, might lead either to the evolution of increased body mass or in this case fecundity. Deep, killing frost, as well as hunger, increases mortality at the northern limits of range in P. leucopus. By creating open habitats in spring, frost and mortality favor increased fecundity (since an increase of body mass was not observed). Could seasonal low density-open habitat conditions in the Northland favor, let us say, in about 10,000 years and probably less (i.e., since the Wisconsinan glaciation), an increased litter size, and could it also favor those mice that produce two spring litters in quick succession? This author believes Lord’s Rule is explained best by a

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combination of diurnal nursing time and seasonality, favoring larger litters in the north with small litters favored southward. Mating begins in February with gestation about 22-25 days (Svihla, 1932). In central Wisconsin it usually begins a little later, in March, and ends in September. Lactation may continue into October. The female shows a post-partum estrus and those that live can breed again. Nursing the previous litter seemingly slows gestation of the new litter, extending gestation to about 37 days (Hill, 1972). At birth the newborn mouse weighs about 1.52.0 g, and is naked and blind. The fur develops rapidly, the ears come erect, and after about 12-14 days the eyes open. The young are weaned in about 3-4 weeks (Layne, 1968). Young-of-the-year first enter the populations in Wisconsin in June. Mortality. A predominant cause of mortality in central and northern Wisconsin is the aforementioned lack of snow cover and consequent deep frost (Long, 1973). Nevertheless, in central Wisconsin, where soil frost depth is greater than anywhere in the state, P. leucopus is the dominant small mammal. The shrubby and savanna vegetation of the central sands plain possibly allows P. leucopus to thrive. The populations fluctuate with food abundance too, including mast failures, but the fecundity quickly replaces the losses. Predators that eat white-footed mice are many, including mostly nocturnal species because the P. leucopus is seldom out in the day. Owls that take them include barn, saw whet, screech, long-eared, barred, and great-horned. Apparently the great gray owl does not take them normally (see accounts of Synaptomys and Microtus). Carnivores that prey on white-footed mice include coyotes, foxes, weasels, skunks, raccoons, house cats, badgers, and mink. Sometimes the adults of P. leucopus and P. maniculatus eat young Peromyscus, presumably not their own. I have seen an example of infanticide in June on Washington Island, Wisconsin, where the two species are found together (Long, 1996). Shrews and

snakes eat white-footed mice, and they appear in the diet occasionally of kestrels, harriers, and other hawks (Fitch and Bare, 1978; Erington, Hamerstrom and Hamerstrom, 1940; Sterling, 1953; Baker, 1983; Metzgar, 1967; Voight and Glenn-Lewin, 1978). Parasites include trematodes, tapeworms, many species of nematodes, and one pentastomid worm (Whitaker, 1968). Also found infesting these mice are external mites, chiggers, ticks, sucking lice, and bot fly larvae (Doran, 1954) as well as a few internal protozoans. The bot warbles fill the groin area quite often, until the larvae emerge from the hosts, but to not sterilize the infested mice (Miller and Getz, 1969; Timm and Cook, 1979; Timm and Lee, 1982). Whitaker (1968) lists internal parasites for P. leucopus, but he does not record where the infested and infected mice were collected. Home Range and Density. The classic work on home range and territoriality in small mammals was written by W. H. Burt (1940) and was based in part on deer mice studied in nearby lower Michigan. Burt found that populations range from about four per acre in spring to 12 per acre in the autumn. Over a 23-year trapping period in central Illinois, trapping for 3-day periods in late summer and autumn, produced one to 39 mice per acre (Hoffmeister, 1989). Half the population was subadult in winter and summer (Batzli, 1977). In upland woods Batzli found as many as 16 / ha in November, but as low as 3/ ha in September. Even higher densities than those above were found by Blem and Blem (1975). In central Wisconsin (in mostly jack pineoak savanna and shrubby, sandy prairies, and a few white pine forests) surveys based on traplines at 10 m intervals and with 2 traps per station, usually in transects 40 to 100 m in length, Long (1973) found absolutely no mice in line after line following a hard winter (with deep frost). Only in a few ravines, one taken near springs of water, were carry-over adults trapped. Evidently some survived elsewhere, because by June young were appearing in trap

lines again. At peak abundance in autumn, as many as 65 percent of traps contain mice. About 60 percent trapped are males. In some habitats traplines are always empty, e.g., dense vegetation subject to spring flooding (Table Rod-12). In southeastern Wisconsin, Popp et al. (1989) found no regular cycles, but following shortly after an ice storm, which knocked down many branches adding to the debris on the forest floor, a peak of Peromyscus leucopus resulted. Might this suggested cause-effect indeed have resulted from the storm? Can climate generally, or a severe winter or deep frost, or an ice storm, affect density dramatically, in a species considered non-cyclic? On the prairies of the Buena Vista Marsh, where meadow voles and some P. m. bairdii were taken over 25 years of study (Hamerstrom’s journals), there were surprisingly few leucopus caught (Nora Lopez-Rivera, personal corr.). One “peak” (judging from recorded measurements) was actually numbers of two species of deer mice (all formerly considered as leucopus), when identified from the records. Whether or not mast cycles relate to cyclic abundance in P. leucopus is obscured in Wisconsin by the ubiquitous habitat selection of the mouse (see Habitat). The rodent inhabits and seems to prefer oak stands, even flourishing near scattered oaks in cut-over maple-birch hemlock forest. This mouse hoards acorns for winter. In oak forests in southeast Wisconsin and in savannas in central Wisconsin, the numbers of white-footed mice increase in mast peak years and decrease when acorns become scarce, as observed in eastern oak forests (Ostfeld et al., 1996). Acorn abundance “controls” densities of P. leucopus, P. maniculatus, and Tamias striatus in eastern forests. Inasmuch as the white-footed mouse is such an able climber, its home range has a vertical dimension (Horner, 1954). With a flashlight I have seen them perched 12 feet up small trees, and had them winter-nest in my porch siding above the windows (in a nest made of rabbit fur). Gosling (1977) found half TAXONOMIC ACCOUNTS / ORDER RODENTIA

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the mice caught living in nests in trees as high as 13 feet. In competition with our long-tailed Peromyscus maniculatus maniculatus, the white-footed mouse tends to occupy lower branches and nest sites. Burt’s (1940) estimate of home range (ground area only) was about 0.27 acres for males and only 0.21 acres for females. Analysis of the geographic distribution in Door County and northern Wisconsin suggests that ecological replacement has occurred (Long, 1996). Long also found that an invasion of Washington Island, in Lake Michigan, of P. leucopus was coincidental with a sharp reduction in the incidence of P. maniculatus, but maniculatus still persisted in the wetter swamps and forests. Now P. leucopus has suffered something of a drop after becoming widespread and abundant. Both species seem to be fluctuating in density and the winters are continuing mild (see Fig.). (Hypothetically, the white-footed mouse seems less adapted to cold winters.) P. leucopus is now established in hayfields, hedges, on the beach sand dunes, roadsides, and of course in the forests. If ecological replacement occurs it seems likely slow. In 1991, the relative numbers indicated that replacement might occur rapidly. Remark. Dental abnormalities in deer mice are rare, but Zielinski (1978) described a small, supernumerary and anomalous tooth erupting labially, next to the upper first molar. Additional Natural History. Lackey et al. (1985) reviewed natural history for the whitefooted mouse, P. leucopus. Geographic variation. According to Hoffmeister (1989) there is a cline in size in P. leucopus so that some western populations are similar to the nominate race. He found no significant geographic variation in Illinois. I found none in Wisconsin, and suspect the Wisconsin stock invaded in the Holocene (i.e., Recent) epoch, from Illinois. Therefore, in such a short time, geographic variation in Wisconsin would be expected to be insignificant. From place to place, white-

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footed mice live in different habitats and vary slightly in form adapting to them. (P. leucopus from a mesic hemlock habitat will be better furred, darker brown, and longer tailed, whereas in a sandy dune area the same species may be small, scantily haired on the tail, and surprisingly even slightly smaller of foot.) I follow Osgood (1909) in referring all whitefooted mice in Wisconsin and most of Illinois, for that matter, to the race P. leucopus noveboracensis for the reasons detailed above. Specimens examined. Total, 897. This is the largest sample of Wisconsin mammals in the UW-SP mammal collection. Adams, Ashland, Bayfield, Burnett, Chippewa, Columbia, Crawford, Dane, Dodge, Door, Douglas, Dunn, Eau Claire, Fond du Lac, Forest, Grant, Iowa, Jackson, Jefferson, Juneau, Kenosha, Kewaunee, La Crosse, Lafayette, Langlade, Lincoln, Manitowoc, Marathón, Marinette, Marquette, Milwaukee, Monroe, Oconto, Oneida, Outagamie, Ozaukee, Pepin, Pierce, Portage, Racine, Richland, Rock, Rusk, Sauk, Sawyer, Shawano, Sheboygan, St. Croix, Taylor, Trempealeau, Vernon, Vilas, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood counties.

Peromyscus maniculatus (Wagner) Forest Deer Mouse “The internal cheek pouches enable the mouse to gather and carry small seeds to its secret granaries... in holes of trees or under logs and stumps.” — W. H. Burt, The Mammals of Michigan

The taxonomic problem with the longtailed mice was discussed early by Coues and Allen (1877) and authoritatively by Osgood (1909). The racial differences are subtle and confused by clinal variation. Osgood changed existing classifications, including his own, by resurrecting the available name P. gracilis (Le Conte) and placing in synonymy the names umbrinus Miller and canadensis Miller. P.

m. gracilis is a problematical name for two reasons. First, the type and topotype used in the description and subsequent comparisons are not well made. Miller, an astute and careful taxonomist, had ruled gracilis out as any available name, because the type specimen was so poorly made. He wrote that the tail, although it appeared to be too long for P. leucopus, had no pencil (or tuft), implying it was P. leucopus. Coues and Allen also said it was impossible to separate the two specimens from leucopus. But in those days no one quite knew what was P. leucopus and what was P. maniculatus. Osgood thought the long tail distinguished the type from P. leucopus. Drs. Al Gardner and Michael Carleton recently wrote me saying they examined the holotype and concurred that the specimen was referable to P. maniculatus. The type locality is also questionable, being referred to three states, and as for Michigan, it might have been on the Lower Peninsula in the range of P. maniculatus. The arguments and prestige of Osgood’s (1909) “before its time” monograph seem to have led to general acceptance of the name gracilis. But in some places, Wisconsin and Minnesota for example, the size of the samples used was too small to provide such concrete taxonomy (Long and Long, 1993). A large sample from Isle Royale was referred by Osgood not to the mice known as gracilis immediately southward, nor really to those north of Lake Superior (formerly known as P. canadensis) which differed slightly from them, but to the northern race from Labrador. Southward the trivial character of average length of the tail (of 7 mice from two localities) was used to refer all Wisconsin mice to P. m. gracilis. Long and Long (1993) found some Wisconsin mice on islands were identical with series of Labrador P. m. maniculatus, some on the mainland were slightly different, and those from lower Michigan were slightly different from all the Wisconsin mice. If one considers P. m. nubiterrae to the eastward as a distinctive but similar race (E),

then the following arrangements might apply, using the schematic map. (A) is the nominate race, (B) represents mice from southern Canada northward of Lake Superior, (C) refers to Wisconsin mice, (D) refers to mice in Lower Michigan with long tails. 1. ABCD may be combined together with P. m. nubiterrae (E) a distinct race. Then ABCD would be a variable nominate race known as P. maniculatus maniculatus. Chiefly it would vary in tail length, a trivial character, and tone of upper pelage (yellowish, dusky, brown). 2. If gracilis was valid, its holotype truly from lower Michigan, the name may be used for the small, dark, long-tailed mice there. Then ABC would be the nominate race and nubiterrae probably a valid race. 3. The name P. canadensis may be raised from synonymy and applied to B + C. Some insular populations (Isle Royale, Rock, St. Martin, possibly Washington Island) southward of these populations are referable (identical) to the specimens I have examined from Labrador’s maniculatus (A). Such action solves nothing and describes variation poorly. The current classification lumping BCD together works geographically, but includes B with C when some of them are A, and in-



Schematic map showing P. maniculatus populations A-E. See text.  TAXONOMIC ACCOUNTS / ORDER RODENTIA

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cludes D also which seems slightly smaller and darker than any of the others. Some on Lake Michigan isles in C are identical to A. The most practical assignment is to combine ABCD together as a variable race, relegating the name P. m. gracilis (based on dubious type) to synonymy. The small dark, Lower Michigan populations are only slightly differentiated from mice in southern Canada, northern Wisconsin, and upper Michigan, but may retain the name P. m. gracilis thereby emphasizing only a little geographic color variation. All the mice are morphologically similar.

Peromyscus maniculatus maniculatus (Wagner) Forest Deer Mouse 1845. Hesperomys maniculatus Wagner. Arch. Naturgeschichte, Jahrb. 1 1 (1): 148. Type from the Moravian settlements scattered along the coast of Labrador. 1855. Hesperomys gracilis Le Conte. Proc. Acad. Nat. Sci. Philadelphia, 7: 442. Type possibly from “Michigan”. 1893. Sitomys americanus canadensis Miller. Proc. Biol. Soc.Washington, 8: 55. Type from Peterboro, New York. 1898. Peromyscus maniculatus: Bangs. Amer. Nat., 32: 496. 1897. Peromyscus maniculatus umbrinus Miller. Proc. Boston Soc. Nat. Hist., 28: 23. Type from Peninsula Harbor, north shore Lake Superior, Ontario. 1908. Peromyscus canadensis (Miller): Jackson’s A Preliminary List of Wisconsin’s Mammals. Bull. Wisconsin Nat. Hist. Soc., 6(1-2): 13-34.

The name Peromyscus means little mouse, but the prefix Pero has no certain meaning. The specific part of the binomen, maniculatus, means small-handed. Description. The skull is smoothly rounded with elongate rostrum and elongate palatal slits (incisive foramina). These slits are nearly parallel, i.e., seldom pinched anteriorly, and

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THE WILD MAMMALS OF WISCONSIN

are slightly longer than in P. leucopus. The total length of the skull averages longer than in P. leucopus, although some specimens from the southernmost parts of the geographic range are no longer. The elongate tail is well furred, so that the color is always distinctively bicolored (brown above, white or buffy white below) and it is tufted at the tip. The whiskers are longer than in P. leucopus correlated with the prominent rostrum (snout), and lower ones are much longer and usually white). The ears in many specimens of P. m. maniculatus are enormous, but some have ears no longer than in P. leucopus. Generally this trait distinguishes the two, as does tail length. The combination (Long and Long, 1993) of ear length, tail length, skull length, and length of incisive foramina serve to distinguish at least 95 percent of the specimens. From the tiny, sand-dwelling P. maniculatus bairdii, with which the long-tailed forest mice are reportedly conspecific (perhaps linked by limited intergradation in a few western localities), there may be in nature some intergradation. There is no evidence of intergradation in Wisconsin between P. m. maniculatus and P. m. bairdii. There are six mammae (4 pectoral, 2 inguinal), although only four functional teats are seen in some lactating females. The baculum is a short, slightly curved rod. John Long and William LeGrande (unpublished) determined that the number of chromosomes is 48, both in northern Wisconsin and on Washington Island. See Singh et al. (1966). There is no great difference between Wisconsin and nearby Upper Michigan mice from those on Lake Michigan isles. In the Beaver Islands there is insular variation with some populations resembling those of lower Michigan. The specimens that I have studied from there are slightly smaller and darker brown. Essentially there is a little difference in them and any Wisconsin mice. These also resemble the Isle Royale mice, which have been ascribed by Osgood (1909), himself, to P. m. maniculatus. In most of Wisconsin

there are some mice with a yellowish tone, less brown than in Michigan. Often the Wisconsin mice are russet-brown or a dusky brown. There is no difference apparent from them and the Labrador mice I have examined. The venter is whitish, sometimes creamy. In a small population on the east side of Washington Island, Ron Zimmermann and I once collected a series with some venters tinged with pink or pink-ochraceous. This is a curious but probably transient variation. Jackson (1961) reported that on the Upper Peninsula of Michigan these deer mice often showed white spotting (possibly from parasite bites?). The ears are brownish gray often edged with a thin margin of white, and the eyes are a shiny black. The feet are whitish, as is the underside of the tail, and in this species the dark upper side of the tail may show only as a slender brown line with much of the white showing, even in dorsal view. The pencillate tuft is a mixture of brown and white hairs. There is an intermixture of black hairs dorsally, but not so evident as in P. m. bairdii. The juveniles are gray above and white below. They are difficult to distinguish from P. leucopus (except the ears in P. leucopus are shorter). Adults molt annually in summer (Osgood, 1909: 19-21). Some adult males are about 5 percent larger than adult females. Dental formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. The nominate race is found primarily in the forests of northern Wisconsin and Lake Superior, and most of the islands in Wisconsin waters of Green Bay and Lake Michigan. This species does not occur on the Door Peninsula. Its southern boundary extends somewhat northward of Green Bay across the state, to the Rib River near Athens in Marathon County, and northwest to and beyond the state boundary of Minnesota. There are two relict populations south of the boundary, but the Sheboygan Marsh mice seem eradicated. See Map. For additional evidence regarding ecological replacement of this species by P. leucopus,

see account of that species and Long and Long (1996). Status At this time the populations of P. m. maniculatus are not in any serious peril, and they are beneficial mammals because they help control forest insects, and are prey for forest raptors and predators. They probably help plant forests because they scatter-hoard acorns, beech nuts and other seeds. William Henry Burt, probably the most famous mammalogist in the history of Michigan, called this attractive, large-eyed mouse the “most beautiful mammal in Michigan.” Habitat. This nocturnal long-tailed climber is found in beech-maple forest with hemlock, cedar, yellow birch, and some oak. The mice also live in swampy, boggy, and riparian thickets in spruce-fir, maple, pine, or mixed forests. They inhabit dune heath, in Upper Michigan, but not to my knowledge in Wisconsin. Often the soils are rocky, with outcrops and ravines. The Niagra escarpment provides many bluffs and cliffs for this mouse on Lake Michigan isles. More detail has been compiled on habitats by Hooper (1942) and Long (1996). The long-tailed P. m. maniculatus is more adapted to winter conditions than is P. leucopus, including the tendency to enter torpor, build larger nests, make larger food hoards, diminish food consumption, show regression of sex organs, fur out the pelage, and so forth (Wolff, 1986; Wolff and Hurlbutt, 1980; Vogt, 1993).



Skull of Peromyscus maniculatus maniculatus. Note elongate palatal foramina (i).  TAXONOMIC ACCOUNTS / ORDER RODENTIA

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These deer mice nest in tree hollows, stumps, and possibly abandoned birdnests. Such a scansorial species tends to nest higher in trees and seldom does so on the ground (in comparison to P. leucopus) (Horner, 1954; Stah, 1978; 1980; Wolff and Durr, 1986: Wolff and Hurlbutt, 1982). Only three of 39 P. maniculatus nests were underground whereas 36 were in trees. Nest heights were significantly higher (7.4 m to 4.3 m) in P. m. maniculatus than in P. leucopus. The long-tailed P. maniculatus sometimes invade houses to gather fibrous material for a nest. On Washington Island a friend told me a mouse had transported rug fibers in excess of 100 m to its nest. Usually the nest is a wad of grass stems, mixed with leaves and bark (Cory, 1912). On Lake Michigan isles the nest materials included moss, bird feathers, milkweed down, and dry vegetation (personal observations). Foods. A few grass seeds, acorns, old beech nuts, and several arthropods were all I could find available for deer mice to eat in June on Washington Island. Stomachs seemed to contain these foods finely minced. Possibly these mice eat green leaves then (Clark, 1972); I found no green materials in the stomachs



Table Rod-12 Rod-12. Percent of Washington Island Peromyscus found in three habitats. Long, 1996.  Sand Dunes

Old Fields

Beech-Maple Forest

1975 P. leucopus P. maniculatus

0 0

0 0

0 100

1984-1986 P. leucopus P. maniculatus

0 0

0 0

0 100

1987-1990 P. leucopus P. maniculatus

10 0

5 0

55 29

1991-1994 P. leucopus P. maniculatus

21 0

11 0

50 17

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THE WILD MAMMALS OF WISCONSIN

examined. Some stomach contents seemed berry stained, and seeds became more prevalent in summer. Small arthropods comprise part of the diet. In some stomachs the eggs and jaws of carpenter ants were observed. Jackson (1961) lists as foods, beaked hazelnut, Juneberry (Amelanchier), basswood, wintergreen, pin cherry, hemlock, maple, blueberry, yellow Clintonia, and partridge berry. On Lake Michigan isles Hatt et al. (1948) found evidence at the nests that this species scavenges on crayfish, small fish, even bird bones. Some remains were cached. This mouse has large internal cheek pouches (Burt, 1940) to transport foods for hoarding. There seems no marked difference in the diets of this species and P. leucopus (Zegers and Merritt, 1988). Reproduction. Little information is known of reproduction in Wisconsin for this race. The mice commence breeding in March (Jackson, 1961, suggests late April), and continues into September. The litter size is reported as 3-5. Possibly four litters are brought forth in a single growing season by one mother (Burt, 1940), but if the pattern resembles that in other Peromyscus, which seems likely, then many young-of-the-year may breed once or twice in summer and fall, and after winter passes those that survive it may breed once or twice again the following spring. The UWSP museum collection has few specimens of pregnant females, and Jackson (1961) could find no young in July (1919) on Outer Island, in the Apostles. In other Wisconsin Peromyscus, the young enter the populations in June. On Washington Island I caught young in early July. From a litter of five weaned mice, I kept one six years in the laboratory and another one almost as long (and subsequently may perish, although they are long-lived). Mortality. Because this mouse is difficult to identify in scats or owl pellets, little is known of its predators. P. leucopus may prey on the young and may drive them from their homes (see account of P. leucopus). When present, Blarina surely preys on these mice. Snakes, owls, and other birds of prey doubtless take

them. Raccoons rob my traplines of mice on Washington Island, and doubtless eat the young if they can get them in trees or on the ground. Weasels, martens, fishers, foxes and other carnivores eat Peromyscus whenever possible. Forest fires destroy them, and tree-cutting, logging, and natural succession remove habitats, which reduces the populations. Two kinds of lice, tick, flea, and mite infest this mouse according to Jackson (1961) who mentions botflies and internal worms. I observed botflies on mice from Washington



Map showing geographic distribution of Peromyscus maniculatus maniculatus in Wisconsin and for P. maniculatus in North America. See account of P. m. bairdii. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

255

Island. P. m. maniculatus usually seem clean of mites and fleas. Home Range and Density. In northern Michigan, Manville (1949) found the home range to vary between 500 to 1,500 square yards, a fraction of an acre. Juveniles had smaller home ranges. Blair (1942) determined the home range to be more than 5.5 acres in males, 3.75 acres in females. See table Rod-13. Breeding females were seldom caught near one another, but males were frequently, indicating the females are territorial. (Or they may stay near their nests.) The home range has vertical dimension that has not been studied On foggy nights the mice may be seen climbing in trees. Occasionally a winter cabin in the Northwoods is overrun with these mice. One autumn and early winter on Rock Island, Tom Jessen caught nearly 100 in one of the “Icelandic” houses there. Jackson (1961) reported from the field notes of Clarence Birdseye, of subsequent frozen foods fame, who worked for the U. S. Biological Survey, that in Luce County, Michigan, in the summer of 1910, he caught a total of 61 mice in one cabin. He saw 8 drowned in a kettle, and dogs, cats, and poisons killed many more in surrounding shacks. On Washington Island I counted as many as 45 to the acre in beech-maple-hemlock forest. In the fields and along rock walls I caught none. Usually several are taken in each trapline in suitable habitat on all the Green Bay islands (except Poverty Island which is dominated by Clethrionomys). In the northern forests they were never reported to be as abundant as observed densities in peak years on Washington Island. Remarks. Not only are these mice beautiful; they are gentle and docile, not leaping away as does P. leucopus or biting the fingers. They are cautious climbers, and one can hold them (but do not alarm them) so long as they are not allowed to climb your arm or escape on one’s desk. Geographic variation. Although there are subtle differences from one population of these long-tailed deer mice to the next, rang-

256

THE WILD MAMMALS OF WISCONSIN

ing from Labrador in eastern Canada westward through Ontario and into Minnesota, and extending southward into northern Wisconsin, Upper and Lower Michigan (persisting also on most of the islands and even small isles in Lake Superior and Lake Michigan), the long-tailed Peromyscus maniculatus are morphologically similar. Mice in lower Michigan differ from the others in uniform brown upper parts and small size, with the tail actually or relatively a bit longer. If mice in southern Canada, Upper Michigan, and Wisconsin differ from the typical mice of Labrador, it is in slightly smaller size of skull, especially the rostrum, and in a more often yellowish brown color. The tail tends to longer size. The typical mice of the nominate race have dark upper parts, a shorter tail, and robust rostrum and skull. These traits are seen in mice on Isle Royale, and of mice from the Islands of Green Bay and some other isles in western Lake Michigan. Washington Island mice were slightly smaller than those on Rock, St. Martin, and Big Summer islands. On the Beaver Islands across the Lake in eastern waters, the mice are somewhat smaller and darker brown, at least on some of the islands there, but they average a little larger than those I examined from the Lower Peninsula. In northern Wisconsin there is fluctuating variation in both size and color of examined specimens, with narrow rostra and yellowish pelage tones prevailing. Specimens from Ontario are indistinguishable from them; and that resemblance of Ontario specimens to P. m. maniculatus was mentioned by Osgood (1909). He felt the mice on Isle Royale (a large sample) were typical of P. m. maniculatus. In the Apostle Islands the deer mice are variable, from isle to isle, but not so closely resembling the Labrador specimens. In southern Wisconsin, the relict mice are small and dark perhaps resembling the mice in Lower Michigan. Probably many years ago the small, dark brown mice were distributed continuously around the south end of Lake Michigan. I refer the forest deer mice all to the nominate race.



scription seem more apt to describe a speci-

Species and Sex

Habitat/ Home Range

men of Mus musculus (the number of mammae, the position and protuberance of the eyes and so on). Indeed, the authors themselves use

P. m. maniculatus Females

Conifer-Deciduous June:0.19 September: 0.1-0.31 June: 0.18 September: 0.12-0.25 Beech Maple August: 2.31 September: 0.88-5.64 August: 1.39 September: 0.79-3.28 Bluegrass August: 0.63 September: 0.25-1.67 August: 0.51 September: 0.12-2.29 Oak-Hickory August: 0.27 September: 0.16-0.54 August: 0.21 September: 0.006-0.37

Table Rod-13. Home range in acres in adult deer mice in nearby Michigan. After Stickel, 1968. Based upon work by Blair and Manville. 

Males P. m. bairdii Females Males P. leucopus Females Males P. leucopus Females Males

Specimens examined. Total. 309, and from Michigan 52. Ashland, Door, Douglas, Florence, Forest, Iron, Langlade, Lincoln, Manitowoc, Marathon, Oneida, Price, Sawyer, Sheboygan, Taylor, Vilas counties. Other records. Ashland Co.: (Kantak, 1981): Madeline, Oak and Sand isles. Michigan Delta, Charlevoix counties.

Prairie Deer Mouse Peromyscus maniculatus bairdii (Hoy and Kennicott) 1842. Mus Michiganensis Audubon and Bachman. J. Acad. Nat. Sci. Philadelphia, 8: 304. Type from Erie Co., Michigan (probably Ohio, according to Osgood, 1909). Osgood uses this name to describe a white-footed mouse, possibly because of its long tail, and he placed the name in the synonymy of P. leucopus noveboracensis. The same can be said for the name combination that follows (Audubon and Bachman, 1846). In my opinion the name and de-

the name Mus. Other authors (see below) did apply this name to the prairie deer mouse, and not to P. leucopus, but their publications’ dates are later than that of the name Mus bairdii Hoy and Kennicott. 1846. Mus Michiganensis Audubon and Bachman. Viviparous Quadrupeds of North America. Same description verbatim from the earlier description, applied the same way. 1857. Mus bairdii Hoy and Kennicott. Agric. Report U. S. Commissioner of Patents, 1856. Page 92. Type from Bloomington, McLean Co., Illinois. 1883. Hesperomys Michiganensis (Audubon and Bachman). In Moses Strong’s List of mammals in Wisconsin. Geol. Surv. 1873-1879. Page 439. 1902. Peromyscus bairdii: Snyder. Bull. Wisconsin Nat. Hist. Soc., 11, p. 116. 1908. Peromyscus michiganensis (Audubon and Bachman): In Jackson’s A preliminary list of Wisconsin’s mammals. Bull. Wisconsin Nat. Hist. Soc., 6(1-2): 13-34. 1909. Peromyscus maniculatus bairdii: Osgood. N. Amer. Fauna, 28: 79.

The name Peromyscus means little mouse although the prefix Pero is unknown. The name bairdii honors the great mammalogist and museum administrator at the Smithsonian Institution, Spencer Fullerton Baird. The name maniculatus means small-handed or small-footed. Some mammalian subspecies are so weakly differentiated that this one, which acts almost everywhere as a “good” species, seems a taxonomic mistake. If the “mistake” is not in the fact of supposed, indirect, and far-removed intergradation, it may be in an arbitrary perception of the importance of hybridization, local and limited versus wide-spread intergradation. There is some hybridization that takes place in the laboratory (Foster, 1959; McIntosh, 1956; Dice, 1968), although fertility seems limited in hybrids. There is no known TAXONOMIC ACCOUNTS / ORDER RODENTIA

257

hybridization eastward (with P. m. nubiterrae). Westward it becomes paler and may intergrade with short-tailed pale mice, which merely may have higher frequencies of paleness genes. The pale mice do not seem to intergrade much if any with neighboring longtailed forms. Therefore, P. m. bairdii and P. m. luteus of the Great Plains seem conspecific. Osgood (1909) thought that in the southwestern part of its vast geographic range P. m. bairdii might intergrade with western longtailed mice. This western area should be the focus of taxonomical studies, to resolve a problem for deer mice important in at least 11 states and one Canadian province. Description. The adult fur is almost russet or chestnut brown above and creamy below. There is a strong intermixture of dark hairs intense dorsally along the mid-line. The general tone is dark brown. The upper side of the tail is nearly black, the underside white. Occasionally the adults are grayish or tawny brown instead of dark or chestnut-brown. Young mice are juvenal gray above, white below. The meaning of the latinized name, “small-handed” actually refers, of course, to the forefeet, and is truly relevant for identification. Only harvest mice and house mice (see accounts of those species for their characteristics) have feet as small. The hind foot is almost always 17 or 18 mm in length. When on occasion it reaches 19 mm it becomes difficult to distinguish the mouse from P. leucopus. The foot is so obviously slender and delicate (with tiny toes) that recorded measurements (which may be in error) may be misleading. The short (up to 64 mm in length), stout tail is distinctive. In young white-footed mice the hind foot is usually at least 20 mm in length and the tail is attenuate and slender (Long and Long, 1993). The total length is less than 160 mm. See Key. The skull is smooth and rounded, delicate in appearance. It never exceeds 24.5 mm in greatest length. The prominent ears measure less than 14 mm in length. The ears are similar in shape but smaller than those in P. leucopus. The black

258

THE WILD MAMMALS OF WISCONSIN

eyes are large but not so large in relation to the snout as in Mus. The incisors are not grooved as in Reithrodontomys. There are 48 chromosomes (Singh et al., 1966), and six mammae (four pectoral and two inguinal). The baculum is a slightly curved rod. Dental Formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. This little deer mouse is fairly common in suitable sandy and prairie habitats in the southern parts of Wisconsin (see Map). It has extended its geographic range northward into Upper Michigan in those beach dunes, mostly fringing Lake Michigan’s western shore, and prairie areas near Marinette. There is a relict population isolated on the dunes of the Door Peninsula, where the other (long-tailed) Peromyscus maniculatus is unknown (Jackson, 1961). Recent collections from the dunes at Algoma and as far north as Northport yielded the first specimens known to me of P. m. bairdii from the Door Peninsula in over 60 years. Two UW-Madison specimens obtained by Frank Iwen, Univ. Wisconsin–Madison, were taken near Algoma. Clearing of forests and creating railroad and highway rights of way encouraged the mouse to disperse northward. This mouse occurs in southern counties on the opposite shore of Lake Michigan, lower Michigan (Hooper, 1942). Status. This mouse seems to do no harm to humankind. It dwells in sparse grasses in



So-called races of Peromyscus in Wisconsin. Above P. m. maniculatus, below P. m. bairdii. Note its short tail, ears, and whiskers. 

prairies or barren sandy fields and dunes. The isolated population in Door County merits protection. Even if it is not a distinctive taxon, it may prove interesting to study. It is a semi-isolated population with narrow habitat preference. The specimens seem stunted, i.e., small, and closely resemble P. leucopus, which in that habitat also seems rather small. Habitat. The prairie deer mouse inhabits open fields and grasslands, without much tree cover or brush, and well drained sandy soils and thin soils on pastures, hayfields, and

even plowed grain fields. They are often found with harvest mice under shocks or bales of hay, in thin stubble of well-drained pasture or drained marshland, in weedy areas, railroad rights-of-way where Equisetum, grasses and forbs are common, dwelling on the ground beneath vines, hazelnuts, and small trees, on sand dunes and sandy lake beaches, and occurring with P. leucopus when the brambles or brush is sufficient for the latter. The nest is never built in trees as seen in other Peromyscus (those with long tails); this species builds it on the ground or at the end



Map showing geographic distribution of Peromyscus maniculatus baidii in Wisconsin. See map for P. maniculatus maniculatus for North American range. Line shows recent northern localities. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

259

of a short tunnel (Howard, 1949). The nest sited under a board, rock, shock of grain, or some other sort of rain protection, is about 10 inches ( = 254 mm) in diameter, constructed of grass or weed stems. Inside it is lined with thistle or milkweed down, fur or feathers, or fine grasses. There is usually a single entrance. The nest is not re-used after once abandoned; a new nest is constructed. Houtcooper (1917) found burrows 16 feet long, and about a foot below ground. Foods. Not much is known about the diet in Wisconsin. It prefers seeds, fruits, and other vegetal foods. Plum pits were observed in the nest or near it, and were observed in one winter nest. Reproduction. Breeding begins in early March and continues into November. A female may bear as many as three litters each year. The male is driven from the nest after the young are born. Gestation is about 25 days. The litter size averages about 3-5 young (range 2-9). Gestation is 23-27 days. The blind, naked young are rapidly furred out and two weeks the eyes open. Weaning takes place after 25 days of post-natal care (22-37 days according to Svihla, 1932). Apparently P. m. bairdii has the same pattern of breeding as does P. leucopus. Winter carry-over mice breed in spring. There is a pause in breeding in mid-summer and reproduction recommences in late summer and autumn. Litters are brought forth as late as November. Mortality. Hardly anything is known of predation on this species in Wisconsin. It is difficult to obtain enough remains from fecal scats and bird pellets to identify this species from the other deer mice. Jackson (1961) lists known predators as striped skunk, weasels, raccoon, red fox, and coyote. Domestic cats, and on the Buena Vista Marsh in central Wisconsin, and probably many other marshes, the harrier (= marsh hawk), and kestrel prey on these mice. Saw-whet, short-eared, longeared, boreal, and great-horned owls eat these mice. Doubtless prairie snakes capture some.

260

THE WILD MAMMALS OF WISCONSIN

Succession of shrubs and trees, plowing by farmers, and fire probably destroy many. Parasites include some of the ectoparasites of the other Peromyscus, and some of their endoparasites as well. Whitaker (1968) lists internal and external parasites for Indiana. Home Range and Density. Home range is less than an acre (Burt, 1948). Males have slightly larger home ranges than females. Breeding females do not show much overlap in home range indicating that they may be territorial. In winter the prairie deer mice may aggregate together in groups as large as 15 members. After winter the deer mice disperse from their winter quarters to commence breeding. In barren soils density of P. m. bairdii may seldom exceed 9 per acre. Mice in nature usually live no longer than 2 years, and the turnover is considerable. Howard (1949a) found that of 1,200 mice less than 240 reached sexual maturity, and only 8 lived longer than 73 weeks. Seldom would one find a sharp peak of abundance. Nora Lopez-Rivera (personal correspondence) found a sharp peak in density in the records of Fred and Fran Hamerstrom, kept faithfully over a period of 25 years. Analysis of the hind foot and tail measurements carefully recorded revealed that some of the high-density mice were in fact P. leucopus. Therefore, there was no peak for P. m. bairdii. They are seldom taken in high numbers in the prairies of the Buena Vista Marsh or the sandy hazelnut and savanna areas of central Wisconsin, but in southern Wisconsin they were taken in fair numbers by Stromburg (1979). Geographic Variation. None has been observed in Wisconsin. Specimens examined. Total, 150. Adams, Bayfield, Buffalo, Burnett, Columbia, Dane, Door, Dodge, Eau Claire, Fond du Lac, Iron, Iowa, Kenosha, Kewaunee, La Crosse, Manitowoc, Marathon, Milwaukee, Monroe, Ozaukee, Pepin, Portage, Price, Racine, Rock, Rusk, Sauk, St. Croix, Vernon, Waukesha, Waupaca, Waushara, Winnebago, Wood counties.

2

3



Upper right tooth-rows of Wisconsin microtines. The patterns are as distinctive as signatures on antique vases. Pitymys ochrogaster and P. pinetorum are identical, Microtus pennsylvanicus (middle) has a distinctive posterior islet on the middle molar. There is neat cusp alignment (Clethrionomys far right) and deep re-entrant angles on one side only in Synaptomys (second from right. After Hazard. 

3’

2’ Subfamily ARVICOLINAE Gray (=Microtinae Schrank) Voles and Allies

4

The voles and bog lemmings are difficult to identify, and one often must resort to examination of their skulls and teeth. See Fig. above The much larger muskrat with its laterally compressed and scaly tail is well known. The smaller microtines may be identified by use of the following key, which excludes the muskrat. 4’ Key to the skulls of voles and bog lemmings. After Long, 1990 1.

1’

Upper middle molar with anterior loop, three closed prisms, and one distinctive, small posterior loop or islet; posterior upper molar with anterior loop, three closed prisms, and distinctive posterior crescentic loop; anterior lower molar deeply constricted with five closed prisms and a posterior loop ....... Meadow vole Microtus pennsylvanicus. Upper middle molar with only three prisms; posterior upper molar with two; posterior loop not crescentic; anterior lower molar with fewer than five closed prisms beween loops ........................ 2

5

5’

Molars with deep re-entrant angles on one side only, opposite side comprised of sinuous arcs; each upper incisor with small groove extending the length of the tooth ........................... Synaptomys 3 Lower molars with shallow, sinuous reentrant angles on outer (i.e., labial) side; 3 large and 1minute prisms on lower middle molar ......... Southern bog lemming Synaptomys cooperi Lower molars with little indentation (reentrant angles) on labial side; 3 large prisms on lower middle molar; known in Wisconsin or Michigan only from fossils ........................................ S. borealis Molars with re-entrant angles on labial and lingual sides, upper incisors lacking grooves ............................................ 4 Teeth small with neatly regular indentations, sometimes more curved than pointed, having relatively thick enamel border; teeth rooted in adults; posterior loop of third upper molar irregular in shape; lower anteriormost loop deeply constricted as in meadow vole, with only 3 closed prisms and a posterior loop ................ ................................. Red-backed vole Clethrionomys gapperi Teeth larger; posterior prism of middle upper molar terminating abruptly in a shoulder or bulge confluent with posterior salient angle; posteriormost loop of third upper molar spear-shaped (subtriangular); lower anterior molar slightly constricted anteriorly and deeply constricted posteriorly, with 3 prisms and a posterior loop .................... Pitymys 5 Tail exceptionally short; fur fleecy, walnut or reddish brown; forefeet with robust claws; skull broad, with interorbital breadth more than half the length between the tips of the nasals to the posterior ends of the premaxillaries ............. ....................... Pine or Woodland vole Pitymys (= Microtus) pinetorum Tail somewhat short, fur coarse and grizzled, buff or orange-brown; forefeet

TAXONOMIC ACCOUNTS / ORDER RODENTIA

261

small; skull narrow, interorbital breadth about half the length between the tips of the nasal bones and the ends of the premaxillaries ......................... Prairie vole Pitymys (= Microtus) ochrogaster Genus Clethrionomys Tilesius (=Myodes Pallas 1811, ?nomen oblitum) Red-backed Voles The teeth are small and primitive, reportedly rooted in adults; salient angles less pointed (i.e., more arcuate) than in Microtus or Pitymys; upper third molar elaborate and irregular in form; posterior hard palate shelf-like, a transversely edged palate. The dorsal fur is reddish, and the venter whitish or cinnamon buff. I provisionally retain the well-established Clethrionomys (= Myodes by priority). See above.

Clethrionomys gapperi (Vigors) Southern Red-backed Vole 1830. Arvicola gapperi Vigors. Zool. Journal, 5: 204. Type from between Lake Simcoe and Toronto, Ontario. 1928. Cleththrionomys gapperi gapperi: Green. J. Mammal., 9: 255.

The name Clethrionomys means alder mouse. The trivial part of the binomen honors a Dr. Gapper from Ontario. Description. This small red-backed vole has a lightly built skull. The prisms and loops in the cheek teeth are neatly aligned and the teeth are small. Reportedly the teeth are often rooted in adults. Ostensibly a primitive feature, though shared by Phenacomys, rooted molars provide the basis for this species being mentioned first among the Wisconsin arvicolines (formerly microtines). The incisors are usually pale yellow. The skull is small and rather circular in profile. No other arvicoline has such a shelf-like or straight posterior border of the palate (it demarcates the

262

THE WILD MAMMALS OF WISCONSIN

anterior border of the pterygoid fossa (i.e., posterior nares). The teeth are narrow and small. The upper third molar has an anterior loop, three closed prisms, and a complex, irregular posterior loop, resembling the pattern in Microtus. The more arcuate angles are more even in linear alignment, and much more delicate with the tiny prisms “neatly outlined”. The upper middle molar consists of an anterior loop and three closed prisms (which is ordinary in arvicolines). The lower first molar might be said to terminate with two posterior loops in tandem, only two enclosed areas intervene between the complex anterior part and the last loop. The anterior portion is pinched so that a tiny inner salient may occasionally be closed off as well. The third lower molar is distinctive in its three similar and large outer salient angles all in a row, and three small inner salient angles neatly arranged opposite. There are four pairs of mammae in females, two pectoral and two abdominal. Small flank glands are often evident in some males. The baculum has three distal processes and a basal stalk. There are 2N = 56 chromosomes (Merritt, 1981). The red-backed vole is easily identified, except in juveniles, which are dark brown. The dorsum is russet or chestnut reddish brown, set off by ochraceous (almost yellowish)-grayish-tan sides. The sides are usually flecked with



Partial skull of Clethrionomys gapperi. Note hard palate shelf and molar teeth. 

dark blackish, a false pattern of guard hairs, but they are actually gray bases of the hairs showing through the pelage. A few brownish guard hairs in dorsal and lateral pelage are evident. The ventral fur is either a grayish or pure white, although up to 40 percent at some localities may show pale ochraceous or cinnamon buff. The pale coloration is conspicuous on the throat and lower cheeks, often extending as a ventral line to whitish feet and claws. The general effect is of a tricolored mouse, red-brown above, gray orange on the sides, and whitish below. The tail is medium



Maps showing geographic distribution of Clethrionomys gapperi in Wisconsin and North America. 

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in length. Six tubercles are reported on each hind foot. The coloration in juveniles appears as a rich rusty brown with just a tinge of russet. The venter in juveniles is brownish or gray with just a tinge of white. Young mice in winter attain adult coloration, which fur develops rapidly, faster than in summer. Molts reportedly are in autumn and spring. The coloration (reddish dorsum, whitish venter) and dentition clearly distinguish this species from all other arvicolines in Wisconsin. The longer tail clearly sets a red-backed vole apart from the short-tailed woodland (= pine) vole and southern bog lemming, which do resemble dark Clethrionomys. The tail is short to medium, and the ears rather prominent for voles. Jackson (1961: 225) gives external measurements as follows: Total length ranges up to 150 mm, tail only 32-42 in adults, hind foot 18-20, ear 14-16. Weights vary from 25 to 36 grams. Total length of skull ranges only to 24.8 mm, with the width of cranium varying from 12.0 to 13.6 mm. Dental Formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. Woodlands and swamps as far south as Dane County. This boreal mammal is found on islands in Lake Superior and Lake Michigan. The species does not occur in the deciduous woodlands and prairies of southern and western Wisconsin. See Map. Status. The red-backed vole is fairly common although seldom abundant, occurring in boreal communities and definitely beneficial to humankind. A valuable component of northern food chains, it eats many seeds and seldom comes in contact with human agriculture. Habitat. Red-backed voles are found in the boreal forests in Wisconsin, occasionally in swamps and marshes if some trees are present. They may be found on uplands and slopes of hills, or along sloughs and stream valleys. The soils may be rocky, of black dirt, sandy loam, overlain with leaf litter, or brush.

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Logs and stumps strewn over the forest floor seem ideal for this vole. They occur in hardwoods, conifers, mixed woodlands, tamaracks, quaking aspens, or silver maples in wetlands, but are most common in cedarbeech-hemlock, pine-maple, tamarack-maplehemlock, and spruce-fir forests. Red-backed voles thrive where deep snow lingers into spring. Getz (1968) suggested they prefer habitats near water. The species never occurs in grasslands, but may make short and poorly defined runways in ground vegetation near its home. It occasionally digs burrows resembling the tunnels of the shrew Blarina, and it tunnels under deadfalls, logs, torn out tree roots, rock outcrops (personal observations), and decaying stumps (see Fig.). Two nests were described by Jackson (1961) in Price County. These were excavated by following the tunnels. The first was found at the end of a side branch ten inches ( = 254 mm) in length, not off the main tunnel. It was surrounded by tree roots. The nest was a carpet of grass stems, parts of dead leaves, and mosses. The nest carpet entrance of a tunnel led Jackson to find a second nest. The main burrow led about 14 feet (4.3 m) from one elm to another and thence to a rotted stump under which (at a depth of 18 inch-



Burrow system of Clethrionomys gapperi. After Jackson (1961) and C. A. Long’s notes. 

es) the nest was found. The burrow extended about 3 inches below the surface. At each tree there were several branch passages dropping to depths of 12 to 18 inches. The nest was under a buried root of the rotted stump. This nest was about 4 inches in diameter and one inch deep, and comprised of a slightly hollowed but uncovered clump of dry leaves, bark, hazelnut shells, hemlock cones, twigs, sphagnum, and green mosses. The mosses were uppermost in the nest. Svihla (1930) reported grass-lined nests, and Banfield (1974) found nests in Canada occasionally in tree cavities or in limb crotches as high as 20 feet above ground. Nests can even be sited wit hin tunnels in the snow. Foods. The food contents in the stomach of the red-backed vole are finely ground. In Wisconsin they have been seldom examined. Red-backed voles opportunistically roam the woods feeding on plant parts, berries, and nuts. During the growing season they feed on grasses and in summer the contents of the stomach are often stained green. Hamilton (1941), in New York, found that nearly three fourths of the food was green vegetation finely minced. About 10 percent of stomach contents were remains of insects. Some spiders, snails and centipedes were also eaten. Fungi, bark and roots supplement the summer food (Schloyer, 1977; Banfield 1974). In autumn and winter the seeds of beech, pine, cherry, alder and dogwood are eaten as are hazelnuts, bark, buds, and grass seeds (Krefting and Ahlgren, 1974; Abbot and Quink 1970; Vickery 1979). Jackson (1961) adds to this list seeds of maples, hemlock, spruce, pin cherry, shadbush, black alder, mountain ash, blueberry, partridge berry, and Clintonia. Caches of nuts and seed were found including Rubus, Amelanchier and Vaccinium, but the vole may carry a food item into its burrow to eat it in security, giving the impression of hoarding food. There are no known winter caches. Reproduction. This vole is not sociable (Manville, 1949; Merritt, 1981). Females seem to exhibit territorial defense of their

home ranges (Mihok, 1979; Perrin 1981). Body weights drop in winter, so often tiny voles in adult pelage are taken in traps. Most reproduction ceases then, but voles may breed in winter. In our collection there are juveniles taken in winter. Both lactating females and juveniles were taken in late November. Most young enter the population in summer and September. There is a postpartum estrus. Svihla (1930) calculated the gestation period as about 17-19 days. Two litters 18 days apart suggest weaning may take place in 17 days. There could be four litters per summer, but in the usual Wisconsin pattern carry-overs usually produce spring young, and young-of-theyear produce autumn young. Probably Clethrionomys follows this pattern. They may not produce four litters in a year, but several over 12 months. Some voles live up to three years (Banfield, 1974). In Wisconsin the mean litter size was 4.75, with two modes (3, 6), and I observed a range of 3-6. The reported range is 2-8 for the species. Only seven pregnant females were in this collection, taken from February to late September (except for a few winter breeding records). A female from Poverty Island, Lake Michigan, in Michigan, had six embryos in August. Svihla (1930) described the young born naked with eyes closed, each weighing about 2 g. Fur begins to develop four days after birth. The incisors erupt by seven days, and the eyes open in 10 or 11 days. Mortality. The predators of red-backed voles include both hawks and owls because these voles are active day or night. Red-shouldered and rough-legged hawks, and an occasional red-tailed hawk catch them by day, and barred, great-horned, and screech owls take them by night (Banfield, 1974; Errington et al., 1940; de la Perriere 1970; and Jackson 1961). James Fitzpatrick (field notes, 1964) observed a snowy owl hunting where Clethrionomys was the dominant rodent. The rare great gray owl occasionally takes one. Bears, raccoons, coyotes, wolves, red foxes, weasels, striped skunks, badgers, bobcats, and TAXONOMIC ACCOUNTS / ORDER RODENTIA

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house cats all catch them on occasion (Pollack, 1951; Voigt et al., 1976; Long and Killingley, 1983). Probably short-tailed shrews (Blarina) eat them. Tapeworms, fleas, sucking lice, mites, chiggers, and ticks infest these mice (Jackson, 1961; Manville, 1949; Timm, 1975; Scharf and Stewart 1980; Merrit 1981). Being forest mammals they are often devastated by forest fires (Wrigley, 1975; Krefting and Ahlgren, 1974). Home Range and Density. Nothing has been done on ascertaining the home range size of this species in Wisconsin. Manville (1949) in Upper Michigan found a high density of 4.4 per acre in white cedar habitat. He found that females were territorial but males not so much. Occasionally red-backed voles aggregate in groups for winter. Robinson and Werner (1975) found 6 to 8 voles per acre in Upper Michigan. In Minnesota Gunderson (1962) found home range of about one third of an acre. In winter Beer (1961) found that voles kept to narrow, well-packed paths in home ranges about 0.25 acres. They seldom left the security of a brush pile or fallen log (of 17 mice recaptured). Blair (1941) found home ranges in the growing season as large as 3.6 acres for a mouse caught 22 times. No difference was found for home range size of males or females. Remarks. For remarks on the relation between Clethrionomys and Microtus pennsylvanicus, see account of the latter species. The red-backed vole is often taken with masked and short-tailed shrews (e.g., Timm, 1975). The red-backed vole is seldom abundant but reaches high densities in some years. On Washington Island, since the invasion of white-footed mice, red-backed voles seem scarce. Red-backed voles are active day or night, winter or summer (Merritt, 1981), and readily climb trees. Populations may have irregular multi-annual cycles. Red-backed voles are thought to be solitary but Pitts (1983) caught six adults in the same tunnel beneath a decayed stump. Long (1976) also made multi-

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ple catches of red-backed voles on St. Martin Island, Lake Michigan. One specimen (UWSP 1040) had a belted white color pattern, from Waupaca, Wisconsin. It showed the ventral white extending fairly continuously forward to each manus. Geographic variation. Colors are variable, and large samples are essential to compare color from place to place. The variability is constant geographically. The voles are brighter in winter. Additional Natural History. Merritt (1981) reviewed natural history of the red-backed vole. Geographic Variation. No geographic variation was observed in the red-backed vole. Specimens examined. Total, 296. Adams, Ashland, Bayfield, Clark, Columbia Co.: Portage, 1. Dane Co.: Town of Burke, Madison, 1. Door Co.: Washington Island, Pedants Lane, 14. Douglas, Dunn, Florence, Fond du Lac, Forest, Iron, Jackson, Juneau, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Marquette, Oneida, Ozaukee, Portage, Sawyer, Shawano, Sheboygan, Taylor, Trempeleau, Vilas, Washburn, Washington, Waupaca, Waushara, Wood counties. Other records. Jackson 1961; Pitts, 1983. Ashland Co.: All Apostle islands except Madeline and Long isles (Kantak, 1981). Monroe County; Johnson (1978). Widespread in Upper Michigan, see Baker 1983.

Genus Pitymys McMurtrie In Pitymys the lower first and upper third molars are primitive. The M/1 has the anterior island slightly constricted, with only two to three salient angles between it and the posterior loop. The upper third molar has only two islands (two closed salient angles) between anterior and posterior loops. The close resemblance of the complex molar teeth in P. ochrogaster and P. pinetorum persuades me to combine the two species in Pitymys. Repenning (1983) included Microtus quasiater for the same reason. Pa-

pers bv Pfaff (1990) support this combination. Pfaff found both Pedomys and Pitymys distinct back into the Irvingtonian, middle or early Pleistocene Epoch. This age suggests they may comprise a valid genus. DeCoursey (1957) had difficulty separating fossil ochrogaster and pinetorum even as species. He relied on such characters as enamel thickness, shape of the lower m/3s, and the variable distance between re-entrant angles (three labial and four lingual). Although teeth in American Pitymys differ from those of some Microtus, their simple pattern (Carleton, 1985) might support including Pitymys in a catch-all arrangement of Microtus. Zakrewski (1985) found Pitymys and Pedomys (P. ochrogaster) congeneric. Allozyme variation (Modi, 1987; Moore and Janecek, 1990), which provides different information than dentition, also shows quasiater related to ochrogaster. Two diagrams using the same isozyme matrix, the Rogers’ Genetic Distance dendrogram and the Unrooted Tree of Fitch and Margoliash, illustrate contrasting relationships. The RGD tree shows Pitymys pinetorum and P. ochrogaster in a related cluster if M. californicus and M. quasiater are included. This cluster is a subgenus if Microtus contains the entire assemblage. The Fitch-Margoliash diagram shows P. ochrogaster and M. (= Pitymys) quasiater related, but apart from a branch pinetorum and Microtus californicus. This suggests a basic difference between the two Pitymys branches, which is reflected by their habits and morphology. I think it argues for inclusion of both branches in a larger grouping, either in a separate genus Pitymys, or within the Microtus. One might also argue for four separate genera from these charts. And one might argue for several arvicoline (microtine) genera based on morphological characters. In six of six phylogenetic dendrograms, Modi (1987) found P. pinetorum and P. ochrogaster related, and Microtus californicus also close to them. In one of the six, pinetorum and ochrogaster were set apart from the other voles. With no consideration of the congruent and

complex cheek teeth, nor the paleontological origin of Pedomys and Pitymys, Shenbrot and Krasnov (2005) say “molecular data” support the narrow interpretation of the subgenus. Pedomys is somewhat related in molecular characters (not to M. xanthognathus).

Pitymys ochrogaster (Wagner) Prairie Voles 1842. Hypudaeus ochrogaster Wagner. In Schreber. Die Saugethiere... Suppl. 3: 592, type from America, probably New Harmony, Indiana (Bole and Moulthrop, Publs. Cleveland Mus. Nat. Hist. 5: 157,1942). 1853. Arvicola austerus Le Conte. Proc. Acad. Nat. Sci., Philadelphia, 6: 405, type from Racine, Wisconsin. This name is a junior synonym. 1898. Microtus (Pedomys) ochrogaster: J. A. Allen. Bull. Amer. Mus. Nat. Hist., 10: 459. 1966. Pitymys (Pedomys) ochragaster: Ellermann and Morrison-Scott. Checklist of Palearctic and Indian Mammals. British Museum Nat. Hist., P. 681. 1990. Pitymys ochrogaster: Long. The voles and bog lemmings of Wisconsin. Trans. Wisconsin Acad. Sci., Arts & Letters, 78: 88. See also Zakrzewski, 1985, The fossil record [of microtines]. Monographs Amer. Soc. Mammalogists, No. 8.

This binomen means ochraceous-bellied mouse. Because they are found in grasslands they are called prairie voles. Many workers follow Hall (1981) and a few others in assigning these voles to the diverse genus Microtus [When diverse genera are assigned to this genus, their overlaps allow assignment of other divergent genera to it, creating a sort of a variable catch-all taxon.] Usually workers focus attention on the distinctness of prairie voles by use of the subgenus Pedomys. I try to call attention to the close similarity of the dentition of P. ochrogaster with that of the pine vole Pitymys pinetorum. Assigning them to the genus Microtus does not accomplish that. The complex molar teeth both in TAXONOMIC ACCOUNTS / ORDER RODENTIA

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the upper and lower jaws are practically identical in the two species. That surely means common ancestry, which the use of Microtus obscures. Description. The prairie vole is stout and slightly grizzled, having slightly rusty ochraceous brown intermixed dorsally with buff, black, and gray hairs. The venter is usually overlain with bright ochraceous. The tail is of medium length, the ears short, and the eyes bright brown. The skull is more or less rounded in adults, but the braincase becomes more angular as the animals age. The auditory bullae are moderately inflated. The upper incisors lack grooves. The vole-pattern of prism development on the upper molars shows typical anterior loops, posterior loops, and intervening prisms, all of which are dentine islands surrounded by enamel walls. The middle upper molar lacks the distinctive minute loop or islet posteriorly, which characterizes the common Microtus pennsylvanicus. The posterior upper molar has fewer prisms (only two closed triangles, and with an elongate cshaped posterior loop) than M. pennsylvanicus, and the lower first molar shows a minor constriction (not entirely closed off) of the anterior loop resulting in fewer prisms than in M. pennsylvanicus. The lower third molar has three transverse loops with continuous dentine (i.e., no closed triangles). The teeth, regardless of complexity, closely resemble those of Pitymys pinetorum. A skull figure precedes Muridae. The cranium of P. ochrogaster is much narrower than that of P. pinetorum. See account of the pine (or woodland) vole for additional characters. The baculum of P. ochrogaster has a basal stalk and three minute prongs extending into the glans penis. It measures 3.2-4 mm in length (Stalling,1990). The chromosomes number 2N = 54, FN = 64 (Hsu and Benirschke, 1971). There are six mammae, but some have reported the typical Microtus eight. In closely related P. pinetorum there are only four. Often in P. ochrogaster only the four abdom-

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inal teats are used to nurse a litter. A hip gland prominent in M. pennsylvanicus is small or absent (Stalling, 1990). The color is generally a brownish gray with a rusty tone in the dorsal fur, which is flecked with blackish and buffy-ochraceous tips of hairs. The sides are similar to the mid-dorsum but paler, and the venter is gray washed with cinnamon-ochraceous or even orange or rarely rusty In young animals this ochraceous color, on the venter, is hardly developed, and the belly seems gray, but the coarse dorsal fur is distinctively gray (in M. pennsylvanicus the young are exceptionally dark brown with a slightly reddish tint). Hind feet are buffy brown with 5-6 tubercles on each. The bog lemming Synaptomys also has coarse redbrown fur but its tail is remarkably short and its upper iincisors are slightly grooved (see account of that genus). There is an annual molt in summer in P. ochrogaster, but it may occur (in a duration of three weeks) anytime in the year according to Stalling (1990). The molt begins pectorally, spreads across the undersides and upwards, and ends on the dorsum. There are two races differing significantly in size in Wisconsin. The males average slightly larger than females, but the sexes are similar in size according to Stalling (1990). See accounts for each subspecies below. Dental formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. Large prairie voles have ranged northward from the Illinois prairies into the southern and southwestern grasslands of Wisconsin, usually dwelling on the dry, well-drained slopes of the southern uplands. The minor vole ranges along the glacial sands left by the Wisconsin glacier, and occurs in low numbers in a band from Stevens Point, across the Wisconsin River westward, as far south as the Necedah National Refuge, and far westward of Wisconsin, always showing small size and dwelling in bleak, sandy habitat. Possibly this kind is one of the few Wisconsin taxa with western origin, which immigrated eastward into Wisconsin, or inva-

sions may have ranged northward along receding glaciers in several states. Status. This species is fairly abundant in some of the southern counties where the soil is sandy loam, usually on the highlands with sparser vegetation and in scattered cedars and prickly pear. It often comes into contact with Microtus pennsylvanicus although the latter prefers more moisture in its diet and habitat. The prairie vole is important in the food chains of carnivores, raptors, snakes, and other predators that live in the high, dry prairies. It feeds on weed seeds and on some insects. Prairie voles do not make much impact on agriculture in Wisconsin according to Martin (1956), Crawford (1971) and Jackson (1961). The larger prairie voles in the southern subspecies (P. o. ochrogaster) are not in any apparent peril, although herbicides and destruction of the prairies themselves may decimate and eradicate some future populations. As for the minor prairie vole, which does not intergrade with the other prairie vole in Wisconsin, and which may be a valid species, it is perfectly harmless and is in great peril. In central Wisconsin it seems to have been eradicated, not so much by agriculture but by deliberately combining plowing and fire to control vegetation and prevent wild fires along railroad tracks. The known populations are



Photo of central Wisconsin Pitymys ochrogaster minor. This rare mammal’s population was eradicated. 

no longer there. This race (or perhaps a species) seems destined to vanish from Wisconsin before we know about it. Habitat. The prairie vole prefers dry prairie or old fields with more or less sparse vegetation including Andropogon, Panicum, Sorgastrum, Poa, forbs, lichens, some brush, such as wild plum, hazelnut, brambles, jack pine, and other short, stubby grasses. Occasionally the dry habitats merge with more lush vegetation, dense grassland, alfalfa, and so forth. Microtus pennsylvanicus may co-exist with prairie voles in such dry-wet grasslands. In general the prairie voles inhabit western and southern grasslands in Wisconsin, following along unplowed railroad rights-ofway, roadsides, and ranging into jack pineoak savannas, cedar glades, and weedy fields. This vole often makes its surface runways and burrow systems in soils of sandy blowouts and sandy prairies, on well-drained highlands and weedy slopes, and in cut-over grain fields, hazelnut groves, and occasionally open meadows and oak groves. It avoids wet places such as marshes, seldom occurs in woods, and never in forest. Jackson (1961) stated that the preferred habitat was “native prairie sod.” Extending all about the home are numerous surface runways, which are conspicuous paths, where obstacles such as large stones are avoided, plants cut off, and the trails are occasionally rutted or trenched in the soil. Piles of cuttings are often evident. A runway may extend as far as 70-80 feet (22-24 m), and occasionally farther. They average about two inches (5 cm) in width. Many show signs of excavation as ruts. One or several openings lead into underground tunnels (Getz and Carter, 1996). Grass cuttings are often used for the nests and found with food caches (Hoffmeister, 1989). Getz and Carter (1996) describe the nest as approximately 10 to 15 cm in diameter, comprised of tightly interwoven and finely shredded grass. Materials are opportunistically used to protect nests, such as a piece of plywood left in a field, bark or rocks. Nests occasionally are found above TAXONOMIC ACCOUNTS / ORDER RODENTIA

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ground. Prairie voles pile excavated dirt over a nest site forming a mound (Getz and Hofmann, 1986). The tunnel entrance to the underground nest is about one and one half inches (3.6 cm) in diameter. Getz and Carter (1996) recorded a diameter of approximately 3 cm. Often excavated soil is thrown out the entrance. The tunnel drops nearly straight down, and is more easily dug in sandy soil. Its depth ranges from “a dozen or more centimeters” below the surface. Jackson (1961: 239) described a nest in Sauk County made of barley



Maps showing geographic distribution of Pitymys (= Microtus) ochrogaster in Wisconsin and North America. 

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grasses, 5 1/2 inches (138 mm) in greatest diameter by four inches wide by three inches depth. The entrance into the nest chamber was about 7/8 inches (24 mm) in diameter. Foods. Cole and Batzli (1979) found that succulent forbs were required in the diet of the prairie vole. Cole (1977) had previously reported that prairie voles eat clovers (Trifolium sp.), dandelions (Taraxacum), alfalfa, Penstemon, Ambrosia, Solidago, Poa pratensis, some timothy (Phleum), and big bluestem (Andropogon) in Illinois. In winter, Long (1968b) found wild plum seeds cached and eaten, in central Illinois. Each seed was opened the same way on the same side. Roots and mosses were eaten in winter and spring, and Long also reported gnawed roots. Fisher (1945) found large caches of horsenettles, and Criddle (1926) found caches of wheat, rye, and oats made by P. o. minor. In Indiana important foods were bluegrass, red clover, lespedeza, tumblegrass, and roots. Energy budgets were studied by Fleharty and Mares (1973). Getz and Carter (1996) suggest that essential forbs are not always available to prairie voles. Famine affects the social system (see below) and cyclic densities. Reproduction. In southern Wisconsin the praire vole may breed most of the year, but little if any in winter. A female may produce several litters in a year. Gestation is about 2021 days. Litter size is about three or four (range 2-6). Young weigh 2-3 g at birth, and are born naked with eyes closed. Pelage grows rapidly and the eyes open after 9-10 days. By the 17th day, the young are furred and can forage for food (Fitch, 1957). The young can breed in 36-40 days perhaps even in 26 days (Stalling, 1990). According to him, the young are born 30-35 mm in length, with eyes closed. The only records of reproduction I have from Wisconsin are as follows: P. o. minor lactation 22 July, 2 subadults Sept. 25 and 20 October; P. o. ochrogaster testis 12 mm on 3 July, young on 1 July and 1 November. The voles usually live less than a year, but Getz (1965) kept one in captivity for 35 months.

In Illinois the prairie vole has young in any month, but none was observed pregnant in August or January by Hoffmeister (1989). In 330 adult females, 94 contained embryos (mean 3.67, 1-8) according to Hoffmeister. Cole (1977) found 56 females in bluegrass habitat to average 3.66 embryos; in alfalfa the average litter size was 5.03 (N = 30) in summer and in autumn 5.19 (N = 21). A chemical signal, a pheromone, in the male’s urine stimulates estrus in virgin females. The pheromone is usually received from an unfamiliar (probably not closely related) male by sniffing of the genital area. In two days she achieves estrus and mates. The female usually has a post-partum estrus, mating again and usually with her original mate (Getz and Carter, 1996; Carter and Getz, 1993; Hofmann et al., 1984; and McGuire and Getz, 1991). Growth was discussed for captive prairie voles by Hoffmeister and Getz (1968). Skulls are judged adult when the basioccipital-basisphenoid suture closes. In old adults the cranium becomes angular in dorsal view. Mortality. Prairie fires kill many prairie voles in Wisconsin, and may destroy the habitat in thin, sandy soils with little vegetation, preventing re-establishment of the vole populations. Hard winters might destroy some populations of voles in Wisconsin, for the prairies suffer deep frost where the winds clear off the snow. Predators that feed on prairie voles include several kinds of raptors of prairie and savanna (Stalling, 1990). These include kestrels, marsh hawks, red-tailed and rough-legged hawks, and prairie dwelling species of owls. Weasels, striped skunks, badgers, foxes, and coyotes eat them, and rattlesnakes, fox snakes and bull snakes catch a few. Garter snakes probably eat young voles. Getz et al. (1990) discussed the important impact of snakes on numbers and social organization of prairie voles in Illinois. In Wisconsin snakes are not abundant, not in the central parts of Wisconsin certainly, and they probably enter hibernation sooner. The competition with Microtus pennsylvanicus often TAXONOMIC ACCOUNTS / ORDER RODENTIA

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drives the prairie voles from lush vegetation onto bleak sandy soils where runways are less protective (bordered with thin growths of grasses). The voles may have less contact with forbs, berries, and other foods. Drought and loss of available water also play a role in mortality. Parasites include five species of fleas, one chewing louse, six mites, and internal trematodes, cestodes, and nematodes (Jackson, 1961). Timm (1985) listed cestodes, spiny-headed worms, mites, ticks, lice, and fleas. Little is know about diseases in these voles, but the numerous ectoparasites possibly transmit some diseases to humans and other mammals on contact. Home Range and Density. The home range (Jackson, 1961) is between 0.1 and 0.2 acres. Swilhart and Slade (1989) found males to utilize much larger home ranges than females which suggests a promiscuous mating system. Stalling (1990) gives home range values as 0.11-0.22/ha. Usually the home range, larger in males, is less than 0.1 ha. Density may be as high as 20 per acre. Getz et al. (1979) found peak densities of the larger prairie voles in Illinois in alfalfa mixed with goldenrod and grasses, as many as 240 mice per ha in November. Lowell Getz (personal correspondence) told me that the number was as high as 638 per ha in 1985. They found only 110 in July 1976. In 1974, there were fewer than 10 per ha. In some populations there are only annual cycles (Getz et al. 1987). The presence of some other species seems to decrease prairie vole abundance, as Sigmodon in Kansas, and M. pennsylvanicus in Illinois (Stalling, 1990). Where vegetation is sparse the voles are fewer (Fitch, 1958, in Kansas; Mumford 1969, in Indiana). Getz et al. (1981) found prairie voles dispersing along railroad rights-of-way. The populations of P. o. minor that formerly occurred in Portage County, Wisconsin, were either in such areas or near them. The minor subspecies seems never to have been common in central Wisconsin. It was local in distribution, and was also found on thin sandy soils or in sand barrens near dry prairie near Necedah.

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Remarks. Active day or night, especially before dawn or darkness, the prairie vole goes about its activities of feeding, nesting, and breeding. It is often (exceeding half the breeding adults) monogamous, and stays mated for relatively long periods (Getz and Hofmann 1986). These sociable and “comical” mice threaten, box, wrestle, and play, but with little actual fighting. They are not so likely to kill one another, or to foul their surroundings, as are captive M. pennsylvanicus. Having less need for water (Getz, 1963) the animals seem cleaner and in my care made excellent pets. Jackson (1961) also believed prairie voles in Wisconsin were more colonial and sociable than meadow voles. In my experience that is true, in either P. o. ochrogaster or diminutive P.o. minor of central Wisconsin. Although they threaten one another by standing as tall as possible and gaping, there is little biting. Often they cuddle together. Thomas and Birney (1979) described parental care and the mating system in this species for Minnesota. The social behavior and mating system have been well studied in central Illinois by Getz (1993), Carter and Getz (1993), Getz et al. (1992), Getz et al. (1993), Hofmann et al. (1984), McGuire et al. (1993); McGuire et al. (1990), and Getz and Carter (1996). Briefly the mating and social behavior is sketched as follows. Based on 25 years of laboratory and field studies and monitoring of 850 free-living social groups of prairie voles, Lowell Getz and his associates found several mating systems that showed variance due to certain factors. These were chiefly the quantity of foods and the population density. In a species known for periods of low and remarkably high abundance, sometimes cyclic (i.e., multi-annual), an abundant food supply permits population growth, whereas mortality, especially predation, lowers density. The main social group is the monogamous pair, with or without young. The paired adults stay together, sharing nest and home range. The male contributes “considerable time and effort” constructing and maintaining a nest,

helping groom the young, and retrieving them when they wander from the nest. Unfamiliar adult males are excluded from the nest. Threequarters of such pairs persist until one mate dies. A widow remains alone, or stays with young. Thus, the single female consitutes a second, derived social group. A widower wanders away from the nest. Between 24-45 percent of the small adult voles wander unattached. The third group is communal, an extremely interesting “extended family”, comprised mainly of the breeding adults and their offspring. These may have grown to maturity, remain in the natal nest, and may help in the care of the young. Such a group is “philopatric.” Getz and Carter (1996) report that 68 percent of males and 73 percent of females remain “at their natal nests.” Males and females that seem “unrelated” may join the extended family. However, 70 percent of the adults, in addition to the parents, are philopatric offspring (that stayed home). Of wanderers, the unattached female usually finds welcome in a nest, either as a single or joining in a pair. Group members seldom (not more than 4 percent) switch to other groups. The social groups vary in size seasonally. Communal living increases in mid-October (in central Illinois) and remains high in winter. The group size averages 8 voles at these times, and often may exceed a dozen. After suffering winter mortality, the survivors of various communal groups pair anew, mixing members of different families. Incest in families of monogamous parents is prevented, and in communal groups there is mostly outbreeding. This rules out inbreeding, which is often a cause of a communal clan system, with breeding restricted to one or two pairs. Another cause for such a system is patchy environment. Both the runway-system, extending in branching patterns that do not fill the areal space, and the lack of sufficient foods to feed large populations could account for such an extended family system. Getz and Carter (1996) discuss the latter, i.e., when forbs may be in short supply. Monogamy and

philopatry are adaptive in keeping young voles secure at home where food and mates are easier to find in times of plenty. When food is abundant, monogamy is not strictly practiced. Geographic variation. The two distinct races do not overlap or intergrade; they are allopatric in Wisconsin. Habitat differences and intervening woodlands and river bottoms keep the two kinds apart. Accounts of the two subspecies are below. Information above is for the species.

Pitymys ochrogaster ochrogaster (Wagner) Prairie Vole 1842. Hypudaeus ochrogaster Wagner. In Schreber’s Saugthiere... Suppl. 3: 592.Type America, possibly New Harmony Indiana. 1898. Microtus (Pedomys) ochrogaster: J. A. Allen. Bull Amer. Mus. Nat. Hist., 10: 549. 1853. Arvicola austerus Le Conte. Proc. Acad. Nat. Sci. Philadelphia, 6: 405. Type from Racine, Wisconsin.

Description. See account of the species. For comparison with P. o. minor, see account of that race. Some measurements in mm of three specimens from Lynxville average as follows: Total length, 153 (152-155); length of tail, 39 (38-40); hind foot length 18.7 (1819); greatest length of the skull 26.8 (25.826.9); length of the maxillary tooth-row 6 (5.6-6.5); zygomatic breadth 15 (14.9-15.1); interorbital breadth 4 (3.95-4.1); cranial depth 9.6 (9.6-9.7); and length of nasals 7.55 (7.57.6), and weights 47 (44-50) g. Geographic Distribution and Status. See account of the species. See Map. Specimens examined. Total, 23. Crawford Co.: Lynxville, 3 USNM. Dane Co.: Beeny, Sec. 18, T8N, R7E, 1 UW-Madison. 5 mi. N Cross Plains, 1 UW-Madison. Dodge Co.: Beaver Dam, 1. Rock Co.: Milton 5 UWMadison. Sauk Co.: Pleasant Valley Road, near Sumpter Church, 3. 1/4-3/4 mi,. S, 2 mi. W Prairie de Sac, 3. 4 mi. W Prairie de Sac 4. TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Pitymys ochrogaster minor (Merriam) Minor Prairie Vole 1888. Arvicola austerus minor Merriam. Amer. Nat. 22: 6. Type from Turtle Mountains, lower slopes, Bottineau Co., North Dakota. 1942. Microtus ochrogaster minor: Bole and Moulthrop. Science Publs. Cleveland Museum Nat. Hist., 5: 160. 1990. Pitymys ochrogaster minor: Long. Trans. Wisconsin Acad. Sci., Arts and Letters, 78: 94.

Description. There is only one significant difference noted between the two voles, that of size. Their behavior and habitat preference are also somewhat different. The auditory bullae are relatively more inflated in P. o. minor, although the opposite has been reported. Not one large vole has been found in central Wisconsin. That is highly significant. The cranial measurements in mm of six adults from Stevens Point are 24.6 (24.1-25.6) for greatest length of the skull, zygomatic breadth 13.7 (13.5-13.9), interorbital breadth 3.95 (3.84.0), and length of the nasals 6.59 (6.7-7.3). One specimen from Clark County was, respectively, 25.9, 13.4, 3.8, and 7.0 mm. Geographic Distribution. See Map. Cory (1912) speculated on this little vole’s presence in Wisconsin. It escaped notice until I began catching them, with never an adult obtained as large as would be found in the southern subspecies (see Long, 1976). The race seems to have extended its range on glacial sands from Minnesota, where it also is imperiled, especially by land use. Intergradation between the large and small voles was once reported, since disputed, in southeast Minnesota, which intergradation ought to be studied. There is no sign of it in Wisconsin. The two races approach one another in two areas, but are separated by about 40 miles (64 km). Status. This little vole is in grave peril. No specimens have been taken in central Wisconsin in over ten years. Plowing the habitat is extremely detrimental to this vole, which

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persists on thin, sandy soils. When plowed into the sand, the habitat is destroyed. Habitat. Wydeven and Wydeven (unpublished report, 1976) collected P. ochrogaster minor and M. pennsylvanicus together at a sandy habitat near the Little Plover River, called the Stream Lab. The meadow vole preferred the lush and dense vegetation. After the grasses were burned off the land was plowed with the result that these voles vanished. Eradication also was the case along the Soo Railroad tracks at the edge of Stevens Point, near the Country Club, and the property later was developed (sodded, fenced). After fire and plowing this population also vanished from the right of way. Specimens examined. Total, 29. Clark Co.: Brick Creek, near Owen-Withee, 1. Foster Twnsp., 2 UW-Madison. No specific locality 1. Juneau Co.: 4.5 mi. N, 1 mi. W Necedah, 2. Portage Co.: Stevens Point, 14. Whiting, 2. Plover, 5. 8 mi. S Plover, 1. Waushara Co.: Saxeville, 1 UW-Madison.

Pitymys pinetorum (Le Conte) Pine Vole or Woodland Vole 1830. Psammomys pinetorum Le Conte. Ann. Lyc. Nat. Hist., New York . 3: 133. Type from pine forests of Georgia, probably near the Le Conte Plantation near Riceboro. 1841. Arvicola scalopsoides Audubon and Bachman. Viviparous Quadrupeds of North America. p. 97. Type from Long Island, New York. 1896. Microtus pinetorum: Miller. N. Amer. Fauna, 12: 9. 1858. Arvicola kennicotti Baird. Mammals. In Reports Explor. Survey... 8(l): 547. Type from Illinois (see Long, 1990, for discussion of specimens examined by Baird). 1894. Arvicola pinetorum: Ellermann and Butler. Proc. Indiana Acad. Sci., p. 127. 1966. Pitymys pinetorum: Ellermann and MorrisonScott. Checklist of Palearctic and Indian Mammals. British Museum (Nat. Hist.), London.

1990. Pitymys pinetorum: Long. Trans. Wisconsin Acad. Sci., Arts and Letters.

The binomen means a mouse from pine forests, but seldom is this mouse found in them. For that reason in recent years the name “woodland vole” is often used for a common name. The name of the synonym P. p. schmidti honors an amateur naturalist, F. J. W. Schmidt, from Clark County, Wisconsin, and the name kennicotti honors a naturalist, Robert Kennicott, from the Chicago region. Description. The body is modified for fossorial life, in that the head is broad, the forefeet and foreclaws well developed, the tail short for turning about in the burrow, and the fur is soft and fleecy, said to be “mole like.” The behavior is likewise curious and fossorial, for the mice seldom leave the tunnels, throw up dirt in the fashion of moles, and are exceptionally difficult to catch. (I have tried and never caught one.) Although the teeth are similar to those of P. ochrogaster (see account of that species), the skull is so much broader it can be identified (see key to voles and bog lemmings in Microtinae). Reportedly there are six tubercles on the hind foot. Chromosomes number 2N = 62, FN = 62 (Hoffmeister, 1989). There is a report of eight mammae; most agree to six. The baculum’s stalk has three distal calcified projections. The dentition is discussed under the account of P. ochrogaster, and in the key. Although the teeth are similar in P. ochrogaster and P. pinetorum, they occur in different habitats, i.e., prairie grasslands and deciduous



Photo of Pitymys pinetorum. By Karl H. Maslowski. 

woodlands, respectively. The pine vole also superficially resembles the red-backed vole (see account of that species) and the bog lemming, which has coarser, grizzled fur and a groove on each upper incisor (see account of that species). The western race, P. p. nemoralis is reddish and comparatively large, judging not only from the single specimen Jackson reported, but based on numerous specimens examined from the race itself. The pine voles in central and southern Wisconsin (P. p. kennicotti) are duller in color, even in pelage showing its maximum coloration between molts. The dull brownish voles do show a reddish tint, more chestnut than red, but a dull walnut (purplish as in some walnut wood) brown is the dominant tint. That color becomes constant southward into Illinois. Baird examined, and his name was based upon, some of the same pine voles that I examined on loan from the Chicago Natural History Society collection. They differ from the reddish voles westward and eastward. The name by Baird seems appropriate; the name by Jackson is a junior synonym. I have no idea what color the pine or woodland voles are in southern Michigan. A darker fur is replaced in May or June by a lighter fur, and a winter molt begins in November (Smolen, 1981). According to Reich (1981) the annual molt is mostly of underfur. For P. p. scalopsoides from eastern states, some measurements in millimeters are as follows: Total length, 121 (110-133), tail length (very short) 21.3 (16-24.5), hind foot 16.6 (14.5-18) where N is 25. For Wisconsin voles some external measurements are from Clark County (N = 4), as follows: 119-127 in total length, length of tail 20-23, and in length of the hind foot, 16.5-18. They are 110-126, 14-16, and 16-18 from Wood Co. (N = 3), and one from Sauk Co. 109, 17, and 15, respectively. Some cranial measurements for three specimens from Wood County are in mm as follows: greatest length of the skull mean 25.1 (range 23.1-26.2), zygomatic breadth 14.1 (range 13.7-16.0), and interorbital breadth 4.6 mean (range 4.5-4.75). TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Dental formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. Found locally in leaf litter, with some clay in the soil, and probably with affinity to relict hickory-maple woodlands. Pine voles seem confined to hardwoods or mixed hardwoods in the southern half of the state. Occasionally they range from the thick humus and clay-loam soils of the woodlands into weedy pastures, road rights-of-way, or orchards. A western race has managed to cross the Mississippi River into western Wisconsin, but so far



Maps showing distribution of Pitymys pinetorum in Wisconsin and North America. 

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is known from a single specimen. The more widespread race has extended its range northward in the past as far as Clark and Wood counties, and long ago as far as the Door Peninsula. Today it is found in very few localities. There is a questionable record from Brown County, which Jackson (1961) reported as pinetorum (based on a lost specimen in the Neville Museum, in Green Bay). See Map. Status. As mentioned in the Distribution, the populations are local and small. Possibly all populations are relicts from an earlier warm Holocene time period. The vole is beautiful, and in Wisconsin seems to live apart from our agriculture. It follows that the Department of Natural Resources Bureau of Endangered Resources might want to takes steps to preserve this endangered species. In a survey of nuisance voles, of those that do humankind the most damage, the pine vole was rated the worst in the United States, especially injurious in orchards. It is a difficult problem to justify preserving such a pest. In Wisconsin the pine vole is so interesting a mammal, filling a niche like some sort of forest-dwelling mole, and so uncommon, it might well be preserved. No species is bad everywhere. In Wisconsin, the species probably fills a useful role in the food chains of deciduous woodland predators. It makes soil, kills insects, and eats plant parts when in that kind of habitat. Habitat. Pine [= Woodland] voles prefer deciduous woodlands with clay soils (not much sand), covered with thick leaf litter and mold, under which the dirt from tunnels and hills aand excavations are evident. The fallen leaves are primarily maple with hickory observed at all localities I have seen in Wisconsin (Schmidt, 1931; Long 1974; Long, 1990). These voles also range into overgrown fields not far from their woodland sources. The distribution, as mentioned above, is local and many suitable habitats seem uninhabited by these voles. They are difficult to catch in traps. Jackson (1961) reports pine voles from grazed red and white oak woodlots having friable top soil, a habitat I have personally not

seen, and from beech and hemlock woods, also which I have not seen. He also mentions sandy soils and brushland (see also Pool, 1932; Jameson, 1949). The tunnels and mound systems I have observed require clay to resist collapse. The pine vole occurs in a wide range of habitats outside Wisconsin (Paul 1970). It is most commonly taken in hardwoods (maple, hickory, oak) forests but in southwest Wisconsin numerous burrows were found on a dry, grassy hillside. In Clark and Wood counties the burrows ran under maple leaf litter in gray sandyclay loam soils that roofed the burrows. When abundant, meadow voles may replace Pitymys in competition (Paul 1970). This burrowing rodent approaches in behavior that of the moles (see Talpidae) as it excavates tunnels and throws up hills in friable soil under thick leafy litter. Usually the burrow extends immediately below the surface, raising up the soil above it in a mole-like run. It may descend as low as several inches [~75 mm], and occasionally as deep as a foot [0.3 m]. The nest cavity may be an enlargement of the tunnel or in a side branch often protected above by a stump or tree root. Dry leaves and grasses are wadded into the tunnel, and two or three entrances penetrate this nest. Schmidt (1931) describes the nests of voles from Clark County as follows: “Two nests were located... two inches below the surface... traps set at the entrances of the nests caught both adults and half grown young. These nests had an outside measurement of 100 mm, and were constructed of maple leaves... The surface burrows of pine voles were constructed just below the leaves, and they often form a network covering several square yards. From these burrows under the leaves other burrows penetrate the soil. Dirt brought up from below is left under the leaves. This distinguishes the mounds from those of Condylura cristata, which are piled up on top of the leaves or grass... In diameter the burrows of pine mice are 30-35 mm wide and 25-30 mm high. Pine mice burrow both day and night... Mice caught shoving out dirt were always coming out head first.”

Foods. Smolen (1990) lists foods of pine voles in New York and Pennsylvania as grass TAXONOMIC ACCOUNTS / ORDER RODENTIA

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roots and stems in summer, fruit and seeds in autumn, and bark and roots in winter. Dentition of the pine vole not only resembles that of P. ochrogaster, but the foods do likewise, even from different habitats. Forbs and shoots of grasses probably were the foods eaten in spring. No doubt these voles also feed on grubs, and perhaps worms. Worms are difficult to find in stomach contents, but seem likely for a molelike mammal to eat. There may be more diverse fare than so far discovered, but the primary foods seem to be roots and parts of plants. In the eastern states this vole emerges from its burrows to feed on bark, and causes extensive damage to orchard trees. Schmidt (1931) reports tubers of Dutchman’s breeches, and an unknown tuber as foods. Hoffmeister (1989) reported food contents of 13 pine voles taken in autumn in Indiana consisting of roots, green vegetation, and mast, in 63 percent of the food volume (and at a frequency of 96 percent). There also was a little insect material and the fungus Endogone. When these voles are found in grassy vegetation one presumes they eat parts (probably roots and bulbs) of grasses and forbs (see Benton, 1955), and berries. Domestic strawberries and blackberries were eaten. Reproduction. Not much information is available on reproduction in Wisconsin pine voles, so we must rely on other states for such studies. Pine voles produce fewer and smaller litters than do M. pennsylvanicus according to Schadler and Butterstein (1979). Apparently in Michigan the pine vole can reproduce at a high rate (Linduska, 1950). At milder latitudes the pine vole can sometimes breed year round (Paul, 1970). Peak reproduction takes place in July and August (Kirkpatrick and Valentine 1970). Hoffmeister (1989) reported Illinois pine voles to breed in March and April and into November. In Wisconsin the breeding season is probably similar, perhaps a little shorter than this. Females are aggressive in courtship according to Benton (1955). Gestation is about 20-24 days. Litter size averages about 3 (2-5 embryos, rarely more but up to 7). At birth each young weighs about 2 g and is naked and blind. In 9

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days young are active, well furred, and the eyes are beginning to open. Eyes open by 12 days, and the young are weaned from 16-24 days. The young weighs then about 15 g, almost 2/ 3 the adult body weight. Males begin breeding at about 7 weeks, and females in 10-11 weeks. There seems to be a postpartum estrus. The young pine voles can be aged by the weights of the eye lens (Gourley and Jannett, 1975). Additional information on growth and development is summarized by Smolen (1990). Mortality. Jackson (1961) and Schmidt (1931) suggested carnivores such as weasels and skunks, snakes, and especially short-tailed shrews were predators of pine voles. No studies have been made in Wisconsin. Land use, such as lumbering or developing a ski run in their habitat at Powers Bluff, Wood County, could be an adverse problem for that local population. Some known predators from elsewhere include red fox, gray fox, raccoon, house cat opossum, least weasel, and mink. Smolen (1990) recently listed avian predators, barn, long-eared, short-eared, barred, screech and great-horned owls, as well as red-tailed, broad-winged, and marsh hawks. Parasites include a cestode (Catenotaenia), the whipworm nematode Trichurus, and a spiny-headed worm (Benton, 1955; Doran, 1954). Fleas, sucking lice, and mites infest the fur (see Baker, 1983). A complete listing of parasites for this species is provided by Smolen (1990). Timm (1985) also reviewed parasites including ticks, the parasitic beetle Leptinus, and the botfly Cuterebra. Home Range and Density. Burt (1948) reported the home range to be only one-fourth acre, and the maximal home range for an adult male was 93 yards in greatest diameter. Actually the home range is confined for the most part to the burrow system. The mice can live at least a year (Burt 1940; Miller and Getz, 1969). Miller and Getz found only 19 percent of the mice marked in their study in recaptures up to two months later. Being non-territorial and inhabiting burrow systems, adults of both sexes and subadults mingle freely (Smolen 1990).

There are fluctuations in population size of the pine vole (Benton 1955; Gottschang 1965; Burt 1940). Miller and Getz (1969) working in Connecticut found the species to fluctuate from 0 to 5.8 voles per acre over a five-year period. Gettle (1975) working in Pennsylvania found voles to attain a peak of 49.2 per acre. Hamilton (1938) found them thriving in New York orchards at 300 per acre. In Wisconsin there is no evidence for high densities such as these. Remarks. In their burrow systems, pine voles are active day or night. Schmidt (1931) found a young Wisconsin pine vole completely docile, but an adult he kept leaped at him and threatened to bite his finger. A curious anomaly that would probably confuse a worker trying to identify P. pinetorum was observed by Fish and Whitaker (1971), which was a specimen having grooved upper incisors as seen in Synaptomys cooperi. Additional Natural History. Smolen (1981) wrote a thorough review for the pine vole. Geographic variation. As mentioned above, there are two races, but the western one is known from a single specimen in western Wisconsin. The races are distinctive in both size and color.

Pitymys pinetorum kennicotti Baird Kennicott’s Pine or Woodland Vole 1858. Arvicola kennicotti Baird. Mammals of the Explor. Pacific Railway route... Part 1 Mammals, p. 547. Type from Illinois, and the specimens I examined were from northeast Illinois [Chicago Nat. Hist. Soc.]. They are inseparable from the synonym Microtus pinetorum schmidti Jackson, but distinctive from P. p. scalopsoides eastward and P. p. nemoralis westward. 1912. Microtus pinetorum scalopsoides (Audubon and Bachman). In Cory. Mammals of Wisconsin and Illinois, Chicago Field Mus., 11: 222, and others. 1941. Pitymys pinetorum schmidti Jackson. Proc. Biol. Soc. Washington, 54: 201. Type from Worden Twsp., Clark Co., Wisconsin. 1990. Pitymys pinetorum kennicotti: Long. Trans. Wisconsin Acad. Sci., Arts and Letters. 78:90.

Geographic Distribution. See map. Found in southern Wisconsin in suitable habitats. Status. See account of the species above. Specimens examined. Total, 12. Clark County. Worden Twsp. 4 USNM; 1 UWM (I also saw one collected by Schmidt in the Leningrad (Petersburg) Zoological Institute. Dane Co.: Town of Vermont 1 UWM. Westport 1 UWM. Sauk Co.: Klondike Pond 2. Wood Co.: Powers Bluff 3. Other records: Illinois: Long, 1990, in northeast Illinois 20 specimems.

Pitymys pinetorum nemoralis V. Bailey Great Plains Woodland Vole 1898. Microtus pinetorum nemoralis V. Bailey. Proc. Biol. Soc. Washington, 12:89, type from Stilwell, Oklahoma. 1990. Pitymys pinetorum nemoralis: Long. Trans. Wisconsin Acad. Sci., Arts and Letters, 78:90.

Jackson (1961) reported one specimen from Lynxville, Crawford Co., Wisconsin, collected July 31, 1930, under leaves and dry grass close to an old brush heap on a dry hillside 50 feet above water level of the Mississippi River. There were many burrows and runways under the leaves. Two workers (Van der Meulen, 1978; Repenning, 1983) consider this large red vole to be a distinct species, on criteria of size and morphology of the teeth. Study is necessary to confirm this opinion. Description. The size of this pine vole is large, with massive teeth. Size and chestnut-reddish brown color are the only distinguishing features. The holotype of P. p. nemoralis is dark rufescent, and the topotypes are not only large but quite broad across the zygomata. Specimens from Minnesota and Iowa have been assigned to P. pinetorum nemoralis, and in size and color the distinctive Lynxville specimen agrees closely with the type and topotypes.

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Specimen examined. Total 1. Crawford Co.: Lynxville, l USNM.



Meadow Voles. Ernest Thompson Seton. 

Genus Microtus Schrank Meadow Vole and Allies Teeth elaborate, lower first molar with deep constrictions forming separate islands or prisms, five salient angles between anterior island and posterior loop, upper third molar elaborate with three closed prisms (three closed triangles on either side) between anterior and posterior crescentic loops. Microtus pennsylvanicus is a large, long-tailed, dark brown vole.

Microtus pennsylvanicus (Ord) Microtus pennsylvanicus pennsylvanicus (Ord) Meadow Vole

The binomen means a tiny-eared animal from Pennsylvania. Description. The largest, darkest vole in Wisconsin, the meadow vole often exceeds 160 mm in length. It has a long, blackish tail, blackish gray-brown feet, and its belly is overlain with whitish, pale buff (and surprisingly, occasionally in rust, reddish, cinnamon buff, or ochraceous). The skull, rostrum, and nasals are long and narrow, the braincase well extended posteriorly. The upper third molar consists of an anterior loop, three closed prisms, and a distinct posterior crescentic loop. In the middle upper molar an extra small posterior loop is squeezed in, rarely absent in adults. The lower first molar is pinched (constricted) anteriorly, so that there are five closed prisms behind the anterior loop. This species is identified with certainty by the minute loop of the middle upper molar, and the identification confirmed by the extra prisms in upper third and lower first molars. The skull varies to 28.6 mm in length, the yellowish incisors projecting forward. The incisive foramina exceed 5 mm in length. The baculum is a stalk with three calcified projections. There is a slight reddish (not ochraceous) cast in the dark walnut brown underparts (especially in late summer and fall), which are evenly colored and hardly grizzled at all. The dorsal pelage, long and lax in winter, is remarkably constant in color throughout the state.

1815. Mus pennsylvanica Ord. In Guthrie, A new geography 2nd Amer. Ed., vol. 2, p. 292. Type from “Meadows near Philadelphia,” Pennsylvania. 1895. M[icrotus]. Pennsylvanicus: Rhoads. Amer. Nat., 29: 940. 1841. Arvicola fulva Audubon and Bachman. Proc. Acad. Nat. Sci. Philadelphia, 1: 96. Type from a “western state”, probably Illinois. 1858. Arvicola riparia var. longipilis Baird. Reports of an Explor. Survey... Part I, Mammals, Type from West Northfield, Illinois, or Racine, Wisconsin.

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Skull of Microtus pennsylvanicus.. 

In ventral coloration the range of whitish to buff to buff-ochraceous and rarely even darker rust varies remarkably, based on a scale of pale to dark ochraceous, one to five. The standards are (1) specimen UWSP No. 1610, pure silvery white; (2) buffy white No. 377; (3) whitish buff No. 1089; (4) buff No. 947; (5) buffy ochraceous No. 3190 or 2259. All these specimens are from central Wisconsin. Included with the value (5) were dark ochraceous No. 4579 from Waupaca County, 4851 from Vernon County, and 5024 from Clark County. From Marathon, Wood and Portage counties a large sample fell into these frequencies: pure silvery white 1; buffy white 16; whitish buff 37; buffy ochraceous 46; dark ochraceous 4. Such frequencies were similar in other parts of Wisconsin. Jackson (1961) almost named Wisconsin meadow voles as a subspecies characterized by buffy venters. From the foregoing it follows that Microtus pennsylvanicus cannot always be distinguished from Pitymys ochrogaster by the color of the belly, but white bellies are characteristic of pennsylvanicus. From Portage County, a gray vole had hairs whitish basally. Jackson (1961) described yellow voles from Alderly, Dodge County. Two albinos from Madison and 6261) is from Horicon Marsh. This vole was normal above except for a faint intermixture of white hairs below the ears and approaching the vibrissae.



Mammalogists also use dental records. Microtus pennsylvanicus, showing posterior islet on middle molar. Pitymys ochrogaster [and other voles] lack it. Synaptomys cooperi, from Door County, shows deep labial (lateral) reentrant angles, and a faint, lateral incisor groove. 

The left hind foot was normal, the other three feet white. The tail was normal. The venter was pure white without gray at the hair bases. There are six tubercles on the hind foot. Chromosomes number 2N = 46, FN = 50. There are eight mammae. According to Reich (1981) the annual molt is mostly of underfur. Total length to 188 mm (but large meadow voles seldom exceed 165 mm), tail 42-56 mm, hind foot 20-23 mm, and ear 20-23 min. Weights vary to 56.9 g. Greatest length of skull varies up to 28.6 mm, width to 15.6 mm (see Jackson, 1961). Dental Formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. The meadow vole is found throughout the state, in boreal and grassy habitats, marshes, bogs, wet and dry prairies, agricultural land, meadows, rights-of-way, and even lawns. Status. The meadow vole is abundant, one of the most abundant mammals in the state. It is injurious to humankind, especially to farmers, eating grain and the plants themselves; girdling bushes and trees, causing damage in orchards; trenching lawns, golf courses, and cemeteries; competing with rarer species; and it constitutes something of a health threat by transmitting diseases to other mammals, and by its parasites indirectly spreading diseases. There are few mice in captivity as objectionable in aggressiveness and filthiness; special precautions must be employed. To be fair, they are neither likely to bite nor to be filthy in their natural surroundings. They are, by virtue of numbers, very important members of food chains in wetlands and prairies. They constitute a major food item for most raptors, and most of the carnivores. For some of these predators meadow voles are the chief food eaten. Snakes also eat them. The rare great gray owl apparently feeds almost exclusively on this species. Wisconsin’s authority on raptors, the recently deceased Fran Hamerstrom, found that raptors, and especially the harrier, depend so much on these voles that breeding output is closely related to the cycles of the voles. TAXONOMIC ACCOUNTS / ORDER RODENTIA

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Habitats. Meadow voles are found on wet, grassy or weedy soils, fields, and wet meadows, in marshes, bogs, along riparian grassy shorelines, in grassy glades or open woods, occasionally in cultivated fields, often occurring on lawns, in gardens, and rarely entering houses. The meadow vole prefers black soils and wet environments due to a need for water. It swims well, even diving, and young have been seen struggling over the water surface (Long, 1970a). Jackson (1961) mistakenly believed that the shrew Blarina brevicauda was the most common mammal in Wisconsin. He suggest-



Maps showing geographic distribution of Microtus pennsylvanicus in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

ed that if M. pennsylvanicus were found in more diverse habitats then it would be the most abundant. (I would judge the most common wild mammal in Wisconsin to be either the meadow vole or the white-footed mouse.) He suggested that the meadow vole did not occur in sandy areas, dense timber, or gardens. I have not taken them in dense forest where grasses are absent from the forest floor, for they dwell in and feed upon forbs and grasses. I have taken them in swamps, bogs, along streams, rivers, on golf courses, lawns and other bluegrass areas, in gardens, sandy areas, Christmas tree plantations, and brushy savannas. The greatest densities are, indeed, as Jackson (1961) mentioned, in the rank grasses, reed and cattail marshes, meadows, grassy orchards, vines, briars, fencerows, pastures, hay, alfalfa and clover fields, wet prairies, dry prairies where vegetation is lush, riparian vegetation, railroad and highway rights-of-way and beach grasses (rarely). These voles seem to require runways in grassy or sedge vegetation, where cuttings and runways proclaim their presence. Publications treating this wide-spread and abundant mammal include Getz 1960, 1961, 1970; Blair 1940; Manville, 1949; Golley 1960; Ozoga and Verme 1968; Dice and Sherman 1922; Hamerstrom 1979, 1986; Mumford and Whitaker 1982; Getz et al. 1981; Krebs 1977; and Tiatt and Krebs 1985. In winter, snow provides security for the vole as it makes its rounds under the snow.. The snow moderates the microclimate as well as providing insulation against cold air temperatures (Pruitt 1954). Nests are constructed of grass clippings in short underground burrows, in the surface runway also, under rocks or pieces of wood, even in the tunnels under the snow. The nests are globular, with at least one entrance. Some are mere platforms in the runways. Some are in tunnels 8-9 inches below the surface of the ground. Jackson (1961) provides a photograph of such a nest. Weilert and Shump (1977) provide dimensions for 20 nests, which averaged 148 mm diameter, 72 mm depth. Nests are kept clean, which is in marked contrast to their cages and live traps.

Foods. This vole eats seeds and green parts of grasses, sedges, and forbs. The mouse also eats hay and cultivated crops, berries, insects, fungi, occasionally small bird eggs, and small vertebrates, including its own kind. The digestive system is somewhat inefficient (Golley 1960) and these voles occasionally engage in coprophagy (Oelette and Heisinger 1980). Several examples of cached food hoards have been found, but there is no common pattern for hoarding food. Several other students on this subject include Zimmermann (1965), Maxson and Oring (1978) and Gates and Gates (1980). Reproduction. This vole, which often increases dramatically in a 4-5 year cycle, is remarkably fecund. It breeds both early and late in the year (Keller and Krebs 1970), has large litters, and has a postpartum estrus. The annual number of litters may number from 410. In contrast to the generally monogamous prairie voles, the meadow vole is promiscuous (Getz et a1. 1981) and the female will repeatedly mate (Madison 1980). The females are somewhat territorial (Burt 1940). The young become sexually mature in less than a month (Timm 1975). The gestation period is about three weeks. The litter size exceeds 4.5 in several published studies (5.6 in Illinois, Hoffmeister; 4.54, 5.8; and 4.81 in Indiana, Keller and Krebs, 1970, Mumford and Whitaker, 1982). The range is 1-9 young. In Wisconsin Microtus pennsylvanicus can breed every month of the year (Jackson, 1961: 233) and usually continues into November in central Wisconsin, a full month later than Peromyscus. In 27 pregnant females from Wisconsin, the mean embryo count was 5.2, with modes of 4 and 6. The observed range was 4-8. The peaks of breeding were in April and July. The females were found pregnant from March to October and lactating until 14 November. The young weighing about 3 g each are born naked and blind (Whitmoyer 1956). In five days the incisors erupt and short pelage has grown out. The molars erupt by seven days, TAXONOMIC ACCOUNTS / ORDER RODENTIA

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and begin to open by eight days. The female may be in mid-pregnancy when her previous young are weaned, often by the 12th day. Young have been live trapped out of the nest as small as 10 g, suggesting some young leave the nest even younger than 12 days; the 12day-old voles average 14 g (Golley 1960). Age may be determined by weight of the eye lenses (Thomas and Bellis 1980). Sexual maturity is poorly correlated with age because the young may breed early in life. Angularity of the cranium, long rostrum, closure of the basioccipitalbasisphenoid suture, and body weight all may provide suitable criteria for aging this important species. Some recent workers consider the exact age of sexual maturity in these “reproductive machines” as irrelevant, and use biomass instead of “age” for life tables. Mortality. With a high biomass and potential energy available to nearly all carnivorous species in Wisconsin, this prey species in natural habitats is surprisingly beneficial. It is preyed upon by such diverse predators as game fishes, snapping turtles, probably other turtles, probably bullfrogs in the southern counties, many snakes, most owls, most hawks, ravens and crows, herons, shrikes, sand hill cranes, gulls, short-tailed shrews, dogs, cats, muskrats, and most other carnivores. Doran (1954), Jackson (1961), and Timm (1985) review the numerous parasites of the meadow vole. These include blood protozoans, cestodes, nematodes, spiny-headed worms, and flukes (Zajaac and Williams, 1980). Ticks (at least 11 species), mites (more than 80 named species), lice, botfly larvae, and fleas infest these voles (Hatt, 1930b; Mauer and Skalely 1968; Manville 1949; and Scharf and Steward 1980). Parasitic beetles (Leptinidae) also infest this vole on occasion (Timm 1985). Home Range and Density. Home range is usually defined as the area traversed in normal activities. Madison (1985) bases home range on daily range. He divides the spatial distribution as stable home range, variable home range, and shifting home range. About 3/4 of home ranges in voles are reportedly

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stable. According to Burt (1940, 1948), the home range exceeds 1/15 acre (267 sq. m), or 1/10 acre (400 sq. m). The known range is 0.15 acre to 0.75 acre (0.06-0.3 ha) (Blair 1940; Getz 1961; Manville 1949). Within the home range there are defended sites, both at nests and feeding areas (Ambrose 1973; Burt 1943). Females are more territorial than males (Madison 1980). There is considerable overlap in home ranges and males wander more than do females. The habitat affects home range size, as does the availability of food and the density of voles. Diet and predation and the previous year’s reproductive success greatly affect the local abundance of this species. Floods doubtless drown many in the wet habitats. Hamerstrom (1985, 1986) shows how the mouse is not only affected by predation but its abundance allows harriers to breed more frequently in a summer. Being especially abundant in appropriate habitat, the interrelations between this vole and other mice are important (Grant, 1969; 1971). Meadow voles seem to adversely affect Synaptomys cooperi (Getz, 1961; Linzey 1981), where bog lemmings avoid pure grass stands, but meadow voles lose out in competition with the smaller pine voles, (Novak and Getz 1969). (The rare pine vole has not been studied here.) Red-backed voles seldom compete with Microtus (Iverson and Turner 1972) and where found with Peromyscus, the deer mice may outnumber Microtus as much as 12 to 1 (Brewer and Reed 1977). Blarina feed on meadow voles in summer and winter (Eadie 1952). Prairie voles and meadow voles segregate into respective microhabitats (Krebs 1977; Zimmermann 1965; Miller 1969). Jackson (1961) explained that the periodic increases in vole populations are due to three factors: accelerated breeding rate, increased litter size, and increased number of litters. All of these, of course, would increase the abundance of a population. Population crashes are likely the result of high predation and food shortages. Consequent shortage of food for the predators can cause voles to dis-

perse, lower their breeding performance, or cause voles to starve or die from other causes. Concomitantly, as the predators are on the wane, the voles increase while the food availability naturally increases. This is the concept of seasonality. The vole builds up its population in subsequent years depending on the survivors lasting the winters, and peak numbers cycle up again. Being a complex dynamic system with numerous variables, the cycle may not be the same in all regions, nor may it be in synchrony from one region to another. Basically there is a 4-5 year cycle or a 3-4 year cycle (Krebs and Myers, 1974; Tiatt and Krebs 1985). Not surprisingly, there are also annual fluctuations in some places or some decades. Jackson (1961) believed that meadow voles over large regions may attain densities of over 200 per acre, but in Michigan Aumann (1965) found densities to be 5060 per acre (21-25 per ha). Using 25 years of data collected on the prairies of Waushara and Portage counties by Fred and Fran Hamerstrom, one of their associates Nora Lopez Rivera found some deviation from a 3-4 year fluctuation. Nevertheless, the cycle was fairly regular and about five years (see Fig.). Remarks. This mostly nocturnal vole is surprising sociable in nature, but almost vicious in close quarters or unnatural surroundings. It has been observed to stand on its hind legs and box or threaten much larger enemies (i.e., human) and even mobbing bluebirds (see Long 1970a). Confined meadow voles fight and may eat one another. The adults often eat the young when they are found out of the nest. The female is attentive to its young, returning them to the nest with “mother love” (Bailey, see Jackson, 1961). Additional Natural History. A biology of the meadow vole was published by Reich (1981). Geographic Variation. None was observed. Specimens examined. Total 548. Adams, Ashland, Bayfield, Burnett, Clark, Columbia, Crawford, Dane, Dodge, Door Co.: Lost Lake Bog, Chambers Island, in



Multi-annual Cycle for Microtus pennsylvanicus in central Wisconsin. Nora Lopez-Rivera, from Hamerstrom journals. 

Green Bay, 1. Florence, Fond du Lac, Forest, Grant, Green, Iowa, Iron, Jackson, Juneau, Kenosha, Kewaunee, La Crosse, Lafayette, Lincoln, Manitowoc, Marathon, Marinette, Milwaukee, Monroe, Oconto, Oneida, Outagamie, Ozaukee, Pepin, Portage, Racine, Richland, Rock, Sauk, Sawyer, Shawano, Sheboygan, St. Croix, Trempealeau, Vernon, Vilas, Walworth, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood counties.

Genus Synaptomys Baird Bog Lemmings Re-entrant angles of cheek teeth deeper on one side, shallow on the opposite, so that prisms extend as nearly transverse lophs across the tooth surface. The salient angles



Sketch of Southern Bog Lemming by R. P. Grossenheider. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

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are reduced on the outerside of the lower molars, and on the inner side of the upper molars. There is a tiny groove extending along the outer border of the anterior face of each upper incisor.

Synaptomys cooperi Baird Southern Bog Lemming 1858. Synaptomys cooperi Baird. Report Explor. Surv.. Part 1 Mammals, p. 558. The type locality has been fixed at Jackson, New Hampshire. 1896. Synaptomys fatuus Bangs. Proc. Biol. Soc. Washington, 10: 47. Type from Lake Edward, Quebec. 1912. Synaptomys cooperi fatuus: Cory. The mammals of Illinois and Wisconsin. Field Mus. Publ., 153: 237.

The name Synaptomys means a mouse that yokes something together. In this case, the name stands for a mouse that stands evolutionarily intermediate, so to speak, between voles and true Arctic lemmings (Arvicola and Lemmus). There is something misleading about the vernacular name southern bog lemming. Southern bog lemmings often occur in habitats that are not bogs. Furthermore, this species is southern in relation to a northern bog lemming, found northward. The southern bog lemming is boreal, and populations found in the south of the range are usually relicts from a cooler time when Pleistocene glaciations had displaced these mice southward. Description. The southern bog lemming is a chunky mouse with tiny tail and grizzled, coarse pelage (except drabbed in worn winter fur). The tail and short ears are often hidden by pelage. There is usually a faint groove along the anterior face of each upper incisor, near the outer border. The skull is subquadrate, i.e., nearly square, resembling Arctic lemmings in the projections of the braincase outward into the orbital space. The rostrum is short and the zygomata bowed out. In the upper cheek teeth the outer re-entrant an-

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gles are exceptionally deep, whereas the inner angles are shallow, so that the upper teeth are zagged and not zigzagged. The lower teeth have the deep re-entrant angles on the inside, and the shallow angles outside, so that these teeth are zigged and not zigzagged. On the middle lower molar is a small outer prism. The short tail, coarse grizzled fur, grooved incisors, squarish braincase, and onesided re-entrant angle pattern distinguish this species. Externally the bog lemming resembles Pitymys pinetorum because of its short tail. There is a superficial resemblance in their skulls as well because P. pinetorum has such a broad skull. Comparisons of the races are given in their accounts below. The upper parts are a mixture of gray, pale ochraceous brown, and dark brown or black guard hairs. The venter has a whitish, grayish, buffy, or tan ochraceous wash over dark plumbeous gray bases of the hairs. The feet are usually brownish but sometimes gray. The tri-radiate baculum has a stout basal stalk (Burt 1960). There are eight mammae in the female. The chromosomes number 2N=50, FN=52 (Hoffmann and Nadler, 1976). The size is comparable to that of other Wisconsin voles, but adults average larger than all except Microtus pennsylvanicus. Four adult males from Drummond averaged in total length 113 (110-115), tail length (16 (1019), hind foot length 17.6 (17-18), and length of ear from notch 9 (5-10). In cranial measurements six adults from Gogebic and Taylor counties, Michigan, and two from Bayfield County averaged in condylobasal length 25.0 ± 0.23 (24.4-25.5), nasal length 7.05 ± 0.05 (7-7.2), zygomatic breadth 15.2 ± 0.33 (14.6-15.7), lambdoid breadth 12.25 ± 0.1 (11.9-12.45), and cranial depth with bullae 8.5 ± 0.13 (8.2-8.8). Dental Formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. The southern bog lemming occurs almost always in low numbers, but may attain local concentrations. The occurrences are found from one end of

the state to the other. They are not known in the Apostle Islands in Lake Superior or in some of the southwestern prairie counties. They are found on islands off the Door Peninsula in Lake Michigan. See Map. Status. The southern bog lemmings are seldom common, and are harmless to humankind. They are important in food chains in wet-soil habitats and bogs, as well as on black soils of highlands. Often found near water, the bog lemmings seem adversely affected by Microtus pennsylvanicus and by human land use. No irruptions have been noted in Wisconsin, as seen in other states. The race on the small isles of Door County, in Lake Michigan, named S. c. jesseni, has a very limited distribution. For that reason it is quite vulnerable to eradication by humankind. There is quite a lot of land protected from development on Washington and Rock islands, but no effort has been made to protect the sedge meadow habitats. The southern bog lemming S. c. gossii, from western Wisconsin, represents a small, localized population. It probably has no protection, because its geographic range is practically unknown. The southern bog lemming has declined in Lower Michigan (Master, 1978). Habitat. The southern bog lemming is occasionally taken in wetlands. I examined a specimen taken by Russ Mumford, put on display at the Purdue Science Camp, trapped in the tamarack and sphagnum bogs near the Pine and Popple rivers, in northeastern Wisconsin. From throughout Wisconsin, Long (1990), Long and Long (1988), Clark (1972) and Jackson (1961) describe a variety of habitats including sedge meadows, fencerows with red pines, upland hardwoods, Christmas tree plantations, marshlands, and bouldery ground in spruce forest near the Rib River. Long (1964b) caught one on black bouldery ground near a lake in southwestern Ontario. Timm (1975) caught them in mesic, mixed conifers and hardwoods in Minnesota. In Indiana, Mumford (1969) caught them in grasses and sedges. Hoffmeister (1947, 1989) took them

once in great abundance in blue grass near a muddy stream. Subsquently he took them in much smaller numbers. They have been taken even in beech-hemlock woods (Hamilton, 1941) in New York. In upper Michigan they are found in spruce bogs, tamarack bogs, and wet and dry hardwood forests (Dice and Sherman 1922) and blueberry barrens and pine hardwoods (Robinson 1975). One problem for Synaptomys seems to be the presence of Microtus pennsylvanicus (Getz, 1961). Beasley (1978) found P. ochrogaster and Synaptomys to cycle concurrently in Illinois. Bog lemmings avoid pure grass habitats and survive at brushy edges (Linzey 1981). When bog lemmings are abundant there are complex systems of runways extending and branching through the sedges and grasses. These are littered with grass clippings and greenish scats. Sometimes when Synaptomys are present, but not abundant, there is no sign of runways at all. Burrows are dug in the ground, as are tunnels in snow. In some burrows young are reared without nests of grass (Hoffmeister, 1947; Hayase, 1949), but grass nests have been reported (Jackson, 1961; Connor 1959; Burt 1928). Jackson says the grass nest has up to four entrances and is lined with fur, feathers, or fine grasses. Foods. Conner (1959) concluded that the chief foods are green monocots, especially grasses and sedges. Other foods reported included mosses, liverworts, fungi, ferns, forbs, woody plants, fruits of raspberry, blackberry, huckleberry, cranberry, plant roots, bark, insects, snails and other invertebrates. This vole usually eats the basal and seed parts of a grass or sedge and leaves the stem as a “cutting”. The green fecal scats indicate green vegetation is important in the diet. Reproduction. Following the usual temporal breeding pattern in Wisconsin mice, Synaptomys probably breeds in spring and autumn (April through September). The mice are so scarce that little is known about their pattern in Wisconsin. The only evidence for breeding in this collection is from WashingTAXONOMIC ACCOUNTS / ORDER RODENTIA

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Ventral skull of Synaptomys. After Hall. 



Maps showing geographic distribution of Synaptomys cooperi in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

ton Island, an isolated relict population. Beasley (1978) found breeding peaks in Illinois, but the bog lemming breeds anytime in the year according to Burt (1928). Males are reproductive at least from April to December, and females have a postpartum estrus. Hoffmeister (1989) found breeding pregnancies or births in S. cooperi cooperi from April into November. In Pope County, Illinois, 65 percent of females were pregnant in late April. The gestation period is about 23 days (Connor 1959). Litter size averages about three (range 1-7) in Ontario, and in one sample from Illinois (19 pregnant females) 3.58 (Hoffmeister, 1989). Beasely (1978) listed the mean as about 3 (1-8). At birth, young southern bog lemmings weigh about 3.9 g each, and have scant fur dorsally (Hoffmeister, 1989) or are naked except for vibrissae (Connor, 1959). They are born blind with ears closed; eyes open in 10-12 days. Weaning begins in some females in 14 days, and seems complete in three weeks. The juvenal fur is replaced with an adult pelage by 60 days. The males may be sexually mature in 35 days (Connor, 1959) but usually both sexes are breeding 60 days after birth. Mortality. Synaptomys is taken by diurnal and nocturnal predators. These include snakes, screech, barn, long-eared, greathorned, and even the great gray owls, numerous mammalian carnivores, such as red and gray foxes, bobcat and house cat, coyote, gray wolf, probably shrews, all the weasels, mink, and martens. Doran (1954) mentions tapeworms are common parasites. Connor (1959) and Timm (1975) report mites, sucking lice, fleas, and ticks. These parasites probably contribute to mortality. Home Range and Density. Burt (1940) recaptured an adult female seven times in August and September in Lower Michigan, and obtained an estimate of home range about 0.5 acre. Buckner (1957) estimated home range at 0.11 acre for males and 0.14 acre for females in Ontario.

The fluctuation of numbers in this species is mentioned often in the literature. It seems a “boom or bust”. There are interrelations with other voles (see Getz 1961), effects of climate, nutrition, and of course land use. Over-trapping can cause eradication. The cycle seems to be a 3-4 year cycle (in southern Illinois at least) (Beaseley 1978). In southern Michigan Blair (1948), Linduska (1950), and Burt (1940) suggest peaks in 1936, 1938, 1942, and 1946. Lows were observed in 1937, 1939, 1940, and 1941. The occurrences are quite local in distribution in Wisconsin, which can be one reason why a person might catch 20 bog lemmings one year and none the next. Linduska (1950) caught 18 on half an acre, which makes a very high density of 36 per acre (0.4 kg). Hoffmeister and Warnock (1947) obtained 35 in an acre in one year, but in most subsequent years the numbers were low or medium. Usually the distribution is thinner than that, of course; other estimates are 14 per acre (Stegeman, 1930), and 2-14 per acre (Banfield 1974). On Washington Island when bog lemmings seemed abundant (they had never been taken previously or since) in a hedgerow and lawn (about one acre) six were taken in two nights. Others were observed on other dates feeding under a bird feeder. On Swenson Road, bog lemmings were not taken at all except in a sedge meadow of about two acres. They did not range through the meadow, but were concentrated at one end. Three were taken on one occasion, but usually one or none on other evenings. These data give an estimate of about six per acre.

Synaptomys cooperi cooperi Baird Cooper’s Southern Bog Lemming Synonymy given for species above. Description. As defined by Wetzel (1955) the nominate race for the bog lemming occurs both east and west of Lake Michigan. It is TAXONOMIC ACCOUNTS / ORDER RODENTIA

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characterized by a rather narrow, high cranium. All specimens examined in the UWSP collection, except those from Door County, proved referable to this subspecies. They show little variation in color. Some specimens had a rich reddish chocolate color intermixed with ochracaeous, gray and black. Winter specimens were bleached and less grizzled. Young specimens were darker brown. Specimens from the Upper Peninsula of Michigan were referable to S. c. cooperi. Using a scale from reddish to grayish brown, the dorsal pelage being lined with dark guard hairs and darkened from below by the underlying basal gray, the most reddish specimen, was No. 5742 from Portage County. A shade paler is Mus. No. 2197 from Crivitz. Next is 5038 from Bayfield County, where the light ochraceous color separates from the dark brown lines of the guard hairs, and finally the ordinary coloration—a grayish, ochraceous brown, as seen in 5626 from Bayfield County. Scaled from 4 to 1, all the adult and probably mature bog lemmings were compared against these specimens taken as standards, and the color values were recorded. In the far north, from Fish Hawk Lake, Gogebic Co. Michigan, the skin was reddish (3). From Menominee County, Upper Michigan, four specimens averaged 1.5 (1-2). A vole from Delta County, Michigan was 3. From Bayfield County, five specimens averaged 1.7 (1-2), and another with worn pelage (in June) was dark grayish. Langlade County specimens were 1 and 3, averaging 2. An Oconto County specimen was a 2. A specimen from Marathon County was 1, and the Portage County specimen 4. A specimen from Douglas County was 1 (Long, 1990). For measurements, see account of the species above. Geographic Distribution. See Map. Status. See account of the species. Specimens examined. Total 34. Ashland Co.: 6 mi. SE Clam Lake 9 . Bayfield Co.: Drummond 12. Burnett Co.: Crex Meadows 1. Douglas Co.: Wascott 2. Langlade Co.:

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Camp Susan 3. Marathon Co.: 7 1/2 mi. NE Athens on Big Rib River 1. Marinette Co.: 9 mi. NW Crivitz, County A 3. Oconto Co.: 11 mi. NE Suring 1. Portage Co.: Dewey Marsh 1. Taylor Co.: Near Medford 1.

Synaptomys cooperi jesseni Long Jessen’s White-footed Bog Lemming 1986. Synaptomys cooperi jesseni Long. Mammalia, 51: 324. Type from Ted Jessen’s property on Swenson Road, Washington Island, Door Co., Wisconsin. Named in honor of Tom Jessen, Washington Island, the former Supervisor of Rock Island State Park.

Description. In dorsal and ventral coloration the specimens from Rock and Washington islands, remote and widely separated from the mainland bog lemmings (Long and Long, 1988), resemble the nominate race. However they have conspicuous white feet. The tails and feet are generally grayish, but there is usually pure white distally in most of the claws and toes. The toes and claws may occasionally be whitish in S. c. cooperi, but they are seldom pure white. The whiteness is not nearly as extensive, not set off cleanly by dark pelage of the feet, and not nearlv so constant. White toes are even fairly constant on the forefeet in the insular specimens. Even the hind dew toes are white on the Rock Island specimen. They are white also on UWSP 6548 and 6549 from Washington Island. All ten toes are white on these specimens. On Washington Island, eight distinctively white hind toes (excluding dew claws) were seen in each of eleven specimens. Seven white toes were seen in the other two, and even in these there was at least a trace of white in all eight. In 22 adult mainland and Upper Michigan specimens whitish toes were seen in only five specimens. Some specimens from Menominee County, Michigan, show several white hind toes, as does one specimen from Bayfield

County, in northwest Wisconsin. But these from the mainland are less distinctive than the least whitish-footed specimens on Washington and Rock islands. White toes are seldom observed on the forefeet of any mainland specimens, but all the front toes were pure white on the Rock Island vole, and toes of the front feet were white on seven from Washington Island. Some toes of the forefeet were white on the others also, except two of the eight specimens had only dark toes on the forefeet. White toes seem a sporadically appearing character in bog lemmings, but on Washington and nearby Rock islands it is ordinary (and in fact constitutes a remarkable and conspicuous difference allowing the large majority of bog lemmings to be identified on sight). There is also a difference in the skull; the island mice have significantly broader skulls. Jessen’s bog lemmings from Washington Island, Wisconsin, averaged for total length in six males and three females, respectively, 118 (112-122), 123 (119-126), tail length 17 (1519), 18 (16-20), hind foot length 19.4 (1821), 19 (17-20), and length of ear 11 (10-12), 11.3 (11-12). Six adults from Washington Island and one from Rock Island averaged 23.6 ± 0.2 in condylobasal length, 6.87 ± 0.14 (6.37.3) in nasal length, 15.67 ± 0.03 (15.6-15.8) in zygomatic breadth, 12.93 ± 0.13 (12.613.4), and cranial depth including bullae 8.62 ± 0.1 (8.3-9). Geographic Distribution. Rock and Washington islands, Door County, Wisconsin. Status. See account of the species. This race has a very limited distribution, on two small islands. Remarks. Cuttings of sedges in the mouth of UWSP 6259 were 3, 4, 5, 5, 6, and 8 mm in length. Pregnant females were taken in April (5 embryos) and late September (3 embryos). Specimens examined. Total 14. Door County: Rock Island Hq., 1. Washington Island, Swenson Road, 6; Airport on Airport Road, 7. The holotype and a topotype are deposited in the U. S. National Museum (Nat. Hist.).

Synaptomys cooperi gossii (Coues) Goss’ Southern Bog Lemming 1877. Arvicola (Synaptomys) gossii Coues. In Coues and Allen. Monograph N. Amer. Rodentia, p. 225. Type from Neosho Falls, Woodson Co., Kansas. 1897. Synaptomys cooperi gossii: Rhoads. Proc. Acad. Nat. Sci. Philadelphia, 49: 307.

This bog lemming resembles S. c. cooperi but is larger and relatively larger in many dimensions. It has especially broad incisors and high cranial depth of the skull. The first reported Wisconsin specimen, referred to S. c. gossii by Jackson (1961), has wider incisors than does cooperi. Across the Mississippi in Minnesota and northeast Iowa, bog lemmings also have been referred to S. c. gossii. S. c. gossii occurs on hillsides and fields in southern and southwest Wisconsin. The habitats seem to be dryer than usual for bog lemmings. They may be expected to occur in wetlands as well. This race was named in honor of an early Kansan naturalist B. F. Goss. Recent specimens from Fort McCoy are assigned to this race, not so much by size, but the skull seems deep in cranial depth, the incisors are notably wide even in young bog lemmings, and the venter was invariably rusty ochraceous (whereas in S. c. cooperi the venter is usually whitish, never this brightly ochraceous or tawny). These bog lemmings were taken on highlands in oak savanna and grasses, as was Jackson’s record from Lynxville. A female was lactating, a male was in breeding condition, and young animals were taken 28 August 1995. Specimens examined. Total, 5. Crawford Co.: Lynxville, 1. Monroe Co.: Fort McCoy, 4.

Genus Ondatra Link Muskrats The muskrat was first named by Linnaeus, who considered it a kind of beaver. To this day many mammalogists consider it a webTAXONOMIC ACCOUNTS / ORDER RODENTIA

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footed beaver-like creature, but it is not. The hindfoot at best might be regarded as partially webbed. This brownish, long-tailed, aquatic mammal is more exactly a gigantic, long-tailed vole than a beaver. It has the peculiar zig-zag molar teeth of voles. The molars show salient and re-entrant angles, comprising in the occlusal view a series of prismlike islands of dentine more or less enclosed by sharp-angled walls of enamel. The aquatic specializations include the following: the hind feet have conspicuous fringes of stiff hairs, and the long scaly tail, compressed laterally for sculling propulsion, has a small fringe. The fur is not remarkable except that the guard hairs and dense underfur are soft and pretty and also durable. Closely related to Neofiber, the round-tailed muskrat of Florida, this North American genus contains according to some workers a weakly differentiated Newfoundland species, 0. obscurus (Bangs), as well as the wide-spread species 0. zibethicus (Linnaeus). The latter is the type of the genus. It ranges from Alaska through most of Canada and the United States, and southward to northern Mexico. (The author was with Dr. Syd Anderson’s field party that collected the first one in a turtle trap in Chihuahua.) Introduced into the Old World, they are now taken for fur in



Muskrat. By Alan Long. 

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Russia, China, and much of Europe. One difference between Ondatra and the Wisconsin voles, aside from much larger size and the aquatic specializations, is the presence of five functional clawed toes on all four feet in the muskrat (the thumb bears only a small nail).

Ondatra zibethicus (Linnaeus) Ondatra zibethicus zibethicus (Linnaeus) Muskrat “What makes the muskrat work so hard to guard its musk? Courage!” — Lion in Wizard of Oz. 1766. [Castor] zibethicus Linnaeus. Systema naturae Ed. 12, 1: 79. Type locality of the nominate race and the species is Eastern Canada. 1795. [Ondatra] zibethicus: Link: Beytraege zur Naturgeschichte, 1: 76.

The name Ondatra has no known meaning; probably it was taken from an Indian name. The specific part of the binomen, zibethicus, is Latin for musky odor. There is immense confusion about spelling of this name; those who make themselves a rule that when the generic name ends with “a” then the trivial name also ends with “a” are in this instance led astray. The word zibethicus agrees with Ondatra in gender and number, and should not be revised. An early day corruption of the species name Muskrat to “mushrat’ reminds me of a long ago use in Wisconsin of a binomen “Mus rattus”. Seemingly a silly mistake, this binomen is actually available for the black rat ( = roof rat) Rattus rattus. Description. A cat-sized or smaller rodent having brown fur, elongate, compressed, mostly naked tail (having numerous scales evident), and feet with fringes to facilitate swimming. The skull is similar in form to those in the voles, with the braincase subquadrate and sharply angled, even protruding into the orbits in dorsal view. The rostrum is long and narrow with flaring zygomata.



Skull of Ondatra zibethicus. 

The interorbital breadth in comparison to the zygomatic breadth is relatively narrower than in the voles. The dentary is very sharply bent, with the lower incisor and its root nearly straight and having a sharp angle with the axis of the posterior part of the dentary. The incisors are usually orange and quite formidable. In occlusal pattern the cheek (molar) teeth are zig-zag with flat surfaces. The large upper third molar’s pattern is distinctive for there are two or three closed triangles between the anterior and posterior loops. The three-pronged baculum is protrusible in adult males. The annual molt begins in autumn. Adult pelts show mottled molt areas and juveniles show bilateral molt areas (Applegate and Predmore 1947, Shanks 1948, Linde 1963). This is the best aging character for the genus, because the teeth are all rooted and show no patterns of wear. Teats on a pelt indicate female sex. There are two pectoral and four inguinal mammae. Perineal scent glands are at the base of the tail in breeding adults (Jackson, 1961). I (1978a) discovered a small epiphyseal attachment on the dorsal aspect of the scapula, which becomes fused in adults to the scapula itself. The diploid number and fundamental number of chromosomes are 54 (Hsu and Benirschke, 1971). Muskrat fur is usually a dark, rich walnut brown with tones of dark rust, cinnamon, or a golden-bronze sheen. The intermixed guard

hairs are blackish. The venter is much lighter, tending to a pale grayish ground color overlain with golden, cinnamon, or tan color, occasionally reddish tawny, and sometimes tan or gray-fawn brown. The mid-dorsum and legs may approach black because of the intermixed black hairs. The head is concolor with the body. The short ears are practically buried in the fur. The tail is slate gray or darker, sometimes brown, and the naked parts of the feet are much the same in color, gray or brown. Jackson (1961: 246) reported two albinos from Wisconsin. Occasionally there are yellowish or cream colored mutants. Exceptionally large for an arvicoline rodent, the adult muskrat exceeds 400 mm, the hind foot is greater than 60 mm, and the adult skull exceeds 55 mm in greatest length. Weights vary from 2-3 pounds (1-1.4 kg). Dental formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Distribution. The muskrat is found in boreal forests, prairies, wetlands, streams and lakes, along Lake Michigan and Lake Superior shores, in urban areas, in the southern riparian lowland forests, along the Mississippi and other huge western rivers (i.e., Wisconsin, St. Croix, and the Chippewa rivers). It ranges from the security of the waters to almost any habitat in Wisconsin during autumn dispersal, spring breeding dispersal, summer drought, or winter hunger. Along the shores of the Great Lakes the powerful wave action destroys aquatic emergent and sub-



Summer lodge of Muskrat. A. MacKinnon, age 13, from Anna B. Comstock’s Handbook 1911.  TAXONOMIC ACCOUNTS / ORDER RODENTIA

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merged vegetation, and muskrats are transient in these habitats. They do persist in protected bays and behind sand spits where vegetation can grow. Status. The muskrat is an abundant mammal in Wisconsin. For years this was the most important furbearer in the wild, both in numbers taken and in economic yield from the marketed fur (Boutin and Birkenholz 1987). This mammal is protected by state game laws that regulate the harvest. It benefits from wetlands set aside for fisheries and duck reproduction. The current decline of the fur



Maps showing geographic distribution of Ondatra zibethicus in Wisconsin and North America. 

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trade may increase muskrat numbers; there is recent evidence of an upsurge in the market (Table Rod-9). Muskrats are usually the most trapped of the furbearers in Wisconsin because of their abundance. Fur prices are high enough to create a demand and increase the trappers. Aside from fur this mammal makes little economic impact. The flesh is edible, and occasionally is eaten. Some Native Americans have regularly eaten them. Occasionally they are sold in food markets in other states. Muskrats damage dikes (Cook 1957) causing trouble in game management areas. Craven (1984) reported gnawing to a vehicle and rubber fittings on appliances near water. Muskrats may adversely impact native plant communities (Willner et al., 1980). Many animals make use of their abandoned houses. Muskrats rarely eat crops (see Foods below). Their predatory impact is negligible, but they do eat mollusks and perhaps other small vertebrates. Integral to the food webs for marsh communities, they are killed and eaten by some of the larger carnivores, such as wolves, coyotes, and bears, as well as an occasional raptor. Economically valuable, this species has little effect on humankind except as a fur resource and an indirect value as a wetlands prey species. In 1982-3 a total of 7.4 million muskrats were harvested for fur in North America. The $28 million was second only to value for raccoons, which are in fashion (1999). It is important to learn muskrat biology not only because of the economic value of the fur harvest, and its consequential economic value in the work place and marketplace, but also because wetlands are important to sportsmen, fishermen and duck hunters, deer hunters and campers. Related to this, is the aesthetic and functional role of the muskrat in the wetland communities. To manage such animals, one must understand fecundity (see Reproduction below), mortality (see below), and attempt to understand population biology. A game manager must know the density

prior to the harvest. In Wisconsin, Harold Mathiak (1966) studied Wisconsin muskrats for years, and others have kept up the work. Errington (1963) in Iowa conducted a series of masterful studies. Habitats. Some of the various and diverse habitats where muskrats may be found are detailed above. The preferred habitat of this species is one kind or another of wetland. Additionally, there must be available vegetation which can be used for food, and in many places in Wisconsin this vegetation is essential to build conspicuous grassy and mud lodges for winter survival. Ecological requirements are reviewed by Boutin and Birkenholz (1987). Muskrats may live in burrows excavated in the banks of ponds, rivers, and other bodies of water. They also build houses typically smaller than beaver lodges, but some are immense. The muskrat house is built of available marsh vegetation, including marsh grasses, bulrushes, and cattails. At the base these houses may be three meters across. Jackson (1961) reported a house from the Kickapoo River which extended 41 inches (1.1 m) high above the ice, and measured 31 feet (10 m) in circumference. The entrances are usually below the water level and lead inward to a dry nest chamber above the water level. Jackson (1961) sketched the interior of a house from Rock County, and a bank burrow observed in Bayfield County. Cory (1912) sketched a bank burrow. Neither mentioned any nest material inside burrow or house. The natal den reportedly has a nest of grasses for bringing forth young (Smith 1938). Muskrats in Wisconsin make use of air trapped under winter ice, but also maintain breathing holes where they often emerge to eat green vegetation. Sometimes so much aquatic vegetation is heaped around the air hole, the muskrat has created an outlier house in which it eats and rests. In February 1999, I observed near my home two whitetails (Odocoileus virginianus) walk on the ice approximately 60 m (64 yards) away from shore TAXONOMIC ACCOUNTS / ORDER RODENTIA

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to eat the green vegetation thrown out by a muskrat. Crows also rummage through the muskrat’s ice-hole vegetation. Foods. Jackson (1961) and Perry (1982) list numerous species of aquatic plants on which Ondatra feeds. Cattails and bulrushes make up about 80 percent of the diet according to O’Neal (1949). Occasionally muskrats range away from the water to feed on corn, soybeans, and alfalfa (Errington 1963). They also eat mollusks (mostly clams), dead fish, and other flesh (Schwartz and Schwartz 1959, Harold Mathiak, personal comm.). Muskrats also eat algae. On August 6, 1999, Tyler, Stephanie, Claudine Long, and I observed, in Jackson Harbor, Washington Island, a muskrat swimming out from beneath a mat of vegetation (washed up against the shore). It was carrying a huge bundle of green alga resembling Spirogyra. The muskrat swam to a moored boat and climbed up onto the propeller axle a couple inches below the water surface. There, about 3 m offshore, it ate the entire mass. This alga was bright green and showed no sign of gas bubbles. Then the muskrat dived into the crystal clear water, swam down to the bottom, about ten feet depth, and scooped up another mass of alga from the bottom. The algal masses were carried with the forefeet while swimming with the tail and hind feet. The muskrat swam under water out of view. Reproduction. Reproduction may occur in any month in the southern states, but seems limited to the growing season (spring to autumn) in Wisconsin and Michigan. There may be several litters in the season. There is a postpartum estrus. Precocial breeding is rare (Mathiak 1966). Muskrats court, with agonistic behavior between males and between females. Beer (1950) suggested they were monogamous. Gestation is about 25 to 35 days, and the litters may number from one to 11 offspring. Mathiak (1966) found pregnant females in Horicon Marsh from April to November 3; a litter on April 16 suggests breeding about mid-March in the southern counties.

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Muskrats exemplify Lord’s ecological rule for non-hibernating small mammals, that litter size is significantly larger in northern latitudes (Danell 1978, Boutin and Birkenholz, 1987). In Wisconsin, the litters appear from late April to August, and there are usually two litters (Mathiak 1966). The young are born blind with a short, fine and dark fur, but with naked feet (Smith 1938). Each is about 4 inches in length (about 100 mm) and weighs about 22 g. At five days they cling to the mother’s nipples, much as in some voles, and they may hang on even if she enters the water. The eyes open in about 2 weeks. The fur becomes wooly and gray. The young are weaned in about 30 days, and by 200 days they are adult sized. Mortality. Errington (1963) suggested there are two important factors that may decimate huge musksrat populations (aside from human caused catastrophes, such as draining a marsh). These were drought (falling water levels) and disease. He believed the populations compensated for positive or negative factors by “intrinsic sensitivity” to density, which is in my opinion a meaningless phrase. O’Neal (1949) argued for food supply. Fluctuation seems to me a typical irregular cycle due to various factors of mortality and natality. However, cannibalism and strife in highdensity populations (Errington 1940, Mathiak 1966) might be a population control mechanism. Adjusted litter size (from 6.35 to 8.41) could naturally regulate population control. These factors are in need of additional study. Smith (1938) and Errington (1939) studied mortality factors as well. These included severe winter frost, flooding, disease, and overtrapping. In a chaotic cycle an odd thing such as a peculiar predator (such as a crow) might trigger unforeseen scaling and irregular oscillations. Chaos theory has not been applied, nor will it be easy. One of my former students, Makio Suzuki, trailed coyotes across marshes in central Wisconsin, and found where coyotes had killed several muskrats. The aquatic mink

(Neovison vison) is a natural enemy of muskrats (Errington 1943). Other carnivores and some birds of prey also feed on muskrats. Coyotes, foxes, bobcats, mink, wolves, dogs, and other carnivores may kill and eat muskrats. Herons (Ardea) and raptors kill them. Humans trap them in great numbers. Many are killed by automobiles. Diseases and drought (with lowered water levels) wipe out entire populations (Errington 1961) and cold frost drives them helpless from their lodges to range over the snow and ice, to probably fall victim to hungry carnivores. Territorial fighting also drives the losers into danger (Errington 1939). Blood flukes, tapeworms, and nematodes are internal parasites (Doran 1954) and mites infest the fur (Smith 1938). Diseases such as Errington’s disease, tularemia, and coccidiosis cause mortality. Home Range and Densities. Home range, a vague geometric in the best of circumstances, is for the general wanderings of muskrats dependent upon water levels, food availability, high versus low density, and land use by humankind. Home range for muskrats is determined from recapture data, shoreline occupancy, and radio-tagged movements. Home range was calculated as areas 7-30 m in diameter by Takos (1944). Errington (1963) recorded the diameter as 61 m in Iowa. MacArthur (1978) studied radio-tagged muskrats and found them to wander 5-10 m from the lodge when the water around it is covered with ice. Boutin and Birkinholz (1987) report values ranging up to 30 m from the dwelling, i.e., up to 60 m diameter. Various ways to estimate density are counting houses and using the value for litter size (see Boutin and Birkenholz 1987). None of the ways is perfectly reliable. House counts do not account for muskrats in bank burrows, but in marshes there may be no bank burrows. The Wisconsin Department of Natural Resources usually estimate, in marshes, five muskrats per house. Wisconsin’s Horicon Marsh Fur Farm was established for muskrat

management studies. Errington (1943) multiplied the number of known breeding territories by the number of young produced by the mother. Comparison of placental scar counts to the proportion of juveniles in the autumn harvest does not account for mortality of the mothers, and autumn samples may not represent the total population (Boutin and Birkenholz 1987). Densities may vary from none in what seems good habitat, to about three per acre. High densities may reach in good habitat as many as 35 muskrats per acre (Banfield 1974, Lay 1945). The fecundity for a Wisconsin female is about 14-15 young per year. About 10-36 percent of autumn born juveniles survived. In a follow up study, 18 percent survived (Domey and Rusch, 1953). In Minnesota and Iowa the survival rates were 50-53 percent. This is an odd difference, which needs to be explained. Mathiak (1966) estimated that 87 percent of the muskrat population dies during the first year, and 98 percent do not survive two years. This is strong mortality for animals that can live potentially as long as 10 years (Johnson 1925). Obviously juvenile mortality is heavy (see Boutin and Birkenholz 1987). Muskrats may cycle with annual and multiannual peaks. In some places there may be a tendency to cycle every 10-14 years (Errington 1963, Elton and Nicholson 1942, O’Neal 1949, Keith 1963). This cycle may be seen in fur returns for the Mackenzie River District of Canada (Elton and Nicholson 1942). There is some territorial fighting among muskrats, especially when the populations are high (Sather 1958). The mother will defend her “territory” when offspring are present. Major dispersals occur in spring to breeding sites. Males and young move about with the thawing of ice and consequent high water (Sprugel 1951). Sprugel refers to this as the “spring shuffle.” Other dispersal is ordinary, by young-of-the-year, especially in autumn. When water freezes so thick in winter that vegetation is cut off from muskrats, they must leave their lodges (Mathiak 1966, Sather 1958). TAXONOMIC ACCOUNTS / ORDER RODENTIA

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These dispersals have been reviewed by Boutin and Birkenholz (1987). Wandering muskrats may take temporary quarters in burrows of other mammals. Maximum movements are 180 m in summer (Takos 1944), in winter seldom more than 10 m. When populations are at high density, the young-of-the-year are dispersing, and due to food shortages, drought, or frost the muskrats may move as far as 20 miles ( = 32 km) (Errington 1939)! Remarks. Interesting behavior of muskrats includes the deposition of scent and fecal scats at certain sites, probably for territorial marking. Muskrats are both diurnal and nocturnal, with activity peaks in the afternoon and at twilight (Smith 1938, Boutin and Birkenholz 1987). Muskrats seem antisocial, except in winter lodges or in family groups. Even in those circumstances aggression may be expressed when density is high (Errington 1940, but see Errington 1939). In winter there may be large aggregations in a single lodge, with up to 20 muskrats present (Bailey 1937; Lay 1945). I once watched a muskrat defeat a mink in a fight, and after winning the muskrat ran up and down the bank like a crazed person, “looking for more worlds to conquer”. (I stayed out of its way!) One in a frozen marsh caught out in the open was leaping at me, a threat and not all bluff. Additional Natural History. Willner et al. (1980) wrote a fine review of muskrat biology. Geographic Variation. There is only one subspecies in Wisconsin. Specimens examined. Total, 74. Adams, Brown, Chippewa, Columbia, Dane, Door, Fond du Lac, Forest, Grant, Green, Jefferson, Juneau, Kenosha, La Crosse, Lincoln, Manitowoc, Marathon, Marinette, Milwaukee, Oconto, Oneida, Portage, Racine, Rock, Rusk, Shawano, Sheboygan, Taylor, Trempealeau, Vernon, Waukesha, Waupaca, Waushara, Wood counties. Other records (After Balliett and Taft, 1978): Monroe Co., Ozaukee Co. (No specific localities, not plotted).

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Subfamily MURINAE Gray Introduced Rats and Mice The ancestors of these introduced pests in North America are from Asia, but from there these mammals had spread over the earth wherever people dwell. Especially in ports and coastal cities the rats and mice arrive in ships and cargoes, and they eventually find their way inland. They may be expected anywhere people have cities, towns, settlements, and barns. They are responsible for many diseases transmitted to humankind directly or through parasites (including the infamous black plague). They greatly damage interiors and furnishings of homes and apartments, kill poultry, and consume our crops in the fields, barns, and granaries. In slums, they actually attack children and house pets. The Wisconsin murines differ in size but show resemblance in their drab pelage, brown-gray above intermixed with some blackish hairs. The venter is paler than the back, but hardly ever whitish. The skull shows supraorbital, longitudinal but inconspicuous ridges (which are seen in a few of the native mice in North America too). The murines (Norway rat and house mouse) have tuberculate (i.e., bunodont) molar grinding surfaces, the transverse border of the palate lies behind the third molars, and the tails are long, scaly and sparsely haired. The eyes are small relative to the head in the rats Rattus.

Key to Introduced Rats and Mice 1

Size small, total length less than 250 mm, and tail less than 110, occipitonasal length less than 35, posterior molars quite small, their lengths combined shorter than the length of the upper first molar, the incisor tends to spald off behind the anterior surface, so that the tooth seems notched in lateral view ............... House Mouse Mus musculus

1’

2

2'

Size medium, larger than mice with total length greater than 250, tail longer than 110, occipitonasal length longer than 35 mm, posterior molars in tandom length longer than length of upper first molar, incisors never notched in lateral view .. ............................................... Rattus Tail longer than half the total length, temporal or parietal ridges bowed out, 13 mm or more .... Roof Rat (= Black Rat) Rattus rattus So far unknown in Wisconsin Tail shorter than half the total length, temporal ridges nearly parallel, less than 13 mm separation ............ Norway Rat Rattus norvegicus

Genus Rattus Fischer Norway and Black Rats Although the Black Rat or Roof Rat, Rattus rattus, is not known from Wisconsin, it often shows itself in port cities, such as nearby Chicago. A melanistic rat is not necessarily the black rat, and most black rats are not black. The common Norway rat is seldom seen far

from human habitations, especially in northern and central Wisconsin where winters are severe. The species often turns up as prey in the pellets of great horned owls and other wild predators. Several races of Rattus norvegicus have been introduced into North America, but for all practical purposes there is one variable kind, with no geographic races apparent.

Rattus norvegicus (Berkenhout) Norway Rat “Ernst Mayr tells of a steamer wrecked off Lord Howe Island, east of Australia, in 1918. Its rats swam ashore. In two years they had so nearly exterminated the native birds that an Islander wrote, ‘This paradise of birds has become a wilderness, and the quiet of death reigns where all was melody’.” — Rachel L. Carson, The Sea Around Us, 1950. 1769. Mus norvegicus Berkenhout. Outlines of the Natural History of Great Britain and Ireland. 1:5. Type probably from England, assumed to be Norway. 1912. Epimys norvegicus (Erxleben): Cory. Field Mus. Nat.Hist., 11: 180. 1916. Rattus norvegicus: Hollister. Proc. Biol. Soc. Washington, 29:126.



Dorsal aspect of skulls of Rattus norvegicus (left) and R. rattus and its upper cheek teeth. After Hoffmeister, 1989. 

The generic name Rattus is a Latinized old English word meaning rat, and norvegicus is possibly a sarcastic joke about Norway as the presumed locality whence the rats came. This inappropriate scientific name is valid. Perhaps this rat, being such an enemy of humankind, should be called a “Dirty Rat,” an epithet made famous by the tough-guy actor James Cagney. Description. See Key characters above, and accompanying figure. The pelage is grayish or brownish except for color aberrations, and the tail is sparsely haired and scaly. The rostrum of the skull is elongate, the diastema nearly twice the length of the maxillary toothTAXONOMIC ACCOUNTS / ORDER RODENTIA

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row. Pronounced parietal ridges are widely separate, and the molars have three rows of cusps on unworn teeth. The baculum is a small, jointed rod. There are six pairs of mammae. The chromosomes number 2N = 42 (Hsu and Benirschke 1967). A long-tailed variant from Portage County has teeth characteristic of R. norvegicus, not R. rattus. Measurements reveal that Norway rats, contrary to “big-city” myths, are never exceptionally large (total length 300-482 mm; tail 120-215, hind foot 31-44, ear length 15-22 mm, and weights vary from 170-850 g, with the average about 300 g. Young rats are difficult to identify, being as gray and small as other rodents; their tail is scaly and hind feet (which grow faster than other body dimensions) huge. Dental Formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Range. The Norway rat may occur anywhere in Wisconsin where people are present. Rats are especially abundant in city buildings, near waterways and run-down buildings, and in barns and barn lots. Status. Occasionally locally abundant, the Norway rat is injurious to humankind, destroying fowl, grain, and property and spreading diseases. On the positive side of the ledger, it eats some weed seeds, and is fed upon by owls and occasionally by other predators. The albino Norway Rat, with pretty pink eyes, is an important laboratory animal, where it often seems surly and aggressive, if not downright vicious. It is often kept as a pet, and I knew a lady who adopted and babied a real biting “devil,” loved it, and it became docile and affectionate. Even love-reared rats may cause an allergy in many who handle them. They are used as food for pythons and boa constrictors, are excellent dissection animals for general zoology, and serve humankind in diverse scientific experiments. Habitat. See Distribution above. This rat makes burrows (2-3 inches in diameter = 5176 mm), less than 18 inches (= 457 mm) deep in the ground, and varying in length to

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six feet ( = 1.8 m). It often gnaws holes in wood for ready passage, such as the famous rat-holes described in Huckleberry Finn by Mark Twain. The rat runs about under floors, tunneling into stored crops and so forth. It follows certain defined paths, which are called runways. The nests are bulky, made of grasses, sticks, and other available materials (Baker 1983). Foods. The Norway rat eats most anything edible, especially grain around farms, and young domestic fowl, garbage, and carrion. Reproduction. Breeding can take place at any time but is more frequent when food conditions are good. Females can breed when four months old, and may produce six to 12 litters per year. Litter size is usually 6-8 offspring, but Burt mentioned a record of 22 (Burt 1946). Gestation is three weeks. There is a postpartum estrus. The newborn young weigh about 5-6 g each, and are born naked. In 9-15 days the eyes open. Fur appears by seven days. Weaning takes place in a month, when the young are about 45 g in weight. Mortality. Enemies of the Norway rat are listed by Lantz (1910) and Baker (1983). Parasites are exceptionally important causes of mortality (Doran 1954, Banks 1910, Jackson 1961, Stiles and Crane 1910) affecting both the rat but also its hosts (including humans). Home Range and Density. Home range is rather small, maximum distances travelled about 150 feet (Davis et al. 1948). In Baltimore, the density in the city was 25 to 150 in a city block. A colony usually is comprised of 10-12 individuals. A litter of half-grown young swells this number considerably. Baker (1983) suggests a high of 300 rats at a single farm. Remarks. These rats form small colonies, usually eight or ten, and although fighting is commonplace there are sociable aggregations almost everywhere the rats thrive. Dominance and submissiveness are discussed by Calhoun (1962). They are nocturnal mostly, but can be observed often during the day. Dominant males seem to suppress breeding in a colony,

for when the male is removed, promiscuous breeding takes place. Additional Natural History. Calhoun 1962; Bjornson, Pratt and Littig 1969; Zinsser 1935; Henderson and Craig 1932. Geographic variation. None is evident. Specimens examined. Total, 29. Clark, Dane, Fond du Lac, Jackson, Manitowoc, Marinette, Milwaukee, Oconto, Portage (includes Rosholt, long tail, but teeth norvegicus), Price, Racine, Trempealeau, Vernon, Waupaca, Waushara, Winnebago, Wood counties.



Mus musculus Linnaeus House Mouse 1758. Mus musculus Linnaeus. Systema naturae, ed. 10. 1:59. Type from Sweden.

The name Mus means mouse, and in Old English ‘thief’. The trivial name musculus means little mouse. This mammal is also called the “laboratory mouse”. Description. See characters in the Key above. The house mouse resembles Rattus and superficially, because of small size, it re-

Map showing geographic distribution of Rattus norvegicus in Wisconsin. Known throughout North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

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sembles deer mice, harvest mice, and jumping mice. The house mouse differs from deer mice in having darker underparts and a scaly tail. The skull has tuberculate (i.e., bunodont) teeth, the posterior margin of the palate extends farther posteriorly. The incisors are usually notched in lateral view; for the posterior and distal part spalds off. From the harvest mouse Reithrodontomys, the house mouse has a dingier venter, and the tail is longer and scaly. There are no grooves on the upper incisors in Mus. The jumping mouse has a white belly, a much longer tail, and much



longer hind feet. Its skull resembles that of Mus, even in size, but in jumping mice the incisors are grooved, and the incisive foramina are much wider. There are eight to ten mammae. The diploid (2N) chromosome number is 40 (Hsu and Bernirschke 1967). Probably it is their anal scent glands that produce a musky odor, possibly the urine adds to it, and there is a mild odor produced by the feet. For cranial measurements, see Table Rod-14. The total length varies from 125-200 mm, and the tail from 60-100 mm. House mice weigh up to 28 g.

Maps showing geographic distribution of Mus musculus in Wisconsin. Known throughout North America. 

302

THE WILD MAMMALS OF WISCONSIN

Dental formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic range and Status. State-wide and injurious to humankind. Habitat. The house mouse in summer may be found in human habitations but often ranges into the nearby fields, almost any kind of field where vegetation is dense or the food grains are available. In winter the mouse generally moves into the habitations of humankind, although some probably pass the winter in the sheltered southwestern coulees and southern prairies. Nests are made of grass, or in houses of shredded paper, feathers, or any fine material, in a sheltered place. Baker (1983) reports that in fields the house mouse excavates a burrow and makes a nest of grass and fine materials for rearing young. Foods. House mice eat almost anything, preferably seeds, fruits, garbage, and insects. Reproduction. The house mouse is polyestrous, has large litter size, and a postpartum estrus, this mouse has incredible fecundity. Females may breed at 45 days age. Gestation is three weeks or even a little less. Young are born pink and naked, with eyes and ears closed. They weigh about 1 g each. Litter size is about 6 (3-13). They are furred by 10 days. The eyes open by 14. Weaning takes place in three weeks, and the female may already have produced another litter. The mice may live a year in houses, perhaps only a few months in the fields.

Mortality. The same predators that eat deer mice will also, on occasion, eat house mice. A great enemy of this mouse is humankind, appropriately in this case, as well as house cats and dogs. Parasites are similar to those of the Norway rat, and the same references are useful. Marsh and Howard (1976) have published an excellent control book. Home Range and Density. Fitch (1958) found Kansas house mice to wander in areas 20-100 feet in diameter. Populations fluctuate significantly, and sometimes there are explosions that make national headlines (82,000 per acre) (Hall 1927). Lowery (1974) found 500 per acre. Outdoor numbers peak in autumn. Additional Natural History. Biology of the laboratory mouse, by Snell 1943. Mouse genetics are summarized by Grueneberg 1943. Geographic Variation. None has been observed in Wisconsin. The mice are a hodgepodge of mutants, their ancestors introduced from around the world. Possibly they may adapt to certain areas (if not regions) by rapid evolution. The great majority of the specimens collected are wild type color (termed “agouti” in mouse genetics), but mutants abound. It is impossible to assign this variable mouse to any known geographic race. Specimens examined. Total, 102. Clark, Columbia, Dane, Door, Eau Claire, Green, Iowa, Jackson, Jefferson, Juneau, Lafayette, Lincoln, Manitowoc, Marathon, Marinette, Milwaukee, Monroe, Oconto, Oneida, Portage, Price, Racine, Richland, Rock, St. Croix, Trempealeau, Vernon, Waupaca, Waushara, Winnebago, Wood counties.



Table Rod-14. Cranial measurements Mus musculus. Darlington, 5 ad males. Lafayette Co. 6 ad females.  Occip. nasal l. Zygo. Br.



Palatal views of the skulls of the harvest mouse, house mouse, and jumping mouse. After E. R. Hall and his artists. 

L. nasal

Max. t-r

21.6 ±1.15

11.25 ± 0.5

7.4 ±0.4

3.48 ±0.15

21.36 ±1.36

11.38 ±0.5

7.56 ±0.28

3.6 ±0.2

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Family ZAPODIDAE Coues Jumping Mice and Siberian Birch Mice Although Klingener (1984) assigned the birch mouse and jumping mice to the jerboas, Dipodidae, I am unconvinced. Not only is the Zapodidae a distinctive and ancient group (from the Upper Oligocene, mid Pliocene epochs), but the Dipodidae shows extreme specialization in evolution of a fused tri-radiate cannon bone in the hind foot and having auditory bulla large and some species possess a complex “honey comb” inner structure. Besides remarkable specializations for jumping, some dipodids have fusion of the last five cervical vertebrae and some even of the axis, whereas zapodids show none. The lower jaw is remarkably different in the two groups. The characters in common, admittedly important, are the enlarged antorbital foramen and the peculiar lacrimal-jugal articulation (Lyon, 1901). But the foot structure alone, with a tri-radiate “cannon bone” of the hind limb specialized far beyond that of any Artiodactyla, would separate Zapus from Dipus as pigs from camels, so it would seem. As Lyon mentioned early on, and many recent workers have re-affirmed, the Zapodidae show affinity to the Muridae (Myomorpha) regardless of their hystricomorphous antorbital canal. The Zapodidae range across two continents, from Europe eastward through Siberia (subfamily Sicistinae, birch mice), southward in China (Zapodinae, genus Eozapus), and across North America in suitable habitats of Canada and much of the United States (Zapodinae, Zapus and Napaeozapus). The American jumping mice have elongated tail and hind legs and are able to leap incredible distances (in Napaeozapus as far as two meters). Unlike some other leaping or saltatorial mice, the auditory bullae are not enlarged, nor are the ankle bones fused. There are no external cheek pouches, and the molar teeth are rather hypsodont (unless worn smooth).

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THE WILD MAMMALS OF WISCONSIN

Usually (except in Napaeozapus) there is an upper premolar present on each side, conspicuously reduced in size, and the orange or dark yellowish upper incisors are grooved on their anterior faces. Zapodids have much larger infraorbital foramina than do many murids, including New World forms of the Muridae. Unlike murids, the ovate incisive foramina are tremendously wide and deep, probably functional as organs of Jacobson (enhancing taste). The much folded molars, presence of upper premolars, elongate hind feet and tail, and wide incisive foramina set this group of mice apart from other Wisconsin mice. The adaptation of hibernation, lasting in Zapus for as long as 6 months in Wisconsin, is another interesting trait. In Wisconsin, the grooved incisors alone would identify the two zapodid species, except that Reithrodontomys and Synaptomys also have grooves. No mice are likely to be confused with the long-tailed, longlegged zapodids. None of the other Wisconsin mice shows such yellowish-ochraceous tones in the dorsal pelage. The much folded enamel surfaces of the molar teeth are also characteristic, the labial border of each elaborated and defined by re-entrant “bays” (see Fig.) as several arcuate cusps and crests. There are four along the border of MI or of M2 (these cusps are less arcuate in Napaeozapus, especially the second cusp for each tooth, which is not so isolated but is confluent with the mid-portion of the tooth surface). There is one lingual (inner) re-entrant groove on each of these molars. Also of interest is the jugal, expanded and elevated anteriorly so as to join the maxillary at a vertical suture, and even to contact the lacrimal bone in the orbit. The auditory bullae are vase-like, each opening by a large meatus. The two premaxillaries fuse between the upper incisors and form a keel, and the upper incisors are orange anteriorly but the orange overlies ivory-yellow enamel behind the surface.

Key to Wisconsin Jumping mice 1

1’

Tail almost always lacking a white tip, color of fur on sides yellowish tan, upper premolar present and of reduced size, labial cusps of upper molars distinctly arcuate, the second on M-l/ and M2/ isolated by re-entrant groove, tail usually scaly, caudal hairs not conspicuous ..... .................... Meadow Jumping Mouse Zapus hudsonius Tail showing a more or less distinctive hirsute white-tipped end, color of dorsum and especially of sides bright but darker tawny ochraceous orange, upper premolar lacking, labial cusps of upper molars indistinct, the second on M1/or M2/ confluent with mid-surface of tooth, tail scales intermixed with conspicuous hairs, especially beyond hind feet ........ ................. Woodland Jumping Mouse Napaeozapus insignis

Genus Zapus Coues Jumping Mice “He glides around the fire much as the others do, but at the approach of danger, he simply fires himself out of a catapult, afar into the night. Eight or ten feet he can cover in one of these bounds and he can, and does, repeat them as often as necessary... Since the creature is chiefly nocturnal, the traveller is not likely to see it, excepting late at night when venturesome individuals often come creeping about the campfire... what is the reason for this indeterminable tail? The answer is, it is the tail to

Zapus hudsonius (Zimmermann) Meadow Jumping Mouse 1780. Dipus hudsonius Zimmermann. Geog. Geschichte die Mensche vierfussigen Thiere. 2: 358. Type locality Hudson Bay. 1781. Dipus labradorius Kerr. Animal Kingdom. Page 276. Based on description by Pennant. 1822. Gerbillus canadensis Desmarest. Mammalogie, 2: 321. 1825. Gerbillus labradorius Harlan. Fauna Americana. Page 157. 1799. Dipus americanus:Barton. Trans. Amer. Philosolphical Soc.,4: 115. 1829. Meriones labradorius: Richardson. Fauna Boreali-Americana, 1:144. 1843. Jaculus labradorius Wagner. Suppl. Schreber’s Saugthiere, 3: 294. 1899. Zapus hudsonius hudsonius: Preble. N. Amer. Fauna, 15: 15.

The name Zapus means, “Oh, what a big foot” referring of course to the hind foot. The trivial part of the binomen, hudsonius, refers to Hudson Bay, although no type specimen exists from Hudson Bay. Anderson (1942: 37) chose Fort Severn, Ontario, as a locality from which typical jumping mice can be obtained. Description. The characteristics were set forth above for the family Zapodidae. In comparison to Napaeozapus, the meadow jumping mouse averages smaller and the baculum is shorter. The tip is flattened (Burt, 1960). Upper premolars are present. The number

the kite, the feathering to the arrow; and observation shows that a Jumping Mouse that has lost its tail is almost helpless... one individual de-tailed by a mowing machine had no control of the direction, and just as often as not went straight up or landed wrong end to, and sometimes back where it had started from.” — Ernest Thompson Seton, in Ghosts of the Campfire, 1913.



Sketch of Zapus hudsonius by Wm. E. Hitchcock. 

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of chromosomes is 2N =72, which is a rather large number (Hoffmeister, 1989). There are four pairs of mammae. The dorsum is furred with guard hairs and underfur, a mixture of ochraceous or yellowish and dark brown or black. The longitudinal band is darkened by the black hairs, which are fewer and less visible on the sides, and lacking altogether in the lovely lateral band (not always present) of golden ochraceous or yellow adjacent to the white underparts. The tail is bicolor, blackish above (often grayish or brownish), pale whitish below. The large eyes are black. The upper surfaces of the feet are white or grayish white. Rarely the mice show white spotting, and one was melanistic. Occasionally they have white-tipped tails (Whitaker, 1972; Schorger, 1951). The upper incisors are orange or yellow. Although most workers conclude the sexes are the same size, Whitaker (1972) and Whitaker and Wrigley (1972) report the females are slightly larger. The total length is about 200 to 256 mm, and the tail approximately 60 percent of total length. See Table Rod-15. Dental Formula. I 1/1, C 0/0, P 1/0, M 3/3 =18. A reduced P4 is present, and the upper incisors are distinctly grooved. See Fig. under Mus. Geographic Range and Status. This beneficial, beautiful mouse is state-wide (see Map). Habitats. Often found in wet situations, such as swamp and marshes, the meadow jumping mouse will occasionally be found in well-drained meadows and mature forest. The meadow jumping mouse is abundant in grassy shorelines of streams and ponds. Whitaker (1963) mentions the importance of herbaceous ground cover, and Getz (1961) reported that the mouse avoids sparse vegetation. Other reports on ecology are found in Quimby (1951) and Hamilton (1943). In Wisconsin I have often taken Zapus in marsh grasses, jewel weed, and dense grass near tamarack swamps, and have observed them occasionally in open forest, on both wet and dry soils. Ross et al. (1968)

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found them more abundant in Minnesota on mima-like mounds than on surrounding wetlands, probably as these higher sites are more suitable for burrows. The meadow jumping mouse makes a nest of dry grasses and leaves about 6-7 inches in diameter with one entrance on a side (Dexter, 1954; Jackson, 1961). It may be placed in dense vegetation or shallow excavations. In winter the hibernation nest is situated in deeper tunnels (two feet or even deeper). The hibernation nest may contain a few leaves. Foods. Little is known about the foods of Zapus in Wisconsin. Whitaker (1972) summarizes several studies including his own. Hamilton (1935) mentioned berries and nuts as well as seeds, fruits, and insects. Whitaker (1963) reported on 796 individuals from New York, finding that insects make up about half the food in spring, whereas seeds are only 20%. As summer passes seeds become more important, animal foods less, and the fungus Endogone becomes an important component. The most important animal foods then were lepidopterous larvae and carabid and curculionid beetles. In Indiana, in a sample of 131 individuals, Whitaker (1970) found that seeds comprise most of the diet (50.4%), the species depending on the season. Impatiens and Setaria were important by volume and frequency. Lepidopterous larvae, insects and slugs were also eaten. Reproduction. Quimby (1951) found the gestation period to range between 17 and 21 days for four females. He concluded that in Minnesota most births take place between 15 June and 30 August, but peaks occur in late June, mid-or late-July, and in mid-August. Pregnancies are noted by several workers in every month of summer and early fall, but there is more breeding in June. The latest litters were September. Most females produce two litters. Quimby (1951) found an average of 5.7 young per litter (N = 17, range 4-7) in Minnesota, and Townsend (1935) reported 4.5 (N=17, 37) for New York. Krutzsch (1954) reported a mean of 4.5 (range = 2-8) from over a wide



Upper molar row of Zapus. After P. Krutzsch, 1954. 



Maps showing geographic distribution of Zapus hudsonius in Wisconsin and North America. 

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geographic range. Whitaker (1963) reported 5.5 (N = 78) with a range of 2-9. In Wisconsin specimens, few pregnancies were noted. Lactating or pregnant females were obtained from June into July in Portage County, and ranged from June into October judging from other records in Wisconsin (June 23 in St. Croix County; through July, in Adams County; July 9 in Ashland County; 25 September near Pittsville, Wood County; and 27 October near Necedah, Juneau County). Breeding seemed to last through September but occurred only sporadically after July. None was observed in August in our specimens. Nora Lopez-Rivera found three records of pregnancy from the Buena Vista Marsh in the Hamerstrom’s field journals. They were June 2, July 26, and August 2. Thus, the pregnancies for Zapus in Wisconsin occur in every month, from early June until late October (1 record). Litter size averaged 6 (range 5-8) for six pregnant females. I reared one live litter of five wonderful young [on milk-egg food] in Portage County. On the Buena Vista Marsh, 3 females contained 6-7 embryos (Hamerstrom records). Altogether the 10 females averaged 6.2 (5-8) embryos. Juvenal mice entered the population in July, and again in early fall (specimens taken 20 September in Dodge County; 19 September in Columbia County; 22 October in Vernon County; and 10 October in Oconto County). Jumping mice were taken as late in the fall as September 22, 11 October, 18 October, and 27 October, after which the mice enter hibernation. Whitaker (1963) discussed ontogeny of 19 newborn young. The young measured 34.4 (range 30-39) mm in total length, the tail 9.3 (7-11), hind foot 4.7 (3-6). The average weight for 14 neonates was 0.8 g (0.7-1.0 g). Quimby (1951) described the newborn young as pink and naked with minute vibrissae. After about a week the vibrissae became visible to the naked eye, the tail became bicolored, the pinnae of the ears unfolded, and claws appeared. The incisors erupted on the 13th day. They were

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THE WILD MAMMALS OF WISCONSIN

white. By three weeks the body was haired out. The eyes had opened in the fourth week. Adult pelage had appeared approximately at this time, replacing the juvenal fur. The incisors had become orange, and the tail had grown 10-fold. Growth slowed thereafter, and adult size was attained in 60 days or more. Mortality. Many predators prey on jumping mice, including frogs, snakes, fishes, foxes, wolves, weasels, mink, and house cats. Birds of prey include several hawks, especially red-tailed and marsh hawks, as well as several kinds of owls (Whitaker, 1963; Baker, 1983). Known parasites are well summarized by Whitaker (1972), and reportedly mites are the most common external parasites. Several species of fleas, botflies, chiggers, sucking lice, and mites were also reported. Internal parasites included trematodes, tapeworms, and nematodes. Carmichael (1979) reported blood flukes, Schistosomatium douthitti, from jumping mice in Minnesota. Home Range and Density. Quimby (1951) reported home range from 0.19-0.87 acres for females, and 1.1-0.14 acres for males, in Minnesota. In another study he found the males to have larger home ranges (2.7, 9 males and 1.57, 17 females). In Michigan, Blair (1940) determined the home range as about the same for males and females (0.89 to 0.92 acres, for 26 males and 24 females). Quimby (1951) and Muchlinsky (1988) suggested that for the most part the population turned over in summer, the new adults replacing the carry-overs from the year previous. The populations vary in size from year to year, but two studies agree fairly well, placing the number of meadow jumping mice at about 12 per acre (Quimby, 1951; Blair, 1940). The habitats for these mice are not far removed from Wisconsin. Remarks on Hibernation and Behavior. The solitary meadow jumping mouse is usually nocturnal, but often seen by day. It can climb, and occasionally does to cut seed heads off tall plants such as timothy (Whitaker, personal correspondence). It is an able swimmer,



Table Rod-15. Cranial and external measurements and weights (g) of Zapus hudsonius. 

Greatest length skull

Condylo- Zygomatic Inter Length Maxillary Length Total Length Length Length Weight basal breadth orbital nasals tooth Incisive Length Tail Hind ear grams length breadth row foramen Vertebrae Foot

intermedius St. Croix Co. 23.03 ±0.66 N=5.00

20.86 0.21 5.00

10.86 0.52 5.00

4.22 0.22 5.00

8.30 0.87 5.00

3.72 0.33 5.00

4.42 0.29 5.00

202.25 14.13 4.00

121.50 ±8.89 N=4.00

28.25 2.22 4.00

9.75 1.71 4.00

Sauk Co. 22.05 ±0.90 N=7.00

20.10 0.97 7.00

10.27 0.18 7.00

4.06 0.17 7.00

8.54 0.54 7.00

3.76 0.22 7.00

3.91 0.32 7.00

196.30

121.00

27.30

10.30

3.00

3.00

3.00

3.00

hudsonius Bayfield Co. 22.37 ±0.65 N=20.00

20.80 0.67 20.00

10.64 0.34 20.00

4.21 0.16 20.00

8.45 0.58 20.00

3.89 0.19 20.00

4.20 0.22 20.00

205.82 6.47 20.00

124.94 ±6.47 N=20.00

29.29 1.45 20.00

9.88 0.96 20.00

17.83 3.00 17.00

Portage Co. 22.05 ±0.75 N=16.00

20.01 0.87 16.00

10.53 0.31 16.00

4.13 0.16 16.00

8.24 0.42 16.00

3.79 0.22 16.00

4.24 0.21 16.00

202.40 2.87 13.00

121.58 ±4.86 N=13.00

29.34 0.91 13.00

12.44 1.38 13.00

20.50

for several minutes at least, swimming frog style either with head out of the water, or with head and body completely submerged. It can leap usually about 1 meter for the initial jump, which helps them escape predators. Once I attempted to leap on one, and it was 20 feet away before I landed (my knee upon a sharp rock). The jumps are much shorter after the initial leap. Two-meter leaps have been reported as errors, but Jackson measured a leap slightly greater than that. Hibernation of Zapus is interesting, which in Wisconsin is genuine and seems to last from late October until mid-April. The physiological data on hibernation have been well summarized by Whitaker (1972). A litter I reared surprised me, because the young mice ate the eyes of one that had begun to hibernate, and ate another entirely except for the skin. During the summer the young were amiable to one another, and to me, but as hibernation approaches in September, they must be separated.

13.00

Muchlinsky (1988) measured the soil temperature at 50 cm depth to estimate emergence temperature for Zapus hudsonius during the years 1977-1988. Males emerged slightly earlier than females (males April 20-May 11, and females May 6-7, until May 29). The soil temperature varied from 8-15 degrees C. Additional Natural History. Whitaker (1972) reviewed the biology of Zapus hudsonius. Geographic Variation. There are two geographic races recognized in Wisconsin (Krutzsch,1954). He drew a line across the northern parts of Wisconsin assigning all specimens north of it to the nominate race, which mice are darker especially on the sides. Jackson (1961) drew the line somewhat differently, probably intuitively and hopefully ascribing races to the lake country in the north and the prairie country in the southwest and southeast (near Green Bay). He changed one marginal record from Oconto County from the southern race to the northern. Inasmuch as TAXONOMIC ACCOUNTS / ORDER RODENTIA

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the cranial measurements do not vary greatly, nor seem to be diagnostic in Wisconsin, I attempted to assign the races on the basis of color, the tawny ochraceous ones southward and the dull-sided darker ones northward. I only compared specimens of large size because young animals are never as bright as the older ones. The results (see Fig) show some variation in color, as would be expected, but fair constancy in the northern and central populations. It is necessary to shift the boundary southward in the central counties, for populations there are decidedly dark. Krutzsch (1954) made his assignment based on a huge taxonomic revision, but in Wisconsin the specimens were rather few. Jackson made a sensible assignment owing to his knowledge of the ecology of Wisconsin, but my specimens in the central counties (Marathon, Portage, Juneau) do not fit either arrangement. I provisionally redrew the boundary line between the races (see Map). In cranial characters I could not distinguish significant differences on which to draw subspecies boundaries, and color also had limited use. Inasmuch as color in Z. h. hudsonius is reportedly darker and more tawny on the sides (i.e., more light brownish orange instead of yellowish) than in intermedius, I composed two series of comparative skins including no. 3775 Adams Co. and 5835 Marathon County for orange (the latter darker) and for black intermixtures on the sides 7082 Pierce Co., 4650 Adams Co., 5837 Bayfield Co., 5839 Bayfield Co., the last darkest. These were weighted 1 to 2 and 1 to 4, respectively, and the samples were averaged with the two values added (large values darkest). On the whole, the earlier observation that specimens are dark in the central counties as well as in the north was borne out. In Marathon and Portage counties and some localities westward, the dark color is due more to the presence of orange, and in Bayfield County and other localities black hairs cause dark color. The race Z. h. intermedius is not always distinctive, intergradation occurs wide-

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THE WILD MAMMALS OF WISCONSIN

ly over Wisconsin, and the traits of skull and color vary in a spurious microgeographic and confusing manner. Concerning cranial characters, Krutzsch (1954) lists for Z. h. hudsonius the auditory bullae broader (less inflated), condylobasal and zygoma longer on average, braincase broader, and incisive foramina shorter even though the overall size is larger. In Wisconsin specimens of intermedius approaching hudsonius, he noted longer bullae and wider bowed foramina. In these characters there is much overlap in Wisconsin. A series of intermedius from St. Croix County has small skulls (Table Rod-15) and the incisive foramina are narrow (less bowed). The Sauk County intermedius are similar but have relatively narrow foramina. The large Drummond series (Bayfield County) shows larger dimensions and wide-bowed foramina, resembling the Portage County series. Juneau County skulls resemble hudsonius, whereas Adams County skulls east of the Wisconsin River resemble intermedius.

Zapus hudsonius hudsonius (Zimmermann) 1780. Dipus hudsonius Zimmermann. Geographische Geshichte... 2: 358. Type from “Hudson Bay” but now fixed at Fort Severn (see text). 1852. Meriones americanus: Lapham. p.44. Type from near Philadelphia, as Dipus americanus Barton, 1799. 1899. Zapus hudsonius hudsonius: Preble. N. Amer. Fauna, 15:15.

Description. Pelage dark, sides dull and less tawny, auditory bullae larger, incisive foramina broad. Geographic Range. This race is found in northern counties. See Map. Specimens examined. Total, 109. Ashland, Bayfield (includes Outer Island, Apostle Islands 1), Douglas, Florence, Iron, Juneau, Langlade, Lincoln, Marathon, Oconto, Oneida, Portage, Wood counties.

Zapus hudsonius intermedius Krutzsch 1954. Zapus hudsonius intermedius Krutzsch. Univ. Kansas Publs., Mus. Nat. Hist., 7(4): 447. Type from Ridgeway, Iowa.

Description. Pelage brighter tawny on average especially on the sides. Measurements are given in Table Rod-15. Geographic Range. This race of jumping mouse occurs in suitable habitats thoughout much of southern Wisconsin. See Map. Status. This mouse of marsh, swamp, meadow and forest avoids cultivated fields, and has never been considered a pest. It can be considered beneficial to humankind, because it feeds on plant seeds, many considered as “weeds”, and on insects, many of which are pests. It is a prey species of numerous carnivores and birds of prey. The numbers of specimens indicate the mouse is uncommon, but it can be locally abundant. This mouse also has much aesthetic value, for it is

of curious form and habits, hibernates in winter, and is exceptionally beautiful. Specimens examined, Total , 72. Adams, Buffalo, Clark, Columbia, Dane, Dodge, Iowa, Manitowoc, Monroe, Pierce, Sauk, Sheboygan, St. Croix, Vernon counties. Additional Record. Marlin Johnson caught a meadow jumping mouse in extreme northern Door County.

Genus Napaeozapus Preble Woodland Jumping Mouse The genus Napaeozapus differs in several characters from other zapodids and is thought to be evolutionarily more advanced. Resembes Zapus hudsonius, especially in the southern parts of its range (where bright colored Zapus are common), the woodland jumping mouse tends to be more brightly orange or ochraceous on the sides and in the pure ochraceous lateral line (when present). It has the terminal portion of the tail hirsute and white (5-20 mm). The hairy tail is less scaly in appearance and more sharply bicolor; the overall size is larger on average; there are no premolars present; and the upper Ml and M2 show less conspicuously arcuate labial cusps (i.e., less prominent re-entrant grooves defining the cusps. There are 72 chromosomes as in Zapus (Whitaker and Wrigley, 1972).

Napaeozapus insignis (Miller) Woodland Jumping Mouse 1891. Zapus insignis Miller. Ame. Nat., 25: 742. Type from Restigouche River, New Brunswick. 1899. Napaeozapus insignis: Miller. Bull. New York State Mus. Nat. Hist. 6: 330.



Color scale values for Zapus hudsonius in Wisconsin. Under each value is the sample size. Dark pelages are mostly in the northwest and center. This finding roughly agrees with Krutsch 1954, but the variation is irregular and the differences not distinct. 

The generic name refers to the animal’s habitat: woodlands. It also exclaims, “Oh, what a foot,” referring to the hind foot. The specific name insignis means conspicuous, as in insignia, and doubtless refers to the TAXONOMIC ACCOUNTS / ORDER RODENTIA

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white-tipped tail. The description is given above for the genus.

Napaeozapus insignis frutectanus Jackson 1919. Napaeozapus insignis frutectanus Jackson. Proc. Biol. Soc. Washington, 32: 9, February 14, holotype from Crescent Lake, Oneida County, Wisconsin.

Description. See above. Napaeozapus averages slightly larger than Zapus hudsonius. See tables Rod-15-16. Dental Formula. I 1/1, C 0/0, P 0/0, M 3/3 = 16. Geographic Range. The woodland jumping mouse is found in the boreal or northern parts of Wisconsin (see Map). Frank Iwen identified a specimen (UW 24342) from Fort McCoy, southwest Wisconsin. I examined the specimen; its tail was not tipped white, but the color was rich orange brown. Anterior premolars were reportedly absent; we could not find the skull. Status. This jumping mouse is and always was rare, known in Wisconsin only by 14 specimens in 1961 (see Jackson, 1961). The number of specimens has about doubled, but the species remains rare in comparison to most Wisconsin mammals. Napaeozapus is not a pest, and owing to its beautiful colors and clean graceful appearance its habitats should be preserved. It is an interesting mammal, because it hibernates and is evolutionarily adapted for jumping. Napaeozapus is more colorful and a more spectacular leaper than Zapus. Habitats. Occurs in northern forests, including maple, pine, spruce, tamarack, cedar, and similarly wet and boreal woodlands. John Long and I have taken them at the edge of cedar-tamarack swamps near standing water, rusty with mineral deposits, and in jewel weed, mosses and ferns on black wet soil away from the standing water. My students have taken them near small streams in northern Wisconsin. Zapus is often taken in association with

312

THE WILD MAMMALS OF WISCONSIN

Napaeozapus. Whitaker and Wrigley (1972) conclude that Napaeozapus inhabits the spruce-fir and hemlock-hardwood forests in the eastern half of North America, especially balsam fir and eastern hemlock. Locally, the mouse prefers cool, moist habitats within the forest or at its edge. It also occurs, as noted above, in bogs and swamps, but occasionally inhabits dryer areas (Sheldon, 1934). Damp rocky areas are often preferred. Preble (1956) noted that the largest populations in his experience were found along streams in grasses, sedges, and alders. Whitaker (1963) noted a preference for low herbaceous vegetation. Although often taken together, Zapus and Napaeozapus may segregate in different plant communities, with Zapus primarily in meadows and Napaeozapus primarily in woods. Hamilton (1935), Preble (1956), and others found Zapus invading Napaeozapus habitats, but not the other way around. My trapping in Wisconsin has yielded results consistent with that view. Little is known about dens, nests, and burrows of Napaeozapus. Apparently the mouse usually places its nest in a burrow, but occasionally makes it in low vegetation. Stupka (1934) found a nest made of leaves and dry grasses in a brushpile in Maine, and Snyder (1924) describes a natal burrow excavated near Lake Nipigon, Ontario. The burrow extended about 5 1/2 inches below the soil, for a length of about 1 meter, before ending in a blind pocket. The nest cavity was about 14 inches (= 355 mm) from the entrance, about 6 by 5 inches, and contained a nest of dry leaves. There were five young in the nest. Foods. Nothing is known of food habits of Napaeozapus for Wisconsin, but they are probably similar to those elsewhere, and, where the two species coexist, probably similar to food habits of Zapus. Before the fungus Endogone was known to be a food for jumping mice, the foods were classed as mostly seeds and insects. Most (some 70%) of the foods were seeds, depending on their availability in season, and berries. About 30% of the diet consisted of insects and soft-bodied



Upper molar rows of Zapus and Napaeozapus. After Krutzsch. 



Maps showing geographic distribution of Napeozapus insignis in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

313

invertebrates (Hamilton, 1935; Sheldon, 1934; Whitaker, 1963; Wrigley, 1972). Larval Lepidoptera, adult beetles, larval flies, spiders, centipedes, worms, and other insects are eaten. Some leaves and shoots are consumed (Whitaker, 1972). Endogone may make up 35 percent of the diet (Whitaker, personal correspondence). Reproduction. The number of woodland jumping mice taken recently in Wisconsin almost doubles the 14 specimens (from 10 localities) discussed by Jackson (1961). Nevertheless, breeding information is meager. One lactating female (2207) from Oconto County was obtained July 22, 1970, and a young Napaeozapus (sex?) was obtained 7 August 1971, from Chippewa Lake in Bayfield County. Most of the individuals examined were males. From outside Wisconsin the gestation period was roughly determined as about 29 days or even longer. Quimby (1951) suggested a shorter time. Whitaker and Wrigley (1972) suggest 23-25 days, based on lab matings. Other gestation periods estimated were 23 and 25 days. Napaeozapus seemingly are not sexually active until their second year. Eighty litters from a wide geographic range averaged 4.6 (2-7), and 45 counts of placental scars averaged 4.3 (2-7). Apparently Napaeozapus has no postpartum estrus, although late breeding may occur after the young are weaned (Schwentker, 1939). Pregnant mice were collected in early May, although only a few. Births peak in June



and parturition continues sporadically through July. A second peak was apparent in August (in sharp contrast to our Wisconsin data for Zapus) and many of the females produce second litters. Late season pregnancies were in August, and the latest observed September 1. In second litters, litter size is reduced. Second litters are less often produced in the northern latitudes (Wrigley, 1972). As in Zapus, a turnover of the carry-over adults occurs. The old mice are replaced by young of the year (Muchlinsky, 1988). Newborn young are hairless and pink with loose skin (Lane and Hamilton, 1954), whitetipped tail prominent (Snyder, 1924). Vibrissae are visible and the tiny ear pinnae folded. Measurements reported were: total length 35.2 mm, tail length, 11.0, hind foot length 5.0. After a week the vibrissae were 2 mm long and the ear pinnae larger. By 10 days, pigment spots were visible and the ear pinnae had unfolded. By 14 days fine hair covered the body. Lower incisors were visible by 19 days. By 21 days the dark dorsal band on the fur appeared. Eyes opened by 26 days. The incisors were grooved and yellow by 31 days. By 34 days, the young resembled adults except the pelage was paler, more yellowish rather than orange-brown. The adult pelage appeared between 63 and 80 days (Wrigley, 1972). Mortality. Predation on woodland jumping mice by carnivores, snakes, and birds of prey is important. Fish may swallow them if they fall into a pond or stream. Some records of predation include screech owl, mink, wea-

Table Rod-16. Cranial measurements of Napaeozapus. 

Greatest length skull

Condylo- Zygomatic Inter Length Maxillary Length Total Length Length Length Weight basal breadth orbital nasals tooth Incisive Length Tail Hind ear grams length breadth row foramen Vertebrae Foot

Wisconsin 24.26 ±0.42 N=7

21.83 ±0.51 N=7

Cheboygan Co., Mich. 24.0 21.3

314

12.17 ±0.25 N=7

4.62 ±0.42 N=7

9.50 ±0.42 N=7

4.02 ±0.17 N=7

4.89 ±0.2 N=7

230.17 ±6.64 N=12

142.27 ±3.07 N=12

30.42 ±0.9 N=12

13.33 ±2.5 N=12

11.7

4.45

8.5

4.4

5.0

233

142

31

16

THE WILD MAMMALS OF WISCONSIN

20.95 & 2.27 N=2

sels, striped skunk, domestic cat, bobcat, and timber wolf. Internal parasites include protozoans, tapeworms, and roundworms. External parasites include fleas, mites, ticks, and botflies (Wrigley, 1972). Home Range and Density. Home range seems about 1.0 to 6.5 acres in females, and in males 1.0 to 9.0 acres according to Blair (1941). In New York, Napaeozapus are fairly abundant; Townsend (1935) found as many as 24 per acre. In Michigan Blair found 2.7 per acre, and Manville (1949) estimated 0.26 per acre. Brower and Cade (1966) estimated 5.2 per acre in New York. Whitaker (1963) observed frequencies up to 0.21 per 100 trap nights. Remarks on Behavior and Hibernation. Usually after several leaps the woodland jumping mouse hides in vegetation unless closely pursued. It climbs in bushes, but has never been seen to ascend a tree. They swim with head above or below the surface (Wrigley, 1972). Usually nocturnal, they have been seen in daylight. Late records, preceding hibernation, are in late September for adults, and for young-of-the-year October. Wisconsin specimens show collection dates from 10 May until late September, with one adult taken 16 November. These mice put on weight before entering their hibernaculum, and subsist on fat until they emerge in early May or, in females, a little later. The earliest emergence date known is 16 April in Pennsylvania. Geographic Variation. Minor variation was seen in the length of the white on the tail, which in Portage and Marathon counties seemed reduced, and in one specimen from Pulaski Road, Marathon County, lacking. There is one race in Wisconsin. Specimens examined. Total, 24. Bayfield Co.: Clam Lake Field Station 2. Chippewa Lake Field Station 4. 3 mi. NW Clam Lake Field Station 1. 1 mi. N Grandview on 10mile Creek 1. Drummond 1. Douglas Co.: St. Croix River 2. Forest Co.: Laona 1. Langlade Co.: Summit Lake, Camp Susan 1. Marathon Co.: 1/2 mi. N on Pulaski Road 2. Marinette Co.: 9 mi. NW Crivitz on Co. A, 1. Monroe

Co.: Fort McCoy 44.01N, 90.4W 1 UW (skull not seen). Portage Co.: 1 mi. E Jordan Pond, in Jordan Swamp (1/4 mi. N Hwy 66) 1. Price Co.: T32N, R2W, Sect. 9, 1 Hamerstroms. Sawyer Co.: 1/2 mi. N Couderay 3. Taylor Co.: 16 mi. S Medford 1. Wood Co.: Mead Wildlife Area 1. Michigan. Cheboygan, 5.

Family ERETHIZONTIDAE Thomas New World Porcupines Form stout, forearms robust, dorsum with long guard hairs, wooly under fur, and conspicuous sharp quills; molars flat-crowned, rooted, and hyposodont; angular process of dentary inflected; infraorbital canal larger in diameter than foramen magnum of spinal cord; plantigrade feet specialized for a clambering, arboreal niche. Nevertheless, porcupines are often on the ground. The origin of this hystricomorph family was in Central or South America, but it, like the opossum, ranged northward, and today porcupines are on the Arctic slope of Alaska.



Sketch of Porcupine in tree. By Walter A. Weber. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

315

Genus Erethizon F. Cuvier North American Porcupine Races reviewed by Anderson and Rand, Canadian J. Res., Sec. D, 21:292-309, 1943. 1822. E [rethizon]. F. Cuvier. Mem. Mus. Hist. Nat. Paris, 9:432. Type Hystrix dorsata Linnaeus, 1758, Syst. Naturae.

Description. See account of Erethizontidae above. The Erethizon have a well-developed hallux, but the tail is not prehensile. The related South American Coendu is the opposite. Normally a single young is born per year. Young are born with hair and quills enclosed in the amnion. The genus is monotypic.

Erethizon dorsatum (Linnaeus) 1758. [Hystrix] dorsata Linnaeus. Syst. naturae, 10th ed. 1:57. Type locality Eastern Canada. 1822. E[rethizon] dorsatum: F. Cuvier. Mem. Mus. Hist. Nat., Paris, 9:432.

The word Erethizon means something of an irritation, and the word dorsatum refers to the upper parts or back, where the formidable quills are found.

Erethizon dorsatum dorsatum (Linnaeus) Description. See remarks above under Erethizontidae. The porcupine is a mediumsized mammal, but is an exceptionally large rodent. Among Wisconsin rodents, only the beaver Castor exceeds it in size. The neck is so short it seems absent, and indeed the anterior two cervical vertebrae are compressed and fused together. The tail is short and well armed with quills around the border, which quills are slapped in the face of an enemy. The shaggy whitish-yellow guard hairs and long yellowish quills give the porcupine an appearance of prickly, yellow and black, plumpness. The longest quills exceed 60 mm.

316

THE WILD MAMMALS OF WISCONSIN

In winter the hair on the shoulders grows out longer. The quills are spinose, with black tips. The limbs are stout, as are the claws, and the plantigrade feet have exceptionally broad soles, naked and scaly. There are five toes on the hind foot, four on the forefoot. The belly is covered with sparse blackish or brown hair (no quills). The face is furry, and the eyes fairly large. The ears are small and the rhinarium broad. The tail is bristly on the lower sides. There is a distinctive but variably formed baculum, with a club-like base and flattened (dorsoventrally) shaft (see Burt, 1960). Jackson (1961) reported six teats, four pectoral and two abdominal, but Burt (1948) and Baker (1983) report only four pectoral mammae present. Uldis Roze told me that perineal glands, paired pockets near the ventral midline, larger in males, are likely used in dragging and leaving odors (produced by sebaceous secretions and bacteria (Staphylococcus, Cryptococcus)). The porcupine skull is large for Wisconsin mammals, with formidable orange incisors. The high, flat-crowned cheek teeth show a peculiar folded molar pattern. The nasals do not extend as far forward as the incisors, although the fleshy nosepad does. The interorbital breadth is quite wide. It is over 50 percent of the greatest breadth of the zygomata, which zygomata narrow anteriorly. The infraorbital canal is enormous, larger even than the foramen magnum. The angular process



Skull of Erethizon dorsatum. 

of the dentary is inflected. The sagittal ridges converge near the occiput to create a sagittal crest in adults. The palate does not extend posteriorly as far as the last molars. The ground color of the porcupine dorsally is black or dark brown, with stout yellowish or ivory hollow quills intermixed with grayish or whitish guard hairs and dark wool. In winter the shoulder hair greatly lengthen. The underside is dark brown. Jackson (1961) reported albinos from Wisconsin. Two from Wisconsin were placed in my freezer lacking, unfortunately, any additional data. Molt takes



Maps showing geographic distribution of Erethizon dorsatum in Wisconsin and North America. 

TAXONOMIC ACCOUNTS / ORDER RODENTIA

317

place in late spring and summer (Po-Chedley and Shadle 1955). The porcupine varies to 900 mm (35.5 in) in length, weight to 30 lbs (13.5 kg). The skulls average 100 mm (approx. 4 in) in total length. Dental Formula. DF = I 1/1, C 0/0, P 1/1, M 3/3 = 20. The 20 teeth include four upper molariform teeth. The dental formula distinguishes the porcupine skull from the flat-skulled marmot, which has prominent postorbital processes. Geographic Distribution. This boreal mammal ranges or did range northward as far as the Arctic Slope of Alaska, and southward along the Rockies into Mexico, and southeastward into west Texas. All of Michigan, Wisconsin, Minnesota, most of Iowa and Indiana, and northern Illinois lie within the probable geographic range (Hall and Kelson 1959). Apart from archaeological records (Parmalee 1967, 1963), there is only one historic record of porcupines in northern Illinois. Kennicott (1859:91) mentioned a record from Whiteside County and the banks of the Illinois River. Neither he nor Hoffmeister (1989) accepted this record. Lyon (1936) listed records from Indiana near the Illinois border, and Bowles (1975) thought the species was probably in northeastern Iowa. There are historic reports from southern Wisconsin (Jackson 1961). Now there are no populations remaining there. Deforestation and land use have devastated porcupine numbers in the former hardwood forests south of the “tension zone.” The northern forests still support this mammal in fair numbers. Jackson (1961) noted the retreat of the species, listing authentic records “before 1870” in Richland and southern Sauk counties. He mapped reports from Walworth (1917), Sheboygan (1917), and Dane counties, and westward (Buffalo County) along the Mississippi. He examined a specimen from Monroe County, and proposed 1961 marginal limits as extending from Burnett, into Rusk, Clark, and Shawano counties, and northern Door County. No records are known now from the southern parts of the Door Peninsula.

318

THE WILD MAMMALS OF WISCONSIN

Jackson’s (1961) line agrees with mine (for the present distribution). I mentioned above that there are no porcupines on islands in Door County, but porcupines still exist in fair numbers on the forested Peninsula north of Sturgeon Bay. Porcupines regularly occur in northern Portage and Wood counties. They seem absent from southern Portage County. Porcupines possibly occur in Monroe and Juneau counties on occasion, and two were dead on Highway 10 at Wedgee and Fivemile creeks, in Clark County. See Map. Status. A century ago many American children were taught to “Save the porcupine” because a lost person in the North Woods can always capture one and eat it. That is a fanciful legend. Perhaps porcupines are as rare as people who get lost in the North Woods, at least in the remote forests wherever they happen to get lost. The porcupine is edible (Jackson 1961). It is not uncommon in Upper Michigan. Many people consider the porcupine a nuisance. It damages trees by feeding on the leaves, bark, and buds, and sometimes kills trees. It gnaws on cottage decks, eats plywood, chews on cabin walls, and even rubber tires, and occasionally cuts electric wires. It is active day or night. The observed damage seems important, but in the big picture it is insignificant. Injury from quills may inflict great pain and injury to dogs, natural predators, and even humans. Quills tend to work inward, not outward, and I personally know of rare mortality to black bear and elk. Doubtless some coyotes and dogs die from quill injuries on occasion. Quills may be removed with pliers, but the quill must be loosened by gentle side-to-side movements, close to the wound, with great caution used to prevent breaking the quill. Snowshoe hares and deer eat porcupine “leavings” (i.e., dropped plant parts) dropped from a tree in winter. Bears, fishers, and other carnivores occasionally kill and eat their ventral parts. The fisher is considered the primary controlling predator of porcupines. Native Americans have used, and do use, the quills in artistic embroidery.

The aesthetic value of the porcupine, which is a most curious creature, is well known in American literature (e.g., Mother Westwind’s Stories). It lives in the forests posing for pictures near resorts, stirring up interest at campsites, and is tolerated in managed forests. Local damage is caused in some tree plantations. The status of the porcupine must be watched closely, as it has retreated northward significantly in its geography. With land use of humankind relentlessly removing trees, we can expect less habitat for porcupines. Less attention should be given to “control” of a “nuisance”, and more attention to preserving an unusual mammal. Habitat. The porcupine is found in forests or open woodlands, particularly the mixed conifer-hardwoods of Northern Wisconsin and Upper Michigan (Earle 1978, Kelly 1973, Golley 1957, Dice and Sherman 1922). The porcupine prefers for shelter a hollow log or tree, or a small cave. Shapiro (1949) found dens protecting the porcupines more against wind than cold. Temporary dens may be used, sited as one km away from another. Fecal droppings signify the presence of a den. Burt (1946) reported an occurrence of 20 porcupines in a winter den. Foods. Seasonal vegetation includes buds in spring, nuts in autumn, inner bark in winter, and leaves and twigs in summer. The trees utilized for foods are conifers (balsam, hemlock, black and white spruce, ce-



Quills of porcupine. Showing scales. Po-Chedley. 

dar, white, red and jack pine, and tamarack) and some deciduous trees (willow, beech, various maples, yellow and paper birch, and aspens). The porcupine sometimes wanders far after food, into deciduous forests for leaves (in summer), and often into coniferous forests where phloem is eaten after midOctober and in winter. In summer, the animal was observed to graze, so to speak, only 15-60 minutes per day. Second growth forest is preferred over mature forest (Golley 1957, Brander 1973). In summer porcupines often forage on the ground, eating such foods as roots, leaves, and hazelnuts. Porcupines have fed even on pond lilies. Bone is often gnawed by porcupines, and any trace of salt is eaten. Porcupines have searched human habitations for salt (Jackson,1961; Rogers, 1981). Others report corn occasionally is damaged. Reproduction. Shadle (1944,1946, 1948 and 1951) documented the reproductive behavior of the porcupine. Struthers (1928) and others have supplemented this information. Breeding takes place from November to early December. The porcupines are promiscuous. The idea of copulation is mind boggling, but presumably a pheromone in a urine secretion seduces a female’s cooperation, i.e., holding down her quills. Other observers make no such claims. They mention nose-sniffing and “amorous” noisy vocalizing, sometimes answered with a loud cry of rejection. Betsy Graham, in central Wisconsin, heard the noisy courtship as early as 28 October 2001. Gestation is long (209217 days) and the litter size is usually a single young. Occasionally there are two. Birth varies from April to mid-June. At birth the young porcupine weighs about 1.2 lbs, with the minute quills beginning to grow out, all encased in the mother’s amnion. The young is clothed in long, silky hair at birth. It can whine, and has deciduous teeth erupted (Shadle and Ploss 1943). Thus, the porcupine is born in a rather precocial state, in a small litter, and after a long gestation. In porcuTAXONOMIC ACCOUNTS / ORDER RODENTIA

319

pines, which lack post-partum specialization and bonding, intelligence is apparently not enhanced by this pattern, judging by the lack of playfulness and little evidence of intelligence in young porcupines. The young sucks from nipple to nipple. Weaning takes place in two weeks. The juveniles or young subsist on solid food, and the mother pays little attention to it (Jackson 1961). However, Gehring (1993) observed a mother defending her young against ravens. Porcupines are slow to develop sexually. Maturity is attained in 1 1/2 - 2 1/2 years. Porcupines live about six years in nature, as long as 10-11 years (Brander, 1971). Aging of cementum annuli is reported by Earle and Kramm (1980). Long life seems necessary for a mammal with limited fecundity. Mortality. There are few enemies of the porcupine. Black bears and fishers occasionally kill them, but not often as Seton and others have implied. Coyotes eat them. Automobiles and hunters kill them. A small porcupine may be preyed on by birds of prey, even ravens (Gehring 1993), if the mother does not defend it. Parasites include a mallophagan, sucking lice (Eutrichophilus), ticks (Dermacentor, Ixodes), tapeworms (Shizotaenia), and roundworms (Dipetalomema, Dirofilaria, Molinema, and Wellcomia) (Jackson 1961; Doran 1954). Curtis and Kozicky (1944) counted 1,528 tapeworms and 5,184 roundworms in one female. Porcupines contract mange (Baker 1983). Home Range and Density. Season and habitat affect home range (Shapiro 1949, Taylor 1935). Porcupines migrate from winter to summer ranges, as far as 1500 m (Dodge 1967). This home range may be called a shifting home range. Average daily movements in Minnesota (Marshall et al. 1962) were 393 feet (125 m) in daytime and 264 feet (83 m) at night. In Upper Michigan home range was a circle about 300 m diameter. This home range declined; in winter it was restricted to a circle of 16 m diameter (8 m radius).

320

THE WILD MAMMALS OF WISCONSIN

The highest density ever reported for porcupines was in northeastern Wisconsin (Stoeckeler 1950), a high of 96.7 individuals per square mile of mixed hardwood-hemlock forest. Golley (1957) suggested upper Michigan supported at least two per square mile. Brander (1973) reported 40-58 porcupines per square mile in old-growth hardwood-hemlock forest in western Upper Michigan, and in Iron County-winter counts—at 24 per square mile in cut-over forest areas. In heavily logged areas in summer, there were 32 per square mile, and 43 per square mile in areas selectively logged. The mature hardwood-hemlock forest seemed a winter refuge for porcupines on the Upper Peninsula. Remarks. The porcupine defends itself by turning its rear end toward an attacker. A predator is more successful if it attacks the face, but the porcupine is quick to turn about. The tail switches back and forth suddenly driving numerous quills into the attacker’s face. Although arboreal, the porcupine clambers best in trees and branches with diameters less than 6-10 inches. They are too clumsy to climb trees with great circumference (Harder, 1979). Porcupines are able swimmers, and although they seldom dig in the ground, they do dig long tunnels in snow radiating away from winter dens. Communication among porcupines is reviewed by Seton (1953) and Baker (1983). Additional Natural History. A monograph on the porcupine was written by U. Roze (1989). Geographic Variation. There is no geographical variation in Wisconsin and Michigan. Specimens examined. Total, 30. Clark Co.: Wedgee Cr., on Hwy 10, and. Fivemile Cr. D.O.R. Examined but not preserved. Door Co. Corporate limits Ruddville, above canal 1. Near Rock Creek, 1), Douglas, Forest, Iron, Langlade, Marathon, Marinette, Oconto, Oneida, Outagamie, Portage, Price, Rusk, Sawyer, Washburn, Waupaca counties.

ORDER CARNIVORA Meat Eaters

Family CANIDAE Gray 1821 Dogs, Wolves, Foxes

The Carnivora is an order of both modern and primitive mammals, descended from ancient Insectivora and their direct descendants called Creodonts. Carnivores had specialized their habits and teeth (early to middle Paleocene epochs) to kill prey. Particularly in the development of the carnassial pair of teeth (P4/ and M/1) and elongation of the canine teeth is this specialization evident (except in some omnivorous Carnivores, in which the carnassials were specialized for crushing and show little shear). Seven Recent families are found throughout the world, excepting Australia (which now has introduced the feral dingo and huge feral house cats). Some workers include in the Carnivora the pinnipeds (seals, sea lions, and walruses) evolutionarily derived from the Carnivora. Five families of carnivores occur in Wisconsin. These flesh-eaters range in size from the rare, mouse-sized least weasel (Mustela nivalis) to the huge, omnivorous black bear (Ursus americanus). Most of the predatory, furbearing quadrupeds belong to Carnivora. All are called “carnivores,” a word not to be confused with the general meaning of the word, “eaters of flesh,” which are, of course, described as “carnivorous”.

Canids are cursorial, lithe but strong meateaters having large canines, long limbs, long ears, and almost a full (primitive) complement of toes and teeth. There are four functional digits on each forefoot (and a non-functional dew toe as well), four on the hind foot, and 42 teeth. The snout and bony rostrum are slender, the lower jaw articulates at the mental symphysis for nipping and slashing prey. The claws are blunt. Some canids (wolves) hunt in packs; but foxes hunt alone or in small family groups.

Key to the Canidae 1

1'

2

2'

3



Coyote feeding young. By E. R. Kalmbach. 

Skull dog-sized and lightly built, basilar length (posterior edge of upper incisors along mid-axis to anterior notch of foramen magnum) usually less than 147 mm, frontal bones concave dorsally “dished”) ....................................................... 2 Skull large and massive, basilar length usually more than 147 mm, frontals convex dorsally in profile, never dished .... 3 Tip of tail white, ears black on outer surface, sagittal ridges converge posteriorly in a V-pattern and they are not conspicuous, dentary lacks a prominent step anterior to the angular process ...... Red Fox Vulpes vulpes Tail having a continuous dorsal black longitudinal stripe, ear pinna reddish or rufous, sagittal ridges prominent and bowed laterally, inferior margin of dentary bone having a prominent step ....... Gray Fox Urocyon cinereoargenteus Skull massive with broad rostrum or snout, robust canines (anteroposterior length exceeds 11 mm), upper carnassial exceeds 23 mm, canines extend approximately to and occasionally beyond level of mental foramina, P 4/ - P 4/ breadth (transverse) divided into length

TAXONOMIC ACCOUNTS / ORDER CARNIVORA

321

322

THE WILD MAMMALS OF WISCONSIN

$9.99

$20.47

$36.17

$27.22

$6.74

$2.53

$1.53

1,997

3,800

259

4,925

2,103

11,368

5.593

243,879 976 29 335 5,692 4,660 2,334 2,104 850

$14.63 $9.18 $43.70 $4.33 $1.47 $15.63 $10.38 $33.05 $2.97

$13.85

8,662

1997-1998

$8.76

175,973

1994-1995

Harvest

*Coyote value low, approx. $20,000 to $23,000.

Raccoon Red Fox Gray Fox Coyote Bobcat Fisher Striped Skunk “Weasels” Opossum

Raccoon Trends Up down UP Red fox Trend Values down Gray fox Trend Down, value also Coyote Number and Value down Bobcat Pelt high,trapped high, harvest value low Fisher Trend Downward Striped skunk Thousands wasted “Weasels” species?Trend Harvest low Opossum Thousands wasted

Species

$3.5 million $8,959 $1,267 $1,450 $8,367 $72,835 $24,226 $69,537 $2,524

$8,500

$29,000

$14,000

$134,000

$9,000

$78,000

$20,000

$120,000

— — — — — — — — —

11,469

51

2,442

2,072

8,432

$1.5 million 119,716

Trapped

$1.54

$2.33

$3.23

$20.88

$45.47

$12.31

$9.03

$15.91

$8.86

$1,034,576 3,304 618 1,773 789 27,402 5,337 68,230 2,14 9

??

8,100

1,586

61

2,172

1,571

5280

89,513

Trapped

$4,278 19,000

$4,500

$1,692

$18,000

$1,000

$44,700

$6,700

$79,000

$96,900

1998-1999 Total Pelts Value

2,778

1,992

524

862

27

3,631

752

5,014

109,417

1995-1996

Harvest

3,842

399

294

735

11

2,020

734

4,430

171,255

1996-1997

Harvest

$1.40

$2.20

$3.26

$30.73

$44.75

$11.57

$9.37

$16.49

$14.57

$5,378

$877

$836

$22,500

$492

$2,337*

$6,877

$73,000

21,800

??

9,064

1,485

83

2,268

1,120

7,374

$2.5 million 108,340

Trapped

Table Car-1. Some fur harvest summaries for terrestrial furbearers in Wisconsin. B. Dhuey, personal correspondence. The price of pelts may drive numbers up, but low prices may not drive opossums down, and some furbearers are low, i.e., scarce. Skunks, also opossums, at low prices show many more trapped than skinned,. The value of the harvest is extremely diverse, ranging from tremendously high values for raccoons to hardly anything for bobcats, weasels, and skunks. The reader is referred to the muskrat and beaver accounts for aquatic furbearers. 



3'

from anterior premolar to and including last molar is less than 2.7 ............ ..................................... Timber Wolf* Canis lupus Skull narrow with slender rostrum or snout, canines elongate and less massive (less than 11 mm anteroposterior length), upper carnassial less than 23 mm, canines may extend below level of mental foramina of mandible, ratio of P 4/ - P 4/ exceeds 2.7 in maxillary toothrow ...................................... Coyote** Canis latrans

Genus Canis Linnaeus These are the large dogs in Wisconsin, including the domestic dog (Canis familiaris), the timber wolf (C. lupus), and the coyote (C. latrans). In Wisconsin, some dog X coyote hybrids (“coy- dogs”) may be found. I suggest this is seldom.

and habitats. But they agree in their general form and characters; the Coyotes everywhere are sons of the desert, Ishmaelites living by their wits. Further, they are alike in their vocal gifts—our Ishmaelite is also a Troubadour.” — Ernest Thompson Seton 1823. Canis latrans Say. In Long. Account of an expedition to the Rocky Mts... 1:168. Type from Engineer Cantonment, 12 mi. SE of the present town of Blair, Nebraska, W Bank of Missouri River. 1897. Canis pallidus Merriam. Proc. Biol. Soc. Washington, 11:24, type from Johnstown, Nebraska. Not Canis pallidus Cretzchmas, 1826, type from Kardofan, North Africa, now referred to Vulpes. This name pallidus Merriam is a synonym, and not usually regarded as an invalid homonym, which it is and which makes the name unavailable. 1898. Canis nebrascensis Merriam. Science, N.S., 8:782, a renaming of the homonym Canis pallidus Merriam.

Canis latrans thamnos Jackson Canis latrans Say Coyote “While we speak broadly of the Coyote as though it were one species, it should be remembered that scientists recognize at least a dozen kinds that are closely akin, and yet have their own peculiarities

*

**

Some dogs resemble wolves cranially, but the orbital angle (between tangents to dorsal surface and to the line frontal-top of zygoma) exceeds 52 degrees in dogs. Coyote X dog hybrids (“coy dogs”), although uncommon due to low influx of genes already may be changing the characters of the wild coyotes. Gradual introgression eventually breaks down species distinctness. Many coyote skulls in Wisconsin seem small and have short canines, not extending down to the mental foramina, whereas other skulls are typical of coyotes. The coy-dog skull is usually small with short canines, the cranium somewhat arched as in dogs, the rostrum short, and the pelage and body may reflect domestic dog characters.

1949. Canis latrans thamnos Jackson. Proc. Biol. Soc. Washington 62:31, type from Basswood Island, Apostle Islands, Ashland Co., Wisconsin.

The name Canis means “dog” in Latin, and the name latrans means “barking.” The Aztec word coyotyl, from which “coyote” is derived, also means “barking dog.” In early Wisconsin it was called the “prairie wolf” to distinguish it from the gray or northern timber wolf, Canis lupus. Description. Having size of a fairly large domestic dog, the coyote also has about the same, but slenderer, proportions. The canine teeth are relatively longer (although there are exceptions), and either snout or rostrum of the skull is more slender. The external ears are large and pointed. The eyes are usually yellowish with a round dog-like pupil. The legs are long, but the feet small. The forefoot has 5 toes, but the innermost is reduced, and each TAXONOMIC ACCOUNTS / ORDER CARNIVORA

323

hind foot has four toes. The dew-toe on the coyote’s front foot is better developed than that of the wolf. There is a scent gland at the base of the tail. The skull is flattened, hardly arched at all. The zygomata flare away from the braincase. There is a median sagittal crest, less pronounced than in adult wolves. The postorbital processes are large, convex bulges, instead of being sharply pointed. In a “good” coyote specimen the canines extend below the mental foramina of the dentaries. This is one criterion separating coyotes from dogs. Another character is the high arched cranium of the dog. A third is the slender palatal width of the coyotes. The ratio of the length of the upper premolar-molar toothrow to the breadth between the alveoli of the first molars is 3.1 or more. This ratio is 2.7 or even less in dogs (Howard 1949). To compare wolves, see account of Canis lupus. The baculum (62-89 mm in length, Burt, 1960) is spindle-shaped with a deep trough, i.e., showing a deep urethral groove. Kennelly (1978) reports the karyotype is 2N = 78, the same as for dogs and wolves. There are eight mammae. The coyote pelage is grizzled buff to yellowish gray and sometimes rufous brown strongly intermixed with black guard hairs. These are dense and coarse, especially along the mid-dorsum. The fur resembles that of the husky dog or timber wolf. The throat and belly is a “dirty” or buffy white. The tip of the tail is blackish. The face, ears, forelegs and feet are brownish, even rust, but around the lips there are whitish hairs. The molt takes place annually, between late spring and autumn, when the fur comes in prime. Pups are yellowish or buff-gray. Male coyotes are larger than females in most measurements. Males often exceed 1,000 mm (39.4 in), ranging up to 1300 mm (51 in) in total length. Skulls average 180 mm (7.1 in) in length. Weights vary to 45 lbs (20.3 kg), and rarely are even heavier in some males. Females seldom exceed 25-28 pounds (1112 kg). Smith (1984) lists weights of adult male

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THE WILD MAMMALS OF WISCONSIN

coyotes (kg ± 1SD) from the years 19781981, as 12.2-17.2, and for females 9.513.2. Coyotes older than one year averaged 14.0 ± 1.4 (N = 10) for males, and 11.2 ± 0.9 (N = 10) for females. Dental Formula. DF = I 3/3, C 1/1, P 4/4, M 2/3 = 42. Geographic Distribution. Coyotes are sparsely distributed but range statewide in appropriate habitats. The habitats are exceptionally varied depending on the absence of dogs and wolves to some extent, and are related to year-round food availability. Status. Any victimized farmer and his relatives and neighbors will, of course, consider occasional depredation as too often. Appropriate security for the livestock lessens depredation. Coyotes will kill sheep, calves, pigs, and chickens, but not as often as generally believed. They kill fawns, an occasional adult deer (usually sickly), and numerous birds, rabbits, and rodents. Poisoning of coyotes was carried out for decades in western states even to the detriment of many beneficial fur-bearing mammals. To some extent, the known feeding on livestock carrion led to some wrong assumptions and to many false accusations of livestock predation. A bad reputation exaggerated for the coyote led to intense persecution—hunting, trapping, and even bounties in many



Skull of Canis latrans. 

states. The coyote seems to be maintaining its genetic identity, increasing its geographic range, and maintaining its populations in the face of approximately 30-40 percent mortality caused by humankind. Coyotes feed on harmful mice and rabbits and thereby do a service. The coyote tends to cull out the starving, weak and sickly, benefiting some wild prey populations. We are skeptical about most claims of coyotes killing adult cattle. Today, trapping is regulated, hunting permitted, and the fur valuable ($10-20 per pelt) (Table Car-1). In the not-to-distant past, bounties were paid for Wisconsin coyotes (Smith, 1984, Table Car-2), a practice that proved both costly and ineffective. Historically, the coyote apparently was unknown in northern Wisconsin and Upper Michigan until after 1900 (deVos, 1964). The reason for this restriction to the savannas and prairies (and avoidance of the northern forests) is not clear. Coyotes may have been ex-



Table Car-2. Wisconsin coyote harvests or bounty records (1930-1982) and pelt values. Smith (1984) and Dhuey (1999). 

1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953

1,949 1,422 1,387 1,785 2,111 2,324 1,775 1,824 1,587 1,131 913 924 885 1,125 1,936 4,134 3,317 3,604 2,875 3,135 2,844 2,826 2,638 1,696

$5.04 3.59 4.12 3.20 7.80 2.14 4.17 3.36 2.37 — — — — — — 2.32 1.09 2.38 1.00 1.00 1.00 1.00 1.00 1.00

1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977

2,557 $1.00 2,118 1.00 1,785 1.00 no bounties no bounties 2,058 1.00 3,673 1.00 2,580 — last bounties 518 — — — 197 5.21 229 2.22 185 2.38 1,104 5.46 2,424 5.46 1,799 5.36 2,715 7.91 1,849 11.39 3,839 17.25 2,753 17.25 3,153 18.81 4,986 33.99 5,125 29.44

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

6,788 2,815 2,730 3,728 2,694 3,238 2,865 2,253 2,535 2,547 797 433 392 3,117 3,554 2,727 2,442 3,631 2,168 3,330 2,092 ?? ?? ??

$47.20 32.18 23.70 26.71 19.76 15.02 13.44 14.21 15.63 14.53 7.07 7.06 6.17 5.99 14.10 14.61 20.47 12.51 11.00 10.00 7.06 ?? ?? ??

cluded by timber wolves. The coyote now ranges throughout these same forestlands and even crosses ice to visit most of the islands in Lake Superior and Lake Michigan. It breeds on some of them. (It is not a permanent resident on Washington, Rock, or Detroit islands, but lives on the Door Peninsula.) The coyote has become more abundant in northern than in southern Wisconsin. From St. Croix, Dunn, Eau Claire, Jackson, Monroe, southern Juneau and Adams, Marquette, Winnebago counties and northward along Lake Michigan up to Brown County, there are few coyotes. Rolley reported increases in all six state DNR districts for 1991-1992, especially in southeast Wisconsin (400 per cent), even 600 percent (Rolley, 1996). The harvest for 1999-2000 was estimated as 21,745 (Dhuey, 2000), mostly from Grant, Crawford and Racine counties. A survey of trappers provided an estimated harvest of 10,695. Coyotes are increasing in the Kettle Moraine State Forest, southeast Wisconsin, and in closely adjacent areas. In the Northwest District recent sightings are highest in frequency since 1986. In 2003, coyotes were protected in northern counties during the deer season. Habitats. Coyotes occur wherever suitable prey occurs, but forest edge, clearings, clear-cuts, farms, and highway rights-of-way certainly benefit the coyotes. They prefer mixed woodlands and hardwoods, aspen, and marshland, but also inhabit unusual (even urban) habitats. A coyote’s burrow may be used for several years. Often the coyote enlarges an abandoned burrow of a badger or woodchuck. There may be several entrances for a den. Resting outliers may be used on hillsides in clumps of conifers or other trees, even on snowdrifts. Gier (1968) reported that 10 percent of Kansan natal dens had two females and double litters. Camenzind (1978) and Nellis and Keith (1976) found den sharing to be rare. W. E. Berg (personal correspondence) doubts if such sharing occurs in Lake States coyotes. The nest is often bare earth in a burTAXONOMIC ACCOUNTS / ORDER CARNIVORA

325

row. Long (1964) reported one made above ground and the high water table in a Kansas marsh. Tunnels usually run 3-4 feet below the ground surface. Foods. Food studies include analysis of stomach contents (Sperry 1941, and others), scat analysis (Beckoff 1978), and following trails in the snow (Beckoff 1978, Berg and Chesness 1978). Mice were the primary food, and deer carrion and birds were high in incidence. Excluding livestock carrion, the snowshoe hare, shrews, and the porcupine were often eaten. In a national study, Sperry found



Maps showing geographic distribution of Canis latrans in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

rabbits and hares most important as prey, mice important as well, while deer remains and other carrion were often scavenged. Comparing the main foods of coyotes in Minnesota and Wisconsin, the patterns are similar. Smith, in 1978-1979, examined 8,674 scats of coyotes in northwest Wisconsin, also examining over 1500 stomachs from northern Minnesota, not so many in Wisconsin. White-tailed deer flesh is fed on throughout the year, but not much from August-November in Wisconsin, or May to August in Minnesota. In Wisconsin, deer as food peaks in December and continues through June. Snowshoe hares are fed on year round, but the numbers diminish in winter. The number of hares eaten is correlated with the hare cycle. When hares are scarce, more porcupine flesh is eaten (Smith, 1984). In Wisconsin the percent frequency of small mammals eaten (up to 19 percent), often Peromyscus leucopus and Microtus pennsylvanicus, rises in September, October, and November, when mouse populations are high. Although the frequency of rodents eaten is high, the weight is low, about 4 percent by weight. Some vegetation is eaten year round, but chiefly from June to October. Vegetal foods include berries, buds, grasses and seeds. There was noted correlation between fat indices in coyotes and deer flesh in the diet. Coyotes that fed on deer fed seldom on livestock. In Minnesota, and not in Wisconsin, the percent of lifestock was 5 percent over 11 years. Ruffed grouse were taken during their spring drumming. Fawns as prey peaked in May-June, and declined in July (Smith, 1984) and thereafter. The diet varies from



Coyote. Scratchboard, by Dan Metz. 

such things as berries to carrion, reflecting availability and season. In southern Wisconsin livestock carrion is 44 percent and rabbits 21 percent. Some vegetation, birds, and other foods are eaten (Fruth, 1986; Niebauer and Rongstad, 1977). In Minnesota, the 1,558 aforementioned stomachs collected over an 8-year period showed that white-tailed deer meat was the predominant food, occurring there in 48.6 percent of stomachs (41.8 percent total weight of foods). In that study, livestock eaten as carrion occurred in 18.9 percent (23.3 percent total weight). Mice were found in 23.1 percent (only 4 percent total weight). Porcupine was found in 20.1 percent (4.0 percent), and snowshoe hare in 18.4 percent (12.8 percent). These food items were 85.5 percent of the total contents. A study of 670 coyote scats collected in Minnesota over six years showed deer in 40.9 percent, with low frequencies in August and October. The deer remains were over 54.8 percent in winter and only 27.1 percent in snow-free woods. A difference found in study of scats compared to other analyses of coyote diets was a significant amount of plant parts and seeds. Data from some coyote trails were summarized by Berg and Chesness (1978). Baker (1983) lists numerous plants and other foods of the coyote, in Michigan. Some deer predation may result from pack hunting (Fruth, 1986). About 14 percent of capture attempts on deer were successful. A deer was caught by a pack of coyotes after a chase of 2,254 m (1.4 mi.), and another after a chase of only 15 m (15 yds). Both were fawns. On 703 km of coyote trails coyotes fed on deer 54 times; 52 times carrion was involved (Smith, 1984). Reproduction. Coyotes are monestrous, resembling the domestic dog in reproductive pattern (Hamlett 1938, Gier 1968). Producing a single litter per year generally leads to monogamous parents. They produce large litters and care for the pups. Coyotes may pair for several years, but not necessarily for life. TAXONOMIC ACCOUNTS / ORDER CARNIVORA

327

Juveniles may breed their first year if environmental conditions are favorable (Gier 1968). Usually coyotes commence breeding in their second year. In northern Wisconsin counties juvenal breeding is unlikely. Smith (1984) reported pregnancy rates in juveniles up to 23-35 percent. Adult females showed 58 percent pregnant, and yearlings 38-40 percent. Not all the adult females breed. Breeding occurs between February and March. Estrus lasts 4-5 days. Ovulation is late during the estrus period (the day varies). Food availability directly increases corpora lutea counts (4.5 to 6.5 corpora lutea), and 50 to 80 percent of females are ovulating females. Smith (1984) found 5.5 ova to produce 4.4-4.8 embryos in Wisconsin. Transuterine migration of embryos is common, leading to approximately equal implantations in each uterine horn. Gestation lasts 60-63 days (Kennelly, 1978). Up to seven pups are born, in early spring. The young weigh about 250 g at birth. Their eyes are closed, but the skin is furred. The eyes open and the ears become erect in 10 days. The young emerge to play after 3-4 weeks. Both parents may bring food to the young, although in Wisconsin usually the mother alone bring dead rodents or regurgitated foods. Weaning occurs in about 8 weeks. The mother teaches the pups to hunt. In nine months the pups attain adult size. Aging of coyotes has been studied by Lindhart and Knowlton (1967) and Roberts (1978). Juvenile survival is lowest in mid-winter (Smith, 1984). The mean adult survival rate was 62 percent (SD = 16). Coyotes may live nearly 16 years (Crandall, 1964). Mortality. Golden eagles, rare in Wisconsin, have attacked adult coyotes. Badgers have eaten the pups. Wolves might drive away or kill an occasional coyote. As wolves return to Minnesota and Wisconsin, this interspecific aggression will doubtless increase. Starvation in coyotes may cause some mortality. Humankind and disease are the worse enemies of coyotes. Humans hunt them, trap coyotes for

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fur, kill them as “livestock killers,” and occasionally run over them with automobiles. Poison baits were used extensively in the past, but are illegal today. Gier et al. (1978), Pence and Custer (1981), Custer and Pence (1981), and Voigt and Berg (1987) reported on parasites and diseases in coyotes. The tabulation of Gier et al. is more than a species list (Table Car-3) for the effects of a parasite or disease “in Texas cannot be interpolated to Nebraska. . .Neither can effects... during the winter be transferred to summer... or those during times of nutritional stress be transferred to times of plenty.” Sometimes lice and mange mites are tolerated by coyotes, and then suddenly the complex of the two is a killer. Lists of parasites are given by Jackson (1961) and Baker (1983). Some diseases include parvovirus, canine hepatitis, rabies (rarely), plague, and especially distemper. Home Range and Density. Following 217 winter trails in Wisconsin, Smith (1984) found 61 percent of coyotes solitary, 32 percent in pairs, and only 6 percent in groups of three. Huegel (1979) found as many as five coyotes in a pack; whereas pairs comprised 87 percent. Although family groups are typical of coyotes, they seldom form packs as do other wild dogs. Fruth (1986) gives the home range for Wisconsin coyotes as 5-10 mi2. Smith (1984) calculated home range for males as 22.6 km2 and for females 15.6 km2. Smith (1984) found that Juveniles comprised 80 percent of the dispersers. Yearlings comprised nine percent. Nomadic wanderings accounted for 11 percent. One juvenile dispersed 160 km (100 mi.), and an adult female moved 440 km (275 mi.) into central Iowa. Home range determined for 100 Minnesota coyotes from 1970-1975 varied by age and sex. Adult males averaged 68 km2, and for adult females the average was 16 km2. Males overlapped and wandered freely, but females excluded one another from territories. Of their total home ranges females occupied



Table Car-3. Some parasite diseases affecting Wisconsin coyotes. From the table in Gier et al., 1978, Pence and Custer, 1981, Trainer and Hale. 

Parasite

Geographic Range

Normal Host or Source

Demodectic Mange Sarcoptic Mange

The mite Demodex canis The mite Sarcoptes scabei Ixodes kingi Dermacentor andersoni Trichodectes canis Pulex simulans Rhabdovirus

Cosmpolitan in dogs, wolves, foxes Dogs, wolves, foxes Wisconsin Raccoons, foxes Mammals Canids North America Carnivores North America Cosmopolitan in canids Cosmopolitan Cosmopolitan Inhalation Cosmopolitan Musty river bottoms Cosmolitan dogs, cats

Rabies Distemper Virus of Carve Saliva, feces Hepatitus (fox encephalitis) Histoplasmosis Toxoplasmosis

Adenovirus Saliva, feces Histoplasma Toxoplasma Feces, urine

54, 22, and 61 percent in pre-denning, denning, and post-denning periods. More than 70 percent of young-of-the-year disperse from their natal territories. Dispersal may be as far as 100 miles (160 km), but usually 2-4 km (Beckoff 1982). Prior to dispersal juveniles average square 5-8 km2 in their wanderings. In Upper Michigan, density of coyotes in Alger and Schoolcraft counties was determined as one per 4 miles (6.4 km) by following snow trails (Ozoga and Harger 1966). Seasonal changes were reported by Andert and Gipson (1979). The relation of age structure in a population for coyote, wolf and both foxes is discussed by Kleiman and Brady (1978). Smith (1984) obtained similar results in winter populations, with 50 percent in juveniles, 20-37 percent yearlings, and a few examples of older age up to 12.5 years (Car-4). Remarks. Coyote communication, which is complex and varied, is reviewed by Lehner (1978). The yipping, barking, and howling constitute some of nature’s most lovely nocturnal music. Coyotes also communicate by scents and fecal sign. The intelligence and adaptability of coyotes are legendary. A review of coyote-damage and control research is given by Sterner and Shumake (1978) and by Wade (1978). Economic importance of the coyote, a long standing hot issue, is ably discussed by Baker (1983) and Voigt and Berg (1987).

Coyotes crossmate with dogs to produce fertile coy-dogs, which show intermediacy of characters (Seton, 1929, Kennelly and Roberts, 1969, Mengel, 1971, Gipson, 1978). Coyotes also rarely cross with wolves (Kolenosky, 1971). An emerging problem is hybridization with domestic dogs, which are increasingly in contact with coyotes. The coyote conceivably could be genetically altered out of existence. It is somewhat difficult to find a good skull of a coyote in some places in Wisconsin, a skull showing the coyote’s pure characters. Nationally, the coyote seems to be maintaining its form, behavior, and increasing geographic range. Gipson et al. (1975) found decreased fecundity in the hybrids. The heterozygosity of Wisconsin populations should be appraised. In the UW-Madison collection are 3 coy-dogs from Fort McCoy and one from Douglas County (3 mi. N, 9 mi. W Solon Springs).



Table Car-4. Mortality Table in Minnesota (1970-1982) and Wisconsin (1978-1983). After Smith, 1984. 

Trapped Shot Snared Car killed Dog killed Natural causes Other

Minnesota

Wisconsin

37 27 11 6 0 6 12

22 50 — 12 0 6 10

TAXONOMIC ACCOUNTS / ORDER CARNIVORA

329

Smith (1984) reported “Sampson” (lacking guard hairs) coyotes (in both sexes) from 1979-1981. They were produced by a pair of normal appearing coyotes. Additional Natural History. Voigt and Berg (1987) mentioned that even with thousands of references, the biology of the coyote is an enigma today. Bekoff (1977) is a fine reference source. Three fine works are Young and Jackson, 1951; Beckoff, 1978; and Dolnick et al., 1976. Geographic Variation. There is a single subspecies found in Wisconsin and Michigan. Specimens examined. Total, 16. Adams, Bayfield, Columbia, Florence, Iron, Marinette, Oneida, Portage, Price, Rusk, Sawyer, Other records in Wisconsin (Balliett and Taft, 1978): Winnebago Co. Michigan. Delta Co.: Big Summer Island 1.

Canis lupus Linnaeus Timber Wolf or Gray Wolf “Those Wisconsinites who cherish this state’s history, its abundance of natural resources, and its leading role in environmental awareness must not allow the timber wolf to vanish a second time, because this state may never get another chance.” — Dick Thiel, The Timber Wolf in Wisconsin 1758. Canis lupus Linnaeus. Systema naturae, 10th ed., p. 39. Type from Sweden.

The word Canis means dog, and lupus means wolf. Eastern wolves in North America are more likely to be called Timber Wolf rather than Gray Wolf, but both names are popular. Taxonomically revised by Goldman in Young and Goldman, 1944. This old-fashioned appraisal, describing microgeographic variants as races, surprisingly refers wolves from a vast eastern region ranging from Minnesota, upper Michigan, and Wisconsin, northwards to Hudson Bay, into Ontario and Quebec, and southeastward to Ohio, even

330

THE WILD MAMMALS OF WISCONSIN

northern Florida, all assigned to one race characterized by grizzled gray color and rather small size. This wide-ranging race was known as Canis lupus lycaon Schreber. Recently Nowak (1996) ascribed Wisconsin and its surrounding regions to a wide-ranging race Canis lupus nubilis Say, with type from Iowa. The wolf was formerly distributed throughout much of Eurasia and North America, and in this hemisphere ranged from the Arctic slope and the coasts of Greenland, occurring on many islands, and extending deeply into southern Mexico (see Map). Now they are greatly restricted by eradication in many places, by prolonged poisoning of predators even until the1950’s, and by over-hunting and trapping. The intolerance of people, as well as removal of habitats and routes of dispersal, led to the restriction of wolves to a few states along the Canadian border, much of Canada, and Alaska (in North America). Presently the Timber Wolf is found chiefly along the northern border of the contiguous states, where it is classified as endangered or threatened. It is abundant in northern Canada and Alaska, and reintroduced to Arizona. When wolves are downlisted from endangered to threatened, problem wolves that destroy pets or livestock may be removed. After wolves fill up remote habitats, any translocation of wolves to such places becomes impractical, and even results in their extermination. The only practical removal seems selective and highly restrictive hunting or trapping (?by special conservation agents).



Timber Wolf. By E. Hamerstrom Paulson. 

Canis lupus nubilis Say Timber Wolf or Gray Wolf 1775. Canis lycaon Schreber. Die Saugthiere... Theil 2, Left 13, pl. 89. Type from Quebec, Quebec (type locality fixed by Goldman, J. Mamm., 18:38, 1937), 1937. Canis lupus lycaon: Goldman. J. Mamm., 18:45. 1823. Canis nubilis Say. Long’s expedition... Rocky Mountains. I. P. 169, Type from Council Bluffs, Iowa. See also Cory, 1912: 321. 1996. Canis lupus nubilis: Nowak. Canadian Circumpolar Inst. pp.387, 395 map. For 1995.

Description. The largest wild dog in Wisconsin, the massive size and coloration of the wolf are similar to that of the Husky breed of domestic dog. The skull is massive, about 230260 mm (10-11 in.) long and 120-140 mm (6-7.25 in.) in zygomatic breadth. The appearance of a wolf suggests to many people the word “powerful”. The ears are long but less pointed than in the coyote, the body is long with elongate, slender legs having large feet, the heel pad of the front foot at least 4 cm (1.6 inches) wide, armed with robust, blunt claws on the four toes (also, there is one small dew-toe). There are four toes on each hind foot. There is a bristly-haired scent gland at the base of the tail, never found in domestic dogs, a large, hairy “ruff” on the cheeks, a wide nosepad, and eyes with a round pupil. The wolf often runs with its brush-like tail “streaming behind,” whereas the tail of the coyote is more often held low. This behavior varies depending on the social status of the animal (both in wolf and coyote). The skull is huge with robust teeth. The cranium, not including the sagittal crest, is flattened so that the orbital angle (from frontal down to zygoma) is 40o to 45o compared to more than 50o in wolf-like dogs (Mech, 1974; Iljin, 1941). The canines are not elongate, but may extend down to the level of the mental formanina in some wolves. The muzzle and rostrum are relatively wider than in

coyotes (Chiarelli 1975). The canines are not widely separated as in dogs. Across the upper molars the breadth divided by the width of the last molar is 5.4 or less, whereas it is 5.5 or more in dogs. The occiput of the wolf is developed for the origin of powerful jaw muscles, and in the adults a large sagittal-crest develops. It extends posteriorly above and parallel to the flattened braincase, not dipping ventrally as in other canids. No other Wisconsin canid has a canine 13 mm or more across the base. The baculum is trough-shaped and large. It bows upward, and the broad groove extends to 4/5 of the length. The length varies from approximately 83-99 mm (Burt, 1960). There are 10 mammae, 5 on each side. Small anal glands are present. There are 2N = 78 chromosomes, as in the coyote and domestic dog (Chiarelli 1975). The fur is coarse, almost shaggy, with long, black-tipped guard hairs and short, dense grayish or brown underfur, which shows through as the fur ripples with movement. The guard hair has a black tip, a cinnamon or buff subterminal segment, and it is gray basally. Various pelages show yellowish, rust, iron gray, or mostly black. The tail is blacker at its tip. The belly and inner sides of the legs are whitish, grayish, or buff, and the underside of the tail tends to buff or gray (less black). Middorsally the concentration of black usually intensifies. Cinnamon or reddish brown tones



Orbital angle of wolf skull, which is only 40-45°, less than in dogs. Ilgin (1941).  TAXONOMIC ACCOUNTS / ORDER CARNIVORA

331

show on the grayish legs, and are intermixed on the crown (especially on the cheeks), and about the ears. Wolves vary in the intermixture of colors. Some are melanistic, white, or reddish-brown, but black and white phases are very rare in the Great Lakes region (Kolenosky and Standfield, 1975). The foot pads are black. The fur molts annually in late spring and summer, over a period of several weeks (Young and Goldman 1944). Prime fur is attained by growth of summer fur into winter (Stains 1979). Tufts of hair help protect the footpads in winter. The young molt juvenile fur and replace it with adult fur in about 30 days. The average total length is about 160 cm (63 inches), up to 175 cm (about 69 in.), and weights vary from 23-41 kg (50-90 lbs). A few weigh as much as 45 kg (100 lbs.). The mean weight of adults live captured in Wisconsin was 28 kg (62 lbs) for 13 females and 35 kg (77 lbs) for 18 males (Wydeven et al. 1995). Males are larger than females. Winter wolves weigh more than summer wolves. See Description above. Dental Formula. DF = I 3/3, C 1/1, P 4/4, M 2/3 = 42. Distribution. The wolf formerly ranged throughout Wisconsin and surrounding states. Now it is restricted to a few counties (a recent report lists 11) in northern Wisconsin. By 1995, it became re-established in the Central Forest (this forestland, a useful and somewhat distinctive deer management region, is discussed in the account of the white-tailed deer beyond). Some wolves move back and forth across the Minnesota boundary, in northeast Minnesota and northwest Wisconsin. The present-day population straddles the Michigan-Wisconsin boundary. Status. Since 1974, the timber wolf in the Great Lakes region and northeastern United States has been listed as an endangered species by the federal government. The wolf soon (2007) may be downlisted to threatened status. The Wisconsin DNR classified wolves as endangered in 1975, and since 1979 has annually estimated the population

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THE WILD MAMMALS OF WISCONSIN

size (Wydeven et al., 1993, 1995, 1999 etc.). Mid-winter populations ranged from as low as 15 wolves in 1985, to as high as 200 or more wolves in 1999 (Wydeven et al., 1995, 1999, 2002). The minimal wolf population in 2005-6, was 415-502 wolves, in 115 packs, known from at least 29 counties. I was interested in depredations, especially angering many hunters recently by killing their dogs. Depredations have been gradually increasing in incidence year after year, and in 2002 consisted of calves, two cows, a horse and its colt, some sheep, deer on game farms, and attacks on about ten domestic dogs. Obviously, considering both the pros and cons, the progress reports of the Wisconsin Department of Natural Resources on our wolves seem fair and honest, and that is essential for management of a rather controversial species, which seems now to be accepted as a valued carnivore in Wisconsin.



Skull of Canis lupus. Bee and Hall (1956), courtesy of James Bee. 

In Upper Michigan, the gray wolf thrived until white humans eradicated most of them in the late 1800’s. A population of about 100 wolves persisted until 1955 (Arnold 1955). Bounties caused the numbers to dwindle thereafter, to seven in 1958, and only one wolf was bountied in 1959. The bounty law was repealed in 1960, and by 1965 full protection was accorded the wolf. In the 1960’s the population was reported as perhaps 12-25 wolves, with sightings reported in nine Michigan counties. By the late 1960’s the Upper Michigan wolves were nearly extirpated. After the population fell to six (Hendrickson et al. 1975) four radio-collared wolves were transplanted from north-central Minnesota (Weise et al., 1975). They died within eight months.



North American recent distribution of timber wolf. 



Map showing recent geographic distribution of Canis lupus in Wisconsin. Formerly widespread in North America, but resticted in recent years to the Northern Rockies, northern Wisconsin and Minnesota, New England, and perhaps Arizona. After Wydeven and others. ~ 1995-2006.  TAXONOMIC ACCOUNTS / ORDER CARNIVORA

333

In 1961, Jackson had reported that the wolf was “making its last stand in the United States in the northern parts of Michigan, Wisconsin, and Minnesota”, but it had little chance of survival in Wisconsin where its numbers were reduced “probably to less than 50.” He mapped records of wolves in almost all the Wisconsin counties prior to 1900 (as early as 1827 in Manitowoc County), but in few counties after 1900. In 1914 or 1916 (see Thiel, 1993), one was killed in Wautoma, in central Wisconsin. Other reports, since the turn of the century, range from Burnett and Barron counties westward, Oneida (1930’s), Chippewa, Marathon, Shawano, Brown, and Door counties eastward. Wolves were present occasionally on Washington Island and in the Apostles. Even in northern Wisconsin wolves dropped from sight, reoccupied counties in northern and central Wisconsin (see Map), and lone wolves have occurred as far south as Portage in Columbia County (Mech et al., 1995). The population is recovering in Wisconsin, and also has re-established itself in Upper Michigan. Jackson (1961) had estimated the wolf numbers in 1835 as 20,000-25,000. [Wydeven (1993) suggested 3,000-5,000 wolves was a more accurate estimate.] Human persecution, loss of habitat, and reduction of ungulates had already eliminated wolves from southern and central Wisconsin by 1900. The bounty system, from 1865-1957, was a major factor in extermination of the wolf. By the 1940’s, fewer then 100 wolves remained, and by 1950 there were fewer then 50 (Thiel, 1993). In 1957, the wolf was protected, but probably became extinct in that decade (Thiel, 1978). By the 1970’s wolves were recolonizing Wisconsin from Minnesota (Thiel and Welch, 1981). Thiel (1993) recounted the reappearance of wolves in Douglas County (in 1975). The slow re-population in northern Wisconsin has continued to this day. Most killed are shot or killed by cars. At least 83 (in 1995) wolves were found in northern and central Wisconsin, and wanderers may range south-

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ward. Perhaps 80 existed then in Upper Michigan. Wolves now have returned to some forested counties in central Wisconsin. Education programs have apparently taught people about the value of wolf preservation. Heavy fines for poachers also may have helped the wolves (Table Car-5,6). Wisconsin wolves varied from a low of 15 in 1985, to 40 in 1991. The mean annual increase was 1.21 from 1986-1991. In the early years of recovery human-caused mortality was intense, but it has lessened. Canine parvovirus was prevalent in the mid 1980’s and probably caused high mortality. This problem too has diminished (Wydeven et al., 1995; Wydeven, 1993). Recolonization from Minnesota continues (Wydeven 1993), and the habitats available suggest the wolf population will continue to increase both in Wisconsin and Upper Michigan, on public and private lands. The landscape (or environment) seems favorable for more Wisconsin wolves, judging from an analysis by Mlandenolf et al. (1995), relying on fractal analysis of patchy vegetation, road systems, and other factors. The steady observed increase and spread of wolves is likewise indicative of future success. Regulated hunting perhaps will be allowed in Wisconsin when the wolves exceed 300 (see table Car-6). The Wisconsin Department of Natural Resources has recently published in the news media a concise history of wolves, succinct and interesting, as follows: 1830’s, a statewide population of 3,000–5,000 wolves; bounties offered in 1865; no wolves remaining in the southern two-thirds of Wisconsin by 1900; wolf bounties were lifted, after millions of dollars were spent to eradicate this carnivore, 1957; federal protection as an endangered species, 1974; the Wisconsin DNR declares our wolves endanged [and few if any remained in Wisconsin] 1975; five wolf packs were found in Wisconsin numbering about 28 individuals, 1979; the federal government reclassifies gray wolves in Wisconsin from endangered to threatened, and there

were about 323 wolves in Wisconsin, March 18, 2003. Note that the wolf is still protected and managed in Wisconsin under “threatened” classification. Although wolf furs are popular for trim on coats and as wall hangings, there is no commerce allowed at present in Wisconsin because of the wolf’s potected status. Fur harvests are permitted in Canada and Alaska (Carbyn, 1987). In literature, the wolf has an awesome reputation of following sleighs, attacking children, and so on. These accounts are largely fictitious, and there is only one record of North American wolves attacking a man (Peterson, 1947). (In 1994, news accounts reported that a Wisconsin child lost an arm to two caged wolves in a northern Wisconsin zoo.) Nevertheless, when wolves are more numerous and come into increasing contact with people, common sense and responsible parenting are necessary. Always ensure the security of children in remote areas. [Virtually any wild mammal can be dangerous to man in certain circumstances.] Livestock also requires security, and there will be some depredations of unprotected domestic animals. Habitat. Forests are the home for Wisconsin wolves. Presently the mixed coniferhardwood forests and forested wetlands of northern Wisconsin are the most prevalent habitats used by the wolves (Mladenoff et al. 1995). Wolves do not avoid open country and will wander through many habitats. Traditionally wolves only occurred in the most remote regions were they where free of human persecution. In recent years wolves have moved into farmlands. The major factors determining suitable habitat are lack of human persecution and presence of adequate prey (e.g., white-tailed deer and beaver). A den sketch is provided in Carbyn (1987). The natal den is dug at a well-drained site usually on a ridge, by the parents, or is enlarged from an abandoned woodchuck, fox, or badger hole (Young and Goldman 1944). Occasionally they use a beaver lodge, hollow logs,

rock crevices, and other protected sites. A natal den usually has a single entrance, but occasionally there are two. The diameter of the entrance is about 36-63 cm (14-25 inches). No mention is made of an internal nest. A den may be re-used for several years. Den-site selection is discussed by Unger (1999). In winter wolves may burrow into snowbanks, under fallen trees, or even sleep in old beaver lodges. They may endure a blizzard by lying in the snow curling the tail over forepaws and nose. Foods. Wolves are opportunistic predators that generally specialize on ungulates. The white-tailed deer is the chief food for wolves in Wisconsin (Thiel 1993; Thompson 1952) and Upper Michigan (Baker 1983). The wolf pack succeeds in running down and killing young, old, weak, or sickly individuals (Fuller and Keith 1980). After 1,000 m, the chase is usually abandoned. A large carcass, such as a moose, allows the pack to gorge and re-group (Mech 1966). Some wolves eat up to an estimated 9 kg (20 lbs.) of flesh each. Wolves normally can go 3-4 days without food, but have been known to go 7 -17 days without eating (Paradiso and Nowak, 1982). A healthy wolf needs a mininum of 1.7 kg (3.5 pounds) of flesh per day. Many studies on feeding of timber wolves have been made by Mech and his associates (1970, 1974, 1977, 1982; Mech and Frenzel 1971; and others). Other foods used by wolves in in Upper Michigan include shrews, snowshoe hare, red squirrel, deer mice, meadow voles, jumping mice, an occasional porcupine, ruffed grouse, crayfish, and grasses (Manville 1948, Stebler 1944, 1951). To this list may be added raccoon, woodchuck, flying squirrel, chipmunk, redbacked vole, bog lemming, muskrat (Baker 1983), various plants, feral cats, some livestock, and carrion. A wolf in Wisconsin was even known to feed on fish and great blue heron (Ardea herodias) chicks at a heron rookery (Robinson et al., 1991). Mandernack (1983) discussed food habits of Wisconsin wolves. When does are solitary, or when does are with fawns, wolves often hunt them alone TAXONOMIC ACCOUNTS / ORDER CARNIVORA

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or in pairs over wide regions. In winter when the deer yard together, wolf packs move from yard to yard preying especially on old deer and on the numerous young. Many other animals scavenge on the remains of wolf kills including foxes, bears, coyotes, and mustelids. Small rodents gnaw the bones. Birds scavenging at wolf kills include eagles, ravens, crows, jays, chickadees, and even woodpeckers. Reproduction. In a typical pack hierarchy only the socially dominant (an alpha) female produces pups. They are sired by the dominant male. The other members of the pack assist in caring for the pups and the attentive mother, thereby protecting their own genes (by kinship), and also performing a defense of the pack territory. When prey is abundant, two females may produce litters in the same pack. If a subordinate mates, it may be chased out of the pack (Peterson 1979), but may bring forth pups. The female is monestrous, and rarely is capable of conception at 10 months (Medjo and Mech 1976). The reproductive pattern is similar to that in dogs. Usually breeding does not commence until 22 months, and often does not occur until the third year. Wolves may breed at least until their 11th year if they live that long. They probably may live occasionally to 16 years of age. Under intense exploitation of wolves, as many as 90 percent of adult females will breed, but in unexploited populations only about 60-65 percent breed. The female has estrus about five to seven days in late winter. Mating begins in February or earlier. Copualtion may last over 30 minutes, and the pair may become “locked” as in domestic dogs. Wolves court much as do dogs, but remain paired for life (Mech 1966, 1974). Gestation is about 63 days. The litter size is about 5-7 pups (varying from 410 or more, or about 6, 1-11 according to Paradiso and Nowak 1982). The pups are born in mid-April in a specially excavated natal den or at some alternate site prepared several weeks in advance of the births. The pups are kept at the den area for the first two

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months, after which they are moved to some outlier (often called a rendezvous site), remaining until late summer or early fall (Fuller, 1989). The same den may be re-used. The pups are born furred, eyes closed, ears non-erect and closed, with the fur colored a “sooty” drab whitish color (Jackson 1961, Mech 1970). Weighing about a pound (0.7 kg) each, the growth is rapid (Van Ballenberghe and Mech 1975). The eyes open in 11-15 days (Mech 1970) and the ears stand erect about the same time. The pups begin to spend time outside the natal den at 10-24 days, but normally remain near the den site for another month (Fuller, 1989) unless the mother moves them. Pups are moved about by the mother when 8 to 10 weeks old, usually in June (Mech, 1970). They are weaned by 50 days, and pack members regurgitate meat for the pups to eat during most of the summer. Another female may occasionally “babysit” the pups. The mother may move the young to as many as 10 outliers at this time of development. By late summer the pups (2/3 grown) join the pack in their nomadic travels. Milk teeth are replaced by 16-26 weeks (Schonberner 1965). Aging of wolves by cementum layers has not been successful. Wolves live at least 15-16 years (Crandall, 1964). Mortality. The chief mortality is caused by humans by illegal shooting and trapping and by automobiles. Human intolerance and human activities helped to eradicate wolves, but changing social attitudes have been instrumental in protecting the species. Fortunately for the Wisconsin wolves, humancaused mortality declined from 72% from 1979-1985 to 22% in 1986-1992 (Wydeven, 1993). The Wisconsin Department of Natural Resources is studying the impact of the northern highway 53 on Wisconsin wolves (Shelly and Anderson, 1995, unpublished). Under natural conditions starvation and exertion lead to higher mortality rates when prey species such as deer or bison become low in density. Mech (1977) found that low food availability caused starvation in pups,

reduced litter size, and increased intra-pack aggression. Mortality increased among the wolves, and greater numbers became “lone” wolves. A cougar or bear might prey on wolves, but the wolves may occasionally kill a cougar or bear. Wolves harbor rabies virus, tularemia, tapeworms, spiny-headed worms, roundworms, fleas, ticks, and lice as do other canids (Mech 1970; Mech, Thiel, Fritts and Berg, 1985). Especially serious are sarcoptic mange, blastomycosis (Thiel et al., 1987), distemper, and probably parvovirus (in the 1980’s, see Wydeven, 1993). Wolves carry ticks that harbor Lyme disease (Thieking et al., 1992). In Wisconsin some internal parasites include tapeworms, hookworms, Giardia, Entamoeba, Alaria, and Capillaria (Archer et al., 1986). Starvation and intraspecific strife cause some mortality. Home Range and Density. Some densities and home range data provided by Carbyn (1987) and Wydeven et al. (1995) indicate the timber wolf home range areas vary a lot, from a mean annual home range of 146 km2 – 349 km2 in northern Minnesota, to 253 km2 in central Manitoba, and 179 km2 in northern Wisconsin. From very small summer home ranges, Carbyn reported a radio-collared female that from October to March wandered over a remarkably large 2,819 km2 area (1,088 miles2), entering six pack territories. Young adult wolves, usually as yearlings, may disperse from their natal pack to find a mate and establish a new territory, or join an existing pack. Some wolves may remain with the pack throughout their lifetime (Gese and



Table Car-5. Timber wolf mean annual home range and winter density in central North America (modified from Carbyn 1987 and Wydeven et al. 1995).  Home

Range

Wolf / km2

Northern Minnesota Northern Minnesota Central Manitoba Northern Wisconsin

146 km2 349 km2 253 km2 179 km2

24 33-111 23-27 41-82

Mech 1991). Densities varied from 1/23-111 km2.. Thiel (1993) reports home range and densities in Wisconsin, from 90-300 square miles, with densities varying from from 1/ 2993 mi2. In 1990-1991, there were 12 packs, with pack size averaging 3.2 wolves, territory 2,000 km2, and a wolf density of 18.3/1,000 km2 (Table Car-5,7). Home range on Isle Royale of a winter wolf pack was about 272 square km (105 square mi). In northeastern Minnesota, Mech et al. (1971) and Van Ballenberghe et al. (1975) found the home range to vary from 20-56 square miles. During mid-summer the home range of an adult female with pups was 18 square km (7 square mi ) in Ontario (Kolenosky and Johnston, 1967). The territory is defended by scent marking (Peters and Mech 1975, Rothman and Mech 1978), howling (Theberge and Falls 1967), or active aggression toward intruders (Mech 1977a). The howls serve to call the members together and to warn intruders to stay



Table Car-6. Recovery of Canis lupus in Wisconsin. After Thiel, 1993; Wydeven et al. (1995); and Wydeven (1995). There were 18 packs. After 2000, there seem over double this number.  Year

Locality

Number

1975 August 3 By 1979 1979 July 9 November 1980 1980’s 1981-1982 1982-1983 1983-1984 1984-1985 1985-1986 1986-1987 1987-1988 1988-1989 1989-1990 1990-1991 1991-1992 1992-1993 1993-1994 1994-1995

Douglas Co. Douglas Co. Lincoln Co. Lincoln Co. N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin N Wisconsin

1 4 1 1 30 approx 50 27 19 17 15 16 18 27 31 34 40 45 40 56 83-86

TAXONOMIC ACCOUNTS / ORDER CARNIVORA

337

away. A lonely wolf gives the “lonesome howl,” a short call that rises in pitch and dies away with a sad note. If answered the wolf responds with deep howling. Both alpha male and female scent mark by lifting the hind leg. Other pack members do not scent mark and urinate in squat positions. Two packs may merge for winter hunting. Pups normally do not join adults hunting until late September or early October, but spend the summer at outliers (= rendezvous sites) within the territory. Wydeven et al. (1995) report winter territory size as 137 km2 on average (range 42287 km2) and a year round size 179 km2 (range 49-323 km2). Mean dispersal distance was 114 km (68 mi) for 16 wolves, the longest 480 km (288 mi), for a wolf that went north to Ontario. Fuller (1989) and Gehring (1995) provide data on population dynamics of wolves, mostly in Minnesota. A pack seldom exceeds a dozen individuals and usually consists of fewer than that. In recent years in Wisconsin mean annual pack size ranged from 2.6-6.2 (overall mean 3.9) (Wydeven et al., 1995). The density averaged about 19 wolves per 1000 km2 in occupied territories. In 2000, there were 66 known packs. Wolves can run perhaps 35-44 miles per hour, and for long distances at a rate of 5



Table Car-7. Wisconsin Home Ranges and Densities: Thiel 1993: 136 (In part based on Bill Feeney’s secret study).  Locality

Years

Pleasant L CampScott L Willow Pack “ “ Michigan Co. Twin Lakes Ave. Michigan Cusino “ Huldert “ Ave.

1940’s 1940’s 1941-9 1944-6 1946-8 1941-50 1944-46

186 225 300 124 150 90 86 166

29-93 32 75 31-42 42-50 45 — 49

1938 1950 1950 1950 179

260 75 48 335 39

65 25 8 56

338

Range Size

1/x Wolf Density

THE WILD MAMMALS OF WISCONSIN

miles (8 km) per hour (Carbyn 1987). They usually trot or walk in nearly straight lines, putting the hind foot in the track of the forepaw. The winter territory size varies inversely with the deer density (1980-1990) (see accompanying Fig.). While preying on deer the movement of wolves was 1-3 miles per day (Mech 1971a). The greatest movement was a straight-line distance of 886 km (531 mi) (Fritts 1983). Wolves move up to 45 miles (72 km) per day. Usually wolves move about 20 km per day (Mech et al. 1971). Estimates of wolf abundance can be made by radio-telemetry studies, howling surveys, and winter tracking (Wydeven et al., 1995). Counting wolves by “howling” techniques was pioneered by Bill Feeney and Clarence Searles in Wisconsin in April 1944 (Thiel, 1993). Thiel and Welch (1981) began winter tracking to determine distribution, numbers, and breeding status in Wisconsin packs. In Ontario the age structure was 35% pups, 40% yearlings, and 25% adults, whereas in Alaska it was 42% pups, 29% yearlings, and 30% adults (Mech, 1974). The survival rate is about 43% for pups, 55% for yearlings, and 80% annually for adults. Recent survival rates for Wisconsin wolves one year or older have averaged 82 % (Wydeven et al., 1995). Remarks. Although timber wolves occasionally prey on livestock and pets, so far the frequency of these occurrences is low. Fritts et al. (1992) found a rate of 30 depredation complaints a year in Minnesota, for some 1200 wolves and 7200 farms. In Wisconsin wolf depredation rates are generally less than one percent per year (Wydeven, personal comm.). Wolves may at times contribute to the decline or suppression of deer populations, especially in combination with severe winters and decline in habitat (Mech and Karns, 1977), but wolves generally have limited impact on healthy deer populations. Because of its culling of the weak or sickly, predation at times may actually benefit deer. Tolerance or acceptance of wolves by humans only will be found in the remote parts of Wisconsin. Wolves must be managed.

Additional Natural History. Thiel (1993) reviewed the biology of the timber wolf in Wisconsin, and Mech (1970) wrote a classic book on the wolf. Geographic Variation. There is only one known geographic race in Wisconsin and Upper Michigan. Specimens examined. Total, 10. Douglas Co.: Bear Lake, 2UW. T44N, R13W, 1(1979). T44N, R12W. Sect. 20, 1 UW. T45N, R14W. Sect. 10, 1(1981)UW. Summit Twsp, T45N, R15W, Sect. 29, 1(1981) UW. Iron Co.: Paint Lake 1 UW. Oneida Co.: T37N, 1(1949). T36N, R8E, Sect. 12, 1 (1949). McNaughton 1 (1930’s).

Genus Vulpes Bowdich, 1821 (Not Vulpes Oken) Swift and Red Foxes “The Fox could not reach the grapes, although he sprang again and again; and then, since he had not the power, he left saying, The grapes are sour!” — Aesop’s Fable (about 600 B.C.), and the poet Bahrius (200 A.D.)

Medium to small wild dogs with long, pointed ears, tail round and bushy and about as long as the head and body. Color russet or rufous red to sandy buff, with black feet and white underparts. Canine teeth elongate. The sagittal ridges are V-shaped or nearly so. The type is Canis vulpes Linnaeus. Vulpes Oken is ruled invalid, as all his names are non-Linnaean.

1842. Vulpes fulvus: DeKay. The zoology of New York. Mammalia, p. 44. 1894. Vulpus pennsylvanicus Rhoads. Amer. nat., 28:524. Not Vulpes pensylvanicus Boddaert, 1784, which is a gray fox (=Urocyon cinereoargenteus). His name is an invalid homonym and an invalid synonym. Also known as Vulpes pennsylvania. 1758. Canis vulpes Linnaeus. Systema naturae, 10th ed. 1960. Vulpes vulpes: Churcher. J. Mamm., 41:359.

Vulpes vulpes fulva (Desmarest) See synonymy for the species. The larger fox of the Great Plains, Vulpes vulpes regalis Merriam, approaches the Mississippi River and its type is from Elk River, Sherborne Co., Minnesota. The name Vulpes means fox. The subspecific name fulva means fulvous, an orange or ochraceous-chestnut color. Description. This medium-sized dog, small for the several wild dogs in Wisconsin, is best identified by color (see below) and long tail. The eyes have vertical pupils. The ears are long and pointed, tipped with black. All the feet are black. The front foot has a dew claw, and there are five toes. There are only four on each hind foot. The skull has a globular (subspherical) braincase with no sign of a

Vulpes vulpes (Linnaeus) Red Fox Concerning the fox hunt with horses and hounds: [Such hunting is] when people do the unspeakable to the inedible. — Oscar Wilde. 1820. Canis fulvus Desmarest. Mammalogie... pt. 1, p. 203, in Encyclopedia methodique... Type from Virginia.



Skull of Vulpes vulpes. 

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339

sagittal crest even in old adults (a mid sagittal ridge does develop). Differing from the similar skull of the raccoon (Procyon lotor), the snout of the red fox is slender and delicate, with elongate rostrum of the skull. There are slender but elongate canines. The rostrum of the red fox resembles that of the coyote, but is much smaller (see Measurements), and the domestic dog has relatively shorter canines. The gray fox Urocyon cinereoargenteus is similar in size, but instead of nearly V-shaped sagittal ridges they are lyre-shaped and prominently high (see that account). The red fox



Maps showing geographic distribution of Vulpes vulpes in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

skull is not so flattened, and the rostrum is narrower. There is no “step” on the ventral border of the dentary as in Urocyon. The tail is bushy. There are four pairs of mammae. The baculum is troughlike, pointed at either end. The chromosomes number 32 (Hoffmeister 1989), or 34 (Rausch and Rausch, 1979).. The normal color phase of the red fox is bright rufous-ochraceous of the upper parts, black feet, and white venter and tip of tail. This tip is set off by scattered black hairs. Cross foxes (with brownish fur and often having buff patches near the legs, and a dorsal “cross” of dark fur) and silver foxes (blackish frosted with white-tipped guard hairs, and a white tail tip) may differ from this pattern, and the former may somewhat resemble the gray fox. Especially blackish silver foxes are often called “black”. Genes for the cross fox may be AA (red), BB (black), Ee or AaBBEe (Lariviere and Pasitschniak-Arts 1996). See table Car-8. Juveniles have dark gray-brown fur. Day length initiates the molt in April-June (Lloyd, 1980). In autumn the winter fur molts in, and the guard hairs thin in March. Summer molt is loss of the underfur giving the fox a ragged appearance in April-June. These phases are a single molt, with prime fur attained in winter. The red fox is about two to three feet (600-1,000 mm ) in length. Although popular and technical literature is replete with statements that the tail is half the total length, or greater than the head and body length, I saw no evidence of that, even if one adds to the tail length the hair length at the tip. It is ex-



Skull of red fox, lateral aspect. Miller/Tertzi. 

ceptionally bushy. Total length ranges up to 1.5 m (58 in) and is usually 36-46 in. According to Schwartz and Schwartz (1981) body weights vary from 8-15 lbs (= 3.6-6.8 kg). Ables (1975) reports 4.0-4.5 kg in females, and 4.5-5.4 kg in males. Males are larger than females. Dental Formula. DF = I 3/3, C 1/1, P 4/4, M 2/3 = 42. The incisors have minute lobes distally. Geographic Distribution. The circumpolar red fox may occur anywhere in natural areas, and in some human settlements. It visits or dwells on islands in Lake Michigan and Lake Superior. It occurs regularly and in wetlands, highlands, forests, marshes, sand dunes, prairies, woodlots, forest edge. Status. The red fox is managed by the state as a game animal and furbearer (Pils and Martin, 1978). Wisconsin and Michigan are in the regions where reportedly the greatest fox harvests in the world are obtained. It is an able predator of mice and rabbits, on the obverse face of it, but kills chickens and game birds on the reverse side of the coin. It is considered by many as the most glorious, colorful, and beautiful mammal in the state. By those fortunate to observe the playful pups at the natal den close at hand, the species is an aesthetic blessing of nature. Its status is excellent, due to proper management and its own intelligence. From a sample of 203 red foxes from diverse areas of Wisconsin, Kube (1979) found a mean age of 1.6 years (with some as old as 8 years), a replacement rate of 0.56, and that the species was replacing itself and increasing. However, Rolley (1993) reported that of 1,029 rural residents, responding to recent questionnaires, fox sightings recently had declined significantly (9 percent), which decline continued in 1994-1995 (Rolley 1996). In 1999-2000, the harvest was estimated from a survey of small game hunters as 11,614 (Dhuey, 2000) mostly from Wood, Shawano, and Brown counties. A trapper survey provided the estimate 7,717. The increase in coyotes will probably cause red TAXONOMIC ACCOUNTS / ORDER CARNIVORA

341

fox populations to decrease somewhat (see Sargeant 1972; 1982). In American literature the red fox is considered sly, wily, clever, and a chicken killer. Like the coyote the red fox suffered from bounty hunting. This practice began in 1923, was repealed in 1931, reintroduced in 1959, and repealed again in most counties in 1963. Habitat. The diversity of habitats was detailed in the section on Distribution. Foxes prefer a mix of woodland and meadow, and may thrive in a fragmented landscape. Today (Macdonald and Newdick, 1982) foxes are found in some urban areas. Prey availability is important for red foxes. For a comparison of gray and red fox ecology, see account of the gray fox (Follmann, 1973). Dens are usually found in remote, welldrained areas, such as hay fields, hillsides, shrubby fence rows, forest edge, and clearings. The natal den is usually a burrow used for sleeping as well as rearing the young. A fox family may share its burrow with another fox family, even with badgers in England (Long and Killingley, 1983). A typical den has at least two openings. The burrow may extend 30 feet, dug at a depth of four to 10 feet. The nest is made of grasses in a widened part of the burrow. The burrow is often reworked from an abandoned burrow of a woodchuck or badger. A den has a conspicuous bare mound of earth at the main entrance (Stanley 1963, Schmeltz and Whitaker 1977, Layne and McKeon 1956b, Pils and Martin 1978). Pils and Martin found five communal dens, 11 percent of all dens found in southern Wisconsin in 1972-75. Foods. An opportunistic predator and forager, the red fox primarily feeds on small mammals, reportedly even porcupines and beaver (Payne and Finlay 1975), many birds, even nesting herring gulls (Shugart and Scharf 1977), great horned owl (Pils and Klimstra, 1975), and on carrion of large and small vertebrates. Insects, reptiles, and many fruits and other plant parts are eaten. Mammals used as food are summarized by Baker (1983), in-

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cluding the opossums Didelphis, shrews Sorex and Blarina, and even Cryptotis (in Wisconsin—killed but not eaten), moles, cottontail rabbits, snowshoe hares, chipmunks, woodchucks, ground squirrels Spermophilus, tree squirrels, and flying squirrels Glaucomys, beaver, mice Norway rats, muskrats, porcupines, weasels, mink, skunks, house cats, and carrion. Errington (1935) found mice and rabbits in 25 Wisconsin stomachs. Pils and Martin (1978) mentioned birds in their study of 132 stomachs and 1,020 scats. Birds preyed upon included herring gulls, grouse, ducks, songbirds, poultry, and others. In southern Illinois, Knable (1970) reported fox foods as eastern cottontails, (25% vol., 32% frequency); voles Pitymys (15%, 21 f.); Peromyscus (6%. 15 f.), raccoons (6%, 10 f.); chickens (9%); birds (15%); persimmons (10%); and grasses (16%). Red foxes eat 2.25 kg of prey per week (Sargeant 1928). Food is eaten or often cached for later use. Reproduction. Arnold (1956) and Pils and Martin (1978) reported on the reproduction in red foxes in Michigan and Wisconsin. Storm et al. (1976) added information for the upper Midwest. As many as 5-11 percent of females are barren (Samuel and Nelson 1982). They are mature at 10 months but seldom breed the first year. Courtship begins as early as late December. After courting by males, foxes pair up and, working together, dig a natal den. The foxes breed from late December to mid-March. Estrus lasts 1-6 days. There is a single litter per year. Gestation lasts 51-53 days. The litter is born in March or April (Sargeant et al. 1981). Litter size is 4 or 5 pups, 5 or 6 (Pils and Martin 1978), or up to an incredible high of 17 pups (Holcomb 1965). (However, two litters from two mothers may share the same den and seem of one family.) Prenatal loss may exceed 20 percent. If density is low, more of the red fox yearling females may mate. At birth the pups have their eyes closed, and the teeth hardly erupted. The tip of the tail is white. The newborn weighs 71 to 119 g (Storm and Ables 1966). In ten days the eyes open, and at 20

days the young first emerge from the den to play like puppies. The fur is yellowish by 49 days. By 160 days the young are weaned but brought small prey by the parents, remains of which are strewn around the den area. By October, young are full grown and have replaced the milk teeth with permanent teeth. They begin to hunt on their own and to disperse from their place of origin. Males depart first (Tullar and Berchielli 1980). The young can breed in their first year. Age variation in the red fox was reported by Churcher (1960), Harris (1977), Pils and Martin (1987), and Storm et al. (1976). Aging techniques and growth studies summarized for Ontario show a huge proportion of juveniles (Voigt, 1987). Kube (1979) discussed age classes for Wisconsin (see Status above). Mortality. Man is the worst enemy of the red fox (Pils and Martin 1978). Occasionally, but rarely, large predators such as coyotes and wolves may kill one. Badgers prey on the pups. Raptors may do the same. A real danger for Vulpes vulpes is sarcoptic mange (Sarcoptes scabei). In winter the denuded foxes die of cold. On Washington Island hunters reported mange infecting red foxes in the winter of 1992-1993, and a decline in fox numbers resulted. Pils and Martin (1978) found only 7 percent infected in Wisconsin, but the carcasses are hard to find. Another potential danger is rabies. It had a great impact in Europe in the 1970’s. An occasional fox is rabid in Wisconsin. Canine distemper, parvovirus, canine hepatitis, toxoplasmosis, tularemia, and encephalitis kill foxes (Voigt, 1987). Coyote diseases may be transmitted to red foxes (Sargeant, 1972, 1982). Parasites include mites, ticks, sucking lice, six fleas, tapeworm, heartworm (Dirofilaria immitis), Paragonimus, numerous flukes, roundworms, and a flagellate protozoan (Erickson 1944, Goble and Cook 1942, Morgan 1944, Haas 1970, Scharf and Stewart 1980, Jackson 1961, Baker 1983). Ascarids and hookworm Uncinaria affect many pups (Voigt, 1987).

Automobiles kill many red foxes on the roads, perhaps including 25 percent juveniles. People often kill them accidentally with snowmobiles in Wisconsin. Farm machinery kills some, mostly juveniles in dens. Many are shot and trapped in the appropriate season. The regulated harvest usually is the chief mortality, although locally mange may be the chief cause. Home Range and Density. Home range for the red fox is large, especially for males. It varies from 142 to 1,280 acres. Winter spring home ranges obtained by radio-tracking for 3 vixens averaged 1,495 acres. Foraging for food leads to most wandering. The boundaries of home ranges barely overlap. Home range varies in Wisconsin from 57.5 to 161.9 ha for 7 foxes radio collared. An adult male used 5.12 km2. Home ranges are usually twice as long as wide (Follman 1973, Harris 1977). Ables (1969) found home range significantly smaller in urban areas. On an average night a fox on snow may travel 5 miles (= 8 km) (Arnold and Schofield 1956); the winter home range was 900 acres (= 364 ha). Territories (approximate home ranges in this example) are defended by scent marking, not by combat. Follmann (1973) found defended territories to average larger in males, and to be of greatest size in January (1,091 acres = 2,357 ha). The mean annual size was 626 acres (253 ha), with five months missing data. For females the annual size was 278 acres (112 ha). The range was 172 to 361 acres for females, and 290 to 1,091, in males (see Table Car-9). Caches are marked with urine scent (Henry, 1977). Territorial boundaries are visited regularly, at about 2-week intervals (MacDonald, 1979). Homing is commonplace in displaced foxes. Although red foxes and coyotes forage on the same ground, the foxes avoid contact (Voigt and Earle, 1983). Annual reproduction has been estimated at 214 percent per adult (Layne and McKeon 1956). Mortality of young is high, and it continues in adults, so that young make up most (74 percent) of the fur harvest (Pils et al. 1981). Foxes may live in nature between TAXONOMIC ACCOUNTS / ORDER CARNIVORA

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three and eight years, reportedly five years (Storm et al., 1976; Lariviere and Pasitchniak-Arts, 1996). There seems to be a periodical increase in foxes approximately every 10 years (Arnold 1956). Mange may cause sudden decreases of fox numbers in the cold winters. In southern Ontario, when mortality is high, more red fox yearlings breed (Voigt and MacDonald, 1984). Rolley (1993) reported the results of about 1,000 questionnaires sent to Wisconsin farmers. The average number of litters statewide since 1986 holds to about 1.5 families per farm. Arnold (1956) describes the autumn movements as the “fall shuffle.” The young disperse in late September and early October from the dens, males a month before females. Males may move an average 18.4 mi (29.4 km) from the den, and females average 6.2 miles (9.98 km). Some juveniles move as far as 126 miles (202 km) (Longley 1962) and reportedly 245 miles (392 km) from Wisconsin to Indiana (Ables 1965). (Not only is this distance amazing, but how did the fox avoid Chicago?) Family units often vary from six to ten individuals. Occasionally related families may form a merged group. Pils and Martin (1978) estimate 7 red foxes per 1,000 hectares. Remarks. Even paired red foxes hunt as individuals. The hunting is nocturnal, although occasionally they hunt in daylight. Usually the fox emerges from its resting burrow at twilight. When the fox locates prey often it leaps high in the air to pounce on it. Additional Natural History. Pils and Martin (1978) reviewed the natural history for the red fox. Lariviere and Pasitchniak-Arts (1996) provide a recent review. Geographic Variation. There is a single subspecies of red fox in Wisconsin and Upper Michigan, but a larger red fox ranges up to the Mississippi River from the western plains. Specimens examined. Total, 43. Adams, Ashland, Barron, Chippewa, Columbia, Dane, Door (Washington Island, at Airport; at Pedant’s Lane; at E. Harbor; Ridges Na-

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Table Car-8. Two factor inheritance in red foxes. All color phases can occur in the same litter. Silvers are found on fur ranches. Ashbrook, 1937, and Lariviere and P.-Arts, 1996. 

Ashbrook: Red Cross Silver

AA BB AA Bb (smoky red) Aa BB Aa Bb AA bb aa BB Aa bb aa Bb aabb

Lariviere & P.-A: Red AA Cross AABB, Ee, AaBBEe Black BB

ture Sanctuary at Jackson Harbor, all sight records), Florence, Iowa, Jackson, La Crosse, Manitowoc, Marathon, Marquette, Monroe, Oconto, Oneida, Portage, Price, Racine, Sheboygan, Trempealeau, Vernon, Washburn, Washington, Waupaca, Wood counties. Other Records (Balliett and Taft, 1978): Fond du Lac, Oneida, Winnebago and Langlade counties (not plotted). Michigan. Schoolcraft Co.: 4 mi. N Manistique 1. Big Summer Island in Lake Michigan, 1.

Genus Urocyon Baird Gray Foxes “A gray fox... stomach content: a whole ground squirrel well chewed plus one lizard foot and somewhere inside the ground squirrel a bit of aluminum foil. The secret.”— Gary Snyder. Turtle Island, 1974.

Baird’s description (1858) refers to the bristly line in the tail, dental peculiarities, and the step in the dentary. These may differ only in degree from Vulpes (Seton, 1953), but the genus seems distinct.

The name Urocyon means dog with a tail, but of course all dogs have tails. The question is, what sort of tail? Likely the name refers to the dark, bristly line on the dorsal surface. It may or may not be tipped with black. The long name cinereoargenteus means gray and silver, referring to the dorsal fur. Description. The gray fox is a small, stout canid comparable to the red fox Vulpes, but differing in grizzled, grayish color, rounded, shorter ears less defended by guard hairs, and muzzle shorter, broader, with smaller teeth. The legs are shorter, and the gray fox is slightly smaller than the red fox. The skull of the

gray fox is unique in North American Canidae in two characteristics, the U-shaped or lyrate sagittal ridges and an extra step or notch in the dentary in ventral outline. Some other foxes approach these conditions. A good character is the short muzzle, with short nasal bones and delicate antemolars. Concerning the lyre-shaped sagittal ridges, there is more than merely a curved outline (compared to the typical V-shape in Vulpes vulpes), for the ridges steeply protrude from the cranium on their inner and outer margins, and below the ridges (ventrolaterally) the bone is textured with a pebbly character. There are reports of black phases of Urocyon, and Root (1981) reported a male, young-of-the-year Sampson gray fox (lacking guard hairs) from Richland County, in 1979. The chromosome number differs from Vulpes vulpes, in diploid number (66) according to Fritzell and Haroldson (1982). The baculum is dugout shaped and shorter than in Vulpes. The color is distinctive, grizzled gray above, ochraceous orange laterally, and whitish below. The dorsal underfur is rather buffy and the guard hairs are also buffy basally, but blackish outward, becoming white distally. In many specimens the tips are black. Therefore, there is a mixture of black and white, and the overall tone of gray. There is black around the eyes, usually encircling the muzzle, and the lips are black. On the tail the dorsal hairs are so





Urocyon cinereoargenteus (Schreber) Gray Fox Urocyon cinereoargenteus cinereoargenteus (Schreber) 1775. Canis cinereo argenteus Schreber. Die Saugthiere..., Theil 2 (Heft 13), pl. 92. Type locality vague: Eastern North America. 1775. Urocyon virginianus Schreber. Die Saugthiere... Theil. 3, p.361, 585. Type from Carolina... 1894. Urocyon cinereo-argenteus: Rhoads. Amer. Nat., 2l8:524. Combining adjectives into one name. 1899. Urocyon cinereoargenteus ocythous Bangs. Proc. New England Zool. Club, 1:43. Type from Platteville, Grant Co., Wisconsin. Synonymized here.

Photo of gray fox by Allen M. Pearson. 

Skull of Urocyon cinereoargenteus. 

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stiff and so black that a long band extends to the tip of the tail, which is usually blackish (not white as in Vulpes). The feet are dark brownish or blackish but not as black as in Vulpes. The nosepad is black. Tawny orange extends along the sides and from the ears ventrally, encircling the white chin and throat, composing a handsome collar of orange. The ventral fur is white. There is a single molt with prime fur attained in winter. Gray foxes usually weigh 9-11 pounds (4.1-5 kg) and are about a meter (39 in) in total length. The tail is about 15 inches. Males are only slightly larger than females. An adult male from Fort McCoy measured in total length 1160, tail length 440, length of hind foot 155, and ear length 62 mm ( = 46, 14, 7, 2.4 in.). This male and two adult females from Portage and Washington counties had cranial measurements as follows: condylobasal length 130.3, 126.4, 121.5; length of nasals 50.7, 39.9, 44.9; zygomatic breadth 72, 71.3, 68.4; interorbital breadth 26.4, 26.7, 24.5; maxillary toothrow 55.1, 53.6, 51.2. Dental formula. The gray fox has a typical number of teeth for Wisconsin canids, DF = I 3/3, C 1/1, P 4/4, M 2/3 = 42. Distribution. The gray fox occurs throughout Wisconsin, ranging northward onto the Upper Peninsula of Michigan. The primary range is southern and central Wisconsin. In 1991, the gray fox established itself on Washington Island, probably crossing lake ice from Upper Michigan or the Door Peninsula. Status. Although the gray fox is known from throughout most of Wisconsin, and much of the Upper Peninsula of Michigan, it is rare in northern counties. In several studies on the status of the gray fox, reviewed by Petersen et al. (1977), the gray fox seemed practically confined to the Mississippi and Wisconsin river basins (up to 1921), with some scarce reports later from central, eastern, and Door counties (1953). These mapped extralimital records were based on subjective opinions of wildlife managers and in bounty records. The primary range contracted to the

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southern half of the state (except for rare occurrences) in the 1970’s. Mappings from that time were based on harvest and observations (Petersen et al., 1977). Jackson (1961) believed that the grays had invaded the northern counties, with rare occurrences, from 1910 to 1960. In the far northern counties Florence and Forest, McCabe (1972) mentioned that the first DNR records, beginning in 1927 show a few grays and no red foxes. Eleven years later red fox harvests increased “markedly” as the gray fox “declined”. This trend continued until at least 1972 (see Fig.). Root (1981) suggested grays in southwest Wisconsin were in decline, and advocated a restricted harvest. Gray fox pelts were priced high at that time. Pelts are coarse, usually worth less than those of red foxes. In the 1970’s, Petersen et al. (1977) found gray fox populations throughout Wisconsin were stable or declining. The gray fox then showed its highest abundance in the hilly southwest part of the state, and in the Kettle Moraine and adjacent agricultural areas of southeast Wisconsin. Gray foxes were rare, by observations or harvest records, in northern counties. In central Wisconsin they were present (Long, 1970) and not considered scarce by a local fur buyer. See status map by Petersen et al. Today the general distribution is about the same, with highest abundance in the southwest counties and fair numbers in the Kettle Moraine area. The species ranks sixth among harvested furbearers (behind muskrat, beaver, raccoon, red fox, and coyote). Apparently the number of gray foxes in Wisconsin has steadily increased with protection and management. In Wisconsin, there is an estimate of 12,400 grays (Petersen, personal corr.), and the harvest goal is about 5,100 animals Crossley, 1985). In 1975, Petersen et al. estimated that only 3,000-4,000 foxes occurred in Wisconsin. Dhuey (1994) reports a recent annual harvest by trappers (1,251) and hunters (475) of 1,726 gray foxes. In

1999-2000, the harvest was estimated as 1,553 (Dhuey, 2000), continuing the downward trend. Although pelt price relates to the harvest of gray foxes, another direct relation is seen in the demand for red fox and raccoon furs (Petersen et al, 1977). Fritzell (1987) suggests gray foxes may survive with harvest of 55 percent, but usually less than that would be surer. The status of the gray fox seems good, although Rolley (1996) found evidence that foxes recently declined. Although human centers such as Milwaukee, Madison, Appleton, and even smaller



Maps showing geographic distribution of Urocyon cinereoargenteus in Wisconsin and North America. 

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cities probably eliminate habitat for gray foxes, this adaptable species persists in protected adjacent areas, such as the Kettle Moraine State Forest and nearby farmlands. Fritzell (1987) discusses the interesting biology of this fox, adapting to land use such as farming. Especially in southern and central Wisconsin, famous for dairy farms, there is abundance of food (cottontails, mice, corn, and apples) and many groves of trees, brushy areas, and hedgerows providing cover. These seemed to benefit gray foxes. In the rugged bluffs and hills of southwest Wisconsin conditions are ideal for this species. Habitat. The gray fox is a woodland canid, agile enough to climb trees (Jackson, 1961). Nevertheless, the original range seemed restricted considerably from northern forests. In some situations gray foxes may outnumber red foxes (Follman 1973; Tullar and Berchielli 1982). The author has seen little evidence of that in Wisconsin, where the red fox harvest may dramatically increase while the gray fox numbers fall. For a comparison of the red and gray foxes, Follman (1973) presents a careful study. Smaller than the red fox, and less adaptable to human activities, the grays are less common in Wisconsin, seldom seen, and seldom killed by hunters and automobiles. They persist in numbers cycling irregularly in upland hardwoods and riparian mixed hardwoods in southern counties, inhabiting hardwoods, cedar swamps, tamarack stands, and mixed coniferous forests in northern Wisconsin, and on the Upper Peninsula of Michigan (Jackson 1961, Wenzel 1912). The gray fox thrives in brushy areas near woodlands. Its preference for rough (rocky) terrain may be another reason (the big-timbered bottomlands of several rivers is likely another) that so many occur in southwestern Wisconsin. On Washington Island, where red foxes were common and doubtless cross the ice from one isle to another, the grays surprisingly showed up in 1990-1991. Since then, until August 2002, the gray fox seems to be

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the dominant fox on the island, according to numerous residents. I have seen 1-9 observations of grays each summer since 2002(one dens near my house presently on the north shore) and not a single red fox in that time (except a road-killed red fox in June 2002). In Follmann’s (1973) study in southern Illinois, red and gray foxes were sympatric,



Graph Showing Gray Fox Abundance 1975-1976. Petersen et al. Recent status changes – see text. 



Fox harvests in Florence and Forest counties. McCabe 1972. A competition not well known. 

and the reds usually (except in March, the time of breeding vixens) had larger home ranges or territories. The grays were expected to replace the reds eventually because they have more omnivorous diet and use a greater variety of dens. In winter the grays kept to the oak-hickory highlands most of the day (54 percent use, and especially in daylight), while the reds also used old field and woods during the day. In spring the grays ranged into the fields at night to forage (47% woods to 26% old fields). In summer both reds and grays were usually in the old fields at mid-day. In autumn the use of habitat was variable, but grays were in the upland woods at mid-day (47% use) when reds were there the least. There seems little information on gray fox dens, which are occasionally excavated near a stream in woodland (Hoffmeister, 1989). Dens are often appropriated from another mammal, and seldom if ever found in fallow fields, cultivated fields, prairies, or meadows. Often gray foxes den in hollow stumps and logs, rock crevices, even brush and woodpiles. I do not know if they line their nests with leaves and grasses as the red fox does, but it seems likely that they would. Crossley (1985) reports that dens are typically lined with grass, leaves, or shredded bark. Occasionally the gray fox will rest in the daytime in dense brushy cover. Most dens found in southwest Wisconsin are sited on the east, south, or southeastern slopes of the hill (Fritzell, 1987). The gray fox often sleeps during winter days in excavated dens. The den may be used year-round. Foods. Gray foxes are somewhat omnivorous. They are not likely to raid a chicken yard, a habit which has made the red fox so despised. They are less likely to feed on game birds and waterfowl. Their primary foods are mice, cottontail rabbits, fruits, mast, and arthropods (especially insects, grubs in winter) and considerable carrion (Errington, 1935; Hatfield, 1939; Richards and Hine, 1953). In winter the chief food is the cottontail (Crossley, 1985). Reportedly grays attack porcu-

pines (Weaver, 1939) and eat shrews. They occasionally capture birds, amphibians, weasels, and numerous rodents (Errington, 1935). In season plant foods such as elderberries, grapes, acorns, grain, and apples are eatern. Pils and Klimstra (1975) found in autumn that 70 percent of the diet may be vegetation. Reproduction. The mating season of the gray fox lasts from late winter until March, and gestation perhaps lasts about 53 days (Layne and McKeon, 1956; Richards and Hine 1953; Sheldon 1949). Fritzell (1987) reports 59 days, based on captive foxes. The den is prepared by male and female and she bears on average four pups (1-7). Richards and Hine (1953) determined the litter size to be 3.9 for 44 females, and Root (1991) found 3.5 for 85 females. (Both studies were of placental scars, which is a little higher than true litter size.) About one fifth of the yearling females do not breed (Root, 1991). In other studies about 8 percent do not breed (Fritzell, 1987). The pups are nearly naked at birth (in May), their eyes unopened. They begin to grow a wooly juvenile pelage. From about 100 grams, each pup grows rapidly, and after three weeks prey is brought to them by the parents to eat. Weaning takes place in about 80 days. The baby teeth are replaced by four months, and then the offspring forage alone. Males first, and for longer distances, disperse in autumn, followed by young-of-the-year females. Longevity is 10-11 years (Crandall, 1964), as in red foxes. Mortality. Humankind, of course, traps gray foxes for fur, hunts them, and occasionally kills one with an automobile. As much as half the population of gray foxes in some localities of Wisconsin has been harvested in a single year. Any large meat-eater that might prey on the red fox likely would prey on the gray, especially the pups. Pups show the highest mortality, over 40 percent. Numerous parasites are known from the gray fox, summarized by Jackson (1961) and Baker (1983). These include lice, fleas, ticks, and mites. Internal parasites include flukes, tapeworms, TAXONOMIC ACCOUNTS / ORDER CARNIVORA

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roundworms, spiny-headed worm, and occasionally heart worms. Some gray foxes are infected with rabies, and numerous other diseases such as plague, tularemia, St. Louis encephalitis, Q fever, listeriasis, leptospirosis, histoplasmosis, toxoplasmosis, canine hepatitis, and Tyzzer’s disease. Infections can be a major cause of mortality, but gray foxes are quite resistant to sarcoptic mange. They seem to suffer little infection from heartworm (Fritzell, 1987). Home Range and Density. Richards and Hine (1953) found home range varying greatly in Wisconsin, from 145 acres to as much as 2,155 acres (59 to 872 ha). During winter courtship wandering is more extensive, and around the natal dens the wandering is less. Jackson (1961) and Crossley (1985) give the Wisconsin home range size as 31-765 acres. In southern Illinois, Follmann (1973 found territories larger in males, and greatest size in April (to 501 acres). The annual size of territory was 336 acres for males, 265 for females. The range was 178 acres to 414 acres for a female, and for males 177-501 acres (see Table Car-9). The wild population probably consists chiefly of young-of-the-year (Lord, 1961b). Some foxes may live six years, possibly seven. The populations cycle multi-annually, some peaking approximately every 10 years. In Wisconsin there is no evidence of such cycles. Populations seem usually low, for the animal is seldom observed. Males have larger home ranges, and wander less than Vulpes vulpes. McCabe (1972) found in the years 1937-1955, in northeastern Wisconsin, near the Pine and Popple rivers (in Florence and Forest counties), that gray foxes were in decline, and red foxes, judging from trappers’ reports, were concomitantly increasing. Whether competition is indicated is unknown, for heavy cutting of timber in the region might cause the same effect. I have observed gray and red foxes together on Washington Island from the 1990’s until the present, and the gray foxes are thriving. Indeed, red foxes seem

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to be declining there. Root (1981) found gray foxes in southwest Wisconsin in decline, reportedly from high trapping mortality. He (1981) calculated a composite life table for the gray foxes in southwestern Wisconsin for November-January 1978-1980. Of 636 animals, 420 were young of the year, and 118 were yearlings. Thus, two thirds were youngof-the-year and 85 percent comprised the first two age classes. Trappers collected 243 gray foxes in southwestern Wisconsin. The calculated total mortality in a year was a surprising 66 percent. Additional Natural History. Fritzell and Haroldson (1982) reviewed the gray fox. Geographic variation. There is none evident in Wisconsin. The question whether there is a race U. c. ocythous differing from the nominate race found in Illinois was raised by Hoffmeister (1989) who referred all foxes he examined to the nominate race. No one has addressed the problem in nearby Nebraska, Iowa, Minnesota, Missouri, Wisconsin, or Michigan. Cory (1912), Jackson (1961), and Long (1974) referred the Wisconsin specimens to U. c. ocythous mostly on geographic grounds. Burt (1946) surely relied on geographic grounds, because the rare grays in Upper Michigan doubtless emigrated from Wisconsin. One wonders just how far the concept of geographic grounds has served to map this race (Hall, 1981), from southern Canada southward into Oklahoma and Arkansas. State boundaries seem influential in fixing racial boundaries. The Upper Mississippi Valley gray fox, with type at Platteville, Wisconsin, was described as pale. Ostensibly the pale foxes range into the southern Great Plains as far as Oklahoma. A specimen from Oklahoma in this collection was decidedly pale, both in the whitish hairs of the dorsal fur and the pale ochraceous (rather than rufous) of the throat and sides. The race U. c. ocythyous also is supposed to have long tail, long ears, and slender muzzle. These are trivial, especially in carnivores, where such differences are usual-

ly slight and the character highly variable. In Hall (1989) the race U. c. ocythous is mapped from Platteville, Wisconsin (the type locality) through Wisconsin and most of Upper Michigan, into northwest Illinois, across the Plains to eastern Wyoming, north to Ontario, and south to the Texas border. The specimens I have seen from Wisconsin are not pale, all having the same bright coloration. Although assigning Wisconsin foxes to the pale race, Jackson (1961) examined the holotype in the Museum of Comparative Zoology at Harvard, and reported that it was “greatly faded”. The faded specimen was thought to represent pale Great Plains foxes. In the USNM, I noted pale gray foxes from Oklahoma and the Great Plains, but Wisconsin foxes were darker as are my specimens. The Mississippi River may be roughly the border for the pale foxes, or the racial boundary may lie even westward or southward. All Wisconsin foxes are referable to U. c. cinereoargenteus. The name U. c. ocythous is a synonym, and the name of the pale foxes on the Great Plains must be changed to something else. They seem referable to the southern U. c. scotti (western Texas), which is a pale, prairie race. Specimens examined. Total, 17. Adams, Chippewa (Cadot, specimen not preserved).

Clark, Dane, Door (Washington Island), Dunn, Jefferson, Juneau, Monroe, Pepin, Portage, Washington counties. Other records. Jackson 1961; Long, 1974; Root 1981 (no voucher specimens preserved).

Family URSIDAE Gray 1825 Bears The bears are large, short-tailed carnivores with robust canines and bunodont cheek teeth. The skull otherwise resembles those of large, stout dogs or wolves.

Ursus americanus Pallas Black Bear “The black bear (U. americanus, Gm.) of North America is well distinguished with a flat forehead, smooth and black fur and fulvous muzzle.” — Baron Georges Cuvier, in Regne animal, 1846. 1780. Ursus americanus Pallas. Spicilegia zoologica... Fasc. 14:5. Type from eastern North America. 1961. Euarctos americanus americanus (Pallas): Jackson. Mammals of Wisconsin, Univ. Wisconsin Press, p. 311.



Table Car-9. Mean territories [i.e., home ranges] of foxes in acres. Follmann 1973.  Month Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Yearly

Gray foxes 2 males 4 females 202 488 485 501 452 253 259 380 177 — 243 256 336

262 368 414 179 228 297 — — — 178 204 255 265

Red foxes 2 males 6 females 1091 838 631 385 417 733 — — — — — 290 626

321 229 208 392 311 328 330 361 296 177 172 216 278

Ursus americanus americanus Pallas The name Ursus means bear, a Linnaean appellation, and americanus of course means



Black bear’s bunodont cheek teeth. S. F. Baird, 1858. 

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Black Bear by Georges Cuvier, Regne Animal, 1846. Woodcut. 

an American origin. The word bear is derived from Old English brun, or brown. Black does not always apply; many bears are brownish or cinnamon, and often are spotted on the throat or chest with white Description. The huge size of the black bear and its well-known stout, “roly poly” form make identification easy. When the adult black bear stands on its hind feet and lifts its massive head high, it seems less “roly-poly”. It has a short tail, long claws on all four feet, and dense coarse fur. The ears are rounded. The massive feet are broad, naked-soled, pentadactyl, and plantigrade. The foreclaws are recurved. The eyes are relatively small, and the rhinarium or nosepad is broad. The skull is correspondingly large in adults, wolf-sized in subadult bears, and usually the largest of any Wisconsin carnivore, in length, width, and height. The teeth are quite distinctive, because the cheek teeth are bunodont in relation to the varied diet (see below). The canine tooth exceeds 15 mm in length. Long ago in Regne animal, the great anatomist Baron Georges Cuvier (1846) provides this thorough description of the dentition: “The Bears (Ursus, Lin.)—Possess three large molars on each side of both jaws, altogether tuberculous, and of which the posterior above are most extended. These are preceded by a tooth a little more trenchant, which is the carnivorous tooth... and by a variable number of very small false molars... This sys-

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tem of dentition, almost frugivorous, explains why the bears seldom devour flesh. Students often confuse the skull of a young bear with the massive skull of a male wolf, but one look at the carnassial upper premolar will tell the story. The bear’s cheek teeth are all broad with low cusps for crushing, and they are not developed at all for shearing meat. The rostrum is more robust than that of the wolf. The anterior premolars are separated by gaps, tending to be small, vestigial; and often one, two or more are lacking. Cuvier noted that the cartilage of the nose is elongated and moveable. There are three pairs of mammae, two pairs pectoral and one pair inguinal. The last upper molar is less than an inch (25 mm) in length in the black bear (it is greater than an inch in the grizzly). The baculum is not especially large, is rather club-like (Burt , 1980), and tapers to either end. Slightly curved, it measures 140-167 mm in length. The fur is deep, glossy black with patches of white ranging from a small spot to a large



Skull of Ursus americanus. 

blaze found on the chest of about half of the Wisconsin bears. The muzzle is often cinnamon brown instead of black, and there are many bears that are cinnamon brown, deep walnut brown, or even a yellowish dark brown. Molt occurs in April or May, and the new fur is acquired by June. The hair continues to grow out until prime in October, when it is not only longer but darker in color. In the spring the prime fur soon wears, fades, and falls away. Adult males weigh about 250-350 pounds (113.4-159 kg), and females 120-180



Maps showing geographic distribution of Ursus americanus in Wisconsin and North America. The range area has shrunk. 

TAXONOMIC ACCOUNTS / ORDER CARNIVORA

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pounds (54.5-82 kg). Large males rarely exceed 600 pounds (273 kg). Total length ranges up to 1,780 mm, nearly six feet in total length, but usually bears are smaller. Dental Formula. I 3/3, C 1/1, P 2-4/2-4, M 2/3= 34-42, with the full complement 42. Geographic Distribution. The black bear formerly occurred throughout the state and the Upper Peninsula of Michigan. It disappeared from southeastern Wisconsin by 1860, as a result of human activities, and from central and western Wisconsin by 1890. The statewide bear population probably reached its lowest point around 1915. Since 1950, black bears have increased to thousands in northern Wisconsin, and are expanding their geographic range southward, where bearhuman interactions will become problems. In 1961, Jackson determined Wisconsin’s primary bear range to be bounded by a line from Polk County down to southern Clark County, eastward through Marathon County, and on to Green Bay near Marinette. There was one report from the Apostle Islands in Lake Superior, and none on Washington and Rock islands. By then bears had vanished from Door County. Some transplants were made in Door, Adams, Jackson and Wood counties (Jackson, 1961), but the revival of bears is best attributed to game laws and increased human acceptance. In the past quarter of a century, the range of Ursus has expanded southward into Wisconsin’s central forest lands, and bears occur occasionally in nearly every non-urban county in the state. In the past decade three bears have swum over to Washington Island, and two of them were shot dead. One was seen swimming between Plum Island and the Mainland (see Fig.). They also occur on some Apostles, especially on Stockton Island. Status. See comments in Geographic Distribution above. Schorger (1949) reviewed the history of black bears in Wisconsin, and W. E. Scott (1947) discussed their status about that time. Briefly, bears were protected in Wisconsin by a hunting season in 1917-1918, but usually unprotected prior to 1930. Sea-

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THE WILD MAMMALS OF WISCONSIN

sons for hunting of bears with guns began in 1934, and for bow hunters in 1942. Spring trapping was allowed from 1945-1956. Hunting and trapping seasons protect mammals at least for much of the year. In 1957, bear trapping was entirely prohibited, and in 1965, cubs were protected. In 1985, the bear season was closed, although some poaching was reported. Since then the harvest has been closely regulated and the bear population has more than doubled. Mothers with cubs are now protected. Hunting and number of bears harvested are regulated in management zones. There are two separate seasons of taking bears, one with the help of dog packs and the other using bait or tracking, with no dogs. Chippewas were granted the right of tribal hunting of bears since 1983. In Upper Michigan, 37 percent of the bears taken were killed in their winter dens. An injured bear or a mother with cubs can endanger human life, and should not be approached. Encounters occur often because a bear smells food. Bears can easily outrun a human. Black bears can readily climb trees; therefore, climbing is no escape. Fortunately, a bear usually runs away when it encounters a human. An adult who encounters a bear usually should act unconcerned, neither aggressive nor afraid. A child should scream defiantly, hopefully to bring help. In wilderness, children should always be attended by adults. Jackson (1961) and Baker (1983) mentioned a three-year old Michigan girl killed and partially consumed by bears. The Milwaukee Journal-Sentinel (Aug 21, 2002) discusses a baby killed out of state, and mentions that in Walworth County, Wisconsin (August 1999), a boyscout was dragged 80 feet with his tent, bitten and badly injured (dislocated shoulder). Bears occasionally damage beehives, tear up property such as barn doors, and kill livestock. Pigs, sheep, cattle, dogs, and horses might be killed by a hungry bear. One tried to enter a house through a window at Lake DuBay and was shot. In Wisconsin a farmer may be

compensated up to $5,000 for bear damage under the Wisconsin Wildlife Abatement and Damage program. Approximately 1,000 nuisance bears or more in Wisconsin have been moved to remote locations in the years 19961998, following complaints to the Department of Natural Resources. The transplants were carried out by the U. S. Department of Agriculture, Animal Damage Control. Bears can be bothersome in numbers around garbage dumps, and the ethics of shooting garbage dump bears often has been debated in Wisconsin. Presently it is illegal to hunt at dumps. The bear hide is seldom worth as much as $100, and the hair is so coarse the pelt is usually made into a rug or wall hanging. The fur historically has been used for coats, trim, hats, and lap robes. The meat is excellent, unless tough and stringy from an old bear, or too fat. The hams resemble beef steak. Bear fat or grease was formerly used as a salve to prevent mosquitoes from biting, as a cure for arthritis, and to preserve leather, and the lard was useful in cooking. Some statistics on the harvest of Wisconsin bears are given in Tables Car-10-11, from Dhuey and Wallenfang (1995) and Kohn et al. (1998). In 1999, the harvest was reported as 2,881 bears (Kohn and Rolley, 2000). See



Abundance of black bear in Wisconsin. After Wise. 

Home Range and Density below. Briefly, bears are considered a threat by rural landowners, farmers, and bee-keepers, as a magnificent game animal by hunters, and as a rare, but popular, wild mammal by many naturalists. In my opinion, this species is well managed in Wisconsin, which does not want a surplus of bears near people. Habitat. The black bear prefers heavily forested areas, hardwood and mixed hardwoodforests, dense brushland, rocky terrain, and swamps and occasionally is found in remote marshes. Bears change from one habitat to another in search of berries in season and other plants (Rogers, 1987). Forest openings, then, are useful as a source of berry foods. Oak stands provide hard mast. The bear in summer usually finds a hiding place for rest, its lair, where it occasionally scratches the earth or piles vegetation for a bed. When food becomes scarce in late fall a bear, usually obese with autumn fat, prepares a den for its winter sleep. This hiding place is usually insufficient in size to accommodate the bear’s entire body although if lucky it may find a cave or hollow tree. Usually a partially excavated pit at the base of a wind-blown uprooted tree or even dense vegetation such as evergreens provides what shelter there is, and the bear is eventually partially covered with snow. I have a photo of this kind of “den”. A DNR warden (winter 2004) reported a Wisconsin bear denning in an eagle nest, and when the eagles returned to it the bear had not wakened. Kessler (1994) reports 62 percent of dens near trees or windfalls, 25 percent excavated, and only 8 percent unprotected as “nests.” The pregnant female delivers her litter of cubs in the winter den, which, therefore, is also a natal den. Foods. Jackson (1961) lists a variety of foods including small mammals, bird eggs and broods, garbage and carrion, berries of all kinds, nuts such as beech nuts, acorns, and hazel nuts, ants and their young, honey, fishes, and many other things. Twigs, berries, grapes and other plants, and rarely fungi, are TAXONOMIC ACCOUNTS / ORDER CARNIVORA

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eaten. Other foods are earthworms, insects, mice, nests of hymenopterans, fish caught with the bear’s mouth, frogs and salamanders, turtles and their eggs, hares and rabbits, woodchucks and other squirrels, snakes, other bears rarely, deer (fawns and some adults). Altogether the vegetable matter may be 77 percent, carrion 15 percent, insects 7.4 percent, and small mammals almost 1 percent (Banfield 1974). Some bears feed on livestock. In the Apostle Islands they have been reported to raid beaver lodges (Smith et al., 1994). Baker (1983) discusses the foods of black bears, mostly from studies in places other than Michigan, saying the black bear has a reputation for being continuously and ravenously hungry. Blueberries and acorns were of such importance to influence, by scarcity, depredations on livestock and gardens by hungry bears (Rogers 1976). Manville (1981) mentioned depredations on grain fields, orchards, beehives, and livestock. Two students of bear ecology in Wisconsin found that plants (grasses, sedges, berries) were the main foods eaten. An important food, acorns, surprisingly, was not mentioned as important in either study. The common animals eaten were ants. Norton (1982) studied 630 scats collected during May through August 1976 and 1977. Seasonally important foods were grasses, sweet cicely (Osmorhiza claytoni) and aspen (Populus tremuloides) in spring; gooseberries (Ribes spp.), blueberries (Vaccinium spp.), and ants (Formicidae) in summer; blackcherries (Prunus serotina), wild sarsparilla (Aralia nudicaulus), and domestic oats (Avena sativa) in late summer. Green vegetation comprised the bulk of the diet. There was no mast (acorns and nuts) present in Norton’s study area (see Payne et al., 1998). Bertagnoli (1986) analyzed 337 scats and found 45 kinds of foods (May-August). These were collected in 1978 and 1979, and there were differences in the foods eaten. Grasses and sedges were the chief foods. The plants used most were in Rosaceae. Ants were the most important animal food. Storlid (1995)

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confirms plant foods such as grasses, sedges, serviceberry, wild sarsaparilla, blackberry, and raspberry. Ants and even deer (13 percent of scats) including two fawns were eaten. Reproduction. Bears breed promiscuously in summer (June and early July), mating and pairing temporarily. Females may produce litters, depending on sufficient food availability, by three years, usually four, and as long as seven (Kolenosky and Strathearn, 1987). Females with young avoid adult males. Nursing females do not conceive, therefore females breed in alternate years. Bears become sexually mature at three years to three and a half years of age. The dominant male fiercely drives off competitors. Bears are never monogamous for long periods. Implantation is delayed 4 1/2 months with young born January 15-February 15, perhaps as early as late December. Gestation lasts roughly about 210 days, but development occurs in the last ten weeks. The young weigh only 225-330 g (7.9-11.6 oz) at birth, and are naked and blind. When young develop enough to leave the den, in April, there is natural food available. The young retain their milk teeth. These are replaced when the bears are two years old. The young may stay with the mother even through the winter of the second year. This care lowers infant mortality considerably. Upon emerging in spring the mother eventually drives the yearlings away, but sometimes they stay with her up to 17 months until summer breeding. Many ages ago, Pliny the Elder, in Historia Naturalis, wrote this translated observation, “Bears when first born are little shapeless masses of white flesh a little larger than a mouse, their claws alone being prominent.” One of the truly remarkable things about any kind of bears is the production of such tiny young. To my knowledge, no other carnivore, perhaps no other mammal except marsupials, shows such size limitation of the neonate. Relatively tiny embryos are not the rule in large mammals, sexually promiscuous mammals, or predators. The bear is all three. The question arises, why does the bear

produce tiny young, being large, promiscuous, and on occasion predaceous? The bear sleeps extensively in winter, without a true hibernation, to conserve the body fat, but it often emerges lean in the spring. Since the bear breeds in autumn, but has a delay in implantation, the dormant, unimplanted embryos cannot make use of metabolized energy from their mother’s winter body fat. Neonates gain nutrients (i.e., high in titre) from the mother’s milk for rapid growth and development. It is good strategy for species with dormant embryos to either conceive in spring or bring forth tiny young as do the bears (Ramsay and Dunbrack, 1986). Black bears live long lives, up to 25 years, but usually 10-15 (Crandall, 1964). Bears may live and probably breed for as many as 13 years in the wild according to Baker (1983). In Wisconsin some have been aged well over 15 years. One age is mentioned as approximately 30 (Kohn and Rolley, 2000). The mean age is about four years for harvested bears. The number of young in black bears of Wisconsin is usually three (range 1-3). Matson (1952) reported a litter of five. The altricial young are only six to eight inches (150-200 mm in length, weighing half a pound or perhaps a pound, usually about 250 g each). The eyes and ears are closed, and there is no fur. Fur appears on the back in a week, and at 25 days the eyes open. At 46 days, the ears open and the weight is over five pounds (2.27 kg). By then the upper incisors have erupted. Mortality. Aside from people hunting and killing bears that are pests, the black bear has few enemies. Starvation and disease take the very young (and probably the very old), whereas hunting removes bears one year old and older. Mortality may be high in cubs and yearlings if autumn foods are scarce. Mast failures may effect a heavy mortality. The timber wolf may on occasion kill a small bear (Rogers and Mech 1981). Cannibalism occasionally occurs (Trauba, 1996). Parasites include flea, louse, several ticks (including the tick, Ixodes, that transmits

Lyme disease), and a mite (Manville 1978; 1981; Addison et al. 1978; and Rogers 1975). The mite may cause mange in Wisconsin bears. Worms include Alaria, Baylisascaris, Dirofilaria, hookworm larvae, and Physaloptera. Diphyllobothrium latum is now rare (Rogers, 1975) in bears. The incidence of Trichinella spiralis is low in Wisconsin and Michigan (Zimmerman 1977). There are doubtless some respiratory and viral diseases that affect bears. More study is needed to identify them. Manville (1976) made a thorough study of black bear parasites from bears in northern Wisconsin. Ectoparasites were collected from nine bears captured in 1974, and 104 bears (including 18 recaptures) taken in 1975. Viscera from 28 bears killed by hunters during the 1974 and 1975 bear hunting seasons were examined for internal parasites. Thirty-five of 44 bears from the vicinity of Clam Lake carried the dog tick (Dermacentor variablilis), and one the black-legged tick Ixodes scapularis— a new record for bears. Forty-five of 60 bears from Iron County in 1975 carried dog ticks. Four Iron County bears taken in 1975, had mallophagan Trichodectes pinguis. Mange was observed on five bears; two Demodex mites were found in a scab. A flea was found on one bear from Iron County (1974). Twenty-five intestinal tracts (89.3 percent) contained ascarid worms (Baylisascaris). Fifty-nine of 92 fecal samples had the eggs. Hookworm larvae were found in a bear caught in 1975. Adult filaria worms (Dirofilaria ursi) were found in two. Seventeen (19.5 percent) blood smears contained microfilariae. The worm Trichinella was found in only 6 of 163 (3.7 percent) bears (1970-1973). Dental caries are not uncommon in bears, probably due to their eating sweet foods (E. R. Hall, personal communication). Home Range and Density. Home range studies were made on the Upper and Lower peninsulas of Michigan (Erickson 1964; Manville 1980, 1981). Home ranges of Upper Peninsula black bears averaged 12,955 acres TAXONOMIC ACCOUNTS / ORDER CARNIVORA

357

(5,234 ha) for males and 6,477 acres (2,617 ha) for females. In Lower Michigan, Manville found more extensive wandering, 32,400 acres (12,928 ha) and 16,550 acres (6,668 ha) for males and females, respectively. Abundance of bears is estimated based on harvest figures (tables Car-10-11). In 1995-1996, Kohn et al. (1998) found that young males made up the most of the harvest, through the first four years of life. Yearlings are most often killed. After the males are thinned out, more females are taken from the 4th to 10th year, or occasionally later for very old bears, falling to less than 10 percent in either sex in any of those years. The estimated densities varied from approximately 1 per mile to lower values (1 per 6.3 square miles) according to Kohn et al. (1982, 1998). Weber (1994) found 1/6.1 square km in northeastern Wisconsin, in predetermined “good habitat.” Movements by three bears, all males, in Lower Michigan, were 65, 95, and 35 miles (104, 152, and 56 km, respectively) on unusual autumn excursions. These bears then returned to their home areas by November of the same year. Harger (1970) reported homing in a bear traversing a distance of 142.5 miles (228 km). Some bears stay where they were transplanted. Remarks. Nowack (1991) ably reviews the physiology using the term “hibernation”, as do many lay people and some naturalists, but black bears do not hibernate. They do undergo a drowsiness or torpor the Germans call Winterschlaf. Winter-sleep is a good term for this condition. The great biologist, G. Cuvier, in Regne animal, 1846, used the meaningful French word for drowsy-sleep as “le sommeil” or somnolency. [This word in French means drowsiness or sleep, and does not mean true hibernation.] The body fat in early winter is about 40 per cent of the body weight. The bears subsist on their fat and sleep unconcerned when people are nearby, but they may arouse violently when disturbed. Females often move their cubs to a different winter den if disturbed. Adult males enter their

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THE WILD MAMMALS OF WISCONSIN

dens later than the females and young do, for winter sleep. On the Upper Peninsula the earliest date for denning was October 13. In southern Michigan and in Wisconsin bears doubtless enter torpor later and sleep less, with dormancy perhaps irregular (Manville



Table Car-10. Age classes of bears harvested in Wisconsin, 1986-96.  Year 1986 Males Females 1987 Males Females 1988 Males Females 1989 Males Females 1990 Males Females 1991 Males Females 1992 Males Females 1993 Males Females 1994 Males Females 1995 Males Females 1996 Males Females

1-2 yr

Percent in age class 3-9 yr 10+ yr No. aged Mean age

59.5 43.8 52.6 41.5 60.4 40.9 53.9 42.5 67 46.8 56.9 38.9 63.9 48.4 50.9 37.8 62.6 50.9 55.7 37.7 60 46.8

37.2 41.3 43.2 52 35 51.9 39 47.9 30.4 48.1 37.3 54.9 32.1 45 41.7 57.3 31.4 45 41.4 52 37.3 45.6

3.3 9.9 4.2 6.5 4.6 7.2 7.1 9.6 2.6 5.1 5.8 6.2 4 6.6 7.4 4.9 6 4.1 2.9 10.5 2.7 7.6

210 121 401 200 439 345 397 261 454 331 448 306 474 380 405 286 441 271 600 435 771 536

3.6 4.2 4.1 4.6 3.7 4.7 4.2 5 3.4 4.6 4 4.7 3.5 4.3 4.3 4.6 3.9 4.2 3.6 5.3 3.6 4.7



Table Car-11. Number (%) of black bears harvested in Wisconsin by sex and age class, 1995-96 (After Kohn et al., 1998) .  Age Class (years)

1995 Males

1995 Females

1996 Males

1996 Females

1 2 3 4 5 6 7 8 9 10+

184 (30.7) 150 (25.0) 126 (21.0) 46 (7.7) 35 (5.8) 11 (1.8) 17 (2.8) 10 (1.7) 4 (0.7) 17 (2.8)

84 (19.3) 79 (18.2) 71 (16.3) 34 (7.8) 41 (9.4) 28 (6.4) 26 (6.0) 15 (3.4) 10 (2.3) 47 (10.8)

251 (32.6) 211 (27.4) 104 (13.5) 84 (10.9) 34 (4.4) 34 (4.4) 17 (2.2) 14 (1.8) 2 (0.3) 20 (2.6)

103 (19.2) 148 (27.6) 58 (10.8) 73 (13.6) 33 (6.2) 27 (5.0) 23 (4.3) 16 (3.0) 15 (2.8) 40 (7.5)

1980). The heart rate drops 8 to 10 beats per minute or even lower, but the body temperature drops only about 11 degrees F (3-4 degrees C). Summer temperature is about 100 degrees F (37 degrees C), and in winter it is about 90 degrees F (34 degrees C). In spring, an arousing bear defecates a hard and dry fecal “plug”. Bears may arouse thin or fat depending on their metabolism, the amount of autumn food, severity of winter, and so forth. Thin bears are said to be very hungry, but some emerging bears do not eat for several days. Additional natural history. Pelton (1982) and Nowak (1991) reviewed the natural history for the black bear. Geographic variation. There is but one race in Wisconsin and Upper Michigan. Specimens examined. Total, 10. Ashland Co.: Clam Lake 1. No specific locality 1. Door Co.: Beach, N end Washington Island 1. Langlade Co.: T34N, R9E, Sect. 19, Parish Twsp 1. Lincoln Co.: Hwy 29, N of Antigo 1. Marinette Co.: No specific locality 1. Portage Co.: No specific locality, probably Jordan Swamp 1. Price Co.: No specfic locality 1. Shawano Co.: Between Tigerton and Wittenberg 1. Wisconsin No specific locality 1.



Raccoon family. By T. Swearingen. Kansas University. 

Family PROCYONIDAE Bonaparte The Procyonidae are found in Asia, and North and South America. Most members have annulated tails. The feet are plantigrade, although dextrous. The procyonids are found at home in trees or ranging about on the ground. The cheek teeth, reflecting an omnivorous diet, are bunodont, especially those behind the carnassials. Although the pentadactyl feet resemble those of bears, and the cheek teeth are similarly bunodont, there is no alisphenoid canal and the baculum (and penis) is relatively large and unique. In Procyon lotor the baculum is bifid distally, with rounded terminations, and the end is hooked. The base is robust. Years ago, as a rather crass curiosity it was ground sharp on the end,

suspended on a gold chain, and used as a toothpick. The raccoon in Wisconsin in recent decades has increased from rare to extremely abundant also, in spite of several diseases (see below) and popularity of its fur. This increase in numbers is true in other states.

Genus Procyon Storr Procyon lotor (Linnaeus) Raccoon “The upsurge in raccoon numbers, which has occurred in many areas during recent years... is surely a major irruption”. — Glen C. Sanderson, 1951. [also in furs taken.] TAXONOMIC ACCOUNTS / ORDER CARNIVORA

359

1758. [Ursus] lotor Linnaeus. Syst. naturae, ed. 10. 1:48. Type locality Pennsylvania (fixed by Thomas, Proc. Zool. Soc. London, p.140, 1911).

The name Procyon means early or first dog, although Procyon is not an early dog at all. Some say it means “before dogs.” The word lotor means the washer, based on the supposed and overstated habit of captive raccoons that may wash their food in water before eating it. According to Jackson (1961) Captain John Smith described the raccoon as a kind of badger called “aroughcun”, which came from the Algonquian Indian name arankun. There is a single geographic race in Wisconsin and it extends across Upper Michigan as well. Whether it ranges throughout the Lower Peninsula requires a quantitative appraisal, but previous simplistic assignments by Jackson and Burt, respectively, resulted in one of the previously discussed Jackson-Burt divisions, P. l. hirtus for Wisconsin and P. l. lotor for Michigan. The specimens I have seen both in Wisconsin and Upper Michigan are referable to P. l. hirtus.

Procyon lotor hirtus Nelson and Goldman 1930. Procyon lotor hirtus Nelson and Goldman. J. Mammalogy, 11: 455. Type from Elk River, Sherburne Co., Minnesota.

Description. This medium-sized carnivore, aside from its distinctive color pattern (mask, ringed tail) is recognizable because of the broad head, narrow muzzle, pointed ears, and bushy tail. There are five slender toes on each foot, each with a long claw, and the feet are nearly plantigrade. The soles are naked. The raccoon often sits on its hind feet and manipulates or searches for food with its hands. Often it does this in water. The gait of a running raccoon is peculiar, with the legs extended and the back arched high. The baculum is long, hooked, and distally bifurcate, terminating as two condyle-like structures that

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THE WILD MAMMALS OF WISCONSIN

open the vagina, and hook into it during coitus (Long and Frank 1968). Rinker (1944) reported an os clitoridis. There are six mammae, two pectoral, two abdominal and two inguinal. The chromosomes are usually 2N = 38 (Lotze and Anderson 1979). The raccoon braincase is quite rounded. Occasionally there is a low sagittal crest. One adult specimen (UW-SP No. 2761) has a welldeveloped sagittal crest. The auditory bullae are inflated. The infraorbital canal is often divided as two foramina on each side, at least in Wisconsin and several other states I checked. The upper third incisor has an accessory lobe. The molars are not sectorial, and may be called bunodont. The cheek teeth are subquadrate, about as broad as long. The upper carnassial is somewhat sectorial. The first upper premolar has a single root. There are ten teeth in any row, provided there is no dental anomaly. The hard palate on the skull extends far back, the distance from pterygoid to the back molar about equal to the length of the maxillary tooth row. Anatomical studies on raccoons are summarized by Lotze and Anderson (1979). The raccoon shows a prominent brownblack facial mask set against adjacent whitish hair. The black hides the carnivore’s bright eyes, and the black is continuous with a medial black band from the black nosepad to the level of the ears. They are edged with white. The tail is fairly long and annulated with five to seven blackish bands alternating with pale grayish rings. The fur is grizzled, heavy on the black and iron gray, but occasionally brownish, reddish brown, or yellowish. The underparts have brownish underfur overlain with gray or brown guard hairs. There are numerous color variants known to breeders, and golden red, melanistic, yellowish, and albino are the most common. Long and Hogan (1988) found that albinism in raccoons results from two different recessive alleles, and that albino parents having different recessive alleles may by epistasis produce normal colored offspring. Both these albino phenotypes had pink eyes, but

the golden red mutant had black eyes. The annual molt lasts through most of the summer (Goldman 1950, Steuwer 1942), in Michigan from April to August. Wisconsin specimens showed molt September through late December and prime fur into April. Adult raccoons average 14-24 pounds (5.6-9.6 kg) but may reach 40 pounds (18 kg) (Bluett and Craven, 1985). Raccoons reach a meter (39 in) in total length. Cranial measurements of 4 male adults and 2 female adults are: Condylobasal length 112, 118, 114, 113/ 114, 115; length of nasals —,



Skulls of Procyon lotor. Dorsal and ventral views No. 2186 young, Dorsal 2761 Old with sagittal crest and fused nasals. 

38.8, 36.9, 38.1/ 41.5, 35.3; zygomatic breadth 77.5, 75.2, —, 74.8/ —, —; interorbital breadth 24.3, 25.3, 23.6, 23.6/ 24.9, 22; maxillary toothrow 41.9, 43.6, 41.9, 43.5/42.3, 44.4. Dental formula. I 3/3, C 1/1, P 4/4, M 2/2 = 40. Teeth may be missing or supernumerary (Goldman 1950). Geographic Distribution. The raccoon is found in every Wisconsin county and often in urban and cultivated areas. It is distributed in diverse habitats too, from hills to low swamps, and is found on Washington and Rock islands in Lake Michigan. In Wisconsin, raccoons are abundant along the St. Croix River in the northwest, in southern Wisconsin, and northeastward to Rock Island. They are least abundant in northern counties, unknown in the Apostle Islands, but widespread in Upper Michigan. The raccoon, which prefers hardwoods, was neither wide-spread nor common on the Upper Peninsula until late in the 1930’s (Baker 1983). Records of specimens of raccoons examined and other reports by Jackson and myself practically blanket the state, with the exception only of Shawano, Iron, and Florence counties. A recent study by Amundson and Marcquencski (1985) used carcasses supplied by the Wisconsin Trapper’s Association, with recent records statewide except along the southern counties. Iron County was included. Status. The raccoon is doubtless the most abundant wild carnivore in Wisconsin (Table Car-1), approached in numbers only by the striped skunk Mephitis. Attention to road-kills in Wisconsin in any summer will confirm this conclusion. For example, in July 1998, I observed 1 or 2 dead young raccoons in every county from Redwing, Minnesota, to Appleton, Wisconsin, mostly along Highway 10. Continuing eastward, raccoons were also seen dead in Brown and Door counties. In 1999, the same extensive road-kill mortality was observed, in late July and early August. In 1999-2000 the harvest was estimated as 130,141 (Dhuey, 2000), mostly from Clark, Jefferson and Sauk counties. TAXONOMIC ACCOUNTS / ORDER CARNIVORA

361

The raccoon is managed throughout Wisconsin by hunting and trapping regulations. The old Wisconsin Conservation Department once (in 1936-1950) introduced raccoons into numerous Wisconsin counties; thousands were propagated and released. When this program was terminated the raccoon surprisingly continued to increase. The peak harvest was about 250,000 in 19781979, and the peak price surprisingly lagged two years (1979-1980). The raccoon is aesthetically popular with people, and is seldom killed by them even when destructive in the



Maps showing geographic distribution of Procyon lotor in Wisconsin and North America. 

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THE WILD MAMMALS OF WISCONSIN

garden. Its supposed habit of washing food, well known antics as an adopted pet (but see beyond), appealing “hands”, bright eyes, and soft fur are endearing, even when it overturns the garbage cans, digs up the lawn for acorns or grubs, steals the dog’s food, or eats the farmer’s sweet corn and other produce. When corn sweetens (the so-called “milk” stage) raccoons may ravage an entire field. For large problems the U. S. Department of Agriculture’s Wildlife Services can be notified. A large live trap can trap out raccoons, which may be transported to a remote place (suggested as at least 50 miles away). Not so happily for the raccoon, its fur is luxuriant and valuable. The meat is dark and fatty but edible, and “running” raccoons with dogs (“‘coon” hunting) is a popular sport at night. To hear the cry of hounds on the track of a raccoon or opossum, and the baying of the dogs when the raccoon is treed in the moonlight of a frosty autumn evening is an experience not soon forgotten. In Wisconsin there are a few raccoon breeders, who especially hope for albino raccoon fur (Long and Hogan 1988). In 1993-1994, about 160,000 raccoons were harvested in Wisconsin. Total pelt value ($1,321,000) outranked all furbearers (Dhuey, 1995). Between one and two million are harvested each year in the United States. Habitat. The adaptable raccoon lives in varied habitats, preferring hardwoods with numerous hollow trees for security and denning. It seldom ranges far from standing water. Hoffmeister (1989) suggests 1,200 feet (nearly 400 m) as a limit. Its foods show how much it depends upon lakes and streams. Raccoons may be found in treeless prairies or swamps having no hollow trees. They are often found in urban areas. The raccoon reportedly does not build a nest, but it may line a tree cavity with leaves. It opportunistically dwells with its young in rocky crevices (observed in Wood County, Sand Hills Demonstration Area), attics of abandoned farmhouses, and hollow snags (Stevens Point

on McDill Pond). They may sleep in woodpiles, hay stacks, and ground dens made by other mammals (Lotze and Anderson 1979). Sometimes numerous raccoons hole up together for winter (Mech et al.,1966). Foods. The raccoon feeds extensively on plant parts, especially fruits, and on a diverse diet of animals as well. Raccoons have fed on crippled waterfowl (Yeager and Elder 1945), turtles and their eggs (Erickson and Scudder 1947), herring gull eggs and young in Massachusetts (Kadlec 1971), some other birds, and occasional reptiles, frogs, rarely toads and salamanders (Kaufmann, 1982). In Illinois (Yeager and Rennels, 1943) foods include fox squirrel, muskrat, cottontail, mice, shrews, ducks, cormorant, chicken, fishes, snails, hornets, water bugs and beetles, crayfishes, persimmon, pecan, grapes, pokeweed, and miscellaneous items, opportunistically eaten in the autumn (October to November). Jackson (1961) listed for Wisconsin diet a preponderance of plant foods such as black cherry, chokecherry, pin cherry, currant, wild grape, hawthorn, wild plum, apple, tomato, blackberry, raspberry, strawberry, blueberry, and other fruits and acorns, hickory nuts, hazelnuts and beechnuts, field and sweet corn, oats, and other shoots and buds of plants. Animal foods are as much as 70 per cent of the food volume, particularly in diets including crayfish, snails, and insects, and contain about 3040 percent plants. These animals include crayfish, snails, clams, earthworms, grasshoppers, crickets, beetles, wasps, bees and moths, fishes (especially bullheads), frogs, turtles, eggs and young of birds on occasion, mice, shrews, muskrats, and squirrels (rarely). Dorney (1954) found crayfish and young muskrats were eaten in a Wisconsin marsh, along with corn, berries, waterfowl, and a few muskrats disabled by humans. Some animal foods of the raccoon are carrion. Reproduction. Raccoons of both sexes may breed in their first or delay to the second year. A female may have a second litter on occasion (Bissonette and Csech 1938, Johnson TAXONOMIC ACCOUNTS / ORDER CARNIVORA

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1970, Lehman 1968), but this is doubted by Sanderson (1987), is likely rare, and probably unsuccessful. Late litters are not likely to survive in areas as far north as Minnesota (Mech et al., 1968) and including much of Wisconsin. Some yearling females may not conceive because of extremely cold weather, until their second year (Stains 1956). In Root’s (1981) study in 13 southwestern counties in Wisconsin, only 32 percent of the yearling females conceived. He found some juveniles (10 per cent) resulted from late litters conceived from mid-May through mid-July. Root (1981) found no juvenile males capable of breeding the first year. Root thought his litter size of 3.71 in southwest Wisconsin resembled that of Manitoba (4.1, Cowan 1973) and North Dakota (4.5, Fritzell 1978), but I suggest this may indeed be a significant difference, as the means were based on adequate samples. Breeding takes place in winter (FebruaryMarch), and gestation is about 63 days (Sanderson and Nalbandov 1973). Birth occurs in late March, April, and May, and even later (Baker 1983). The newborn raccoon has blackish skin covered with fine grayish fur, an indistinct black facial mask, and tail rings alternating whitish and black. The eyes and ears are closed. These open in about three weeks. Lower incisors and canines also erupt by three weeks. At nine weeks the young raccoon eats solid food. By 12 to 16 weeks the young is weaned and weighs about 3 to 4 pounds (= 1.4-1.8 kg). In four or five months permanent teeth replace the deciduous teeth (Baker 1983, Hamilton 1936, Montgomery 1964, Stains 1956, and Stuewer 1943). The mother often moves her litter from one den to another. Age of raccoons can be determined by cranial sutural closure, ossification of epiphyses, cementum layers of teeth, the size and extensibility of the baculum, and eye lens weight. Raccoons have lived 12 years in the wild and 22 years in captivity (Haugen 1954, Crandall, 1964, Jones 1979). Mortality. The greatest enemy is humankind by means of hunting and trapping (Steu-

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wer 1943, Johnson 1970, Stains 1956, Whitney and Underwood 1952). About 200,000 per year were harvested in Wisconsin (Table Car-1) by hunters and trappers (Bluett and Craven, 1985). In 1989, over 140,000 were harvested, and in 1991-1992 over 74,000 were trapped. In Wisconsin, automobiles also cause much mortality (Root 1981). Mortality in the raccoon is greatest in the juvenile age class. The value of the raccoon fur leads to high human-caused mortality, once estimated at an incredible 98 percent (43 percent hunting, 55 percent trapping) in southwest Wisconsin (Root 1981). Tom Howard (personal correspondence) suggests this percentage must be considered to include natural as well as human caused mortality, because no population can sustain 98% mortality. The bobcat, fisher (Seton, 1953), red fox, coyote and several owl species are known to prey on raccoons (Stains 1956, Whitney and Underwood 1952). Starvation is suspected as a cause of death. Food shortages, diseases, and parasitism all may lead to mortality (Lotze and Anderson, 1979). Raccoons carry diseases and have been studied a great deal as indicator species for monitoring pollutants. Knuth (1979) studied polychlorinated biphenyls (PCB’s) in raccoons living near the Wisconsin River west of Plover, in Wisconsin. Often found in the semi-aquatic mink, the presence of this dangerous substance in raccoons is, at the least, surprising. Raccoons carry at least 13 pathogens causing disease in humans (Bigler et al. 1973). Except for canine distemper (Robinson et al. 1957) and parvovirus the diseases do not seem of major importance in raccoon mortality. Parvovirus recently and sporadically killed many raccoons, as well as dogs, in Wisconsin. Rabies and tularemia may be suspected in raccoons, but these deadly diseases are not prevalent in Wisconsin raccoons. I knew a fur breeder in Illinois raising raccoons exclusively, who caught Lyme disease from ticks associated with his captive raccoons. Some

raccoon diseases may be transmitted by the raccoon’s urine or feces. Distemper, pneumonia, and parasite infestations periodically decimate American raccoon populations (see Lotze and Anderson 1979). The protozoan Giardia and the roundworm Baylisascaris may be contracted by humans from raccoons. In southern Wisconsin 50-77 percent of raccoons may harbor this roundworm. In northern counties the incidence is less (Amundson and Marcquenski, 1985). Ingestion of aged (about 30 days) eggs of this roundworm from the environment causes the infection. Baylisascaris can infect humans via the eggs passed in raccoon scats. The parasite occasionally causes death in small children and a rabies-like sickness in woodchucks, tree squirrels, and rabbits. In Wisconsin 51 percent of 213 raccoons from 43 counties contained this worm. Juveniles show higher incidence than adults (Amundson and Marcquenski, 1985). Jackson (1961) lists parasites including biting and sucking lice, ticks, and fleas. Internal parasites include roundworms, Trichinella, tapeworms, and one trematode (Clinostomum). Home Range and Density. Males have larger home ranges than do females (Lotze and Anderson 1979). Steuwer found in Michigan that adult males had home ranges as small as 45 and as large as 2,000 acres (18 to 800 ha, respectively), with an average of 500 acres (200 ha). Females had territories as small as

13 acres (5.2 ha) and as large as 930 acres (372 ha) with an average of 268 acres (107 ha). Fisher (1977) found raccoons to move distances of up to 1,720 feet. In Minnesota one super-wanderer travelled 165 miles (264 km) (Priewert 1961). In good habitat for raccoons, densities varied from 1 raccoon per 10 acres (4 ha) to 1 per 16 acres (Dorney 1954, Yeager and Rennels 1943). Steuwer (1943b) calculated densities of 1 raccoon per 16 acres (6.4 ha), but in Clinton County Michigan, Linduska (1950) found only 1 raccoon per 43-55 acres. Bluett and Craven (1985) report densities as 1 to 30 or 40 acres (12 to 16 ha) in Wisconsin. In urban areas the density may be as high as one per 12-20 acres (4.8-8 ha). Remarks. Raccoons are often taken from nature for pets. They may grow up to become aggressive and destructive. They cannot be returned to the vicissitudes of nature and survive. An adult specimen from Dane County (No. 109) has two sets of frontal bones. Some skulls have uncommon, intricate (fractal) sutures (Long and Long, 1992), greatly enhancing their strength.. The species is famous for occasionally washing its food in water. Actually, this has not been observed in nature. In studies on albino raccoons I never heard that any captives do it. A raccoon might share a den with the striped skunk (Shirer and Fitch 1970). They





Raccoon. By Walter Weber. 

Raccoon harvests (1,000) average pelt price. 1973-1983. 

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may aggregate in a group for winter sleeping. Essentially nocturnal, raccoons are curious and playful. They swim well, and can usually best a dog in combat. The female can frequently be found with young by hearing her twittering purrs. Raccoons do not truly hibernate, i.e., vary their body temperature with cold ambient temperatures to any great extent, but they are often dormant or torpid for periods of several days in cold weather conditions. In Wisconsin, to my knowledge, the raccoon in winter has not been studied. Additional Natural History. Lotze and Anderson (1979) reviewed natural history for the raccoon. Geographic variation. There is one race in Wisconsin, northern Illinois, and Upper Michigan. Specimens examined. Total, 39. Adams, Dane, Door, Eau Claire, Iowa, Juneau, Langlade, Lincoln, Manitowoc, Marquette, Oneida, Ozaukee, Portage, Rock (lact. October 15), Rusk, Sheboygan, Vilas, Wal-



Figure showing the status of Bayliscaris procyonis in Wisconsin. In Wisconsin, 51% of 213 raccoons from 43 counties contained this worm. In northern counties the incidences is significantly lower than in the south, where the raccoons are abundant. Juveniles show higher incidence than adults.. After Marcquensky. 

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worth, Washburn, Waukesha, Waupaca, Winnebago, Wood counties. Other Records (Balliett and Taft, 1978). Monroe, Ozaukee, Trempealeau, and Shawano counties. Personal observations of dead on roads: Pierce, Buffalo, Pepin, Clark, Wood, Portage, Waupaca, Ozaukee, Brown, Door counties. Most counties in 1985, Amundson and Marcquenski.

Family MUSTELIDAE Swainson This family includes the martens, weasels, mink, skunks, river otter, and badger. There are few placental families as diverse as this one, and some workers suggest that differentiation has been progressing for many millions of years. Perhaps the family should be divided into two or more families. Recently Dragoo and Honeycutt (1997) proposed that the skunks (Mephitinae) and the stink badgers (Mydaus) should be recognized as the family Mephitidae, in my opinion a premature opinion. For one example, no one has even described the penis and baculum of Mydaus. The crux of the problem is that the paleontological and anatomical evidence suggest badgers are a natural group, allied to one another fairly closely with a good fossil record to prove it (Long and Killingley, 1983; Long, 1881; and Petter, 1971). I suspect the resemblance of Mydaus and skunks is evolutionary convergence. Furthermore, skunks and otters are definitely related closely (Hunt, 1974; Wozenkraft, 1989; Wyss and Flynn, 1983) . On the other hand, those working with molecules and dendrograms find parsimonious arrangements suggesting skunks and Mydaus are much more closely related than the latter is to the other badgers. I submit some older evidence that was either overlooked or ignored by workers (Long, 1981; Petter, 1971), who in these and other works discussed subtle and derived characters tying the badgers together, with Meles and Taxidea not so closely as supposed, and mentioning peculiar articulations of the teeth and

even the mammary gland arrangements suggesting common origin. The least division I could accept at this time would recognize a family (or subfamily) of otters, skunks, and badgers (including Mydaus with badgers). I point out that the parsimonious dendrogram on molecular evidence given by Dragoo and Honeycutt, conflicts with strong morphological evidence, lumps stink badgers with skunks, places Meles and Taxidea close together, and that the family Procyonidae stood closer to them than to the badgers Mydaus. In this work I follow the conventional use of the name Mustelidae, noting only that there is a strong affinity of the mustelines to one another.

Key to Wisconsin Mustelidae

1

1’

2

2’

3

Characters of Skull and Body Dental formula 36 teeth, upper molar rounded posteriorly and sulcate on occlusal surface, with high labial margin, auditory bullae flattened, hind feet webbed, tail stout and furred (not bushy) ......................................... River otter Lontra canadensis Dental formula not 36, upper molar not rounded much inward and posteriorly, not sulcate with high labial margin (except in skunks), auditory bullae not flattened (except in skunks), hind feet never webbed, tail bushy ............................ 2 Upper molar and carnassial both triangular, skull wedge shaped, broader posteriorly, forepaws and foreclaws enormous, black “badges” on cheeks and a short stripe on head and nape of neck . ..................... North American Badger Taxidea taxus Upper molar “dumbbell” shaped* or deeply dished (in skunks), skull not wedge-shaped, forepaws ordinary and not specialized for digging, black “badges” and head stripe lacking ............... 3 Dental formula 38 teeth, with four upper premolars on either side, ear pinna

large and lined with pale hairs, marks of yellow or white confined to chin, throat and head ........................... Martens...4 4 Size large (up to 1.0 m in males), fur brown with legs, back and belly often blackish, hairs grizzled and coarse appearing, throat lacking orange or white marks, ear lined with whitish hairs, tail longer than 290 mm ................. Fisher Martes pennanti 4’ Size medium (up to 0.6 m, approximately two feet total length), color yellowish or reddish brown, head often grayer or yellower, feet and tail darker, fur fine and soft, throat and chin with orange or buff marks, tail shorter than 290 mm ......... ............................... American Marten Martes americana 4’’ Size medium, color brown with white markings on throat and head, fur fine and soft, tail shorter than 260 mm ...... ..................................... Stone marten Martes foina. Non-native introduction SE Wisconsin 3’ DF 34 teeth, with three upper premolars, ear pinna medium or small and lined sparsely with dark hairs, markings not confined to chin, throat and head (except in the mink, which has tiny, obscure ear pinnae) ....................................... 5 5 Upper molar sulcate as in otter, much larger than upper carnassial, auditory bullae flattened (as in otter), color glossy black with bold white stripes ............... ........................................... Skunks 6 6 Size medium (approximately 0.6 m, about two feet total length),