Field book of
ILLINOIS MAMMALS

Donald F. Hoffmeister |
Carl ©. Mohr —

ILLINOIS
NATURAL HISTORY

i SURVEY
Py
# MANUAL 4
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Digitized by the Internet Archive
in 2010 with funding from
University of Illinois Urbana-Champaign

http://www.archive.org/details/fieldbookofillinOOhof

Sastern cottontail, a mammal that is common in Illinois.

ee OF TLLLINOIS
WILLIAM G. STRATTON, Governor

DEPARTMENT OF REGISTRATION AND EDUCATION
Vera M. Binks, Director

Fieldbook of
ILLINOIS MAMMALS

Donald F. Hoffmeister
Carl O. Mohr

MANU A Es -4
Printed by Authority of the State of Illinots

NATURAL HISTORY SURVEY. DIVISION
Hariow B. MI ts, Chief URBANA, June, 1957

Sel Avis: (OFR Sh Pals eNiOnles
WILLIAM G. STRATTON, Governor

DEPARTMENT OF REGISTRATION AND EDUCATION
VERA M. Binks, Director

BOARD OF NATURAL RESOURCES AND CONSERVATION
VERA M. BINKs, Chairman
A. E. EMERSON, Ph.D., Biology WALTER H. NEWHOUSE, Ph.D., Geology
L. H. Tirrany, Ph.D., Forestry RoGER ADAMS, Ph.D., D.Sc., Chemistry
ROBERT H. ANDERSON, B.S.C.E., Engineering

W. L. EVERITT, BE, PhD:
representing the President of the University of Illinois

DELYTE W. Morris, Ph.D., President of Southern Illinois University

NATURAL HISTORY SURVEY DIVISION
Urbana, Ibinois

HARLOW B. MILLS, Ph.D., Chief
BEssIE B. East, M.S., Assistant to the Chief

This paper is a contribution from the Section of Faunistie Surveys and
Insect Identification and from the Section of Wildlife Research.

(44655—5M—9-56) ct@imasiast 2

FOREWORD

a” 1936 the first number of the Manual series of the Natural His-
tory Survey Division appeared. It was titled the Fieldbook of
Illinois Wild Flowers. This was followed in 1939 by the Fieldbook
of Illinois Land Snails, and in 1942 by the Fieldbook of Native
Illinois Shrubs. These were developed under the charge in the
Illinois statute which directs the Board of Natural Resources and
Conservation, under which this Survey operates, “To publish, from
time to time, reports covering the entire field of zoology and botany
of the State.”

That these manuals have served a useful purpose is obvious in
the constant demand for them. The Fieldbook of Illinois Wild
Flowers has long been out of print, and a revised edition is now in
preparation.

Now appears the fourth in this popular and useful series, the
Fieldbook of Illinois Mammals. This work was inaugurated by
Dr. Carl O. Mohr of the Natural History Survey staff over a decade
ago. Upon his leaving the service of the state it was possible to
persuade Dr. Donald F. Hoffmeister, Curator of the Natural His-
tory Museum of the University of Illinois and an eminent mammal-
ogist, to continue this project. Dr. Mohr has recently returned to
Illinois and has collaborated in the final stages of the project.

It is difhcult for one or even two people to develop to completion
a project such as this. We are greatly indebted to Mrs. Leonora
K. Gloyd and Dr. Philip W. Smith of the Natural History Survey
staff for the great amount of painstaking work which they expended
on various duties related to the development of the manuscript. It
would have been most difficult to complete the project without their
unselfish assistance.

Further appreciation should be given to the Survey’s Technical
Editor, James S. Ayars, who has carried on his responsibilities with
characteristic vigor and sensibility, to Dr. H. H. Ross, Head of
the Section of Faunistic Surveys and Insect Identification of this
Survey, who directed the many activities prior to the editing of the
manuscript and who was responsible for continued activity over
the past decade, and to Mrs. Blanche P. Young, Assistant Technical
Editor, for assistance with many editorial problems.

It is hoped that this manual will be found as helpful in educa-
tional circles and among interested laymen as the three volumes
which preceded it.

Hartow B. Mitts, Chief
Urbana, Illinois
February 8, 1957

vil

ACKNOWLEDGMENTS FOR ILLUSTRATIONS

Credit for illustrations used in this fieldbook should go to the fol-

lowing individuals and organizations:

J. C. Allen and Son, Lafayette, Indiana, for figs. 42 top, 57

American Museum of Natural History, New York, N. Y., for figs.
113, 114, 115, paintings by Charles R. Knight

James S. Ayars, Illinois State Natural History Survey, Urbana,
for figs. 9, 85

Lynwood M. Chace, New Bedford, Massachusetts, for fig. 81

William E. Clark, Illinois State Natural History Survey, Urbana,
for figs. 4, 58, 89

R. P. Grossenheider, St. Louis, Missouri, for the frontispiece, which
was reproduced through courtesy of the present owner, J. Mar-
shall Magner, also of St. Louis

E. Raymond Hall, University of Kansas, Lawrence, for figs. 61a, b,
103

N. L. Huff, Museum of Natural History, University of Minnesota,
Minneapolis, for fig. 78

Illinois State Department of Conservation, Springfield, for fig. 72

Illinois State Geological Survey, Urbana, for fig. 112

Illinois State Museum, Springfield, for fig. 45

Illinois State Natural History Survey, Urbana, for figs. 11 top, 43,
44, 50, 59, 77, 86, 88, 93, 105

J. W. Jackson, Brush, Colorado, for fig. 76

Maslowski and Goodpaster, Cincinnati, Ohio, for figs. 47, 55, 63,
64, 65, 75 bottom, 80, 82, 92, 94

Karl H. Maslowski, Cincinnati, Ohio, for figs. 79, 83, 90, 91, 96

Charles A. McLaughlin, University of Illinois, Urbana, for figs.
39, 40, 51, 60, 61c, d, 73, 74

Lorus J. and Margery Milne, Durham, New Hampshire, for fig. 68

Missouri Conservation Commission, Jefferson City, for fig. 67

Carl O. Mohr, Illinois State Natural History Survey, Urbana, for
figs. 1, 2, 3, 5, 6 top and bottom, 7, 8, 10, 11 bottom, 12, 14, 15,
16-20, 21-24, 25-29, 30-34, 35-36, 38, 40, 41, 6le, f, 73, 95, 107,
108, 109, 117, 118, 119, for the small drawings of chipmunk, thir-
teen-lined ground squirrel, Franklin’s ground squirrel, and east-
ern gray squirrel in the front of this book and on pages 212 and
222, and for the drawings on pages 218 and 219

Ernest E. Mulch, Phoenix, Arizona, for fig. 54

Natural Resources Council, Conservation News Service, Washing-
ton, D. C., for fig. 69

x ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

New York Zoological Society, New York, for figs. 66, 87

Gordon Pearsall, formerly Forest Preserve District of Cook County,
River Forest, Illinois, for fig. 62

Herbert H. Ross, Illinois State Natural History Survey, Urbana,
for fig. 98 a

Walter J. Schoonmaker, New York State Museum, Albany, for fig.
75 top

Charles and Elizabeth Schwartz, Jefferson City, Missouri, for figs.
42 bottom, 70

Charles L. Scott, formerly Illinois State Natural History Survey,
Urbana, for fig. 89

Thomas G. Scott, Illinois State Natural History Survey, Urbana,
for fig. 13

United States Fish and Wildlife Service, Washington, D. C., for
MES oy egos, NOT

United States Public Health Service, Communicable Disease Cen-
ter, Atlanta, Georgia, for figs. 99, 100 bottom

University of Illinois, Department of Forestry, Urbana, for fig. 116

University of Missouri, Extension Service, Columbia, for fig. 106

Ernest P. Walker, Smithsonian Institution, Washington, D. C., for
figs. 46, 48, 49, 52, 53, 56, 84, 101, 102

Wisconsin Alumni Research Foundation, Madison, for fig. 100 top _

Wisconsin State Department of Conservation, Madison, for figs.
OMe

CONTENTS

ERT RTIR SETS Fn) oy Sirk w riences vale plc ee wid = halen ROD Ge wie es ale 1
BMPer EOP MAT CLAVE: «ccs. clea co eie eee ee we wale wane eee be 8 ene 1
ENE eae hee digs e dies, yer oid) ¥ 6 aS ova eee me Bes, eee 3
Geographical Distribution................----+eeeee terres 6
Species State-Wide in Occurrence.........----..---+eeeeeee 6
Species Not State-Wide in Occurrence.........-....+---+--: 7
eT TETINS SIVA MIMPALS «oc ps es ache ee wine sen ede ree nee 8
Studying Live Mammals...........-...--- 20s eee te tree eees 8
Making a Collection of Preserved Specimens..............-. 9
eM ec Sa Sew rings won a Sins Sub ane Be Be 13
Davspes g.. Oe TS a eee ee ee Peri ar ae ae 16
ie rer Pt ty CMa i eal. evasive uous Si Fae elevate ed BY 16
PiAnIESeenuve? GLOUNIG > | 666 = foes Feiss ee ee gees 19
High Trails, Runways, and Slides..............-----+--+-+> 20
cert Re re Se aM eo sive oe eel gelte gece wee ars aS
PMT TITIES ec oad ocak seo oye + Sea eee ek ee 25
Key to Tracks of Some Common Illinois Mammals........ 25
SSE TRE AC IS ae os as = ye oe ew pen wine ie 26
Sa Tie LI ren reer eee ee a 26
MEEMMOITEICS Re 2 os ol PO eae s ales be eee Seine eS ee OG 32
SC SES G IIS ae Seer oe ae a
DSR MISTY ANS: Orato Kis ycn rk od a Sse ee Siege 35
Sree EME ERCMUALIS 5 oj. ciafywieie a ie einen sei eee = em aoe Slaten = 35
MESO ULE LENOIS, IWIAMMALS:: .. . <2. ace a Pes ei sts ae gd 35
pepo Ula tie INES... 20. ie ae ee nnn = Sieh gies enc 36
UREN aNTERIPU LCE Set cit he) nk ee MoS a ne od euler wee 37
Checklist of Present Native and Naturalized Mammals
PERT TR TITERS ee Ate cise toes wis, Se sn de pa astaratid NN A. <a eS 38
Pte St MORG CEs 6 nue Se noes Sa aie ok aS Sn 41
Order Marsupialia—Marsupials ..................----- 44
Order Insectivora—Moles and Shrews................--- 49
Giger @ninoptera— Bats es oa AL Oe a 63
Order Carnivora—Carnivores or Flesh Eaters........... 85
Order Rodentia—Rodents or Gnawing Animals......... 123
Order Lagomorpha—Hares and Rabbits................ 188
Order Perissodactyla—Odd-Toed Hoofed Mammals..... 196
Order Artiodactyla—Even-Toed Hoofed Mammals......197
San WHAMALALS ‘OF PREHISTORIC LIMES:.... . 05... o4 50 eee 205
MUA ETABITATS AND THE PUTURE...< 0 ec « sbrs nls oo heal eas ..209
Ea Pe Stes eA Sia ice we awn eines SS SN ew SE 213
IE PUENTE ee TF ag ica icv sepiciere wie Ga "wiahS yam gras ute pe eee et
Some Literature on Illinois Mammals..................... 220
Some Handbooks on Mammals of the United States....... ee a
Some Literature on Mammals of States Near Illinois........221
SL Ree, SRS oe ee ee ee eee ec 223

INTRODUCTION

AMMALS characteristically are warm-blooded animals

that have backbones, are at least partly covered with hair
of some kind during their lives, possess mammary (milk)
glands, and give birth to living young. Any animal occurring
wild in Illinois and having four limbs and a coat of fur or hair
is easily recognized as a mammal.

In addition to man and his domesticated animals, 59 species
of mammals are known to occur in IIlinois. Of these species,
three—roof rat, Norway rat, and house mouse—were intro-
duced from the Old World. The others are native. The com-
monest Illinois mammals are mice, shrews, rabbits, and squir-
rels. Larger mammals, such as beavers, badgers, and deer, are
less abundant. Bison, elk, bears, wolves, mountain lions, and
some other mammals that once roamed the prairies or lived in
the forests of the Illinois area have vanished from the state, or
are present only as caged animals.

In pioneer days, many wild mammals served as sources of
food and clothing for settlers and as means of livelihood for
trappers. Although they are no longer of paramount impor-
tance in this respect, the wild mammals of Illinois today continue
to be a significant asset. The furbearers, such as muskrats,
minks, and foxes, have yielded annually more than a million
dollars worth of fur. The game animals, such as rabbits and
squirrels, have provided millions of pounds of food each year.
Also, some of the wild mammals are a source of welcome recre-
ation to hunters and naturalists.

WHERE MAMMALS LIVE

The casual observer or the average hiker sees very few wild
mammals out-of-doors and he may get the impression that they
are a rarity. Actually, mammals are numerous in almost every
acre of uncultivated land in Illinois—prairie, forest, meadow,
fencerow, and marsh—probably 5 to 12 times as numerous as
birds. In woods there may be 10 to 60 mammals per acre; in
a meadow, along fencerows, and in grassy places along forest

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2 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

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Sieaaied hat ' Flying squirrel Raccoon
Fox squirrel Deer
Gray fox
Opossum Mole mound Chipmunk
White-footed mouse Masked shrew Short-tailed shrew
Mole Pine vole

Fig. 1—Characteristic mammals of the unpastured Illinois forest.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 3

edges, the number per acre may be even greater. Of this num-
ber, about 95 per cent are small mammals—chipmunk size or
smaller. As the hiker wanders through a forest or crosses a
brushy field, he may walk near hundreds of these small animals
without being aware of them.

Habitats.—Each type of habitat has its characteristic deni-
zens. Under the forest floor may be shrews, moles, and voles.
On the forest floor may be skunks, raccoons, foxes, opossums,
white-footed mice, and chipmunks. Above the forest floor may be
flying squirrels, tree squirrels, and various kinds of bats. By
probing into the leaf mold on the forest floor, one may find the
intricate maze of tunnels used by shrews and voles; by breaking
open or turning over a decaying log, one may discover the nest
of a white-footed mouse or a pine vole; or, by probing into an
old woodpecker hole high in a tree, one may arouse a flying
squirrel from his sleep. Mammals characteristic of the Illinois
forest are shown in fig. 1.

In a meadow or fencerow may live one or more coyotes, red
foxes, striped skunks, cottontails, woodchucks, weasels, and
smaller animals. If one looks closely in the grass, he may find
signs of the prairie vole, the least shrew, the thirteen-lined
ground squirrel, and the deer mouse. Some mammals character-
istic of this habitat are shown in fig. 2.

In houses built in the water of lakes, marshes, or streams live
muskrats and beavers. At the edges of streams and lakes, one
may see tracks of raccoons, minks, and muskrats. Some mam-
mals characteristic of this habitat are shown in fig. 3.

Many wild mammals are active principally at night; hence,
most people are unaware of their presence and unfamiliar with
the places in which they live. The comparatively large noc-
turnal mammals—as raccoons and opossums—are occasionally
encountered by day, but the more abundant, small nocturnal
forms such as shrews and mice are seldom seen. Most squirrels
are active and above ground during the day and for this reason
are seen more often than most other wild mammals. Fox squir-
rels in the woods are obvious during the daytime as they hunt
among leaves on the ground; but flying squirrels, which may be
just as numerous, are seldom seen because normally they sleep
all day. Shrews, voles, and other mice are easily overlooked be-
cause they spend much of their lives in their burrows and nest
chambers.

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Red fox Little brown bat

Skunk
Cottontail Woodchuck
Pocket gopher mound
Thirteen-lined ground squirrel
Least shrew Prairie vole
Pocket gopher Storage chamber of prairie vole

Deer mouse

Fig. 2—Characteristic mammals of Illinois fields and fencerows.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS =

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(Cg¥
(ay. vy s
Pal MOY,
wey 3B e

Golden mouse and nest Raccoon Bobcat
Mink Muskrat and lodge
Cotton mouse Swamp rabbit droppings on log

: Sw: abbi
Rice rat wamp rabbit

Fig. 3.—Characteristic mammals of Illinois swamps and stream
margins.

6 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Geographical Distribution.—Each species of mammal is able
to exist only in certain types of habitat and under certain cli-
matic conditions. The area in which a species exists is called its
range or distribution pattern. The range for each species may
change as the habitat or other conditions change.

Enough collecting has been done to provide a knowledge of
the approximate range of each species of Illinois mammal, but
for many species the details of distribution are not well under-
stood. A knowledge of the range of the species is valuable in
giving clues concerning climatic or habitat conditions which
control its distribution.

The study of the geographic distribution of mammals is ex-
tremely interesting, and amateur collectors have a real oppor-
tunity to make worth-while contributions to this study. The
value of their contributions, however, depends on the care and
accuracy with which they collect, preserve, and label their
material. Instructions for the collector are given in this book,
and a general knowledge of the ranges of North American
mamuiunals can be gleaned from such standard mammalogy books
as A Field Guide to the Mammals by Burt (1952) or The
Mammal Guide by Palmer (1954). The collector can check
his records against the maps and accounts of distribution in
these books as well as in the following pages to see if he has
records of interest.

Species State-Wide in Occurrence.—Of the 59 species of
wild mammals in Illinois, 36 occur throughout the state or in
localities scattered throughout the state. These 36 species in-
clude some whose ranges center in Illinois and others whose
ranges center to the north, south, east, or west of this state.
Species such as the cottontail and the house mouse are abundant
and of state-wide distribution in Illinois; others such as the
white-tailed deer and the beaver are also state-wide in distribu-
tion but are comparatively rare and sporadic in their occurrence.

The distribution pattern and abundance of the various spe-
cies of mammals reflect the occurrence, extent, and quality of
habitats suitable for their existence. For example, chipmunks
occur in many localities in Illinois but are confined to wooded,
ungrazed hills and ravines. Moles are generally distributed in
Illinois but, as they require well-drained soils, few of them are
found in the marsh and bog areas of the extreme northern part
of the state.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 7

Species Not State-Wide in Occurrence.—l our kinds of
mammals—the masked shrew, pigmy shrew, least weasel, and
meadow vole—are essentially northern animals and seem to be
limited in Illinois to localities within the northern half of the
state. The red squirrel, which may still occur in Illinois, al-
though it is not listed among the species known to be in this
state, is also a typically northern mammal and, if present, would
be expected only near the northern border.

Ten species of Illinois mammals are primarily southern in
distribution. Six of them—the southeastern bat, big-eared bat,
golden mouse, cotton mouse, rice rat, and weod rat—occur in
the southern fourth of the state. Two of them—the gray bat
and the swamp rabbit—occur a little farther northward, and
two others—the evening bat and the eastern pipistrel—occur
over most of Illinois.

Six Illinois species are predominantly western in distribution.
If only the Illinois distribution of these mammals were consid-
ered, they might be regarded as northern animals. However,
these animals are prairie or plains species and follow the west-
ern prairie habitats which extend eastward across the northern
half of Illinois. Three species—the badger, the thirteen-lined
ground squirrel, and the Franklin’s ground squirrel—occur in
Illinois in only the northern half, but two species—the western
harvest mouse and the white-tailed jackrabbit—are restricted
in this state to the northwestern corner. The sixth western
species—the plains pocket gopher—is unique among Illinois
mammals in that the remnant colony in the state is now geo-
graphically isolated and is distinct in color from its closest rela-
tives. This colony occurs in a few counties of Illinois and ad-
jacent counties of Indiana, in an area bounded on the north by
the Illinois and Kankakee rivers.

For several species of mammals our knowledge of their total
range or their range in Illinois is scant. One of these species is
the introduced roof rat, which is common in the South but which
in the North is found sporadically in only a few areas, usually
in cities. Another species, the Indiana bat, is known from a
very few scattered localities, and until more records become
available we will have no clear picture of its range. The south-
eastern shrew also has a poorly known distribution; it is re-
corded from southeastern United States and from a few locali-
ties in Illinois and Indiana.

8 "LLINOIS NATURAL HISTORY SURVEY MANUAL 4

HOW TO STUDY MAMMALS

Mammals may be studied alive or as preserved specimens.

Studying Live Mammals.—Live mammals may be studied
(1) directly, in the field or in captivity, and (2) indirectly, by
means of their signs—homes, trails or runways, tracks, drop-
pings, and food fragments or remains. Both types of observa-
tions are of importance in contributing to an understanding of
the habits of the animals.

To study mammals in their normal activities in the field, one
must approach them slowly and inconspicuously, remain hidden
in a spot to which they come, or attract them by artifice. One
can sometimes attract mammals by placing baits at strategic
spots or by making imitative calls. For example, an appropriate
squeaking sound will sometimes bring an inquisitive chipmunk
within range for easy observation. At night one can follow the
activity of some mammals in the beam of a flashlight or in the
light of a gasoline lantern.

One good method of studying small mammals and their life
histories is as follows: Select a plot of grass or woodland
which mammals are present and mark it into quadrats; make
a record on cross-section paper of the runways, nests, and feed-
ing stations as they occur in each quadrat; keep notes on the
number of individuals living on the plot, time of activity, pres-
ence and development of young in the nests, and any other items
you may notice. Ground squirrels, chipmunks, and voles are par-
ticularly amenable to such observation.

Another method of studying mammals is to observe them in
captivity. Care should be taken to provide quarters that are
suitable for the animals and for ease of observation. For some
of the shy and nocturnal mammals this type of study may be
one of the most efficient ways of obtaining accurate information
on breeding, rearing of young, food preferences, and behavior
characteristics. The animals can be caught in live traps, of
which there are many kinds to be purchased or made, set near
runways or nesting sites. Mice or shrews may be trapped
in a gallon can or other steep-sided container that has been sunk
in the ground flush with a runway. Some mammals that live
under logs or other objects on the ground can be captured by

raising the objects and seizing the animals before they dash
away.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 9

The number of wild mammals that can be observed in an
area may be increased by improving the habitat for them.
Where there is a scarcity of suitable places for nesting and
hiding, and little available food, the mammalian population is
very low. In agricultural areas, cultivation may be so intensive
that few places are left that are suitable for mammals. Some-
times a few changes in these situations will increase the number
of mammals which can live there. In a wood lot having few
hollow trees, the addition of some nest boxes fastened in the
trees may provide homes for raccoons, squirrels, and opossums.
A fence of multiflora roses should provide sanctuary for cotton-
tails and mice. A ditchbank on which grass and other vegetation
are allowed to flourish will produce many more muskrats than
one that is grazed, mowed, or denuded. The removal of brush
and rotting logs from a wood lot destroys the habitat of mice
and squirrels and, indirectly, of other animals that feed on these
small mammals.

Making a Collection of Preserved Specimens.—If one
wishes to make a survey of the mammals occurring in an area,
he should collect and prepare specimens of at least the small
animals so that they may be identified accurately. Securing
specimens of the various species is usually accomplished by hunt-
ing or trapping. Snap-traps are best for trapping small animals.
Some specimens can be found in steep-sided excavations such as
dry cisterns, window wells, post holes, and deep ditches into
which they have fallen. Often, revisits to such places are profit-
able because animals of different species may fall in at different
times. Mammals as large as or larger than rats may be shot or
trapped. Because most of them are protected by law, special
permission must be obtained unless they are collected only dur-
ing the hunting season, when they may be taken under an ordi-
nary hunting or trapping license. Highways may yield some
specimens that have been killed, but not badly mutilated, by
cars.

A specimen that is small may be prepared for a study collec-
tion in one of the following ways. If only the skeleton is de-
sired, the animal is skinned, eviscerated, and dried; later it may
be cleaned by a culture of dermestid beetles. If for special rea-
sons preservation of the whole animal is desired, it can be kept
in 10 to 15 per cent formalin in a glass jar. Newly born young
are often preserved in this manner. The recommended method

10 IX LINOIS NATURAL HISTORY SURVEY MANUAL 4

parva

Sic ly ay (956

& ry tots

424 svba14>0 STL Ny ,
AAMAAG AWOLHEL IWarrivs

SAMO MMM, WR

Fig. 4.—Study skins: left to right, top row, least shrew, short-
tailed shrew; bottom row, western harvest mouse, pine vole, prairie

vole.

HOFFMEISTER &G MOHR: ILLINOIS MAMMALS 1]

of keeping most specimens for scientific study is as dry skins,
fig. 4, and skulls. After a little practice, such skins can be pre-
pared by a simple type of taxidermy. The following suggestions
give some idea of the steps involved in making a collection of
study skins of small mammals.

1. Assign each specimen a collection number; use this same
number for the skin, the skull, and any field notes or other data
that may have been recorded for the animal.

2. Record in a catalog or notebook the full collecting data
(precise locality, date, habitat, collector) and any additional
notes you may wish to make.

3. Determine the sex and take the measurements of the ani-
mal before starting to prepare it for a study skin or skeleton
and record them in the catalog or notebook; also write them on
a tag (see step 6 below). Usually the measurements taken are
over-all or total length, length of tail, length of a hind foot, and
length of an ear. The head-and-body length is usually not in-
cluded in the standard measurements that are written on the
tag in the following sequence: total, tail, hind foot, ear. The
weight of the animal also is sometimes recorded on the tag.

The over-all or total length is the distance from the tip ot
the nose to the tip of the tail, not including the hair at the end
of the tail. Tail length is the length of this appendage, exclusive
of hair at the tip, when it is at a right angle to the body axis.
Hind foot length is the distance from the back of the heel to the
tip of the longest claw of a hind foot; only one foot is meas-
ured. Ear length is the distance from the notch of an ear to the
tip of the pinna or projecting part of the ear; the length of any
tuft or other hair is not included. Usually and preferably, meas-
urements are given in the metric system and in millimeters. One
inch is roughly equal to 25 (25.4) millimeters (written mm.)
and 1 foot is equal to 305 millimeters.

4. Prepare the study skin. Make an incision down the venter
of the mammal from the mid-thoracic region to a point be-
tween the hind legs; then skin out the body, legs (to the knee or
elbow joints or below), and head. Remove the tail bone from the
sheath of skin covering it, much as you would slip an ice pick
from its leather holder. Carefully clean fat and grease from
the inside of the skin so as to prevent future staining and corro-
sion of the hair side. Fill the skin with a carefully fashioned, firm
cylinder of cotton batting designed to approximate original con-

12 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

tours of the animal. Before inserting the cylinder of cotton
batting, shape the front end of it into a cone somewhat like the
configuration of the head. Place rustless, annealed or tinned wire,
partly covered with cotton, in the skin to replace or supplement
bones of the tail and the legs and feet. Then sew up the skin
along the original incision, pin the specimen in the desired posi-
tion to a sheet of cork or corrugated cardboard, and allow it
to dry.

5. Save and clean the skull. Attach to it a tag bearing the
same number as that given to the skin, so that the two can al-
ways be associated.

6. To the completed skin, attach a label giving the collector’s
name and the collection number, the precise collecting place,
date, sex, and standard measurements of the specimen; allow a
space for filling in the name of the species when the specimen
has been identified.

A specimen that is large may be prepared either in approxi-
mately the same manner as a small one or as a cased or flat
skin. An incision is made along each back leg from the base of
the toes to the anus; then the pelt is peeled forward over the
body—that is, it is cased. All bits of fat and flesh should be re-
moved. The pelt is then fitted over a board or frame that
is rounded at the front end; it is then allowed to dry. A
thoroughly cleaned and dried pelt will keep for months if stored
in a cool place, but tanning is required for long-time keeping
qualities and to reveal the beauty of a good pelt. A flat skin is
prepared in the same way as a cased skin except that additional
incisions are made from the anus to the mouth and from the
base of the toes on one front leg, across the chest to the base
of the toes on the other front leg so that the skin can be pinned
out flat to dry. A pelt that is to be tanned should be pinned
with the fur side next to the drying board to allow for rapid
drying.

There are many details and precautions to be taken in meas-
uring and putting up mammal skins. The University of Illinois
Museum of Natural History has available a motion picture
showing how to prepare specimens. The following books de-
scribe the skinning and stuffing techniques: Methods of Collect-
ing and Preserving Vertebrate Animals, by R. M. Anderson,
1948, Bulletin 69, National Museum of Canada; Handbook of
Mammals of Kansas, by E. R. Hall, 1955, Miscellaneous Pub-

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 13

lication 7, University of Kansas Museum of Natural History;
and A Field Collector's Manual in Natural History, 1944,
Publication 3766, Smithsonian Institution, Washington, D. C.
The beginning collector should study these books carefully.

SIGNS

The study of mammal signs is one of the most interesting
pursuits available to a hiker. By practice in developing an eye
for details, the most observant hunters, trappers, and naturalists
are usually highly skilled in reading signs. The occasional hiker
can train himself to discern and interpret signs and thus add
considerable interest to his field trips.

Most mammal signs fall into one of these six classes: homes,
trails and runways, tracks, scats or droppings, tooth marks, and
food stores and fragments. The interpretation of these signs is
a type of detective work, and it is largely a process of elim-
ination combined with a general knowledge of the mammals
occurring in the region. Several factors, such as the kind of sign,
size and form of the sign, ranges of mammals which could have
made such a sign, type of habitat, and season of the year, must
be considered in each case. For example, suppose the sign con-
sists of a set of small tracks in a snow-covered field adjacent to
a tree-lined ditch in southern Illinois. The size of the tracks
hint that the mammal is smaller than a cat but larger than a
rat, thus eliminating many species. The fact that ground squir-
rels, pocket gophers, and red squirrels do not occur in southern
Illinois removes them from consideration. The habitat suggests
that the animal is a forest-edge species, a prairie animal, or
even an aquatic species, but probably not an inhabitant of deep
woods, such as is the gray squirrel. The snow on the ground
precludes the possibility of a woodchuck, because this animal
would be in hibernation. The list of possible mammals still in-
cludes the fox squirrel, muskrat, mink, weasel, and cottontail.
A close scrutiny of the tracks reveals that the toe marks are long
and slender, thus ruling out the cottontail, weasel, and mink, but
leaving the fox squirrel and the muskrat. The tracks can be
compared with sketches of muskrat and fox squirrel tracks, figs.
21 and 34; these sketches indicate that the muskrat is likely to
leave some trace of a tail mark. If a tail mark is present, it is
likely that the tracks were made by a muskrat.

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Fig. 5.—Entrance to burrow of woodchuck.

HOFFMEISTER G&G MOHR: ILLINOIS MAMMALS

Fig. 6.—Signs of eastern mole: top, runway; bottom, mound,

16 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

This hypothetical case illustrates the type of reasoning that
may be employed in identifying signs. In many cases the list of
suspected mammals can be reduced to a few kinds but not to one
specific mammal. If a combination of signs is available, such as
homes and tracks or runways and food fragments, there is a
good chance for specific diagnosis. In some cases, signs can be
attributed to a specific animal with certainty. Indirect clues,
such as range, habitat, and season, are valid only if based on an
excellent knowledge of the animals likely to be present.

Homes.—The homes of I]linois mammals fall into two chiet
categories: burrows, or homes in the ground, and homes on or
above the ground.

Some kinds of Illinois mammals are adaptable in habits, living
either in burrows or in homes above ground; a few kinds may
inhabit a variety of types of homes. Most species, however,
show a decided preference for particular types of homes.

Burrows—Mammals inhabiting burrows include those that
dig their own burrows and those that use burrows made by other
kinds of mammals. The size of the entrance, size and depth
of the nest below ground, and appearance of the burrow are
indicative of the kind of mammal living in a burrow.

Burrows can be classified, according to size, as follows:

1. Diameter less than 2 inches——Characteristic of about a
dozen species of mice and voles, the shrews, and small rice rats.

2. Diameter 2 to 4 inches.—Characteristic of ground squir-
rels, gophers, chipmunks, moles, and barn rats.

3. Diameter more than 4 inches—Used by large mammals
such as woodchucks, fig. 5, badgers, skunks, opossums, raccoons,
otters, and coyotes.

Weasels and minks commonly take over homes of other spe-
cies. A small weasel may appropriate a mouse nest and a mink
may occupy a woodchuck den.

The size of the burrow may indicate the size of the mammal.
The location of the burrow, the manner in which excess dirt is
deposited, or other signs at the den site may furnish additional
identifying marks. A large hole with a muddy slide nearby may
belong to an otter, a large one with feathers and rabbit remains
may be the den of a fox, and one with a musky odor may be
the home of a skunk or badger.

Among the medium-sized burrows and soil dumps the follow-
ing are distinctive:

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 17

1. A steep mound of earth, usually circular and conical,
thrust upward from the center and associated with one or more
subsurface runs which hump up the ground and are readily
visible, fig. 6, is typical of the work of moles.

Fig. 8.—Entrance to burrow of Norway rat.

18 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Fig. 9.—Arboreal nest of eastern fox squirrel.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 19

2. A more irregular mound, fig. 7, lacking the visible indi-
cation of subsurface runs and the symmetry of the mole mound,
is typical of pocket gophers. This is usually a rough crescent
with a small pustule midway between the tips of the crescent.

3. A hole with a mound of earth to one side and trash scat-
tered about, fig. 8, is typical of Norway rats.

4. A hole in a grassy area with a flat bare area to one side is
typical of thirteen-lined ground squirrels.

There are, of course, many variations from the typical bur-
rows described above.

Homes Above Ground—Many species of mammals make
grassy or leafy nests on the ground or in shrubs or trees. Mam-
mal nests are almost invariably roofed over, not open as many
birds’ nests are, and they do not have the nest materials plastered
together with mud or secretions. However, certain mammals
reconstruct birds’ nests for their own homes. For this reason
the only sure way to ascertain the inhabitant of a covered nest
is to see the inhabitant as it enters or leaves the nest or to ex-
amine the nest for the presence of eggs, young, or an adult.

Mammal homes above ground may be divided conveniently
into three categories: arboreal, hidden terrestrial, and aquatic.

Arboreal nests include those made in trees, in bushes, or in
tufts of herbaceous plants. Several distinctive types may be
found, as follows:

1. Nests made in hollows of trees. These may be utilized as
home sites by raccoons, opossums, fox squirrels, or gray squir-
rels, flying squirrels, bats, white-footed mice, and even gray foxes
or bobcats.

2. Large exposed nests high in trees. These may be the homes
of tree squirrels, fig. 9; if deserted by the original owners, they
may be occupied by raccoons, bats, or sometimes flying squirrels.
At a distance these nests look like crows’ nests but they may be
distinguished by being completely roofed over and usually being
composed of leaves rather than of sticks and leaves.

3. Smaller nests in bushes or herbaceous plants near the
ground. These nests are made chiefly of dry grass or of plant
“down.” Many smali mammals have nests of this type. These
nests may be entirely the work of the mammals occupying them
or they may be reconstructed birds’ nests. Such homes are
characteristic of golden mice, fig. 91, cotton mice, white-footed
mice, and rice rats.

20 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Hidden terrestrial homes are those made in brush piles or
rock crevices, or beneath logs or other objects. Many species of
mammals make homes of this type.

Skunks occasionally make homes under the flooring of old
buildings. Several species of rats, mice, and shrews construct
nests under logs, and opossums and gray foxes sometimes make
their homes inside hollow logs. Rabbits and long-tailed weasels
often make homes in brush piles. Hares hollow out pockets in

Form of white-tailed jackrabbit.

Fig. 10.

the ground, called forms, fig. 10, each just deep enough to par-
tially conceal the animal occupying it.

Wood rats, white-footed mice, chipmunks, gray foxes, rac-
coons, and bobcats frequently make nests or dens in fissures and
crevices of rock bluffs.

Aquatic homes are those built in and above the water of
marshes, ponds, and streams. Muskrats and beavers make
lodges, fig. 11, and burrows, fig. 12. If these homes are aban-
doned by the animals making them, they may be taken over by
minks.

High Trails, Runways, and Slides.—A few Illinois mam-
mals make trails that are conspicuous and characteristic of the
animals making them. Foxes, coyotes, and woodchucks occasion-

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 21

ally beat trails through dense vegetation, fig. 13, especially in
the vicinity of their burrows. Voles make distinctive trails
through grass; these trails frequently are exposed by grass fires
in spring, fig. 14. Muskrats and minks in swimming through

Fig. 11—Top, lodge of muskrat; bottom, lodge of beaver.

duckweed beds leave open-water trails which generally are
longer than those left by fish feeding at the surface. Most mam-
mals, however, use trails common to several species, or use ave-
nues of travel not recognizable as definite trails. For example,
a stream edge may exhibit many tracks of raccoons, opossums,
and minks, indicating a great deal of night trafic but no well-
defined land trail. A forest edge may serve as an avenue ot
travel by many species, although it may have no signs to identity

it as a trail.

Z2 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Recognizable trails may be classified as high trails, runways,
or slides. There are often no sharp distinctions between these
three types, and some trails are difficult to assign to any one type.

High trails are open paths, usually without canopies of grasses
or bushes, and they usually belong to relatively large animals.
Bison trails and deer paths are of this type and formerly were
common in the Illinois area. Present-day mammals making high
trails are red foxes, fig. 13, rabbits, woodchucks, and coyotes.

Fig. 12—Burrow and runways of muskrat.

Runways are tunnels or small trails that often are so low
that the grass must be parted or the debris scraped away it
they are to be discerned by human beings. Although they are
not often seen, runways are abundant in both wooded and grassy
areas. They may be classified as those that are on the surface
of the ground, fig. 14, and those that are just under the sur-
face. Many runways that appear to begin on the surface dis-
appear below the surface and then reappear, forming a compli-
cated maze. Surface runways are much the same for a dozen
or more kinds of shrews, voles, and other mice, but the habitat
may provide clues for identifying the species that use them. For
example, runways in the debris of a forest floor are usually

HOFFMEISTER & MOHR: ILLINOIS MAMMALS

Fig. 13.—High trail of red fox.

24 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

those of pine mice, shrews, or white-footed mice. Similar run-
ways in a meadow or pasture are more likely to be those of
voles, bog lemmings, or deer mice. Other signs such as scats or

Fig. 14—Top, mound, and, bottom, surface runways of prairie
vole. Normally these are hidden in the grass but in the cases
shown here the grass has been burned away; the mound and the
maze of runways that lead to holes opening into a complex under-
ground system of burrows are exposed.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 25

food fragments may be available to aid in eliminating some
species from consideration.

Slides are worn troughs on muddy stream banks where otters,
minks, or muskrats have slid into the water.

Tracks.—Tracks are among the most reliable signs for iden-
tifying mammals, but their characteristics must be memorized or
the tracks compared directly to sketches of known kinds of
tracks. Tracks of many mammals native to Illinois are illus-
trated in the accompanying plates. With a little practice in
identifying tracks, a person can learn to recognize many of
these at a glance.

Kinds of Tracks—vVThe kind of track a mammal makes de-
pends upon whether it is walking, trotting, or running. Tracks
made by an animal when running have individual footprints far-
ther apart than those made by the same animal when walking,
and often the footprints are arranged in a different pattern.

In mud, moist sand, or snow, 2 mammal may make excellent
imprints of its feet and sometimes belly or tail. When made in
thick mud, the prints of the toes are usually spread more widely
than when made in a layer of thin mud. If distinctly made
tracks are found in Illinois, they may be identified through use
of the following key.

Key to Tracks of Some Common Illinois Mammals

1. Footprint consisting of one or a pair of solid impressions,

Ss 2 RN SS a ee ne 2
Footprint consisting of three or more toe marks, figs. 17-30 6
® Each footprint less than 114 inches wide................+- 3
Each footprint more than 114 inches wide................ 4

3. Each set of 4 footprints with a pair tandem and a pair side
by side, or almost side by side, fig. 16............. rabbits

Each set of 4 footprints arranged otherwise...............
mn Pte Fe 02 Si 2 ols aes imperfect tracks of small mammals

4. Each footprint a single subcircular mark................ horse
Each footprint consisting of a pair of marks, fig. 15....... 5
mo auaeh footprint 3 inches Or more across. ....:.....<-.-.---. cow

Each footprint less than 3 inches across, fig. 15............
Oo NG ae Re al eed deer, goat, sheep, pig, calf

6. Imprint of first and of fifth toe of front foot at almost 180-

degree angle, fig. 17; axis of imprint of big toe of hind

foot well separated from and at an angle of at least 90
degrees to axis of imprint of next toe............. opossum

Imprint of inner and of outer toe of front foot at less than

120-degree angle, figs. 18-36; imprint of inner and of
outer toe of hind foot at less than 90-degree angle a 7

26 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

7. Each set of 4 footprints with a pair tandem and a pair side

by side or almost side by side, fig. 16............... rabbits
Each set of 4 footprints usually arranged otherwise. ..... 8
8. Claw marks absent or continuous with the marks made by
the toepads, figs. 18, 21.:.0...2..2.002 eee 9
Claw marks usually apparent and separate from marks
made by the toepads, figs. 24, 29. ... 13. 5. see 10

9. Print of hind foot with 4 toe marks, figs. 18, 25..........
Dek op te UN ig POR ee Oe DI oan ot tore ae weasels, mink, cats

Print of hind foot with 5 toe marks, figs. 20-23............
PRE ae eet) SOL nT ee raccoon, muskrat, rats, river otter

10. Print of hind foot with 4 toe marks, figs. 24, 26, 27........
Son Biases Se eu, Ron. oka tae See ei dog, coyote, foxes

Print of hind foot with 5 toe marks. ....>7.45.,)s50=eeeeee 11
11. Footprints showing webbing between toes, fig. 28...... beaver
Footprints not showing webbing, fig. 29................... 12

12. Prints of front and hind feet rounded, figs. 29-33..........
Rie a ee eke pee woodchuck, mice, voles, shrews
Print of hind foot elongate, figs. 20, 22..)-0 2.2) 13
13. Rounded print of front foot with 4 toe marks, figs. 22, 34..
Ris rer PAO te encarta squirrels, rats, mice
Rounded print of front foot with 5 toe marks, figs. 20, 35, 36 -
EL eR eee ee Pee em A PM raccoon, skunk, badger

Preserving Tracks.——Tracks can be preserved for study ir
four ways. The simplest way is to photograph imprints in snow
or mud and make a collection of pictures of the different types.
A second way is to sketch the imprints and keep the sketches in
a notebook or card file. A third way, which is interesting but
somewhat more laborious, is to make plaster facsimiles. This
may be done by pouring plaster of Paris mixed with water into
and around the tracks and allowing it to harden; then remov-
ing the plaster cast, brushing it clean, greasing it, and pressing
it into a plate of freshly mixed plaster, thus duplicating the
original impressions. A fourth way, similar to the third, can be
used for tracks in mud by letting tallow from a burning candle
drip into the imprints. When the tallow solidifies, it can be
lifted up, cleaned, and stored, or used to make a plaster cast.

Scats or Droppings.—The study of scats or droppings (sca-
tology) is often helpful in providing clues to the identity of the
mammals frequenting an area and also in determining the food
habits of these mammals. As in the case of tracks, some scats
are easily recognized, others have characteristics which seem to
defy adequate description but can be learned by observation, and
some cannot be identified with certainty even by experts.

28 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

ff hah

%, A : ol hy, 6
II

“a ji * Ne

: ibs

ao
b nil
im,

; | VW
ry ° ‘ |
“aN ab ¥ f\ | N /

ih
if

R hy r j

f ,

;

"()

ih i h

30 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Wir ag
thine

1, rr Cd . \ pl te iy |
25 MINK 3 al’ | “° Le
: xh he A

sibs 4 it:

NWO b

AN

27 GRAY FOX

28 BEAVER _ 29 WOODCHUCK

Figs. 25-29.—Signs of Illinois mammals: a, print of front foot;
b, print of hind foot; c, bounding pattern; d, walking pattern;
e, tooth marks on branch,

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 3]

" 9\¢

32
31 DEER MOUSE HOUSE MOUSE

oe
(ly iy my Y amy

Wi?

alt, ss
Ob i

34 FOX SQUIRREL

Figs. 30-34.—Signs of Illinois mammals: a, print of front foot;
b, print of hind foot; c, bounding pattern; cc, hop and stop pat-
tern; d, walking pattern; ¢, droppings; f, food fragments.

SZ ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

i
a an

| af
ae: *;| e

0
J ¥% . ¥ a0,

((

ts r)
Fide bath ae Ih

* tye “a i ("

it

4

\ ; 9 | 24, , ( ° a

‘ wee,

“lly, : d

35 STRIPED
SKUNK

36 BADGER

Figs. 35-36.—Signs of Illinois mammals: a, print of front foot;
aa, claw marks of front foot on hard surface; b, print of hind
foot; c, bounding pattern; d, walking pattern.

Scats of carnivores and opossunis are cylindrical objects which
contain mats of hair, feathers, sometimes teeth or bone frag-
ments of vertebrates, and parts of insects. Those of omniv-
orous mammals often contain seeds of fruits mixed with the
animal remains. Scats of most herbivores are small pellet-like
or oval objects, usually present in considerable numbers. Often
the place of deposition of scats is an important distinguishing
characteristic; for example, scats of the swamp rabbit are in
appearance practically indistinguishable from those of the cot-
tontail, but the swamp rabbit has a habit of leaving droppings
on logs or mounds, whereas the cottontail leaves droppings on
level ground.

Tooth Marks.—In obtaining food or in constructing run-
ways or homes, certain mammals leave distinguishing tooth
marks or signs of gnawing. Rabbits and voles commonly, musk-

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 33

rats and other mammals occasionally, gnaw and eat the bark
of trees, fig. 37. Rats and mice gnaw woodwork in buildings,
fig. 100, food packages, and other materials in constructing run-

“I

Ty ~

Fig. 37—Winter damage to fruit tree by rabbits and_ voles.
The damage to the branches is by rabbits, that to the lower part of
the trunk by voles.

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Fig. 38.—Feeding platform of muskrat. The rice rat makes a
feeding platform that is smaller and of finer vegetation.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 35

Ways or nests or in feeding. Beavers, in their feeding, leave
marks of their teeth on branches, fig. 28e, and, in their home
building, fell and cut up trees, even large ones.

Food Signs.—Food caches, partially eaten food, certain un-
palatable objects, and discarded fragments of food items may
furnish clues to the mammals associated with them. Food frag-
ments may be either animal remains or plant remains.

Animal Remains.—Wings of flies and moths on the floor of a
building or cave, or within a hollow tree, are excellent signs of
bats. Insect remains mixed with snail shells in a ground nest
usually mean the presence of shrews. A shallow hole with frag-
ments of turtle eggs scattered about usually means that a skunk
or a raccoon has had a feast there. Bird feathers around a hole
in a bank suggest the presence of a mink or weasel, and bird
feathers and rabbit remains around a large hole in an upland
situation indicate the presence of a fox or coyote.

Vegetable Remains—Bundles of cut grasses on the open
ground, each section 2 to 3 inches long, indicate that a jumping
mouse lives nearby. If the sections are shorter, fig. 30, and in a
runway, they suggest the work of voles, or their relatives the
bog lemmings or pine mice. In a rock crevice, a cache of nuts
and seeds with such inedible objects as paper and corncobs hints
of the presence of a wood rat; in or near human habitations,
these signs suggest the activity of a Norway rat or a house
mouse. Platforms, fig. 38, of freshly cut grass, cattails, or
rushes in shallow water indicate the feeding site of a rice rat or
a muskrat. A cache of nuts and seeds in a rock crevice may
belong to a chipmunk or white-footed mouse; the same type ot
sign, with possibly an ear of corn in addition, in a hollow tree
or building suggests food of squirrels; and a pile of nuts and
seeds in a ground nest probably belongs to a deer mouse. A
similar nest containing roots might be that of a meadow vole.
In an orchard, a runway leading up to a gnawed apple on the
ground indicates the work of a pine mouse. The combination ot
cut-down trees, sectioned twigs, and wide tooth marks in bark
can mean only the work of a beaver.

SYNOPSIS OF ILLINOIS MAMMALS

This section of the Fieldbook furnishes the hiker and nat-
uralist with a concise account of the native and naturalized

36 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

mammals of Illinois. Keys are provided to aid in identifying the
animals, descriptions are given as a means of checking the re-
sults obtained by use of the keys, and brief statements on the
natural history and distribution are added to assist the user of
this book in learning about the mammals.

To make identification of a specimen accurate and yet as easy
as possible, each key is divided into two parts. The first part
employs only external characters, including the teeth, which may
be examined as they are situated in the head, and should be used
for identifying the whole specimen or a study skin with a skull.

The second part of each key is based entirely on skull and
tooth characters. This part can be used for identifying skulls
or incomplete specimens found in the field, in stomach contents
of animals, or in owl pellets.

The scientific name of the species precedes the account of
each kind of Illinois mammal discussed in the Fieldbook. This
scientific name includes two words, first the name of the genus
to which the species belongs and second the name of the species;
these names are followed by the name of the man who first de-
scribed the animal. The name of the describer is in parentheses
if the animal is not now assigned to the genus in which it was
first placed. Below the scientific name is at least one common
name. When two or more common names are given, the name
on the left side of the page is the one preferred by the authors
of this Fieldbook. Each complete account is divided into the
following sections: description, life history, signs, and distribu-
tion. The description is a summary of the diagnostic characters
of the species, including such features as size, color, and dental
formula. The life history section includes information on the
life cycle, habits, and habitat. The section on signs outlines
characteristic identifying features such as nests, scats, food re-
mains, and runways. The section on distribution notes the abun-
dance of the species, its known range in Illinois, the subspecies
known to occur in the state, and a brief statement of the known
range of the species in North America.

At the end of the accounts of the mammals known to occur
in Illinois during historic times, there is a section dealing with
species of prehistoric times. Following this are a glossary of
terms used in the keys and text and a list of books on mammals.

How to Use the Keys.—In this Fieldbook, a key to the
orders of Illinois mammals is given, page 41, and, under each

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 37

order, a key to the Illinois species of that order. The key to the
orders is intended to help you decide which of the keys to the
species to use in identifying a specimen.

The keys are made up of pairs of contrasting statements (in
abbreviated form) known as key couplets, each couplet pre-
ceded by a numeral. In using a key, start at the beginning, read
the two contrasting statements of the first couplet, and decide
which of the statements best fits the specimen you are trying to
identify. What you find at the end of the statement selected will
give you a clue as to your next step. If a number is at the end
of the statement, follow down the key to the couplet having
that number. Repeat the selection process until you have come
to a statement having a name at the end of it: the name of an
order in the key to the orders and the name of a species in the
key to the species.

Some of the couplets contain references to illustrations that
will aid you in the identification of your specimen.

If you do not understand terms used in the keys, turn to the
glossary for definitions.

Occasionally a specimen will key out readily but be misiden-
tified because a statement in the key has been misinterpreted
or because the specimen is abnormal in one or more characters.
It is well, therefore, to check your identification by comparing
your specimen with the description of the species and the picture
of the mammal. It is frequently helpful to consult descriptions
of closely related or similar species to gain a knowledge of some
of the comparative characters used as a basis for diagnosis.
Sometimes the ranges of the species under consideration may
help you to decide. If, after following these steps, there is un-
certainty as to the identity of a specimen, it should be compared
with identified specimens in a reference collection, such as that
maintained by the Illinois Natural History Survey, the Uni-
versity of Illinois Natural History Museum, or the Chicago
Natural History Museum, or sent to a trained specialist for
identification.

Professional mammalogists are usually glad to determine
dificult-to-identify specimens sent to them by collectors if the
specimens are reasonably well preserved and well packed for
shipment, and if accurate locality data accompany them.

Class Mammalia.—Mammals belong to a large group of
animals called the Vertebrata, characterized by having in each

38 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

adult a backbone or a segmented spinal column. The most prim-
itive vertebrates, which include some eel-like forms and the
fishes, live in water. Many of the more highly specialized forms
of vertebrates, at least in the adult stage, have four feet or
limbs instead of fins. Some of the familiar groups of Vertebrata,
called classes, are as follows:

Class CHONDRICHTHY ES—sharklike fishes

Class OSTEICHTHYES—bony fishes

Class AMPHIBIA—salamanders and frogs

Class REPTILIA—turtles, lizards, crocodiles, and snakes

Class AVES—birds

Class MAMMALIA—mammals

The Mammalia comprise three groups very different in struc-
ture and habits: One group, the egg-laying mammals or Mono-
tremata, is confined to the Australasian Region. The second
group, the pouched mammals or Marsupialia, is primarily Aus-
tralian and South American in distribution but is represented
in Illinois by a single species, the opossum. The third group,
the placental mammals or Eutheria, is the dominant mammal
group in most parts of the world and to it belong all the species
of the Illinois fauna except the opossum.

Members of the class Mammalia are not only abundant but
are also of many different kinds, such as bats, mice, deer, wolves,
elephants, and whales. The most closely related kinds are
grouped together into families, and related families are grouped
together into orders. The 59 species of wild mammals known
to occur in Illinois represent 7 orders and 16 families. Some
well-known orders not found in Illinois include the whales and
porpoises (order Cetacea), which occur only in the ocean; the
sloths and armadillos (order Edentata), which occur in the
American tropics and as far north as Kansas; and the manatees
and sea cows (order Sirenia), which occur in seas and estuaries
in Florida and many other parts of the world.

Checklist of Present Native and Naturalized Mammals
of Illinois

Order MARSUPIALIA

Family DipELPHIDAE—opossums
Didelphis marsupialis Opossum

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 39

Order INSECTIVORA

Family TALPeIpDAE—moles
Scalopus aquaticus
Family SoritcipbAE—shrews

Sorex cinereus
Sorex longirostris
Microsorex hoyt
Cryptotis parva
Blarina brevicauda

Eastern mole

Masked shrew
Southeastern shrew
Pigmy shrew
Least shrew
Short-tailed shrew

Order CHIROPTERA

Family VESPERTILIONIDAE—bats
Myotis lucifugus
Myotis austroriparius
Myotis grisescens
Myotis keenii
Myotis sodalis
Lasionycteris noctivagans
Pipistrellus subflavus
Eptesicus fuscus
Lasiurus cinereus
Lasiurus borealis
Nycticeius humeralis
Corynorhinus rafinesquii

Little brown bat
Southeastern bat
Gray bat
Keen’s bat
Indiana bat
Silver-haired bat
Eastern pipistrel
Big brown bat
Hoary bat

Red bat
Evening bat
Southeastern big-eared bat

Order CARNIVORA

Family PRocyoNIDAE
Procyon lotor

raccoons

Raccoon

Family M usteLiAE—weasels, skunks, etc.

Mustela rixosa
Mustela frenata
Mustela vison
Lutra canadensis
Mephitis mephitis
Taxidea taxus

Least weasel
Long-tailed weasel
Mink

River otter
Striped skunk
Badger

Family CANmAE—wolves, foxes, etc.

Vulpes fulva
Urocyon cinereoargenteus
Canis latrans
Family FELipAE—cats
Lynx rufus

Red fox
Gray fox
Coyote

Bobcat

40 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Order RODENTIA

Family ScrturtmpAE—squirrels

Marmota monax W oodchuck
Citellus tridecemlineatus Thirteen-lined ground
squirrel

Franklin’s ground squirrel
Eastern chipmunk
Eastern gray squirrel
Eastern fox squirrel
Southern flying squirrel

Citellus franklinit
Tamias striatus
Sciurus carolinensis
Sciurus niger
Glaucomys volans
Family GeomyipAE—pocket gophers
Geomys bursarius

Family CAstoripAE—beavers

Plains pocket gopher

Castor canadensis Beaver
Family CricETIDAE—native mice and rats
Reithrodontomys megalotis Western harvest mouse

Deer mouse
White-footed mouse

Peromyscus maniculatus
Peromyscus leucopus
Peromyscus gossypinus Cotton mouse
Peromyscus nuttalli Golden mouse
Oryzomys palustris Rice rat

Neotoma floridana Eastern wood rat
Synaptomys cooper Southern bog lemming
Microtus pennsylvanicus Meadow vole
Microtus ochrogaster Prairie vole

Pitymys pinetorum Pine vole
Ondatra zibethicus Muskrat
Family Murmar—Old World mice and rats
Rattus rattus Roof rat

Rattus norvegicus
Mus musculus

Family ZAPoDIDAE—jJumping mice

Zapus hudsonius

Norway rat
House mouse

Meadow jumping mouse

Order LAGOMORPHA

Family LepormAE—hares, rabbits

Lepus townsend
Sylvilagus floridanus
Sylvilagus aquaticus

White-tailed jackrabbit
Eastern cottontail
Swamp rabbit

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 4]

Order ARTIODACTYLA

Family CervipAE—deer
Odocoileus virginianus White-tailed deer

KEY TO ORDERS
Whole Animals

i norenmos ip. the form. of wings, fig. 39... 622... sc.ee ens o>
Order CHIROPTERA;; bats

Parcuambsoin thie,torm: of legs ..23. . 5. iss oe ns de ee ne 2
meeveet eacn with lor 2 large, hard hoofs...............-%.. 3
Peeecacn with 4 or 5 clawed toes...) 2.2 ec ea eee 4
Snout x Thumb (Polle>)
a
or ae
'
Ear
1
N
\ Antebroch® é
\ ry mbrane PMC
Ge See ee
' aN
I wR o
l aN fie
G*e
i “ay
l Bod
i 4 » eee
|
I i
\" Loteral membrene
1 & y
hae (8
eh
ING:
i ) pr" }
pane %5
a» <
Interfemor n Foot
membrane =
rd yy Keel
oe =
5&Lobule
7)

Fig. 39.—Detailed outline of wing of bat.

42 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Fig. 40.—Characters referred to in the key to orders: a, hind
foot of opossum; 4, lower jaw of opossum, under side; c, rostrum
of muskrat, side view; d, rostrum of cottontail, side view; e, skull
of bat, top view; f, skull of horse, side view.

HOFFMEISTER & MOHR: ILLINOIS MAMMALS 43

we

~

Feet each with only 1 hoof. .Order PERISSODACTYLA;: horse
Feet each with 2 hoofs
Order ARTIODACTYLA: deer, cattle, ete.
Inner toe of each hind foot thumblike, fig. 40a, widely sep-
arated from the other toes; tail long, nearly naked, pre-
hensile, terminal half white
Order MARSUPIALIA; opossum
Inner toes of hind feet not thumblike; tail haired or naked,
not prehensile, terminal half not white 5
Canine teeth decidedly longer than adjacent teeth, fig. 117
wt. ....Order CARNIVORA;; flesh eaters
Canine teeth either much smaller than incisor teeth or ab-
sent, figs. 40c, d, 41. . Perna 6
Canine teeth small, fig. 41; distance between teeth not
greater than length of a single grinding tooth; eyes and
ears either minute or absent; snout long, figs. 45-49
++ ep aie Order INSECTIVORA;; shrews and moles
Canine teeth absent, fig. 40c, d; gap between incisors and
grinding teeth equal to or greater than length of entire
row of grinding teeth; eyes, and usually ears, conspicu-
ous; snout not greatly elongate.
Tail a cotton-like tuft; a small peglike tooth immediately
behind each large upper incisor, fig. 40d
WAR Spy he Ei Order LAGOMORPHA; rabbits
Tail elongate, not a cotton-like tuft; no peglike teeth im-
mediately behind the upper incisors .
Order RODENTIA; rodents

Skulls

Upper jaw without incisors
Order ARTIODACTYLA (in part); cattle, deer, etc.
Upper jaw with incisors............. RAL eee 2

Fig. 41.—Skull of eastern mole, side view.

44 Order MARSUPIALIA

2. Teeth 50, upper jaw with 26, lower jaw with 24; each pos-
terior angle of lower jaw with an inwardly curving
process, fig. 40h; nasal bones broadened posteriorly.....
| AE, aes Gatos! Order MARSUPIALIA; opossum

Teeth 44 or leSs, never more than 22 in either jaw; each
posterior angle of lower jaw without an inwardly curving
process; nasal bones not broadened posteriorly.......... 3

3. Canine teeth decidedly larger than adjacent teeth, fig. 117.. 4

Canine teeth either decidedly smaller than incisors or ab-
sent; figs. 406d) 41.004: ... al de 6

4. Anterior end of skull with a wide, U- shaped Sere fig. 40e;
length of skull tess than 20 mm. (about 34 in.) ........
Se ai Cor, ee Order CHIROPTERA: bats

Anterior end of skull either without a notch or with only
a small angular or narrow notch, figs. 60, 108; length of
skull more than 20 mm.,..... 2. )26)222 eee 5

5. Canine teeth subtriangular in cross section................
Ne ee! ies pe Serer Order ARTIODACTYLA (in part) ; pig

Canine teeth rounded in cross section... --. 2 eee
Wests: eo. Sain) 2 Gear Order CARNIVORA;; flesh eaters

6. Upper jaw having 6 incisors of approximately equal size,
fig. 40f; length of skull more than 250 mm. (934 in.)....

Ee EPs A ee ee Order PERISSODACTYLA; horse

Upper jaw having 2 conspicuously large incisors (in some
groups followed by minute incisors), fig. 40c, d; length of
skull less than 150 mm. .(57% 1n-) ..4 /2 cee 7

7. Gap, if present between front teeth and grinding teeth, no
more than length of a single grinding tooth; canines
small, fig. 41... .. Order INSECTIVORA;; moles and shrews

Gap between front teeth and grinding teeth equal to or
greater than length of the row of grinding teeth; canines
absent, figs: 40¢c, d, 73d. . o. <6. 0. oe 8

8. A pair of peglike teeth immediately behind the 2 large in-
cisors in upper jaw; maxillary region in front of each eye
socket with bony lattice-work, fig. 40d................
gs <i ae RO RL TRT aE Order LAGOMORPHA,;; rabbits

No peglike teeth behind the 2 large incisors in upper jaw;
maxillary regions solid bone, fig. 40c....................

_.Order RODENTIA;; rodents

ORDER MARSUPIALIA
Marsupials

The Marsupialia are unique among mammals in that the
female gives birth to minute living young and carries them for
some time, usually in a pouch of skin (marsupium) or in fur
situated on the under side of her body. The marsupials contain
both large and small forms, including the famous kangaroos,
which may attain almost the size of a small horse, and the little

Family DIDELPHIDAE 45

koala pictured on Australian stamps. Marsupials are most abun-
dant in Australia and neighboring islands, but they have many
representatives in South and Central America. The range of one
species, the opossum, includes much of the United States.
Economic Status.—In Illinois the opossum is trapped for
fur and, to some extent, for food. For both food and fur the
monetary value is low. The opossum is beneficial in that it eats
some injurious insects, but it may at times be harmful to wild
birds and cause loss to farmers by eating poultry and eggs.

DIDELPHIS MARSUPIALIS Linnaeus
Opossum Possum

Description.—The opossum, fig. 42, is as large as the aver-
age domestic cat. Its face is long and subconical, its ears are
naked, its tail is scaly and almost bare, and its feet are decidedly
handlike. The female has on her abdomen a woolly pouch in
which she carries and nourishes her newborn young. The
possum’s face is whitish, its eyes are beady black, and its bare
ears are shiny black, mottled with pink or white. Its feet are
black, and its toes are pink or white. The inner toe of each hind
foot is thumblike, fig. 40a.

The hair making up the dense woolly underfur of most opos-
sums is creamy white, with grayish tips, and the long, guard
hairs are dark gray or black. This combination gives the body a
general grayish appearance. However, in many specimens the
underfur is tipped with brown, which, showing through the
guard hairs, gives the body a brown instead of a gray appear-
ance. A few individuals are almost entirely black, and others
are a very pale gray or nearly white. In the occasional true
albino, the general color is oftt-white, the ears and feet are
white, and the eyes are red. Some very light gray individuals
may resemble albinos but in these the eyes, ears, and feet have
the normal black coloration.

Length measurements: head and body 17-21 inches (430-530
mm.); tail 814-1214 inches (220-320 mm.); over-all 2514-
3314 inches (650-850 mm.) ; hind foot 234-314 inches (60-80
mm.) ; ear 214-214 inches (57-66 mm.). Weight (adults, IIli-
nois): 6-12 pounds.

The opossum skull, 100-125 mm. (4-47 inches) long, can be

distinguished from the skulls of other Illinois mammals by the

Order MARSUPIALIA

sums: top, adult; bottom, mother

Family DIDELPHIDAE 47

small braincase, the inflected dentary bone, fig. 406, and the
large number of teeth (total 50). The sutures between the skull
bones tend to remain open, and there is little fusion of bones
even in the oldest individuals. Dental formula:* I 5/4, C 1/1,
Pm 3/3, M 4/4.

Life History—The opossum, an inhabitant of woodland,
fig. 1, attains sexual maturity at the age of approximately |
year. The female may have one or, rarely, two litters annually,
the first usually in late February and the second in late July.
About 13 days after mating, she gives birth to 7 to 20 young,
each no larger than a honey bee. The young are nude, sight-
less, and scarcely more developed than small embryos. By their
own strength and instinct they make their way from the birth
canal to the mother’s pouch. The mother assists them only by
making a moist path through the abdominal fur with her tongue
and in sitting nearly upright so that the tiny babies will not lose
their way and become entangled in dry hair. When they get to
the pouch, each one seizes a milk-providing nipple on which it
will retain its hold for several weeks. There are only 13 nipples
in the pouch and, if the number of young is more than 13, the
superfluous number starve.

When the baby opossums are 50 days old, they are about as
large as full-grown house mice. By the end of 2 months, their
eyes open, and then for the first time they release their hold on
the nipples. After 10 more days, they leave their mother’s pouch
to clamber about her body, fig. 42, but remain nearby. When
about 80 days old, they are as large as Norway rats. At this
time, they go adventuring on the ground but still return to
their mother’s pouch for nourishment. If the litter is large, they
must nurse in relays. When the young are about 3 months old,
the brood gradually breaks up, and each member wanders about
until it finds a suitable home in a hollow tree or log, or in a
woodchuck or skunk burrow.

When winter comes, the opossum lines its nest thickly with
dry leaves or grass and spends the coldest periods dozing in the
warmth of a coat of fat gained from its autumn feasts. Only
when the nights are not so cold does it come forth to forage,
and then it soon hustles back to its den so that its bare ears and
tail do not become frostbitten.

*An explanation of dental formula is given in the glossary.

48 Order MARSUPIALIA

This slow, dull, and solitary nocturnal animal eats a variety
of food. The chief items of its diet are fruits, insects, some
small birds, mice, garbage, and an abundance of scraps from
the kills of other mammals. An area of about 12 acres of good
woodland that is not heavily grazed and that has plenty of
food and water is probably sufficient to support one opossum.

Abundance of food and suitable habitats and production of a
large number of young would soon result in a tremendous num-

PIGMY SHREW SOUTHEASTERN SHREW

Fig. 43.—Known distribution, in the United States, of insecti-
vores with a limited range in Illinois.

Order INSECTIVORA 49

ber of opossums if it were not for their enemies. Foxes, dogs,
coyotes, possibly minks, and large owls pick them off one by
one. Although opossums are rather easily caught, they have a
unique method otf defense. If surprised away from the com-
parative safety of trees, they may feign death so that a not-too-
hungry enemy may leave them for dead without trying to eat
them. Sometimes, however, they are badly mauled before being
left alone. Considerable numbers are killed by motor vehicles
on highways. Several hundred thousand possums are caught
each year by trappers or fur hunters in Illinois, even though
possum pelts are worth very little.

Signs.—Possum tracks, fig. 17, easy to detect in mud or snow,
are most apt to be found at the edges of ponds and rivers near
woodlands. There is no mistaking them. The print of each
front foot shows five fingers spread wide apart, and that ot
each hind foot shows the large toe thrust out at a right angle
to the other toes, which are rather close together.

Ordinarily possum droppings are in the form of irregular
masses about 2 to 2)% incnes long; usually they contain large
amounts of fruit hulls and seeds and often some fur and feath-
ers.’ The fur and feathers are more than likely from various
creatures that have been killed by some predator other than the
possum.

Distribution.—The opossum is common in IIlinois. The sub-
species in this state is Didelphis marsupialis virginiana Kerr.
The species has a range that includes an extensive area: all of
the eastern United States south of a line drawn from southern
New England to southern Minnesota to western Texas; also
much of western California. The range extends through Mexico
and into South America.

ORDER INSECTIVORA
Moles and Shrews

The Insectivora are the most primitive of the known living
placental mammals; all Illinois mammals except the opossum
are placental. Several families of insectivores are recognized.
Two of these, the Talpidae or moles and the Soricidae or
shrews, are burrowing, thick-furred animals comparable in size
to rats and to small mice, respectively. These two families,
widespread in the Northern Hemisphere, are represented in

50 Order INSECTIVORA

Illinois. The known distribution, in the United States, of three
shrews having a limited range in Illinois is shown in fig. 43.

Economic Status.—All members of the order are beneficial
to some extent, because they feed on soil-inhabiting insects,
many of which are injurious to crop plants. Moles and shrews
are of no commercial value for their pelts. Moles often become
nuisances in gardens and lawns by raising the soil above their
subsurface runways.

KEY- TO" SPEGIES
Whole Animals

1. Front feet more than twice as wide as hind feet; over-all
length of animal more than 150 mm. (57 in.)..........

Cree. ORs aA Se eee ele ......Talpidae (moles) 2
Front feet chp ans Seely same width as hind feet; over-all
length of anima! less than 120 mm. (514 im.)...........

TR AA nO eR MK REG, BIER cn ec Soricidae (shrews) 3

2. Snout naked; eyes not visible; tail length less than 40 mm.
(lisa: iiin)' Suetes nee ass 2 ee et eastern mole, Scalopus aquaticus
Snout with fleshy, finger-like tentacles; eyes visible; tail
length’ more than 50 mm. (2 in.)...2- - 2 eee
Ue, hl’ Sees nam fe -star-nosed mole, Condylura cristata
5. Parl length less than half of head+body length; ears hid-
Cal) AP) Cs 0 OR a eae Meee Ga ws Uw «a 4

Fig. 44.—Rostrums or upper jaws of insectivores, side view:
a, short-tailed shrew; b, least shrew; c, pigmy shrew; d, star-nosed
mole; ¢, southeastern shrew; f, eastern mole; g, masked shrew.

Family TALPIDAE 51

Tail length more than half of head+body KenEt; ears not

PME MT ach a8 9.) bike tS ss, nd he RIS hy WW Aceh G Ae> Samael slo Bk ae Sab 5
4. Over-all length of animal less than 88 mm. (31% in.) ; fur
pray-prown in color............ least shrew, Cryptotis parva
Over-all length of animal more than 88 mm.; fur blackish
mrecolor. 92. es. short-tailed shrew, Blarina brevicauda
5.* Upper jaw, in lateral view, with 3 unicuspids visible on
each side, fig, 44¢.. 2). .......- pigmy shrew, Microsorex hoyt
Upper jaw, in lateral view, with 4 or more unicuspids visi-
Mremenmesteln sides et) AA ees Bis Gai we te Acageiee Phos bee oe 6

6.* Third unicuspid smaller than fourth, fig. 44e ............
Lt eee southeastern shrew, Sorex longirostris
Third and fourth unicuspids subequal or third larger than

E00 eae 27) rs masked shrew, Sorex cinereus
Skulls
1. Zygomatic arches present, fig. 41; teeth not tipped with red
GHEMEOWI phe yl ems oats. ene Talpidae (moles) 2
Zygomatic arches absent; front teeth tipped with red or
BLOWN NON 440-6, Oe G. 8 SS bcc so ee om Soricidae (shrews) 3

2. Teeth in upper jaw Z0, in lower jaw 16; upper incisors
slightly recurved, fig. 44f...eastern mole, Scalopus aquaticus
Teeth in upper jaw 22, in lower jaw 22; upper incisors
mprorechimertorward, fie. 447.2 2.5. i.e 050, Ca yews baeaes
J agile ae ee ...star-nosed mole, Condylura cristata
a) Leeth in upper jaw/ 18.0)... =. least ae Cryptotis parva
(heeth tm upper yaw. 20... .. i... Web wee a eS 4
4. Width of skull more than 11 mm. (36 in. ) ee ae
EAS, ae ee short-tailed shrew, Blarina brevicauda

Midtinat kul tess than’ 2) mm) ies 22205... 25.6 5
5. Upper jaw, in lateral view, with 3 unicuspids visible on
eneb side: fir. 446. 22.0 65). 3 2. p'gmy shrew, Microsorex hoyi
Upper jaw, in lateral view, with 4+ or more unicuspids visi-
PiPeeioe tel Side sims TE. Fol ie ort Pt) eB 6

6. Third unicuspid smaller than. fourth, fies 44e! 05 0.5.2.
Se bE ee a ee southeastern shrew, Sorex longirostris
Third and fourth unicuspids subequal or third larger than
POMTGEM POE FAG s os. ne ses masked shrew, Sorex cinereus

SCALOPUS AQUATICUS (Linnaeus)
Eastern Mole

Description.—The eastern mole, fig. 45, has a rather thick
body, plushlike fur, short forelimbs, broadly rounded hands
with outwardly turned palms, pointed snout, short tail, no ex-
ternal ears, and no visible eyes.

*The characters in this couplet are seen best in a cleaned skull, and only with
dificulty in a whole animal.

52 Order INSECTIVORA

The eyes, which are completely covered with skin, may serve
the animal only to distinguish between light and dark. ‘The
elongate nose is a sensitive probe used in seeking out earth-
worms, grubs, and_other food. The fur appears usually as a
dark or slate gray, but in some lights and at certain angles it
appears as light gray and, in most individuals, has a slight iri-
descence. The summer pelage, acquired after a spring molt, is
slightly paler than the winter pelage. The fur of the under

Fig. 45.—Eastern mole.

parts is nearly the same color as that of the sides and back,
except that on some individuals bright orange or white patches
appear on the abdomen or on the chest.

Length measurements: head and body 514-614 inches (142-
167 mm.); tail 114-114 inches (28-38 mm.) ; over-all 634-8
inches (170-205 mm.); hind foot about 1 inch (23-25 mm.).
Weight (mature male): about 14 pound (90-125 gm.).

The skull is cone shaped, pointed in front and broad at the
back; it is 28 mm. (about 114 inches) long. Zygomatic arches
are present. All of the bones of the skull fuse together early in
the development of the animal, and the cranium appears to con-
sist of but one large bone. All of the teeth have sharp cusps
designed for cutting worms and other items of food, figs. 41,
447. Dental formula: I 3/2,.C 1/0, Pm 3/3, M S/s:

Life History.—The eastern mole lives in runs, burrows, or
tunnels near the surface of the earth, fig. 1. These are the re-
sult of the animal’s “swimming” through the soil in search of

Family TALPIDAE 53

food. In the “swimming” motion a breast stroke is employed.
The mole’s spadelike hands are brought forward alongside its
snout. Then its hands are thrust outward, slightly upward, and
backward, pushing the soil aside and pulling the animal for-
ward. The soil above the animal arches and finally cracks, leav-
ing a humped and broken trail, fig. 6. Along such a run the
mole searches for food. Rarely, an adventuresome or restless
individual will leave its run or burrow for a brief foray above
ground. Only on such an occasion does the mole leave open an
entrance to its burrow. When the mole is at home, every
entranceway is plugged. Meadow mice, pine mice, and shrews
commonly dig into and use mole runways.

Although the eastern mole makes unsightly ridges and hills
or mounds in lawns or gardens, it has the best of intentions,
for usually in this activity it is not eating roots or bulbs but
foraging for worms and insects. Examination of the stomachs
of eastern moles has demonstrated that the bulk of the diet
consists of earthworms, white grubs, and other arthropods. In
the stomachs of 56 moles from central Illinois, 62 per cent of
the food was insects, 26 per cent earthworms, 11 per cent plant
material, and | per cent spiders, hair, and other items (West
1910). Eight per cent of the plant material was corn, found in
the stomachs of 11 of the 56 moles. In the stomachs of these
same animals there were also cutworms, wireworms, white
grubs, webworms, and ants. In a mole stomach collected re-
cently in Champaign County, most of the food consisted of gar-
den peas.

The eastern mole is active throughout the year. In spring
and summer it uses runways or tunnels near the surface and
extends them chiefly when soil conditions are most favorable—
usually following rains. In the fall it devotes much of its time
to making runs or burrows deep in the soil. With the onset of
winter, it uses both new and old runs below the frost line where
insects can still be found.

The female of the eastern mole ordinarily has only one litter
of four young each year. In April or May, the young are born,
naked and helpless, in a crudely constructed nest in a deep run-
way. For about a month, they remain in the nest. By the age
of 3 months they are nearly as large as the parents.

This animal has few enemies and leads a relatively safe life
in its underground burrows. To some wild animals the mole

54 Order INSECTIVORA

is probably distasteful because of a secretion from its skin
glands. Cats are known to catch moles but to refuse to eat
them.

Signs.—An unweathered mole hill or mound, fig. 6, is so dif-
ferent from other animal diggings that it is not easily mistaken.
It resembles the mound made by a pocket gopher, fig. 7, in that
no hole shows if the animal is in its burrow; however, much
more of the earth of the mole hill is in larger lumps or clods.
The dirt plugging the hole is pushed out by each new load thrust
up under it until a steep-sided pile, usually less than a foot
across and about 5 or 6 inches deep, has been formed.

During the summer, freshly made hills are relatively uncom-
mon, and the presence of moles is usually detected by ridges,
5 to 8 inches in width, of broken surface soil or torn sod.

Distribution.—The eastern mole is common over most of
Illinois but uncommon in the extreme northeastern counties.
The subspecies in Illinois is Scalopus aquaticus machrinus (Ra-
finesque), sometimes called the prairie mole. The species occurs
from southern New England to central Minnesota and north-
eastern Colorado and south to northern Mexico and southern

Florida.

CONDYLURA CRISTATA (Linnaeus)
Star-Nosed Mole

This species has been reported from Illinois on the basis of
sight records, but to date no specimens of it from this state have
been captured and preserved. It seems best, therefore, to omit
the name of this species from the list of Illinois mammals until
proof of its occurrence here is established. The star-nosed mole
is northeastern in distribution; the records nearest Illinois are
from Wisconsin, Michigan, and eastern Indiana. Specimens
may be identified by the characters given in the key to insec-
tivores.

SOREX CINEREUS Kerr
Masked Shrew

Description.—The masked shrew, fig. 46, is frequently mis-
taken for a young mouse but, unlike the mouse, it has a fine,
velvety fur, sharp conical muzzle, minute eyes, and pincer-like

Family SORICIDAE 55

teeth that are tipped with red. It has a relatively long tail,
which reaches nearly to the ears when laid forward along the
back. In winter this animal is brown on the upper parts, smoky
gray on the under parts; in summer it is a slightly darker
shade. The eyes and ears are masked or covered by short hair;
hence the common name of masked shrew.

Length measurements: head and body 17¢—21% inches (47-63
mm.); tail 114-134 inches (33-46 mm.); over-all 314-414
inches (80-109 mm.); hind foot about 14 inch (10-13 mm.).
Weight: about 14 ounce (4 gm.).

The skull is slender, tear-drop shaped, and 16.5 mm. (about
34g inch) long. The teeth are numerous (32), small, and sharp
pointed. On each side of the upper jaw there is one large front
incisor which is notched and projected forward. Behind this
tooth are five small teeth, called unicuspids (one-cusped teeth).
The fourth unicuspid is about the same size as or smaller than
the third unicuspid, and the fifth unicuspid is so small that it
may be overlooked, fig. 44g. Dental formula: I 3/1, C 1/1,
Porn), Mi 3/3.

The masked shrew may be confused with the southeastern
shrew. The two are best distinguished by differences in the uni-
cuspids. They differ in distribution; the masked shrew has never
been taken in southern Illinois, and there are no authentic rec-
ords of the southeastern shrew from northern [Ilinois.

The masked shrew may also be confused with the pigmy
shrew, but generally the masked shrew is larger, has a longer

Fig. 46.—Masked shrew.

56 Order INSECTIVORA

tail and longer hind feet, and has five instead of four unicuspids
(three visible in lateral view) on each side of the upper jaw.

Life History.—Little is known about the masked shrew in
Illinois. Elsewhere. an adult female of this species produces
about five young in April. Her ball-shaped nest, 4 or 5 inches in
diameter and lined with fine grass and rootlets, is hidden in a
cavity of an old log or stump.

The masked shrew is generally found under a dense growth of
weeds or in woods, fig. 1. This tiny mammal, like all other
shrews, is a scurrying, vibrating mite of energy, driving narrow
tunnels in leaf mold and darting swiftly about in search of food
day or night, summer or winter. It is a prodigious eater. In a
single day a shrew may eat one, two, or even three times as
much as its own weight in food. Its diet consists chiefly of in-
sects, snails, and worms.

This shrew, like others in Illinois, possesses scent glands that
secrete a musky fluid which renders the animal undesirable as
food for some predators and may account for the fact that cats
sometimes leave shrews uneaten after catching and killing them.

Signs.—Curious parallel tracks in snow (tracks similar to
but smaller than those of the short-tailed shrew), and often
accompanied by a tail mark, may indicate the presence of the
masked shrew. This animal may make small ridged runways
in the snow similar to those of the mole in soil, but the shrew
runways are only about 34 inch across as seen from the surface.
The burrow the masked shrew makes in snow, and probably also
in loose soil, has an inside diameter of about half an inch.

Distribution.—The masked shrew is uncommon and in IIli-
nois is restricted to the northern fourth of the state, fig. 43.
‘The subspecies occurring in this state is Sorex cinereus lesueurii
(Duvernoy). The range of this species includes most of Can-
ada and much of the northern United States, with southern ex-
tensions in the Rocky Mountains to northern New Mexico, in
the Great Lakes region to the Wabash River valley, and in
the Appalachian Mountains to western North Carolina.

SOREX LONGIROSTRIS Bachman
Southeastern Shrew Bachman’s Shrew

Description.—The southeastern shrew, fig. 47, is of about
the same size and proportions as the masked shrew and can be

Family SORICIDAE 57

distinguished with certainty from the latter only by skull char-
acters. The pelage is reddish brown.

Length measurements: head and body about 21% inches (55
mm.); tail about 1 inch (27 mm.); over-all about 314 inches
(82 mm.); hind foot 3g inch (9 mm.).

The skull is shorter than that of the masked shrew but it
is similar in shape. The molar teeth are larger than those of
the masked shrew; the fourth unicuspid on each side of the

upper jaw is larger than the third, fig. 44e. Dental formula:
Pe eGt/ i, Pm 3/1, M. 3/3.

The southeastern shrew can be distinguished from the pigmy
shrew in having five rather than three readily discernible uni-
cuspids on each side of the upper jaw.

Life History.—The southeastern shrew is one of the least
known mammals in Illinois, for less than a dozen specimens
have been collected in the state. One specimen, taken at Fox
Ridge State Park, Coles County, was found beneath a log where
a pond had dried up in a brushy, sparsely wooded portion of the
park. Another individual from the same locality was found in
a wooded ravine.

Signs.—Presumably the signs of the southeastern shrew are
identical with those of the related masked shrew.

Distribution The rare southeastern shrew is known in
Illinois only from Alexander, Coles, Fayette, and Johnson coun-
ties. Specimens taken in this state are presumed to belong to
the subspecies Sorex longirostris longirostris Bachman. The

Fig. 47.—Southeastern shrew.

58 Order INSECTIVORA

species has a range that appears to be discontinuous, fig. 43. One
part of the range apparently extends from Maryland to south-
western Mississippi and northern Florida; another part includes
areas in Illinois, Indiana, Kentucky, and Tennessee.

MICROSOREX HOYI (Baird)
Pigmy Shrew

Description.—The pigmy shrew is probably the smallest
American mammal. An adult weighs only 2 to 3 grams (less
than 14 ounce); it would take 8 of these shrews to equal the
weight of a white-footed mouse, 400 to equal the weight of a
fox squirrel, and several thousand to equal the weight of a
bobcat. This shrew is a uniform light brown on the upper parts
and slightly paler brown on the lower parts.

Length measurements (based on one IIlinois specimen) : head
and body 1% inches (48 mm.) ; tail 114 inches (29 mm.) ; over-
all 3 inches (77 mm.) ; hind foot 3g inch (9.5 mm.).

The skull is similar in many details to that of the southeastern
shrew and that of the masked shrew, but it is smaller; it has
only three readily discernible unicuspids on each side of the up-
per jaw, fig. 44c; the first and fifth are minute. Dental for-
mult Ls a Color m 3/1, Miody oe

Life History.—Little is known about the pigmy shrew, since
it is very rare. The only known Illinois specimen was taken in
the middle of the winter of 1949 (Sanborn & Tibbitts 1949) in
a garage in Cook County. A masked shrew was found with it,
and possibly both shrews were forced there because of a heavy
coating of ice out-of-doors.

Apparently the pigmy shrew inhabits dry woodlands, thickets,
and grassy clearings, where it feeds largely on insects.

Signs.—Inasmuch as the pigmy shrew is similar to the two
preceding species of Sorex in body form and habits, its signs
are probably also similar.

Distribution.—The only specimen of the pigmy shrew re-
corded for Illinois is from Palatine, in Cook County. It belongs
to the subspecies Microsorex hoyi hoyi (Baird). The range of
the species includes most of Canada and Alaska except the West
Coast. It extends into the United States as far as northern
illinois, eastern Ohio, and down the Appalachians to North
Carolina, fig. 43.

Family SORICIDAE 59

BLARINA BREVICAUDA (Say)
Short-Tailed Shrew

Description.—At first glimpse, a short-tailed shrew, fig. 48,
scurrying along in leaf litter may be mistaken for a mouse or a
young mole. Close examination will show that this shrew has
some features of both the mouse and the mole. It is sometimes
called the mole shrew. Unlike the mole, the short-tailed shrew
has eyes that are functional, although small, and front feet that
are not broad and spadelike. This shrew is about the size of a

Fig. 48.—Short-tailed shrew.

mouse but differs from it in having a plush, velvety fur, fig. 4,
sharp-pointed nose, short tail, and a seeming absence of ears,
which are hidden in the fur.

Length measurements: head and body about 3-4 inches
(75-101 mm.); tail 34-114 inches (20-29 mm.); over-all
334-514 inches (95-130 mm.); hind foot about 5¢ inch (14-17
mm.).

The skull ranges in length from 21.0 to 24.5 mm. (less than
1 inch) and in width from 11.3 to 12.9 mm. (about 1% inch).
It has no zygomatic arches. Part of the upper jaw is shown in
hig. 44a. Dental formula: I 3/1, C 1/1, Pm 3/1, M 37/3.

The short-tailed shrew can be distinguished from all other
Illinois mammals by a combination of characters: mouse-size
body; short tail; dark, nearly black, velvety fur; sharp-pointed

60 Order INSECTIVORA

nose; pin-point eyes; relatively large skull (nearly mouse-skull
size) without zygomatic arches.

Life History.—The short-tailed shrew is an animal princi-
pally of forest floors, forest edges, meadows near woods, or
swampy, brushy habitats. Usually it builds its own burrow or
tunnel through leaves or humus. A log may serve as a roof for
its burrow. Frequently, when a log in the forest has been over-
turned or broken open, a furrow-like runway of the short-tailed
shrew is revealed. Burrows of this kind, about 114 inches
in diameter, may be so numerous as to form a network in the
forest floor. A man walking through a forest may find that at
nearly every step his heel sinks into one of these burrows an
inch or two below the surface, fig. 1. Commonly there are 10 to
20 short-tailed shrews per acre in forests and fewer per acre in
grassy, less wooded areas. This shrew is regarded as the most
abundant small mammal in many wooded areas of Illinois.

Its nest of grass, leaves, or hair, or a combination of these
materials, may be hidden beneath a large log or in a subterranean
burrow. This nest is slightly oval in shape and 434 to nearly
6 inches (120-150 mm.) in diameter. The number of litters
a female may have in a year is not known; probably there are
two or three litters of five to eight young each. The gestation
period is 21 to 22 days. At birth the young are helpless, pink
and wrinkled, and each is smaller than a honey bee.

The short-tailed shrew is a ravenous feeder, consuming the
equivalent of its weight in food in a single day. Its food con-
sists principally of invertebrates, such as earthworms, snails,
and insects. Short-tailed shrews in captivity have been ob-
served attacking and killing mice, but no one has reported
seeing a shrew do this in the wild. The production of a poison-
ous substance by the submaxillary glands may aid this shrew
in Overcoming its victim. In wintertime it caches live snails in
its burrows below ground and from this “pantry” it can draw
food as needed.

Shrews of this species occur in the diet of owls and snakes.
Because uneaten carcasses of shrews are rather frequently
found, it is thought that some predators kill these animals and
then find them unpalatable.

Short-tailed shrews may be kept in captivity, but only one
shrew should be placed in a container. If two are put together,
one will soon kill and devour the other. A glass aquarium tank,

Family SORICIDAE 61

with wood shavings in the bottom and a half-pint glass jar placed
on its side for a nest chamber, makes an ideal cage. Water
should be available at all times, and food should be offered in
liberal quantity. An ideal food, used with success by Dr. Oliver
P. Pearson of the University of California, who has raised
many of these shrews, consists of about equal parts of dry dog
meal and hamburger, or horse meat, mixed to hamburger con-
sistency by the addition of water. This diet can be supplemented
with worms, beetles, and grasshoppers. With proper care, short-
tailed shrews may live in captivity to be nearly 3 years old, but,
in the wild, their life-expectancy probably never exceeds | year.

Signs.—The usual gait of the short-tailed shrew in soft snow
is a walk, and the resulting tracks consist of unpaired foot-
prints evenly placed along the trail, fig. 33, at about 1-inch in-
tervals, with the tail mark between them curved gently from
side to side as a result of the swaying of the short-legged body.
A running shrew leaves paired footprints and an interrupted
tail mark; the distance between each set of paired prints then
is about 5 inches.

Droppings of the short-tailed shrew are greenish black when
fresh, slightly brownish when dry, spindle shaped, about a third
of an inch long, and coiled in various ways.

Distribution.—The short-tailed shrew is a common species
throughout Illinois. The subspecies Blarina brevicauda brevi-
cauda (Say), with larger individuals, occurs in the northern
part of the state, and the subspecies B. b. carolinensis (Bach-
man), with smaller individuals, occurs in the southern part.
The area of intergradation between these two subspecies is
poorly known. The range of the species embraces roughly the
southeastern fourth of North America; it extends northward
into southern Canada and westward to about the 100th meridian.

CRYPTOTIS PARVA (Say)
Least Shrew Old-Field Shrew

Description.—The least shrew, fig. 49, is a gray-brown min-
iature of the short-tailed shrew. It can be distinguished from
the masked, southeastern, and pigmy shrews by its shorter tail
and usually by its more grayish color and more effectively con-
cealed ears. It differs from the short-tailed shrew by its smaller
size, fig. 4, and grayish brown rather than blackish color.

62 Order INSECTIVORA

Length measurements: head and body about 214-214 inches
(54-63 mm.); tail 14-34 inch (11-17 mm.); over-all about
214-314 inches (65-80 mm.) ; hind foot 3g inch (9-11 mm.).

The skull length is 16.0-17.0 mm. (about % inch) ; width,
7.5-8.2 mm. (slightly more than 14 inch). The least shrew has
only two premolars on each side in the upper jaw, whereas all
other Illinois shrews have three. Part of the upper jaw is shown
in fig. 444. Dental formula: I 3/1, C 1/1, Pm 2/1, M 3/3.

Life History.—The least shrew often is found in old, weedy
fields, fig. 2, and thus it is sometimes called the old-field shrew.
It is frequently common in bluegrass meadows, occupying run-
ways of meadow mice. It may occur also in brushy, weedy, or

: i ih

li,

lil

Fig. 49.—Least shrew.

marshy situations near woods but rarely, if ever, in forests. It
probably occupies burrows and runways made by various other
mammals, but some surface runs may represent paths made and
used exclusively by the least shrew.

Except for Blarina brevicauda, the least shrew is the com-
monest shrew in Illinois. In some fields, least shrews may be
as abundant as 10 or 15 per acre.

It is not known when the least shrew breeds in Illinois,
when it brings forth young, or how many young are in each
litter. According to limited observations on this species in
other states, a litter may consist of five or six young. The com-
bined weights of these young while still nursing may be several
times that of the mother.

Like other shrews, the least shrew has an insatiable appetite.
An individual kept in captivity ate seven migratory grasshop-
pers in 30 hours. It killed each one by biting the head, and then
it proceeded to eat the insect head first, discarding the wings

Order CHIROPTERA 63

and hind legs as it came to these structures. ‘he captive animal
clambered slowly about the hand of its human captor, occasion-
ally trying to bite, but it was never successful in breaking the
skin. In its natural habitat, this shrew probably preys on
spiders, snails, and worms, as well as on insects.

Signs.—Tracks of the least or old-field shrew are similar in
most respects to those of the short-tailed shrew, but they are
no more than half as large. The tail is too short to leave a
drag mark in soft snow. In snow or soil, the burrow of this
shrew is only about 34 inch in diameter.

Distribution.—The least shrew is probably state-wide in oc-
currence, but it seems to be rare in the northern quarter of the
state. wo subspecies occur in Illinois, Cryptotis parva parva
(Say) occupying the northern two-thirds and C. p. harlani
(Duvernoy) the southern third. The species ranges from Con-
necticut to northeastern Colorado and southward into Mexico

and Florida.

ORDER CHIROPTERA
Bats

Bats are the only mammals that truly fly. They have expan-
sive membranous wings formed of thin skin that extends from
the sides of their bodies out over frames composed of the con-
spicuously long bones of their forearms and fingers down to
their hind legs, fig. 39; in many species, this thin skin encorn-
passes the tails also. Usually bats fly only at night or in the
twilight of evening or of early morning. They are extremely
agile in flight and, although they have poor eyesight, they are
adept at avoiding obstacles and successful in catching insects on
the wing. They guide themselves in the dark by means of a
unique sonar system. ‘Chey emit from their throats squeaks
and supersonic vibrations, inaudible to man, and perceive and
localize the reflected sound waves or echoes through highly
developed mechanisms of their ears.

Bats are distributed over the whole world and are of many
species. One famous bat is the vampire, which is of medium
size and is found in the American tropics. It punctures or
shaves the skin of large mammals (occasionally man) and laps
up the blood as food. The largest bats are the fruit bats or
flying foxes of the South Pacific tropics, some attaining a body

64 Order CHIROPTERA

length of a foot and a wing span of 5 feet. The 12 species of
bats in Illinois, all belonging to the family Vespertilionidae,
are harmless and small, the largest being only 514 inches from
nose to tip of tail and having a wing span of about 14 inches.

The species of bats in Illinois can be divided into two general
groups. Individuals in one group tend to be solitary (live
alone) ; to roost in trees (hang from branches with their heads
down or hide under loose bark); and to be migratory (move
south, probably out of Illinois, late in the fall and north in the
spring). This group includes the red, the hoary, and the silver-
haired bats. °

Individuals in the second group tend to be gregarious (live
together in colonies) ; to hibernate in caves or abandoned mines
in winter and roost in buildings, caves, or hollow trees the re-
mainder of the year; and to be nonmigratory (except in one
species ).

Mating among Illinois bats typically occurs late in the fall,
ovulation and fertilization the following spring. The young are
born in late spring or early summer. At this time the sexes usu-
ally segregate; some colonies consist entirely of males and
others of females with young. he number of young produced
annually by a female is usually one or two; the number varies
with the species involved. The bare, much wrinkled, and blind
young have proportionately small hands, or wings, and modified
bladelike or forked and recurved milk teeth. These forked
teeth presumably aid the young in clinging tightly to the body of
the mother, inasmuch as she carries them until they are too
much of a burden or are old enough to fly. Sometimes the com-
bined weight of two young exceeds that of the mother. Develop-
ment is extremely rapid, some young being able to fly at the age
of 3 weeks.

Signs.—Bats leave signs of their presence in the form of drop-
pings, or guano, and the remains of partially eaten insects. Be-
cause such signs are the same for most species of bats, a brief de-
scription of them is summarized here, rather than in the descrip-
tion for each species. Bats of the first group mentioned above,
sometimes referred to as the tree bats, seldom leave sufficiently
large accumulations of guano and insect remains to be easily rec-
ognized as bat signs. Bats of the second group leave deposits of
droppings and insect remains that may be several feet deep
under the roosting sites. Caves long inhabited by summer colo-

Order CHIROPTERA 65

nies of bats are easily recognized by the mounds of guano and
sometimes by the presence of dark stains on the ceilings where
clusters of bats have been suspended. The known distribution,
in the United States, of five species of bats having a limited
range in Illinois is shown in fig. 50.

Economic Status.—Bats in Illinois are undoubtedly bene-
ficial because they feed primarily on insects and aid in reducing
the numbers of some important pests. Colonies of bats in build-

INDIANA BAT

wrens ssevevetetawes

GRAY Pe SOUTHEASTERN %
BAT Be

BIG~EARED BAT

Fig. 50.—Known distribution, in the United States, of bats with
a restricted range in Illinois.

66 Order CHIROPTERA

ings may be objectionable because the droppings that accumulate
produce an odor that generally is regarded as unpleasant.

= KEY<-1O; SPECIES
Whole Animals

Bats are rather difficult to identify; oftcn a fresh specimen can
be more readily identified than a study skin or preserved speci-
men. The following key to the whole animals is designed for liv-
ing or freshly killed bats and for study skins in which detailed meas-
urements accompany the skin and skull. In each instance, the ear
length, forearm length, or foot length is that of a fresh specimen.

1. Ear more than 30 mm. (11 in.) long; glandular outgrowth
or lump’ on. side of muzzle....°. >... 2.4352
ere ae southeastern big-eared bat, Corynorhinus rafinesquii
Ear less than 23 mm. (7 in.) long; no prominent lump on
side of muzzle :..4...../....%.).., See 2
2. Upper surface of tail membrane completely furred, fig. 56;
under side of wing with a patch of fur on distal part of ~

FORCATM, 25. its Geo le caves ae pe sne « De ee 3
Upper surface of tail membrane entirely bare, fig. 55, or at
least posterior third bare; under side of wing naked ... 4

3. Fur brick or rusty red, dusted with white; forearm less
than 44 mm. (134 in.) Jong; over-all length less than
£15 mum, (415-10). 2 nn .... Yed bat, Lasiurus borealis

Fur a mixture of bright buff, vellows, and deep amber,
heavily frosted wth white in waves over the back; fore-
arm more than 44 mm. long: over-all leneth more than
12 0emmis (ovine see ae hoary bat, Lasiurus cinereus

4. Fur black or blackish brown, frosted with white; premolars
on eaéh.side of jaws 2 above, 3 below .... J =e
ON, A ek eet silver-haired bat, Lasionycteris noctivagans

Fur neither black nor frosted with white; premolars on
each side of jaw not 2 above, 3 below .. 3.4 eceeeeeee: 5

5. Over-all length usually 105 mm. (414 in.) or more; fore-
arm length usually 45 mm. (134 in.) or more ... ......
BEG PER y 2 9 RR Se big brown bat, Eptesicus fuscus

Over-all length usually less than 105 mm.; forearm length
less than-45 sms «.°.) 2..." wee 8. 6

6. Fur on back with hairs not darkened at bases; forearm
length usually 40 mm. (about 114 in.) or more......

SEA Se RCS OEE, sec ch choe aE ie gray bat, Myotis grisescens

Fur on back with hairs darkened at bases; forearm length
usually less: than:40° MM. ..<jc2ede ek es i 7

7. Fur on back with hairs distinctly tricolored; forearm and
fingers red; upper jaw with 2 pairs of premolars
StL ee eastern pipistrel, Pipistrellus subflavus

Fur on back with hairs not distinctly tricolored; forearm

Order CHIROPTERA 67

and fingers brown or black; upper jaw with 1 or 3 pairs
SREPRTA DRS Te ue hes. CAN ohh waite tia lek wide SIE EHS, «es 8
8. Upper jaw with 1 pair of incisors; tragus curved and less
than 4 mm. (about 14 in.) from notch to tip..........
-: Shy lk: oe evening bat, Nycticeius humeralis
Upper jaw with 2 pairs of incisors; tragus straight and
morectuan. 4. mm. trom notch to tip: .......-. 6.0.05. es. 9
9. Ear large, extending 3 or 4 mm. (about 14 in.) beyond end
of snout when laid forward; tragus slender and pointed,

i Se ie i ee Keen’s bat, Myotis keeni
Ear not extending 3 or 4 mm. beyond end of snout when
la'd forward; tragus broadly rounded, fig. 5la ......... 10

Fig. 51.—Ears of two bats: a, little brown bat; b, Keen’s bat.

10. Fur on under side of body white or pale gray; fur on upper
side of body dense, woolly, and brown, with a mole-gray
cast; nose flesh-colored in living bat............ “4
ot hrs ee See southeastern bat, Myotis austroriparius
Fur on under side of body buffy gray or pinkish gray; fur
on upper side of body long, straight, brown, but without
a mole-gray cast; nose dark colored in living bat........ 11
11. Forearm less than 35 mm. (134 in.) long; foot not more
iianne mm: (less than 3¢ in.) Tons m0. foe Sen. >.
gay ee ne ee small-footed brown bat, Myotis subulatus*
Forearm more than 35 mm. long; foot more than 8 mm.
1 cee gly PRT ha eee Ree Seer Te PU Soar ec ices a 12
12. Fur on upper parts of body with coppery or bronzy tipped
hairs; on under parts buffy gray; calear lacking a def-
maltcs Keel) toot; isually 10 mim. lone: - cc.) osc. doe a
“ate a a little brown bat, Myotis lucifugus

*This species may occur in Illinois, but there are no official records of it.

68 Order CHIROPTERA

Fur on upper parts of body without bronzy tipped hairs;
on under parts pinkish gray; calcar with a small but def-

inite keel, fig. 39; foot usually 9 mm. long.............-.
Indiana bat, Myotis sodalis

Skulls
1. Upper jaw with 1 pair of incisors...........-...++++++-++- 2
Upper jaw with 2 pairs of incisors..............--.-.+-.-- 3
2. Upper jaw with 12 teeth .. evening bat, Nycticeius humeralis
Upper jaw with 14 teeth...................--.. Lasiurus spp.
3. Upper jaw with 14 teeth . . .big brown bat, Eptesicus fuscus
Upper jaw with 16 or more teeth...........--..--------- 4

4. Lower jaw with 18 teeth (2 pairs of premolars)... ..
eastern pipistrel, Pipistrellus subflavus

Lower jaw with 20 t-eth (3 pairs of premolars) 5
5. Upper jaw with 18 teeth (3 pairs of premolars)... Myotis spp.
Upper jaw with 16 teeth (2 pairs of premolars). «5c: /-- 6

6. Rostrum (dorsal view) almost as wide as braincase......
Set ht eee roe silver-haired bat, Lasionycteris noctivagans

Rostrum (dorsal view) about half as w:de as braincase....
southeastern big-eared bat, Corynorhinus rafinesquii

MYOTIS LUCIFUGUS (Le Conte)
Little Brown Bat

Description —The little brown bat, fig. 52, is of medium
size but, like all other bats, it appears to be much larger than
it actually is. Although its wingspread may be nearly 10 inches,
the animal weighs only a quarter of an ounce, and the head
and body are only about 2 inches long.

The upper parts of the body have olive-brown or yellowish
brown fur with a bronzy sheen, and the under parts have gray
fur washed with buff. The ears, wings, and tail membrane are
dark brown, nearly black, and are almost free of hair.

Length measurements: head and body 134-2 inches (45-52
mm.) ; tail 114-2 inches (30-50 mm.) ; over-all 314-334 inches
(82-95 mm.) ; hind foot 3¢ inch (10-11 mm.) ; ear from notch
5g inch (14-16 mm.).

The skull is small; it has a short rostrum and an over-all
length of 14.6-15.1 mm. (about 5 inch). The braincase is no
larger than a dried pea. The incisor teeth are so small as to be
hardly visible. Dental formula: I 2/3, C 1/1, Pm 3/3, M 3/3.

Four closely related species—gray bat, Indiana bat, Keen’s
bat, and southeastern bat—may occur in the same roosting

Family VESPERTILIONIDAE 69

place with the little brown bat. The little brown bat can be
distinguished from Keen’s bat by smaller ears, which do not
reach beyond the nose when laid forward, and by tragi, fig. 5la,
that are each less than 6.5 mm. long. It differs from the gray
bat by having forearms that are each less than 42 mm. long. It

.,

Fig. 52.—Little brown bat.

differs from the Indiana bat by having a bronzy sheen on the
back, and from the southeastern bat by its buffy rather than
nearly white under parts.

The little brown bat differs from the eastern pipistrel by its
brown rather than yellow color and from the evening bat by its
lighter brown color. It also has less blunt tragi than either of
these species.

Life History.—The little brown bat is present in Illinois
throughout the year. During the warm months it congregates
in large numbers in attics and steeples; during cold weather it
hibernates in suitable caves and mines in even larger numbers.
In these hibernating chambers, where the temperature is con-
stantly cool but above freezing, individuals of this species may
hang with their heads down, singly or in clusters of 20 to 100
or more, or they may wedge their bodies into cracks. Here they
become dormant and in a state of deep hibernation; they may
not fly or feed until spring, when they break up into smaller

70 Order CHIROPTERA

groups and move into “summer” quarters, such as attics, crev-
ices and cracks of buildings, and hollows of trees. With the
arrival of warm weather, these bats become busy hunters and
feed on insects from dusk to dawn. Once one of these bats has
its “sights” on an insect, it darts and dives, dips and dodges,
until the insect is caught. The bat may either eat the victim
while still in flight, or more likely, roost somewhere to eat it.

The little brown bat frequently is seen in open fields, fig. 2,
and may be found in abundance near lakes and other bodies of
water.

Bats of this species arrive at the “summer” colonies early in
April. Females are then already pregnant; they produce young
between mid-May and mid-July. A female gives birth to a
single young, which she carries with her for a few nights and
later leaves in the roost while she goes forth to feed. The young
is able to fly and fend for itself when about a month old.
Toward the end of summer, individuals of this species store up
great quantities of fat beneath the skin, to be used during the
winter sleep. In the fall they gradually desert the “summer”
colonies and by mid-November all have retreated to hibernating
quarters.

Frequently many generations of the little brown bat use the
same cave to hibernate in or the same building to roost in during
the summer. Bats of this species possess a definite homing in-
stinct and will return many miles to their colonies.

Distribution.—The little brown is the bat most common in
Illinois. However, from some localities it is seemingly absent
in summer, its place being taken by the evening bat. The Illinois
specimens are of the subspecies Myotis lucifugus lucifugus (Le
Conte). The species occurs from Labrador to southern Alaska
and southward to southern California, northern Oklahoma, and
southern Georgia.

MYOTIS AUSTRORIPARIUS (Rhoads)
Southeastern Bat

Description.—The southeastern bat is of medium size and
has large feet. It is grayish brown on the upper parts and pale
gray or white on the belly. The hairs of its dense woolly fur
lack burnished tips. The nose of a live individual of this species
is flesh colored, whereas the noses in other species of Myotis

Family VESPERTILIONIDAE 71

with which austroriparius might be confused are brown or
black.

Length measurements: head and body about 214 inches (53-55
mm.); tail 114-15@ inches (28-40 mm.); over-all 314-334
inches (81-95 mm.) ; hind foot about 3¢ inch (10-11 mm.) ; ear
14—5¢@ inch (13-15 mm.).

The skull is long, slender, rounded behind, has a slight sagit-
tal crest, and attains a maximum length of 14.0-15.5 mm.
(about 5% inch). Dental formula: I 2/3, C 1/1, Pm 3/3, M 3/3.

The southeastern bat is difficult to distinguish from related
species unless specimens are available for comparison. The best
distinguishing characters are woolly fur, grayish brown back,
pale gray or white belly, and large feet, each 10-11 mm. in
length.

Life History.—Little information about the life history of
the southeastern bat is available. In Illinois, this bat is known
to spend the winter months in caves and mines in the southern
part of the state. Bats of this species characteristically hiber-
nate in large, dense clusters.

Distribution—The southeastern bat is known in Illinois
only from caves and mines in Alexander and Hardin counties.
Specimens have not been found in summer, and it is not known
how common or widespread the species is in this state. The sub-
species in Illinois is Myotis austroriparius mumfordi Rice. The
range of the species is poorly known, but specimens have been
taken in southwestern Indiana, west-central Arkansas, Louisi-
ana, Georgia, and Florida, as well as southern Illinois, fig. 50.

MYOTIS GRISESCENS Howell
Gray Bat

Description—The gray bat, which is larger than the little
brown bat, is the only species of Myotis having a forearm 42
mm. or more in length. The attachment of the wing membrane
extends on the leg only as far as the ankle or tarsus. The fur is
velvety, and each hair is of the same gray color from base to
tip.

Length measurements: head and body 2-214 inches (51-57
mm.) ; tail 114-134 inches (33-44 mm.) ; over-all 314-4 inches
(84-101 mm.); hind foot 3-14 inch (10-12 mm.) ; ear about
Y¥g inch (15-16 mm.).

az Order CHIROPTERA

The skull, slightly larger than that of any other Myotis in
Illinois, has an over-all length of 15.9-16.4 mm. (about %
inch); it has a pronounced sagittal crest. Dental formula:
2/3 Cal/T; Pi-5/ SVS fo:

Life History.—In summer, the gray bat sometimes congre-
gates in large numbers in limestone caverns of this state. With
the approach of cold weather, most bats of this species leave
these caverns for places unknown. A few, however, may hiber-
nate in the Illinois caverns. Very little is known about this bat
in Illinois, for it has been taken at only a few places.

Distribution.—The gray bat is known in Illinois only from
Pike and Hardin counties, but it likely occurs throughout the
southern half of the state. No subspecies has been named. The
range of the species extends from eastern Kentucky and Ten-
nessee to western Missouri and northeastern Oklahoma, with an
extension in the east to northwestern Florida, fig. 50.

MYOTIS KEENII (Merriam)
Keen’s Bat

Description.—Keen’s bat is similar to the little brown bat
except that the ears are longer, fig. 516. When an ear is laid
forward, it extends 3 or 4 mm. beyond the tip of the nose. The
tragus in each ear is narrower and longer (about 9 mm. rather
than about 6 mm. long). The color of the fur on the under
parts is a bufher gray than in the little brown bat.

Length measurements: head and body about 1% inches
(47-48 mm.) ; tail 134-134 inches (36-43 mm.) ; over-all 314-
314 inches (84-90 mm.); hind foot 34 inch (8-9 mm.); ear
from notch 54 inch (15-18 mm.).

The skull is essentially as in the little brown bat. Its length
is 15-16 mm. (about 5¢ inch). Dental formula: I 2/3, C 1/1,
Pi3 /3;°M53/3.

Life History.—In Illinois, Keen’s bat hibernates in caves
and mines. It is less gregarious than other species of Myotis;
groups of a few individuals each hang apart from the larger
clusters of other kinds of bats in the hibernating chambers.
Although little is known of its “summer” habits, this bat appar-
ently is not colonial, and individuals find suitable abodes in such
places as mines, attics, crevices of buildings, and under eaves of
houses.

Family VESPERTILIONIDAE 73

Distribution.—Keen’s bat, distributed the length and breadth
of Illinois, may be common in some places, but the records of
the species for this state are surprisingly few. The subspecies
in Illinois is Myotis keenti septentrionalis (Trouessart). The
range of the species is discontinuous, one population occurring
in an area extending from Newfoundland to western North
Dakota and southward to central Arkansas and western Flor-
ida and another population occurring in western British Colum-
bia and western Washington.

MYOTIS SODALIS Miller & Allen
Indiana Bat

Description.—The Indiana bat is similar to the little brown
bat in body and skull size. The fur of the back is composed of
hairs that are blackish brown at bases, dull pinkish gray at
tips, rather than a bronzy brown as in the little brown bat. The
pinkish gray is conspicuous on the fur of the under side. The
Indiana bat differs from ithe little brown bat in that the hind
foot.is smaller (the foot of the latter is 10-11 mm. in length),
the hairs on the toes are much shorter and less conspicuous, and
along the calcar is a keel, or flap of skin, as shown in fig. 39.
The keel is most evident in live animals; frequently, in dry study
skins it cannot be discerned.

Length measurements: head and body 114-17% inches (40-48
mm.); tail 114-156 inches (30-42 mm.); over-all 234-314
inches (70-90 mm.); hind foot 34 inch (7-9 mm.); ear from
notch 34—-5¢ inch (10-15 mm.).

The skull differs from that of the little brown bat in such
small details as having a narrower braincase (less than 7.4
mm., about 14 inch) and narrower interorbital breadth (less
than 4.0 mm., about 14% inch). The number ot teeth is the same
as in other species of Myotis. Dental formula: I 2/3, C 1/1,
Pini3/3, M 3/3.

Life History—The Indiana bat usually hibernates in caves.
In these places individuals hang in compact clusters, often near
groups of the little brown bat. Hundreds of them are neatly
packed together in each cluster. Little is known about the colo-
nies after they leave the hibernating caves. However, some In-
diana bats may spend the “summer” in small colonies in other
caves.

74 Order CHIROPTERA

Distribution.—The Indiana bat is uncommon in Illinois,
although it is abundant in southern Indiana. It has been taken
in Hardin, La Salle, and Jo Daviess counties. No subspecies of
the Indiana bat has been named. The range of the species ex-
tends from New England to southwestern Wisconsin and south-
ward to central Arkansas, northern Alabama, and western

North Carolina, fig. 50.

MYOTIS SUBULATUS (Say)
Small-Footed Brown Bat

Although the small-footed brown bat has not been reported
in Illinois, there are many records of this bat in the northeast-
ern United States and isolated records for Missouri, lowa, and
Kentucky. It is therefore possible that it may be discovered in
Illinois when the caves and mines of this state are thoroughly
investigated. 2

Among the distinguishing features of this species are the un-
usually small feet and the golden sheen of the fur.

LASIONYCTERIS NOCTIVAGANS (Le Conte)
Silver-Haired Bat

Description.—The silver-haired bat, fig. 53, is black or
blackish brown, with white, appearing like silver, at the tips of
many of the hairs on its back. Fur continues from the back
onto the tail membrane and halfway to its tip. The ears are
short and rounded and each has a blunt tragus.

Length measurements: head and body 214-214 inches (54-64
mm.) ; tail about 114-2 inches (38-48 mm.) ; over-all 35¢—43¢
inches (92-112 mm.); hind foot 34-14 inch (9-12 mm.) ; ear
from notch 54 inch (14-16 mm.).

The skull, slightly larger than in Myotis, has a length of
16-17 mm. (about 5% inch). Dental formula: I 2/3, C 1/1,
Pm 2/3; Mi 3/3.

The silver-haired bat can be distinguished from the big brown
bat by the blackish fur with “silver-tipped” hairs on its back and
by its smaller size; from the red bat and the hoary bat by its
darker color and incompletely furred tail membrane.

Life History.—The silver-haired bat is known in Illinois
mainly as a migrant. A few individuals winter in the southern

Family VESPERTILIONIDAE 75

Fig. 53.—Silver-haired bat.

part of the state, but most of them migrate farther south. An
inhabitant of woodlands, fig. 1, this bat lives alone (not in colo-
nies) in the hollows of trees, beneath bark, or under leaves. It
often pursues insects near the tops of trees. It may occasionally
breed in Illinois, particularly in the northern part. An adult
female usually bears two young, in June or July, which must
develop rapidly to be prepared for the strenuous fall migration
southward.

Distribution.—The silver-haired bat is moderately common
throughout Illinois during the summer months. About the last
week of April it is fairly common in the vicinity of Urbana. No
subspecies is recognized. The species occurs from Nova Scotia
and southern Quebec to southern Alaska and southward to
central California, southern Arizona, southern Kansas, southern
Alabama, and southern South Carolina.

PIPISTRELLUS SUBFLAVUS (Cuvier)
Eastern Pipistrel

Description.—The eastern pipistrel, fig. 54, is the smallest
Illinois bat. Its fur is yellowish brown to drab brown, lighter
on the under parts of the body, and the wings are dark reddish
brown. Each ear has a blunt but straight tragus. This pipistrel
resembles the red bat but is paler and much smaller.

76 Order CHIROPTERA

Length measurements: head and body about 134 inches (44-47
mm.) ; tail 114-114 inches (29-39 mm.) ; over-all about 27%-
33 inches (73-86 mm.) ; hind foot about 34 inch (8-11 mm.) ;
ear from notch 34-54 inch (9-15 mm.). Weight: about a sixth
of an ounce (4.2 gm.).

The skull is small, measuring 12.3-13.0 mm. (about 14 inch)
in length. Dental formula: I 2/3, C 1/1, Pm 2/2, M 3/3.

Life History.—The eastern pipistrel spends the winter in
deep sleep, individuals hanging singly or in clusters of several in
the dark, damp chambers of caves. Because of the moisture in
the caves, droplets of water often cover the fur, and, when a
beam of light is played on the bats, the fur appears to glitter like
a coat of pearls, fig. 54.

Fig. 54.—Eastern pipistrel.

Family VESPERTILIONIDAE 77

Toward spring many pipistrels desert the winter caves and
take up abodes in attics of buildings, under porches, and in other
caves. Apparently they return to the same “summer” roosts year
after year. If removed some distance from such a roost, they
exhibit a definite homing instinct to return to it. During the
“summer” months, eastern pipistrels are entirely social and
usually hang in clusters.

In early summer, the sexes tend to separate while the females
bring forth their young. Usually an adult female has two off-
spring.

Pipistrels are early evening flyers and frequently hunt insects
before sundown. Their flight appears to be very erratic.

Distribution—The eastern pipistrel is common in much of
Illinois except in the Chicago area. It seems to be absent from
the Urbana region. It is more common in the southern than the
northern half of the state. Presumably, two subspecies occur in
this state, Pipistrellus subflavus obscurus Miller in the north-
western part and P. s. subflavus (Cuvier) in the remainder of
Illinois. The range of the species extends from New England
to Minnesota (except for Michigan and northern Indiana) and
southward as far as eastern Mexico and central Florida.

EPTESICUS FUSCUS (Beauvois)
Big Brown Bat

Description—The big brown bat, fig. 55, as the name im-
plies, is both big and brown. It has a wingspread of about
a foot but it weighs only half an ounce. It is dark or bronzy
brown, except for blackish ears, wings, and tail membrane. Its
ears are short and its tragi blunt.

Length measurements: head and body 23-27% inches (60-72
mm.); tail 134-17 inches (35-48 mm.); over-all 334-434
inches (95-120 mm.) ; hind foot about 14 inch (10-14 mm.) ;
ear from notch about 34 inch (16-20 mm.). Weight: about
14 ounce (13-16 gm.).

The skull is comparatively large and broad; it is 18.0-20.5
mm. (about 34 inch) in length. Dental formula: I 2/3, C 1/1,
Pm 1/2, M 3/3.

Life History—The big brown bat, common in Illinois in
summer, spends the daylight hours in a variety of places: in
attics of dwellings; in hollows of trees; beneath boards, shutters,

78 Order CHIROPTERA

or awnings; in abandoned buildings and in chimneys. An adult
female produces one or two young in early summer.

Being larger than most other bats, this kind includes in its
diet some of the larger insects, particularly June beetles and

click beetles, mayflies, caddisflies, lacewings, and parasitic wasps.

It is a late feeder, becoming most active when twilight is fading
into darkness.

In late summer, the big brown bat becomes exceptionally fat;
the fat gives a reserve of energy for the hibernation period
ahead. This bat winters in caves and buildings; it hangs less
often in clusters than does the little brown bat or the Indiana
bat. Apparently it is more tolerant of cold than are most other

Fig. 55.—Big brown bat.

Family VESPERTILIONIDAE 79

hibernating bats, and individuals may completely arouse them-
selves in midwinter and even fly abroad.

Distribution—The big brown bat occurs throughout IIli-
nois. The subspecies in this state is Eptesicus fuscus fuscus
(Beauvois). The species is widely distributed in North Amer-
ica, ranging from Nova Scotia and southern Quebec in eastern
Canada almost to the Yukon in western Canada and southward
to Panama. The range includes all of the United States except
parts of Florida and extreme southern Georgia and Alabama.

LASIURUS CINEREUS (Beauvois)
Hoary Bat

Description.—The hoary bat, fig. 56, with a wingspread of
more than 13 inches, is one of the largest bats in North Amer-
ica. The fur is a mixture of bright buff, yellows, and deep
amber, with a frosting of white laid in waves over the back.
This white frosting gives the bat a decidedly hoary appear-
ance. On the throat the fur is more yellowish and on the abdo-
men more whitish than on the back. The tail membrane is com-
pletely furred and much the same color as the back. The ears
are short, rounded, and thickened at the rims.

Length measurements: head and body 3-336 inches (77-86
mm.); tail 214-214 inches (53-64 mm.); over-all 514-5%
inches (130-150 mm.); hind foot about 14 inch (10-14 mm.) ;
ear from notch about 34 inch (17-19 mm.).

The skull is large and particularly broad, as in fig. 40e; its
length is 17-20 mm. (about 34 inch). Dental formula: I 1/3,
ia dim 2/2, MI 3/3.

Life History—The hoary bat normally winters in states
farther south than Illinois and migrates northward in spring.
Some individuals spend the “summer” season in Illinois and
some pass through this state while going farther north. In the
“summer” months, the hoary bat spends the daylight hours in
trees, among the leaves or on the trunks.

The hoary bat tends to be solitary; usually each individual
hangs alone and feeds with only one or two others. Bats of this
species are powerful fliers, and their slower, longer wing beats
undoubtedly permit them to have a more extensive cruising range
than other bats. Usually they start their evening hunting fairly
late, but sometimes they fly before sundown. Although bats have

80 Order CHIROPTERA

relatively few predators, it is known that a long-eared owl in
Illinois fed on two hoary bats.

Normally an adult female gives birth to two young in late
May or early June-and a few weeks later she may be so bur-

Fig. 56.—Hoary bat.

dened with the partially grown clinging young that she finds it
dificult to fly.

The hoary bat is somewhat similar to the red bat and the
silver-haired bat in its migration and solitary habits and in its
habitat preferences.

Distribution.—The hoary bat apparently is quite rare in
Illinois, although there are summer records of it from all parts
ot the state. The Illinois subspecies is Lasiurus cinereus cinereus
(Beauvois). The known range of the species includes most of
North America: from Nova Scotia and southern Quebec north-
westward almost to the Yukon and southward to include most
of Mexico. It does not include Lower California, part of
southern Mexico, and the southern half of Florida.

LASIURUS BOREALIS (Muller)
Red Bat

Description.—The red bat, fig. 57, is the most colorful of
the bats found in Illinois. The brick or rusty red color of its
body, with a dusting of white, clearly distinguishes it from all
other kinds. The wings are dark reddish brown and the shoul-

Family VESPERTILIONIDAE 8]

der patches light brown. The female is of a slightly paler color
than the male. This bat is of medium size, the ears are short
and rounded, and the tail membrane is fully furred on the top
surtace.

Length measurements: head and body 214 inches (55 mm.) ;
tail 114-214 inches (40-55 mm.); over-all 334-414 _ inches
(95-110 mm.) ; hind foot about 3¢ inch (8-10 mm.) ; ear from
notch about 14 inch (10-13 mm.).

The skull is 12.8-14.2 mm. (about 14 inch) in length. Dental
frmmastiel/3,°C 1/1, Pm 2/2,M 3/3.

Life History.—In Illinois the red bat is an early spring and
late fall migrant and a common summer resident. In the late
spring, a female red bat with one or two young attached may be
found on leaves of trees, on the ground, or on house porches;
the mother may be so undernourished and the young so large
that she cannot become air-borne.

Bats of this species are solitary and spend the daytime of
“summer” months beneath bark, under leaves, or in cracks of

Fig. 57—A family of young red bats hanging with heads down
from the branch of a tree (as viewed from directly below).

82 Order CHIROPTERA

trees, or even among tall weeds and shrubs. It is thought that
the coloration of the red bat, particularly the dusting or frosting
of white, enables it to remain better hidden in less protected
places than some other bats.

The long, narrow wings of the red bat make it an excellent
flyer and an adept insect catcher. Sometimes members of this
species start foraging beneath the branches of trees even before
the sun has gone down, but normally they become active about
twilight. They feed on insects around trees and other objects,
including cribs containing corn that is heavily infested with
grain moths.

On one occasion in eastern IIlinois, several red bats were at-
tracted by the watery appearance of freshly tarred roads, or by
insects caught in the tar, and were trapped in the sticky material.
At Starved Rock State Park in Illinois, a red bat and a blue
jay were captured together, the bat fastened by its teeth to the
side of the jay’s head; the bird was nearly exhausted, but the bat
appeared neither exhausted nor hurt.

The red bat frequently migrates southward in groups. It is
not known whether the “summer” residents of extreme southern
Illinois migrate out of the state or whether they overwinter
there.

Distribution—The red bat is common over all of Illinois
during the summer months. The subspecies in this state is
Lasiurus borealis borealis (Miller). The range of the red bat
includes most of the North American continent from extreme
southern Canada to Panama. Apparently not in the range is a
broad, irregular area that extends from central Mexico through
New Mexico into British Columbia and includes part of eastern
California and all of Oregon, Washington, and Idaho.

NYCTICEIUS HUMERALIS (Rafinesque)
Evening Bat

Description.—The evening bat appears to be a miniature of
the big brown bat; it is bronze or chocolate-brown, except for
blackish ears, wings, and tail membrane. The wingspread is
about 10 inches, and the length of each forearm is less than
15¢ inches (40 mm.).

Length measurements: head and body 134-214 inches (46-62
mm.) ; tail 13g—15@ inches (34-42 mm.) ; over-all 314-414 inches

Family VESPERTILIONIDAE 83

(80-104 mm.) ; hind foot 34-14 inch (9.5-14 mm.) ; ear from
notch 14—5¢ inch (13-17 mm.).

The skull is short, broad, particularly between the eyes, and
unique among Illinois bats in having a single incisor, canine, and
premolar in each side of the upper jaw. Dental formula:
Palys, Cel 1, Pm 1/2, M-3/3.

The evening bat is frequently confused with the big brown
bat, but it can be readily told by its smaller size and its shorter
forearms (about 13 inches or 35-37 mm.). It differs from the
little brown bat and other species of A/yotis in having blunt and
curved (rather than pointed and straight) tragi, only six teeth
in each side of the upper jaw (rather than nine), and a skull
that is broader through the interorbital region.

Life History.—In summertime, the evening bat seeks refuge
in buildings, foliage, or hollows of trees. Apparently it is
colonial. The absence of winter records for Illinois indicates
that bats of this species migrate southward. The evening bat
has a feeding and flight behavior that is said by some observers
to be much like that of the little brown bat; the flight of the
evening bat is said by other observers to be more steady and
straight. Members of this species commence feeding early in
the evening, often while the sun is still shining. A female usually
gives birth to a pair of young each year.

Distribution—The evening bat is abundant in southern
Illinois and at least as far north as Urbana; also, it is known
in the northeastern part of the state. The subspecies occurring
in Illinois is Nycticeius humeralis humeralis (Rafinesque). The
known range of the species extends from eastern Maryland to
southern Michigan and southwestward and southward to north-
eastern Mexico and southern Florida, fig. 50.

CORYNORHINUS RAFINESQUII (Lesson)
Southeastern Big-Eared Bat

Description—The southeastern big-eared bat, fig. 58, is
grayish brown or smoky brown. The under parts are silvery,
not buffy as in the closely related western big-eared bat, Cory-
norhinus townsendii. The enormous ears are nearly 1!% inches
long and are joined near their bases above the forehead. Lumps
are present on each side of the muzzle in front of the eyes. The
top side of the tail membrane is not furred.

84 Order CHIROPTERA

Length measurements: head and body about 2 inches (48—52
mm.); tail 134-214 inches (44-54 mm.); over-all 354-414
inches (92-106 mm.) ; hind foot about 14 inch (10-13 mm.) ; ear
from notch 114-114 inches (33-38 mm.). Weight: less than
half an ounce (about 12 gm.).

The skull is of medium size (over-all length about 16 mm.,

or 98 inch). Dental formula: I 2/3, C 1/1, Pm 2/3, M 3/3.

Fig. 58.—Southeastern big-eared bat.

The large, joined ears and lumps on the nose serve to dis-
tinguish this bat from all other kinds in Illinois. Until recently
this bat was known by the scientific name Corynorhinus ma-
crotis (Le Conte).

Life History.—Little is known of the southeastern big-eared
bat in Illinois. It is known to live in winter and summer in
caves or in structures having cave conditions. Individuals live
singly or in small colonies; the females when gravid live in
colonies separate from those of the males. An adult female usu-
ally produces one young in early summer; the young and mother
remain together for a period in a nursery colony. Although the
big-eared bat appears to be a strong flyer, it apparently does not
undertake long migrations and may hibernate in the vicinity of
the summer colonies. The large ears of this bat suggest that
they are unusually effective receivers of sound.

Order CARNIVORA 85

Distribution.—The southeastern big-eared bat is known in
Illinois only from Wabash and Alexander counties; it is evi-
dently rare in this state. The range of this bat extends from
southern Virginia and western West Virginia westward through
southern Indiana and southern Illinois and southward as far as
southern Louisiana and central Florida, fig. 50.

ORDER CARNIVORA
Carniyores or Flesh Eaters

The name Carnivora means flesh eaters. Members of the
order are usually referred to as carnivores. Most of them are
known as predators because they kill and eat other animals.
Domestic dogs and cats belong to this order, as do bears,
weasels, otters, skunks, raccoons, and several other wild animals.

Many of the carnivores are large animals which have van-
ished from densely populated areas such as Illinois and occur
now only in wilder and more sparsely settled parts of the coun-
try. The black bear, the timber wolf, the red wolf, and the
mountain lion are among those which once roamed this state but
no longer live here. The known distribution in the United States
of the least weasel and the badger, two carnivores having a lim-
ited range in Illinois, is shown in fig. 59.

Domestic dogs and cats are extremely similar in skeletal
characters to their wild relatives. For this reason they are in-
cluded in the identification keys prepared for this order.

Economic Status.—Wild animals of the order Carnivora are
probably second only to those of the order Rodentia from the
standpoint of economic importance in Illinois. Several carnivores
are important as sources of fur. The annual income from the
mink, for example, ranks second to that from the muskrat, one of
the rodents. Between 1936 and 1949 the yearly intake from
minks averaged about 35,000 pelts, and, at currently prevailing
prices, these pelts would have a value of almost half a million
dollars. The furs of other carnivores, such as raccoons, skunks,
badgers, and red foxes, are of little value currently, but they
have been valuable in the past and they may be again when
fashion demands long-haired furs.

Because of their predation on rodents and rabbits, weasels,
minks, badgers, and foxes are undoubtedly of great monetary
value to the Illinois farmer. Skunks consume enormous quan-

86 Order CARNIVORA

tities of insects during the summer months. Raccoons and foxes
provide sport to thousands of Illinois residents and a certain
aesthetic appeal to many people.

On the other hand, some carnivores—notably raccoons, weas-
els, minks, skunks, coyotes, and foxes—prey to some extent on
domestic poultry and game birds or their eggs. Although the loss

34

BADGER

Fig. 59—Known distribution, in the United States, of two Illinois
carnivores with a limited range in Illinois.

Order CARNIVORA 87

from such predation is less than is commonly supposed, it has
made these animals unpopular in some areas and among certain
groups of Illinois residents. Destruction of game bird eggs and
young by rodents is sometimes attributed to carnivores.

10.

KEY. TO*SPECIES
Whole Animals

Hind foot and front foot each with 5 toes, all of them with
EMINEM UNONG ACG. 0 5 Been d gine Sk os oc E = gah ee cae RE
Hind foot with 4 toes, front foot with 5 toes, all of them
with claws; the “thumb” situated well above the level of

PEMGLNEELIGES y (GICIUIONIGE «ooo at sates Fas eel wae es: 13
Tail with rings of butt and black; face with black mask

across forehead and eyes, fig. 62...... raccoon, Procyon lotor
ian witnoue sings; face with no dark mask. ..7........0.-. 3

Toes fully webbed; tail long and thickened at base........
ee otek s be river otter, Lutra canadensis

Toes not fully webbed; tail not thickened at base.......... a
Forehead with a median white stripe or square patch..... 5
Forehead with no median white marking................. 4
Body black or black with conspicuous white markings; tail
Beane. lenatiy of head--body'): ..69). 2)... 00.2.4 2c. 25. 6
Body brownish or yellowish gray; tail about a sixth of
lenpth: of head-fbody............4..- badger, Taxidea taxus

Upper side of body with 2 pairs of broken white stripes. ...
RN We OREN ET, spotted skunk, Spilogale putorius*
Upper side of body with 1 pair of white stripes or with a
prominent white patch on nape and back of head, fig. 67
Pemeates 653 eh res ed striped skunk, Mephitis mephitis
Over-all length of animal more than 1,000 mm. (39 in.) ;
tail very short; last molar larger than preceding tooth. .
Ee) ag a ea a black bear, Ursus americanus}
Over-all length of animal less than 1,000 mm.; tail at least
a sixth of length of head+body; last molar smaller than

Pepecrrenie Rte es Ula ats cab gees Liisa pedo opie c cea 8
Cheek teeth 5 above, 6 below on each side of jaws........ 9
Cheek teeth 4 above, 5 below on each side of jaws........ 10

Seeless tan. 90 mim. (315in.): longs 6 64 crete gs wenn =» «

0 ROS ee rere pine marten, Martes americanat
Skull more than 90 mm. long......... fisher, Martes pennanti}
Under parts of animal brown except occasionally for small

light patches on throat and belly; over-all length of ani-

mal more than 410 mm. (16 in.)...... mink, Mustela vison
Under parts of animal white or yellow; over-all length of
RTL ROSS Stash AN () CPT ct... leek dle Sapek i al Ivinee Swale 11

*This species may occur in Illinois, but there are no official records of it.
{This species is no longer found in Illinois.

88 Order CARNIVORA

11. Tail not black tipped, less than 40 mm. (114 in.) long; over-
all length of animal less than 220 mm. (8% in.)
Tail black tipped, more than 40 mm. long; over-all length
of animal more than 230 mm. (9 in.)....... pene e
12. Feet white; tail less than a third of over-all length of animal

Feet predominantly brown; usually tail more than a third

of over-all length of anunal ->.-. 2.22 22

13. Claws retractile, nearly concealed in fur and strongly
curved, fig. 61e¢; total number of teeth 30 or less .......
Claws not retractile, but well exposed and only moderately
curved, fig. 61f; total number of teeth 32 or more...

14. Tail less than a third of over-all length of animal; upper

least weasel, Mustela rixosa

12

short-tailed weasel, Mustela erminea*

long-tailed weasel, Mustela frenata

. 16

jaw with 3 cheek teeth on each side...... bobcat, Lynx rufus

Tail at least a third of over-all length of animal; upper
jaw with 4 cheek teeth om each side. . 2722. eee
15. Skull more than 175 mm. (6% in.) long; over-all length of

animal more than 800 mm. (3114 in.) ..cougar, Felis concolort

Skull less than 100 mm. (about 4 in.) long; over-all length

of animal less than, 700mm: .(2714: in.) ..... 252330 eeeeeee
16. Pupil of eye of living animal elliptical as in cats; length
of head+body less than 30 inches; tail straight and
bushy, 9) rus fwek). 2c. oe x so don Se
Pupil of eye circular; tail and length of head+body varia-
ble but, if head+body less than 30 inches long, tail usu-

ally curled or short haired...) . od... l..t. eee

17. Body gray above; tip of tail black; back of ears black......

Body reddish yellow above; tip of tail usually white; back

common cat, Felis domestica

17

gray fox, Urocyon cinereoargenteus

of ears rusty yellow red fox, Vulpes fulva

18. Tail variable in shape, size, and color, usually not black
tipped and without a black stripe along upper surface;

nose and ears variable...... domestic dog, Canis familiaris

Tail long, bushy, with black tip and tendency toward a

black stripe on the upper surface; nose and ears pointed.. 19

19. Legs, snout, and back of ears reddish; upper surface of
body distinctly reddish and with gray frosting..........

Mar RMR Che oot y ce Cac om. Bengt 4 ep NEY Oa eee red wolf, Canis nigert

Legs and face less reddish; upper surface of body gray and
without reddish cast:?) 2-050... es eee

20. Nosepad more than 24 mm. (1 in.) wide; over-all length of
animal usually more than 1,400 mm. (55 in.)............

Nosepad less than 24 mm. wide; over-all length of animal

A a et? ns ae timber wolf, Canis lupust

less than-1,300:mm. (51 in?) 3... oe coyote, Canis latrans

*This species ‘may occur in Illinois, but there are no official records of it.
{This species is no longer found in Illinois.

Order CARNIVORA 89

“MUdyy,

UMM tay

Is
“4,

“7

Fig. 60.—Characters used in the identification of carnivores:
a, skull of red fox, top view; 4, skull of gray fox, top view; ¢,
lower jaw of red fox, side view; d, lower jaw of gray fox, side

view.

Skulls
ease etetanntemrere sr Oe i Pe Sec a Phage we eis 2
Peter anater Ut k tee Ore OOS POSS ee ow Ces 4
Pee heeus 26; 14-in each jaw: bs. cus! s.. .35 _. bobcat, Lynx rufus
3

See eater a) HAT POLS Pee Ses. in se le a we eee ee

fs lenpth more than 175:mm. (676 in.) .-.... <4 de... 4%
cougar, Felis concolort

*This species is no longer found in Illinois.

90

10.

EI:

12.

13.

Order CARNIVORA

Skull length less than 100:mm. (4 in.) ..,-)3oe3epeeeeee-

a fg CE A es A Soe oes the common cat, Felis domestica
Teeth 40: of more... .... 65-2. sss naa 0. joe 5
Teeth. 38 or fewer... 2... 25% 3-2 «c+ ee, ye 11
Teeth 40; 2 molars on each side of lower jaw.............

Ooh ie ten Dh RT Si Ae ee oh raccoon, Procyon lotor
Teeth 42; 3 molars on each side of lower jaw............. 6
Rostrum short, the anterior end of the nasals midway be-

tween the orbit and the base of the incisors; last upper

molar larger than preceding molar ...2: 73350.

BR ic. Rcd get, AE Geet black bear, Ursus americanust
Rostrum long, the anterior end of the nasals much closer to

the incisors than to the orbit, fig. 60; last upper molar

smaller than preceding tooth... .).2:. 2. 76. ee 7
Frontal bones each with a depression along mesal side of

postorb:tal process, fig. 60; skull length less than 150 mm.

(5760 1m) e ae. aR a oe, 8
Frontal bones each convex, rounding over postorbital proc-
ess; skull length usually more than 150 mm............. 9

Temporal ridges widely separated posteriorly and lyrate in
shape, fig, 60); inferior margin of lower mandible with
poster:or “step” or third notch, fig. 60d_7. oes eee
Ls STs ae TE Ee ee gray fox, Urocyon cinereoargenteus

Temporal ridges close together posteriorly, fig. 60a, or ab-
sent; inferior margin of lower mandible without pos-
terior. ‘step.) fic. G0CiL mes eee ...red fox, Vulpes fulva

Width of skull across zygomatic arches usually more than
105 mm. (41 in.) ; length of skull usually more than 215
mini. (814 im.) S28. oa ae eae ee, ee

1 eee timber wolf, Canis lupust, or red wolf, Canis nigert

Width of skull across zygomatic arches usually less than 105
mm.; length of skull usually less than 215 mm........... 10

Palatal width divided by alveolar length of upper premolar-
molar series equaling 0.32 or less; rostrum width less than
LS percent ot skull lengths)... -..-.4e coyote, Canis latrans

Palatal width divided by alveolar length of upper premolar-
molar series equaling 0.33 or more; rostrum width more
than 18.per.cent of ‘skull: length? .. 2...2.... eee
Pp A Seem ETN a a Smee OF domestic dog, Canis familiaris

Upper jaw with 5 cheek teeth on each side................ 12

Upper jaw with 4 cheek teeth on each side. ............... 14

Lower jaw with 5 cheek teeth on each side...............
BR Ve oe oe he PERO ie ge river otter, Lutra canadensis

Lower jaw with 6 cheek teeth on each side................ 13

Length of skull less than 90 mm. (314 in.) heath
BRE OE ie Stat de Big. sia ad 5 «Soa ves pine marten, Martes americanat

Length of skull more than 90 mm..... fisher, Martes pennantit

*This species is no longer found in Illinois.
tThese characteristics are evident in relatively pure-blooded animals but plainly
will not distinguish between animals which are less than pure blooded.

Order CARNIVORA 9]

Uf
Ves

HUY

Ny
Sy
S
S

Fig. 61.—Additional characters used in the identification of car-
nivores: a, skull of mink, side view; }, skull of badger, side view;
c, palatal bone of skull of spotted skunk, under side; d, palatal
bone of skull of badger, under side; e, claw of domestic cat; f,
claw of dog.

14. Hard palate extending posteriorly to about even with last
molar, fig. 6lc..... + sat ee
Hard palate extending well behind last molar, fig. 61d.... 16
is. interorpital region of skull almost flat......77.........<.
io ee ere eae ree ...spotted skunk, Spilogale putorius*
interorbital region of skull strongly convex ....
ee ee ee ne eee striped skunk, Mephitis mephitis
16. Length of skull more than 100 mm. (4 in.) ; in lateral view,
the anterior portion of each zygomatic arch twice as broad
as the posterior portion, fig. 610... ... badger, Taxidea taxus
Length of skull less than 100 mm.; in lateral view, the an-

*This species may occur in Illinois, but there are no official records of it.

92 Order CARNIVORA

terior and posterior portions of the zygomatic arches ap-
proximately equal in width, fig. Gla... .2 2 Sree ee ov. 17

17. Length of skull more than 55 mm. (21, in.) ; auditory bullae

about as long as upper premolar-molar series in each row
Be Soren ee Tobe edie pode v'ey die Wb > oleae os ICI nan ary ce

Length of skull less than 55 mm.; auditory bullae longer
than upper premolar-molar series... 2. 272 eee 18

18. ‘Length of skull less than 33 mm. (114-18:) 295) gape ee -
Mas OCA Se hs ree hes eee Oe least weasel, Mustela rixosa

Length of skull more than 33 mm. ..long-tailed wea-
sel, Mustela frenata, and short-tailed weasel, M. erminea*

URSUS AMERICANUS Pallas
Black Bear

Description.—The black bear, the largest carnivorous ani-
mal in Illinois within historic times, is recognizable by its large
size, short tail, short black or dark brown fur, and brown
muzzle. On each foot it has five toes with claws.

The skull is nearly a foot long; the back teeth are broad and
flat (for crushing, not cutting). Dental formula: I 3/3, C 1/1,
Pm 4/4, M 273.

This bear is truly omnivorous. In winter, it sometimes sleeps
for periods of several days, but does not truly hibernate.

Distribution.—The black bear existed in the wooded and
swamp areas of Illinois during the last century. It disap-
peared first from the northern and central portions of the state;
some individuals remained in the southern part until the latter
half of the 1800’s. The subspecies which occurred in Illinois
was Ursus americanus americanus Pallas. The present range of
the species includes most of Alaska and Canada, with southern
extensions along the Sierra Nevada to central California, along
the Rocky Mountains to the Mexican Plateau, in the great
Lakes region to central Minnesota, Wisconsin, and Michigan,
and along the Appalachians to northern Georgia; the range in-

cludes also Florida and the Gulf Coastal Plain.

PROCYON LOTOR (Linnaeus)
Raccoon Coon

Description.—The raccoon, fig. 62, is a moderately large,
stocky animal weighing usually 10 to 26 pounds when adult.

*This species may ‘occur in Illinois, but there are no official records of it.

Family PROCYONIDAE 93

Fig. 62.—Raccoon.

It is readily distinguished by a mask of black over its eyes
and by a densely furred and ringed tail of alternate black
and light bands. Its fur is long and coarse; its color usually is
grizzled gray-brown, but varies from yellowish gray to nearly
black. Its muzzle is fairly sharp pointed, and its ears are prom-
inent, rounded, and furred. The feet are broad and plantigrade;
that is, the animal walks on nearly the entire under surface of
the foot. The five toes on each foot are provided with prominent
claws.

Length measurements: head and body about 20-28 inches
(500-720 mm.) ; tail 8-11 inches (200-280 mm.) ; over-all 28-39
inches (700-1,000 mm.); hind foot about +5 inches (95-120
mm.) ; ear 134-214 inches (45-58 mm.).

The skull (length 105-125 mm., or about 414 inches; width
65-80 mm., or about 3 inches) is nearly as large as that ot a
fox terrier dog, but has a short rostrum. The top of the skull
appears to be arched when viewed from the side; a bony palate
extends well behind the last molars. The teeth have short,
rounded cusps adapted more for crushing than for cutting food.
Dental formula: I 3/3, C 1/1, Pm 4/4, M 2/2.

Life History.—The raccoon, or coon as it is popularly called,
is sO common in wooded areas of Illinois that it is known to

94 Order CARNIVORA

nearly everyone. It is most abundant in wooded river bottoms,
fig. 3, and less abundant in wooded uplands. Watercourses with-
out tree cover usually provide less desirable habitat, as do
marshes and strip-mine ponds. Raccoons have always been mod-
erately common in Illinois and at one time were apparently so
numerous along the Kaskaskia River that the Indians are said to
have used their word for the animal as their name for the river.

The raccoon usually selects for its home or den a dry cavity
in a tree, fig. 1. It seems to have no preference for any particu-
lar species of tree so long as the cavity in the tree is large enough
and is dry. ‘The raccoon may also use for its den a dry crey-
ice in a cliff, the deserted burrow of a fox or woodchuck, or even
the lodge of a muskrat. It may also substitute quite satisfac-
torily a man-made den (a box with an opening near the top)
nailed to the trunk of a tree. During the daytime, the coon
sleeps in its den, and during the most severe parts of winter
may remain there in a dormant state for several days. How-
ever, it does not truly hibernate as does the ground squirrel or
the woodchuck, for it may awaken in a few moments; these
other animals may require hours to arouse themselves fully.

At night the raccoon wanders in search of food in woods,
fields, and particularly along streams or other bodies of water.
It feeds on a great variety of plants and animals and is an op-
portunist in that it makes use of any suitable food that is at
hand. In the fall, its diet may consist of three-fourths vegetable
matter and one-fourth animal matter. In the spring and sum-
mer, the greater part of the diet is likely to be animal matter.
Important plants in the diet are persimmons, pecans, acorns,
grapes, pokeweed berries, other fruit, and corn, particularly
corn in the milk stage. Important animals in the diet are insects
and crayfish, and to a lesser extent snails, earthworms, birds,
fish, snakes, and small mammals. When crippled waterfowl be-
come readily available, as during and following the hunting
season, the coon feeds heavily on these incapacitated birds. The
coon hunts skillfully in water and is adept at digging and climb-
ing. In the use of its hands and in its curiosity, it has a human-
like quality.

Breeding occurs in late January to early March, and the
young, normally three or four to a litter, are born usually in
March or April. At 30 days they occasionally leave the nest, and
at about 60 days they forage with their mother.

Family MUSTELIDAE 95

The coon is trapped or hunted in every county of Illinois. As
a furbearer, it is second or third (preceded by the muskrat and
usually the opossum) in the Illinois fur catch each year. More
than 10,000 trappers and hunters harvested coons in this state
in 1939 and in 1940, when at least 32,000 coons are estimated
to have been taken each year. Coon populations have increased
since that time, and the annual catch has undoubtedly increased
also. As a game mammal, the coon provides exciting sport. It
is hunted during autumn nights with the help of dogs and lights.
The clever running of the coon taxes the trailing ability of dogs
to the utmost and furnishes exciting sport to both men and dogs.

Signs.—Coon tracks, fig. 20, are most abundant along the
margins of streams, ponds, and lakes. Prints of individual feet
commonly vary from 3 to 4 inches in length. Tracks of small
coons look somewhat like those of large muskrats, but the latter
usually are accompanied by tail marks; the birdlike prints of the
four-toed front feet also distinguish the muskrat tracks. The
usual gait of the coon is a walk.

Scats or droppings of coons may be found along margins of
streams and lakes, usually on logs. Often great accumulations
of them may be found, because coons commonly follow regular
routes and leave their droppings in a few chosen spots. Large
quantities of crayfish parts, corn, cherry pits, or berry seeds are
characteristic of them.

Distribution.—Raccoons are present in every county of IIli-
nois and are particularly common in those parts of the state
with extensive wooded areas. I'wo subspecies are known to
occur in Illinois, Procyon lotor hirtus Nelson & Goldman in the
northwestern four-fifths of the state and P. /. Jotor (Linnaeus)
in the southeastern fifth. The range of the species includes ex-
treme southern Canada; all of the United States except a west-
ern area that contains parts of the southwestern deserts, western
parts of Wyoming and Montana, and most of Idaho; also the
range includes Mexico and Central America.

MARTES AMERICANA (Turton)
Pine Marten Marten

Description.—The pine marten is similar in shape to the
better-known mink but is slightly larger. Its fur is yellowish
brown on the body and shades to dark brown or black on the

96 Order CARNIVORA

tail and legs. On the throat and chest is a pale buff patch. The
tail (about 9 inches long) is usually half as long as the head
and body (about 18 inches).

The skull, which has a rounded, broad braincase, is approxi-
mately 85 mm. (about 33% inches) long in the male and 75 mm.
(about 3 inches) in the female. Dental formula: I 3/3, C 1/1,
Pm 4/4, M 1/2.

Distribution— The marten was recorded from Cook County
by Robert Kennicott (1855:578), and a marten skeleton taken
“in northern Illinois” is preserved in the Museum of the Chi-
cago Academy of Sciences. Probably the marten once occurred
in several of the northern counties of our state where there
were stands of white pine. There are no records of its present-
day occurrence in Illinois, but there are several for Wisconsin.
The marten is an arboreal animal, principally of the conifer-
ous forests. The subspecies in Illinois was Martes americana
americana (Turton). The species is found from Labrador,
Newfoundland, Nova Scotia, northern New York to Alaska,
and southward in western Canada to the northwestern United
States, with extensions in the Sierra Nevada to south-central
California and in the Rocky Mountains to the northern part of
New Mexico.

MARTES PENNANTI (Erxleben)
Fisher

Description.—The fisher is similar in appearance to the
marten but is larger (head and body about 23 inches long) and
darker, being mostly of a dark brown, almost black color with
a slight frosting of white. It has no buff patch on throat and
chest, although some small white patches may be present. The
tail (about 14 inches long) is somewhat longer than half the
length of the head and body.

The skull is like that of the marten but larger (about 120
mm., or about 434 inches, long). Dental formula: I 3/3, C 1/1,
Pm 4/4, M 1/2.

Distribution.—The fisher formerly occurred in northernmost
Illinois. According to Robert Kennicott (1855:578), it “used
frecuentlv to be seen in the heavy timber along Lake Michigan”
in Cook County and (1859:241) “It has been found, within a
few years, in Northern Illinois, and appears to be an inhabitant

Family MUSTELIDAE 97

ot the woods, alone.” ‘The fisher is chiefly arboreal and in-
habits timbered swamps or woods near water. It feeds on vari-
ous-mammals, including mice and porcupines, and on birds. ‘he
subspecies in Illinois was Martes pennanti pennanti (Erxleben).
The species now has a range from Labrador, Nova Scotia, and
northern New York to northern British Columbia, with south-
ern extensions to Yellowstone National Park and to central
California.

MUSTELA RIXOSA (Bangs)
Least Weasel

Description.— The least weasel, fig. 63, as the name implies,
is the smallest of our weasel-like mammals and also the smallest
known American carnivore. It has a slender body (only about
114 inches in diameter) and a stubby tail about a fourth as long
as the body. Its body is as long as that of an adult Norway
rat, but is much slimmer. The least weasel has two coats or
two “colors” each year, an entirely white coat and a summer
coat that is dark brown above and whitish beneath. The tail
is of uniform color, whether white or brown, and does not have
a conspicuous black tip, although the tip may have a few darker
hairs. The upper sides of the feet are white in summer as well
as in winter. |

Length measurements: adult male, head and body 6-714
inches (153-191 mm.), tail 114-114 inches (28.0-37.5 mm.),
over-all 73-9 inches (188-230 mm.), hind foot about 7 inch

Fig. 63.—Least weasel.

98 Order CARNIVORA

(23 mm.); adult female, head and body 5-714 inches (127-184
mm.), tail 1-114 inches (25-33 mm.), over-all 634-814 inches
(170-217 mm.), hind foot about 34 inch (19-21 mm.). Weight
(adult) : about 2 ounces.

The skull is small (30.5-33.0 mm., or about 114 inches, long)
and delicate. Dental formula: I 3/3, C 1/1, Pm 3/3, M 1/2.

Life History.—The least weasel commonly lives in a den
about 6 inches below ground. It may appropriate the nest cavity
and nest of a meadow vole. Very little is known of its breeding
habits, but they are probably similar to those of the long-tailed
weasel.

The least weasel can go many places that mice can go and
consequently preys on them to a considerable extent. A few least
weasels may be exceedingly valuable in controlling meadow voles
and white-footed mice in fields. In Ohio, one storehouse of 2
least weasel contained nearly a hundred discarded skins of
meadow voles. Probably during the summer it preys exten-
sively on the readily available insects.

Signs.—Tracks of the least weasel are like those of other
weasels but smaller and without tail marks. The toe marks
rarely show. The usual gait of this weasel is a bound. The
long prints of the hind feet, which lead in the bound, are between
34 and 1 inch long, whereas those of the long-tailed weasel are
between 114 and 2 inches long.

Droppings of this weasel are packed with mouse fur and great
numbers of insect parts.

Distribution.—The least weasel, uncommon in Illinois, is
known to occur only in the northern three or four tiers of
counties except in the eastern part of the state, where it extends
south into Champaign County. The subspecies in Illinois is
Mustela rixosa allegheniensis (Rhoads). The range of the spe-
cies includes an area that extends from the St. Lawrence River
northwestward to northern Alaska, with extensions southward
to northern Montana, southern Nebraska, central Illinois, and
along the Appalachians to North Carolina, fig. 59.

MUSTELA FRENATA Lichtenstein
Long-Tailed Weasel

Description.— The long-tailed weasel, fig. 64, is a slender ani-
mal; its length is accentuated by the long, slim tail, which is

Family MUSTELIDAE 99

Fig. 64.—Long-tailed weasel.

slightly bushy. In summer, its fur is a soft brown color except
for that on the abdomen and chest, which is whitish, suffused
with yellow, and the tip of its tail, which is black. In winter
in the northern part of its range, the fur of the long-tailed
weasel turns “white” except for the conspicuous black tip of the
tail; the fur of the under parts is usually washed with a yel-
lowish color. In the southern part of the range of this animal,
both brown individuals and white individuals may be found;
those which do not become whitish have a winter coat that is
thicker than the summer coat and of a different shade of brown.
Much additional information is needed regarding the occur-
rence of long-tailed weasels in Illinois and the percentage of
individuals, if any, that in a particular area turn whitish.

In size, there is a marked difference between the male and
the female of the long-tailed weasel; the male is generally
considerably larger than the female. The sex of a weasel speci-
men should be determined before a positive identification is
attempted.

Length measurements: adult male, head and body 914-1014
inches (235-260 mm.), tail 414-514 inches (110-140 mm.),
over-all 1334-1534 inches (350-400 mm.), hind foot 114-2
inches (40-50 mm.); adult female, head and body 834-914
inches (223-235 mm.), tail 3-414 inches (76-108 mm.), over-all
1134-1314 inches (298-338 mm.), hind foot 114-114 inches
(31-38 mm.). Weight: adult male 6-10 ounces; adult female
3-7 ounces.

The skull of the long-tailed weasel is much like that of the
mink but smaller, less angular, and less strongly ridged. ‘The

100 | Order CARNIVORA

auditory bullae are inflated and long anteroposteriorly. The
over-all length of the skull in the male is 43-50 mm. (about
17% inches); in the female, 30-42 mm. (about 11% inches).
Dental formula: £3/3, C 1/1, Pm 3/3, M 1/2.

Life History.—The long-tailed weasel occurs over much of
Illinois in brushland, along shrubby fencerows, in haystacks,
in brush piles, and sometimes under farm buildings. It preys
principally on rodents and is most apt to be found where small
mammals are abundant. In IIlinois, as in other states, it feeds
heavily upon voles, white-footed mice, ground squirrels, rabbits,
rats, birds, insects, and, in fact, upon almost any animal it can
overpower.

A hungry long-tailed weasel, once on the trail of a rabbit,
is an intent, relentless pursuer. A healthy rabbit, however, will
give the weasel a good run and may cleverly confuse its own
trail by hopping back and forth over a small area. Again, the
rabbit may freeze motionless and be nearly lost to sight in a
tangle of brush so that the weasel may pass it by momentarily.
The rabbit may make a confusing maze of tracks before dashing
off, and the shorter-legged weasel must hustle to keep up with its
prey. But once the gap is sufficiently narrowed between predator
and prey, the weasel makes a quick dash and bites the rabbit at
the base of the skull. Over and over the two may tumble, the
weasel holding on tenaciously until the rabbit ceases to struggle.

The long-tailed weasel usually makes its home in the burrow
of a ground squirrel or larger mammal, after slightly remodel-
ing the entrance and nest. A few droppings near the entrance
and bluebottle flies humming about announce that the burrow is
no longer occupied by a seed- or herb-eater but by a carnivore
that has a store of meat inside. Dry grass, leaves, and mouse
fur are common nesting materials of this weasel.

An adult female gives birth annually to a single litter of
young, usually four or five in number, in the spring. Throughout
the first month the young remain in the den, and food is brought
to them. Soon they are providing their own food. When 3 to 4
months old they are nearly full grown. An adult weasel can
consume each day an amount of flesh equivalent to about a
third of its weight.

Signs.—Tracks of the long-tailed weasel. like those of the
mink and the least weasel, are seen usually in the bounding
pattern, the long prints of the hind feet leading and the short

Family MUSTELIDAE 101

prints of the front feet trailing. Each footprint is oval and,
unlike the mink footprint, it rarely shows toe marks. Unlike
the tracks of the least weasel, its tracks may be accompanied
at times by tail marks. Each footprint is larger than that of
the least weasel.

Droppings of the long-tailed weasel may be found along
fences or near its den. They usually contain insect parts, fur
of mice, and bird feathers.

Distribution—The long-tailed weasel occurs the length and
breadth of Illinois. In this state is the subspecies Mustela fre-
nata noveboracensis (Emmons). The range of the species ex-
tends from southern Quebec to central British Columbia and
into Central America. Records are lacking for Lower Cali-
fornia and some desert regions of Arizona and California.

MUSTELA ERMINEA Linnaeus
Short-Tailed Weasel

To date there are no Illinois records of the short-tailed
weasel, but since this species is known to occur at Beaver Dam,
Wisconsin, only 70 miles north of the Illinois-Wisconsin line,
there is some possibility that it may eventually be found in the
counties of extreme northern I[Ilinois.

The short-tailed weasel is similar to the long-tailed weasel
ini size and general appearance; it differs in that summer speci-
mens have white feet. White specimens of the two species are
dificult to separate but usually differ in tail length (see key to
the Carnivora).

MUSTELA VISON Schreber
Mink

Description.—The mink, fig. 65, is weasel-like in build and
is sometimes referred to as a water-weasel. Its color is dark
brown, except for black at the tip of the tail, white on the chin,
and occasionally white spots on the throat and chest. Its ears
are short and hardly discernible in the fur. The thickly haired
tail is about two-fifths as long as the head and body. The male
is larger than the female.

Length measurements: adult male, head and body 1312-1534

inches (345-400 mm.), tail 714-814 inches (185-210 mm.),

102 Order CARNIVORA

over-all 21-24 inches (530-610 mm.), hind foot 214-234 inches
(55-70 mm.); adult female, head and body 1114-13% inches
(290-340 mm.), tail 514-714 inches (135-190 mm.), over-all
1634-21 inches (425-530 mm.), hind foot 2-214 inches (53-62
mm.).

The skull, fig. 61a, of the mink is similar to but larger than
that of the largest weasel and has a more pronounced median
dorsal ridge and more flattened auditory bullae. It differs from
that of the skunk in that the shelf of the bony palate extends well
back of the last molar, and the last upper molar is dumbbell
shaped. The skull of the male is 60-70 mm. (about 256 inches)
long, of the female 55-63 mm. (214-214 inches). Dental for-
mula Les 7/30 CA lee Ramr3y/ 35 Vii 2

Life History. The mink is at home on land or in water.
It may dig a burrow for itself, or, more likely, it may take over
a muskrat den in a lake or a muskrat burrow in the side of a

Fig. 65.

Mink.

Family MUSTELIDAE 103

stream bank for a home without remodeling it. “The mink seeks
food principally along the shores of lakes or the banks of streams
and ditches. It feeds most often on young or sickly muskrats.
It feeds also on aquatic insects, crayfish, frogs, snails, some
water birds, and, since it is an excellent swimmer, it preys at
times on fish, particularly the smaller kinds. Occasionally, and
as circumstances dictate, it forsakes the stream or lake edge for
a meadow, where it preys upon meadow mice, white-footed mice,
and rabbits.

The mink hunts mainly at night. It is a bold hunter and seems
to spend less time stalking its prey than do weasels. Each
animal probably patrols several miles of lake shore or ditch or
river bank. Like its relatives, the weasels, it kills wantonly
whenever it comes upon a brood of chicks, a family of mice, or
any other concentration of prey species. Its enemies are individ -
uals of its own species, foxes, horned owls, dogs, and trappers.
The mink is hunted and trapped as one of the most valuable
furbearers of Illinois.

An adult female has annually but one litter of young, usually
numbering 5 or 6, in April or May. At birth the young are of
pea-pod size and helpless; in 2 months they may go on short
forays with the mother. The brood breaks up in late summer.

The mink, like the skunk and the weasel, has scent or musk
glands. Although the amount of musk discharged is small, its
odor is potent and perhaps more offensive to man than that of
the skunk or weasel. The scent is emitted by the mink most fre-
quently during the breeding season, when individuals are trying
to attract those of the opposite sex.

Signs.—Although the mink has five toes on each foot, only
four show in each print, fig. 25. Front and hind prints are prac-
tically alike and are about 134 inches across. In the usual gait
of the animal, which is bounding, prints of the hind feet are al-
most side by side and in front, while those of the front feet are
close behind these and one slightly trails the other. Six to 20
inches may separate each complete set. In fluffy snow, the tail
mark may show on each set but not between sets.

Droppings of the mink may be found along the margins ot
waterways and may be recognized by their contents and by their
shape, each having one end more or less spirally twisted. ‘They
generally are packed with hair and crayfish parts and occasion-
ally with fish and frog remains.

104 Order CARNIVORA

In summer, a tuft of fur or feathers and bluebottle flies near
what appears to be a woodchuck or a muskrat burrow are
signs that a mink may be using the burrow.

Distribution.— Fhe mink is fairly common in all parts of
Illinois. The subspecies Mustela vison letifera Hollister is
found north and west of the Illinois River and M. v. mink Peale
& Beauvois in the remainder of the state. The range of the
species includes most of Canada, Alaska, and the United States.
It does not include the extreme north or the arid regions of
southwestern United States.

LUTRA CANADENSIS (Schreber)
River Otter

Description.—The river otter, fig. 66, is an elongate, short-
legged, thick-tailed aquatic cousin of the mink and the weasels.
Its thick, short fur, small ears, round tail, which is thick at the
base and tapered to a tip, and large webbed feet are adapta-
tions for agility and speed in the water. The fur is mostly a
rich dark brown, slightly lighter in tone on the under parts,
grayish brown on the throat, and grayish white on the chin and
lips.

Length measurements: head and body about 28 inches (700
mm.); tail 16 inches (400 mm.); over-all about 43 inches
(1,100 mm.) ; hind foot 514 inches (130 mm.). Width of tail

Fig. 66.—River otter.

Family MUSTELIDAE 105

at base: about 314 inches (90 mm.). Weight: approximately 20
pounds.

The skull is large, especially the braincase, and is about 105
mm. (4 inches) long and 70 mm. (234 inches) wide. It is not
heavily ridged. The auditory bullae are flattened, and the teeth
are massive. Dental formula: I 3/3, C 1/1, Pm 4/3, M 1/2.

Life History.—The river otter lives along streams and lakes.
Only infrequently does it wander far from them on excursions
from one body of water to another. Its large den, usually with
an entrance diameter of about 10 inches, is never more than a
few hundred yards from water. Usually it is in a stream bank
or on a lake shore, either above or below water, and protected
by roots of large trees or by overhanging banks. For its den,
the otter may use a natural cavity or a burrow, such as that
of the woodchuck. Breeding occurs in winter, and about 11
months later a litter, usually of three young, is born. The male
usually stays in the general vicinity of the den, but the female
does not let him join the group until the young are old enough
to travel. During their third or fourth month, the cubs are
forced to learn to swim. A family group may hunt and fish over
a waterway of 10 or more miles during the season. The river
otter feeds on crayfish, frogs, turtles, earthworms, aquatic in-
sects, and fish.

Signs.—Most conspicuous of all otter signs are the slides—
the places where the animals gather to enjoy a slide down clay
or snow banks into water. These slides are a foot or more wide
and may be a dozen to many feet long. Otters remove every
stick and stone from the slides, and, as the water dripping from
their pelts makes the clay or snow very slippery, the descent
is fast.

The surest place to see otter tracks, fig. 23, is on the shores
and islands of large rivers. When much snow is on the ground,
the otter sometimes propels itself by pushing itself along, mak-
ing a deep groove in the snow; even when it walks in shallow
snow its short legs allow its body to drag, leaving a continuous
trail. When traveling at considerable speed through deep snow,
the otter bounds in such a way that it leaves a well-marked,
full-length impression of its long body on the trail.

Distribution.—The river otter was once fairly common along
the large streams of Illino-s, but apparently by the early 1800's
it was scarce in most parts of the state. Since 1900, it has been

106 Order CARNIVORA

seen or taken in 25 counties; records indicate a sporadic occur-
rence in all but the northeastern part of the state. The river
otter in Illinois belongs to the subspecies Lutra canadensis cana-
densis (Schreber)— The range of the species includes most of
Canada, Alaska, and the United States.

MEPHITIS MEPHITIS (Schreber)
Striped Skunk

Description.—The striped skunk, fig. 67, is a short-legged,
black and white animal, about as large as a house cat, but with
a bushy tail and a pointed head. This skunk is predominantly
black in color, but it always has at least a white stripe on the

Fig. 67.—Striped skunk.

Family MUSTELIDAE 107

forehead and a white patch on the top of the head. If an indi-
vidual has no more white than this, it is classified by fur dealers
and trappers as a “black” or “star.” From the white patch, two
white stripes may fork and extend a short distance down the
back (“short stripe” or “narrow stripe’), or the stripes may
extend all the way to the tail and may be joined together
(“broad stripe’). The basal half of each hair on the tail is
white, the other half black, except that the group of hairs at the
tip of the tail may be entirely white. he claws on the front
feet are long.

Length measurements: head and body 15-1614 inches (385-
420 mm.) ; tail 7-9 inches (175-230 mm.), over-all 22—26 inches
(560-650 mm.), hind foot 214-234 inches (58-70 mm.).

The over-all length of the skull is 62-80 mm. (234-314
inches) and the width 40-46 mm. (114-134 inches). It differs
from other carnivore skulls in having on each side only one
upper molar, which is more or less square, and two lower
molars. The auditory bullae are not greatly enlarged, and the
shelf of the bony palate extends no farther than the last upper
molars, approximately as in fig. 6le. Dental formula: I 3/3,
adil, Gua.3/3,;M. 1/2,

One of the characteristic things about the skunk is the odor of
its musk. A yellowish material, composed chiefly of mercaptan,
musk is expelled from glands, one on each side of the anus of
the skunk. ‘The musk is used by the skunk in defending itself.

Life History.—The striped skunk usually lives in a burrow
or underground den—the modified home of a woodchuck or
ground squirrel. It may also live beneath the floor of a barn or
shed. This skunk is at home in a multitude of environments: at
the edge of woods, in brushy country, along fencerows, near
grassy meadows, or around outbuildings; but it seldom strays
far from a drainage ditch, creek, or other source of water.

This skunk normally does its feeding at night, but occasion-
ally it may be abroad in the daytime. It is sluggish in its move-
ments, and usually it shows little fear of potential enemies,
including man. Occasionally it may be seen ambling along in
brush or woods in the daytime, fig. 2. It prefers to depend on
its defensive scent mechanism rather than on rapid flight. When
the skunk encounters an intruder, it first gives a warning by
elevating its tail straight as an exclamation mark, pluming out
its tail hair, and stamping its front feet. If the intruder comes

108 Order CARNIVORA

too close, the scent glands, with nozzles properly focused, go
into action.

The striped skunk eats whatever suitable food is most readily
available. In winter, it feeds on hibernating insects, mice, and
fruits. In the warmer seasons, it feeds heavily on berries and
other fruits, eggs, insects, mice, and some of the smaller birds
and snakes. At any season it may become a carrion eater and
probably includes in its diet many animals killed on highways.
This skunk may den up and sleep during the coldest days of
winter, but it never truly hibernates, as do some of the bats, the
woodchuck, or the ground squirrels.

Young of the skunk are born in late spring and number 4 to
10 per litter. Within a single litter, they may show much yaria-
tion in the amount of white on the back; some may be “blacks”
and others “broad stripes.’ Although the young are blind and
helpless at birth, they grow rapidly and are hunting by July.

Signs.—The prints of the hind foot of the skunk are each
about 214 inches long and rarely show claw marks; the prints
of the front feet are each about 2 inches long, broad, and fre-
quently show claw marks. The track, fig. 35, made by a skunk
traveling at a walk consists of a parallel arrangement of closely
spaced footprints on each side; that by a running animal consists
of sets of footprints arranged diagonally across the direction of
travel, and in each set prints of hind feet are on the outside.

Droppings are about a half inch in diameter and frequently
contain insect parts, berry seeds, and fur. Diggings in leaf mold
or soft ground often indicate where a striped skunk has dug out
grubs or other insects or uncovered a mouse.

Distribution.—The striped skunk is moderately common in
all counties of Illinois. —TItwo subspecies are present, JJephitis
mephitis nigra (Peale & Beauvois) in the southern third and ex-
treme eastern parts of the state and M. m. avia Bangs in the
remainder of Illinois. The range of the species includes ap-
proximately the southern half of Canada, the United States
(except the southern tip of Florida), and northern Mexico.

SPILOGALE PUTORIUS (Linnaeus)
Spotted Skunk Civet Cat

The spotted skunk is known from adjacent Iowa and Mis-
souri, and there is an unreliable 1910 sight record for this ani-

Family MUSTELIDAE 109

mal from Golconda in southeastern Illinois. Because this skunk
is in lowa and Missouri, it may eventually be found in Illinois,
perhaps in counties bordering the Mississippi River.

Diagnostic features of the spotted skunk are outlined in the
key to the Carnivora.

TAXIDEA TAXUS (Schreber)
Badger

Description.—The badger is a short-legged, squat animal
weighing 20 to 35 pounds, fig. 68. It is mostly yellowish gray
in color and has a white stripe extending from the nose over
the forehead and disappearing on the back, white cheeks, with
a black spot on each, yellowish under parts and tail, and black
feet. Its ears are small, its tail is short and bushy, and its large
forefeet are provided with long claws. Its sturdy body and
powerful forelegs make the badger an effective digger.

Length measurements: head and body about 241% inches
(620-640 mm.), tail, from base to tip of bone, 4-6 inches (100-
150 mm.), over-all 28-31 inches (720-790 mm.), hind foot 314-5
inches (90-130 mm.), ear from notch about 2 inches (50 mm.).

Fig. 68.—Badger.

110 Order CARNIVORA

The skull of the badger is broad in proportion to its length
(about 120 mm. or 434 inches long, 85 mm. or 33 inches wide),
the auditory bullae are very large, and the palate extends well
beyond the end of the upper molars, fig. 61b, d. Each lower cut-
ting tooth (carnassial or first molar) has a prominent internal
cusp. Dental formula: I 3/3, C 1/1, Pm 3/3, M 1/2.

Life History.—The badger lives in open country and seems
to prefer sand prairie, as it occurs less frequently on prairies
with heavier soils. It not only readily digs out the burrows of
ground squirrels and woodchucks but makes its own burrows.
In one case, a badger decided to “surface” from its burrow be-
neath a well-packed, frequently used macadamized road near
Savanna; it made an opening through the macadam as if this
material were no harder than soil.

In spring the badger uses its home burrow as a nest chamber
in which to bring forth and care for its young, usually number-
ing three. In winter the animal may sleep for several days
during cold periods, although it never truly hibernates.

The badger is active at night and occasionally during daylight
hours. It preys extensively on ground squirrels, woodchucks,
and meadow mice. Probably three-fourths of its food in Illinois
consists of mammals, most of which are pests to man. It also
eats insects, frogs, a few birds’ eggs and nestlings, and rabbits.

Signs.—Badger tracks, fig. 36, are distinguished by long claw
marks of the short, broad front feet and by the narrower prints
of the hind feet. The prints of the front feet are each about
234 inches long and 2 inches wide, and of the hind feet about
314 inches long and 134 inches wide. The usual gait of the
badger is a shuffle, as shown by the parallel arrangement of the
closely spaced footprints. The width between right and left
prints is about 8 inches. Prints of the front feet are markedly
pigeon-toed.

The burrow is 10 or more inches in diameter and usually
enters the ground at a steep angle. Even shallow beginnings of
badger burrows may be distinguished from the diggings of dogs;
dogs tend to scratch in only one direction, while the badger ro-
tates its body and digs at the side walls. A shallow digging by
a dog tends to be vertically oval in cross section and to have
relatively few claw marks on the sides and many on the bottom.
The badger digging tends to be horizontally oval in outline and
to have a high proportion of claw marks on the side walls.

Family CANIDAE 11

Distribution.—According to a report by Robert Kennicott
(1859:250), the badger was present in northern Illinois at the
time he wrote. It had once been ‘“‘numerous, at least as far
south as the middle of the State,” and had been seen 30 years
before “near the Kaskaskia River.”’ Subsequent reports indicate
that by the late 1800's the badger had nearly disappeared from
Illinois, but in recent years it has re-established itself in the
northern half of the state. It is now common locally in north-
western Illinois and is known as far south as Fulton and Doug-
las counties. The subspecies in this state is Taxidea taxus taxus
(Schreber). The range of the badger includes most of the west-
ern half of the United States, fig. 59, with eastern extensions
into Michigan and Ohio, northern extensions into southern
Canada, and southern extensions into northern Mexico.

VULPES FULVA (Desmarest)
Red Fox

Description.—The red fox is about the size of a small dog
and has a pointed muzzle, prominent ears, and a long, bushy tail.
It is mostly yellowish red in color (the color is more intense
down the middle of the back and on the tail than elsewhere) ;
it is whitish on the belly, throat, cheeks, and inner sides of the
ears. Its feet are black, and its tail is tipped with white.

In Illinois this fox rarely shows marked color variations or
color phases. A “silver” fox is an individual that has black fur,
instead of red, with white hairs sprinkled among the black. A
“cross” fox is an individual that has part of the fur black and
part red, with the black along the back and over the shoulders
forming a cross as seen from above. It resembles a gray fox
superficially. A “black” is entirely melanistic.

Length measurements: head and body 28-34 inches (715-870
mm.), tail 12-15 inches (300-380 mm.), over-all 40 inches
(1,015-1,025 mm.), hind foot 614-65¢ inches (160-170 mm.),
ear from notch 314 inches (85-90 mm.). Weight: 8-14 pounds.

The skull is 135-160 mm. (514-614 inches) long; the two
temporal ridges on top of the braincase, fig. 60a, may closely ap-
proach one another or may converge to form a weak sagittal
crest. The lower jaw has two notches at the posterior end,
fig. 60c, but lacks the “step” of the gray fox, fig. 60d. Dental
formula: I 3/3, C 1/1, Pm 4/4, M 2/3.

112 Order CARNIVORA

Life History.—The red fox is so versatile and so adaptable
in its food habits that it has not only been able to survive but
to increase successfully in the face of constant fur and bounty
hunting and a changing environment brought about by man.

This fox occupies various kinds of habitat, but it seems most
at home in strongly rolling country where land use has resulted
in an irregular arrangement of fields, meadows, and semiopen

Fig. 69——Young of red fox near entrance to den.

woodlands, fig. 2. The range of an established, unharassed indi-
vidual, pair, or family is not extensive, probably having a radius
of about a mile.

In late December and early January, a careful observer will
begin to see the double trails made by paired foxes running to-
gether, indicating that the mating season is under way. As the
winter wears on, the foxes take an increasing interest in dens and
by late February each pair probably will have cleaned out sey-
eral in preparation for the birth of pups. Usually woodchuck
and badger dens are appropriated for this purpose. The male
fox may begin to leave food at the den even before the pups are
born. The young generally arrive in March; the litter usually
consists of four to nine.

The pups first appear outside of the den when they are about
3 weeks old. If the family is undisturbed, the pups will re-
main for about a month at the den in which they were born,

Family CANIDAE 113

fig. 69. The family may then move from den to den, frequently
occupying as many as seven separate dens before finally desert-
ing these underground homes. Although cubs and adults leave
the last den in June, they remain together as a family group
through the summer months.

The red fox is celebrated for its cleverness in obtaining food,
but its prowess in this respect is often overrated. It tends to take
the foods that, within the limitations of its preferences and
physical abilities, are easiest to obtain.

Where many kinds of foods are available in quantity, the
proportions in the annual diet are about as follows: mammals
(largely rabbits and mice) 45 per cent; birds 15 per cent; insects
20 per cent; and vegetable matter (largely fleshy fruits) 20
per cent.

The occurrence of mammals in the summer and autumn diet
is comparatively infrequent due to increased availability of
fleshy fruits and insects in these seasons. Fruit may make up
as much as 35 per cent of the diet during some warm weather
months. Many kinds of insects are included in the diet, but
May beetles, crickets, and grasshoppers generally predominate
over other kinds.

Game birds are eaten by the red fox when the opportunity
arises, but these birds are more difficult to obtain than most of
the foods in the animal’s diet.

Moles, shrews, and weasels often are killed by the red fox
but are left uneaten on the trails. —There seems to be a par-
ticular lack of appetite for weasels.

Signs.—Prints of the feet are oval in shape, fig. 26; those of
the front feet are about 2 inches long and 134 inches wide, and
those of the hind feet are slightly smaller. On soft surfaces
especially, prints of the front feet show a noticeable spread
between the toes. The relatively slender and barlike impressions
of the ball pads lie behind rather than between the toe marks.
On mud and wet snow that are fine enough to hold the impres-
sions, the furry nature of the feet may be detected. On such
surfaces, footprints of the red fox and the gray fox may be told
apart; a slender bail print is the mark of the red fox and a
broader one the mark of the gray.

Track patterns made by the red fox at different gaits are
similar to those made by the domestic dog, except that foot-
prints made by a walking or trotting fox are usually in almost

114 Order CARNIVORA

a straight line, not staggered; prints of hind and front feet on
the same side of the fox generally register well. At both walking
and trotting gaits, the red fox makes tracks that vary from 9 to
16 inches apart. Strides of 14 to 16 inches usually indicate a
trot. Footprints of a galloping fox appear in groups of four;
the distance between groups on level ground measures usually
30 to 88 inches. The length of each group of four prints and
the distance between the groups increase with the rate of speed.

Scats of adult foxes range from short fragments to 12 inches
in length, with an average length of 6.3 to 7.4 inches. Generally
there are two to four segments to a passage and there may be
as many as nine.

The den of the red fox is generally made from the burrow of
a woodchuck, badger, or other animal; the burrow is enlarged
to a diameter of 9 to 12 inches. Frequently it is in a dry, sloping
bank or hillside with more than a 10 per cent grade. If in a
comparatively level area, it is almost invariably on a slight ele-
vation. Pathways, fig. 13, may radiate from the den, which is
usually surrounded with scats, tufts of rabbit fur, feathers,
bones, and the bodies of mice and other prey. Rabbit skulls left
by foxes characteristically have the basal and nasal parts gnawed
off, and only the central parts of the skulls remain.

Distribution.—The red fox is common the length and breadth
of Illinois and is cyclic in abundance. Red foxes in this state
are currently referred to the subspecies Vulpes fulva fulwva
(Desmarest), but further study may show that they are assign-
able to lV’. f. regalis Merriam. The range of the species includes
most of Canada, all of Alaska, and much of the United States.
It does not include parts of the southeastern and Gulf Coast
states and certain regions bordering the Rocky Mountains and
the Sierra Nevada.

UROCYON CINEREOARGENTEUS (Schreber)
Gray Fox

Description.—The gray fox, fig. 70, is slightly smaller and
lighter in weight than the red fox. The upper parts are gray;
the tail is black at the tip and along the upper side; the legs,
feet, sides of neck, and back of each ear are rusty yellow; the
throat and belly are whitish, bordered by a rusty or rufous
color that continues onto the under side of the tail.

Family CANIDAE 115

Length measurements: head and body 28-29 inches (720-750
mm.), tail 11-12 inches (280-300 mm.), over-all 39-41 inches
(1,000-1,050 mm.), hind foot 434-534 inches (120-145 mm.),
ear from notch 234-3 inches (60-75 mm.). Weight: 5-12
pounds, average about 91% pounds.

The skull is about 130 mm. (51% inches) long and has two
prominent ridges on each side of the braincase, fig. 604; each

Fig. 70.—Gray fox.

lower jaw has an extra notch or step, fig. 60d, at the posterior
end. Dental formula: I 3/3, C 1/1, Pm 4/4, M 2/3.

Life History.—The gray fox is an animal of the forest, fig.
1, and of river bottoms and bluffs, but it is sometimes seen in
semiopen brushland. A reduction in lumbering and the establish-
ment of forest preserves and other woodland sanctuaries in
Illinois have provided ideal habitat for this intriguing species.
The gray fox uses a ground den less frequently than does the
red fox, and instead may choose a hollow tree, a hollow log, or
a hole among some rocky cliffs. When pursued or startled, it
may climb a tree, not as nimbly as a squirrel but with surpris-
ing speed, and take refuge among the small branches.

116 Order CARNIVORA

‘The gray fox appears to be even more omnivorous than the
red fox and feeds on a variety of things, including quantities of
berries, fruits, acorns, and seeds, as well as mice, rabbits, insects,
and, occasionally, birds.

Three to five young per litter are born in the spring. In de-
velopment and behavior they are very similar to the young of
the red fox.

Signs.—Tracks of the gray fox, fig. 27, can be distinguished
from those of the red fox only when they are made under the
most ideal conditions. Impressions of the relatively thick ball
pads of the gray fox may sometimes be seen in thin layers of
mud or snow.

The droppings of the gray fox, like those of the red, contain
large amounts of rabbit and mouse fur and bones, and, during
the summer and fall, usually fruit seeds.

Distribution.—The gray fox is common in Illinois only in
rather heavily wooded areas, but is state-wide in distribution.
It is represented in Illinois by the subspecies Urocyon cinereo-
argenteus cinereoargenteus (Schreber). The range of the spe-
cies includes the eastern half of the United States and most of
the southwestern quarter; also it includes Mexico and countries
southward as far as Colombia. It does not include much of the
short-grass prairie area or the Rocky Mountain region north of

Colorado.

CANIS LATRANS Say
Coyote Prairie Wolf

Distribution—The coyote, fig. 71, somewhat resembles a
German “shepherd” (police) dog in size, conformation, and
color, but it carries its tail below the level of its back rather
than curved upward. The upper part of the body is a grizzled
gray or buff, the muzzle reddish brown or gray, and the under
parts are whitish, cream colored, or pinkish yellow. The tail is
bushy, the snout narrow and long, the ears are pointed, and the
legs long.

Length measurements: head and body 32-39 inches (815-990
mm.) ; tail about 12-15 inches (300-375 mm.) ; over-all 44-54
inches (1,120-1,375 mm.) ; hind foot about 7-8 inches (180-211
mm.); ear about 4414 inches (100-115 mm.). Weight: 25
pounds to possibly 55 pounds.

Family CANIDAE 117

The skull of the coyote is 180-200 mm. (7-8 inches) long;
its zygomatic breadth is 97-110 mm. (334-414 inches). Dental
fama st 3/3, C 1/1, Pm.4/4, M 2/3. .

Coyotes and dogs may cross or hybridize. Several hybrids of
these animals are known from Illinois. In size, markings, and
bearing, they naturally are somewhat intermediate between
the coyote and dog parents. It is possible to distinguish skulls
of some coyotes, dogs, and first generation coyote-dog hybrids
by taking certain cranial measurements and determining cranial
indices. Obviously, skulls with intermediate or near-interme-
diate measurements are from animals. having both dog and
coyote ancestry. Convenient indices and formulas for deriving
them are shown below:

CraniAL INDEX
ForMULA Coyote Hybrid Dog
Palatal width between inner margins

of alveoli of upper first premolars
———_lW SS 1 25-32 32-38 32-52
Alveolar length of upper premolars

and molars

Width. of basioccipital bone

x 100 23 .3—28-1 28.0—29.1 29.1—34.3
Width of braincase
Depth of lower jaw below
second molar
x 100 12.2—14.1 14.2—-14.7 14.0—17.8

Length of lower jaw

The coyote of Illinois can be distinguished from the timber
wolf of Minnesota or Michigan by its smaller size (less than 62
inches over-all length not including hair on tip of tail), nar-
rower nose pad (less than 114 inches in width), smaller feet
(each hind foot less than 10 inches long), smaller skull (length
less than 814 inches), and smaller teeth. The timber or gray
wolf does not now occur in IIlino‘s.

Life History.—Although the coyote may never have been
abundant in Illinois, it does not seem to have suffered much
from the settlement of the land by man. In fact, it may have
profited by the opening up of the land. Over a recent 5-year
period, 65 coyotes were taken in Fulton County, central Illinois,
according to a report by Anderson (1951:172). Since coyotes
are interbreeding with dogs, and several hybrids have already
been taken in Illinois, it will be-interesting to determine if the
number of crosses increases.

118 Order CARNIVORA

Probably the coyote in Illinois feeds princ‘pally on rabbits and
rodents, as is the case westward, but no one has studied its food
habits in this state. It feeds also on insects, vegetable matter,
birds, and carrion- Some individuals kill poultry and livestock.
A coyote-dog hybrid from along the Illinois River south of
Hennepin had mice and traces of rabbit in its stomach.

In Illinois, as elsewhere in central United States, the female
coyote has probably one litter each year, with an average of
about half a dozen young. The young are whelped in a den
and spend their first few weeks there. As soon as they are old
enough to eat solid food, they are fed by both parents. When 3
or 4 weeks old the pups play at the entrance to the den and at
10 weeks of age they may abandon the den completely.

The coyote, known also as the prairie wolf or brush wolf, is an
inhabitant of open country rather than woods. An early writer
on Illinois (Anonymous 1837:40) commented, “The prairie
wolf... takes its name from its habit of residing entirely upon

Fig. 71.—Coyote.

Family CANIDAE 119

the open plains... . The most friendly relations subsist between
it and the common wolf, and they constantly hunt in packs to-
gether. Nothing is more common than to see a large black wolf
in company with several prairie wolves.” The actual coyote-
wolf relationship is less friendly than indicated above. Coyotes
often trail wolves for kills left by the larger animals.

Signs.—Coyote tracks, fig. 24, cannot be distinguished with
certainty from some dog tracks. The print of a hind foot of
the coyote commonly measures about 234 inches long, while
that of a front foot is slightly shorter. The register of the tracks
of a walking animal is not perfect; the toe marks of each hind
foot fall at about the center of the track of the front foot on
the same side of the body.

The den of the coyote is usually in a bank or hillside but
sometimes in level ground. It commonly has only one entrance,
which has a mound of earth in front. Well-worn paths radiate
from the entrance and almost invariably lead to one side of the
mound rather than over it.

Distribution—The coyote occurs in much of Illinois, but it
is not common anywhere in the state. Individuals in northern
and central Illinois belong to the subspecies Canis Jlatrans
thamnos Jackson; those in southern Illinois are presumably
referable to C. 1. frustror Woodhouse. The range of the spe-
cies includes most of western North America (central Alaska
almost to Panama) and an eastward extension that continues
through most of the Great Lakes region and ends in a narrow
area north of the St. Lawrence River.

CANIS LUPUS (Linnaeus)
Timber Wolf Gray Wolf

Description.—The timber wolf is a large, long-haired animal
weighing 75 pounds or more and attaining a length of nearly
514 feet. The color is usually gray or light gray-brown. The
muzzle is heavy and blunt, and the nose pad exceeds 11 inches
in diameter. The ears are less pointed than those of the coyote.

The skull is about 255 mm. (10 inches) long, and the teeth are
large (half again as large as the corresponding teeth in the
coyote) and arranged as in the coyote.

Distribution.—In the late 1700's and early 1800's, the timber
wolf was common in the country that is now Illinois, according

120 Order CARNIVORA

to accounts of early explorers and settlers. Reports indicate that
it attacked large game animals and livestock, even hauling down
young horses. The wolf probably fed rather extensively on
bison, elk, and deer before the coming of the white man to the
Illinois country.

By the middle 1800's, the timber wolf in Illinois had been
greatly reduced in numbers and before the end of the century
it had been completely eliminated from the state. The wolf
bounties that have been paid since that time are for coyotes or
prairie wolves, dogs, or coyote-dog hybrids. The subspecies that
occurred in Illinois was Canis lupus lycaon Schreber. The spe-
cies has a range that includes most of Canada and Alaska and
parts of some north-central states, including Wisconsin. Also,
it occurs in isolated areas of Oregon, Colorado, Utah, Arizona,
New Mexico, and Mexico.

CANIS NIGER Bartram
Red Wolf

Description.—The red wolf is intermediate in size between
the timber wolf and the coyote. It is about 5 feet long and
weighs 60 to 70 pounds. The broad nose and the rounded ears
are more like those of the timber wolf than those of the coyote.
The sides of the muzzle are buffy red and the coat color has a
buffy cast.

The skull is slightly smaller (length about 245 mm. or 95¢
inches) than that of the timber wolf; the crowns of the teeth
are more deeply cleft, and the shearing edges more bladelike.
The tooth arrangement is the same as that of the coyote and
of the timber wolf.

Distribution.—In former times the red wolf occurred prob-
ably along the Mississippi and other rivers in the southern part
of Illinois. A young male, now preserved in the American Mu-
seum of Natural History, was obtained on February 7, 1893,
at Warsaw, Illinois, by C. K. Worthen. The red wolf stili
occurs in fair numbers in the Ozark Mountains of Missouri
and Arkansas and southward to Louisiana and eastern Texas.
There is the possibility that some individuals may live in, or
stray into, the heavily wooded portions of extreme southern
Illinois. The subspecies in Illinois was Canis niger gregoryi

Goldman.

Family FELIDAE 121

FELIS CONCOLOR Linnaeus
Cougar Mountain Lion Panther

Description.—The cougar is a large, long-tailed cat measur-
ing nearly 80 inches from the nose to the tip of the tail. The
body is light brown or tawny; the backs of the ears and the tip
of the tail are dark brown.

The large skull is about 8 inches long, and the cheek teeth
are bladelike. Dental formula: I 3/3, C 1/1, Pm 3/2, M 1/1.

Distribution.—Accounts of early settlers and contemporary
travelers indicate that in the first half of the 1800’s cougars or
panthers were found in the forested parts of Illinois. After the
middle of the century, the cougar (rarely called mountain lion
in Illinois) disappeared very rapidly. The form present was
Felis concolor couguar Kerr. The range of the species now in-
cludes part of northern British Columbia and an extensive area
southward through the United States (principally west of the
Rocky Mountains) and into South America, along the Gulf
Coast from Mexico to western Florida, and peninsular Florida.

LYNX RUFUS (Schreber)
Bobcat

Description.—The bobcat, fig. 72, is a short-tailed cat stand-
ing 20 to 23 inches high at the shoulder. Its body is mostly
yellowish gray, with a sprinkling of black; the under parts and
inner surfaces of the legs are whitish, spotted with black; streaks
on the long fur covering the cheeks are dark gray; and the
upper part of the tip of the tail is black. Each pointed ear bears
a small tuft or pencil of hairs. .

Length measurements: head and body about 27 inches (625-
755 mm.), tail about 514 inches (135 mm.), over-all about 33
inches (760-880 mm.), hind foot about 7 inches (170-188 mm.).
Weight: 15-25 pounds, usually about 20 pounds.

The skull is 105-135 mm. (about 5 inches) long. Except for
having three rather than four cheek teeth (premolars and molar)
in each half of the upper jaw, it is not unlike that of the house
cat. Dental formula: I 3/3, C 1/), Pm 2/2, M 1/1.

Life History.—The bobcat frequents wooded sections along
rivers, especially timbered bluffs and slopes that are interspersed
with sunny glades and swampy bottomlands. Broken country

122 Order CARNIVORA

Fig. 72.—Bobcat.

provides an ideal hunting ground for the bobcat, since mice,
rabbits, squirrels, birds, and insects upon which it feeds abound
there.

A bobcat den may be located under a log, within a fallen
hollow log, or within a standing hollow tree. A nest in a dense
thicket may occasionally serve as a home. Little is known about
the life history of the bobcat in Illinois. Information gained
from studies in other states indicates that young are born in
March or April, that there is one litter of about three each
year, and that the young leave the care of their mother and the
company of their brothers and sisters late in the summer. The
rate of development of the young bobcat is similar to that of the
young of the domestic cat.

The bobcat apparently covers a large territory in its hunting,
for an individual seen in a given place one day may be a con-
siderable distance away the next week. This cat, especially
during the mating season, may render a weird and eerie series
of yowls and meows somewhat like that of the common house cat,
but louder, huskier, and infinitely more mysterious. A harsh,

Order RODENTIA 123

mysterious scream has led persons to believe a lion or “cata-
mount” to be present, when only a bobcat has been hunting in
the neighborhood.

Signs.—The bobcat makes tracks, fig. 19, similar in shape to
those of the house cat, but the prints of the individual feet are
each about 2 inches in diameter (as compared to 114 inches for
those of the domestic cat), and the heel pads produce more com-
plicated patterns. When the animal is walking, the hind feet
(which are smaller than the front feet) often overstep the
front feet.

Distribution—The bobcat, which is now rare in Illinois,
occurs in wooded bottomlands, fig. 3, of some of the major
rivers in heavily wooded regions of southern and possibly of
northwestern Illinois. The Illinois bobcat belongs to the sub-
species Lynx rufus rufus (Schreber). The present range of the
species includes western North America from southern Canada
to central Mexico; across northern United States and southern
Canada to Nova Scotia and the lower Appalachians; across
southern United States to southern South Carolina.

ORDER RODENTIA
Rodents or Gnawing Animals

The rodents, or gnawing animals, have only two incisors or
front teeth and no canine teeth in each jaw. The incisors of the
upper jaw are especially large and chisel shaped. Most rodents
occurring wild in Illinois have relatively long tails. In both
numbers of kinds and of individuals, the rodents are the most
numerous of all mammals. They comprise about three-fifths of
the number of species of the North American mammalian fauna.
‘Twenty-five species of rodents are found in Illinois, most of
which are various kinds of squirrels, rats, or mice. The largest
rodent in Illinois is the beaver; the smallest is the western har-
vest mouse.

Economic Status.—Members of the order Rodentia, both
native and introduced, are of tremendous economic importance
in Illinois. For example, a single species, the Norway rat, costs
the taxpayers several million dollars a year as a result of the
spoilage of food and grain, damage to buildings and merchandise,
predation on poultry and native birds, and transmission of dis-
ease. Money spent in attempts to control this rat amounts to

124 Order RODENTIA

millions more. Its small cousin, the house mouse, is less de-
structive individually, but because of its greater abundance
causes almost as much total damage. Both the Norway rat and
the house mouse were introduced from Europe.

Some of the native rodents of Illinois are responsible for con-
siderable economic loss. Some have direct or indirect economic
value. Woodchucks, pocket gophers, ground squirrels, native
mice, muskrats, beavers, and chipmunks do varying amounts of
damage to gardens, cereal grains, and silage crops. Field mice
and voles cause considerable loss in orchards as a result of their
girdling of trees, fig. 37. By their burrowing, such animals as
muskrats and woodchucks weaken dams and embankments.
Pocket gophers and woodchucks make mounds of earth that in-
terfere with mowing operations. Beavers construct dams that
sometimes cause flooding of farmland. Some kinds of squirrels
occasionally eat young birds and bird eggs; some may be nui-
sances in human habitations when they store food or make their
homes in attics or walls. A few native mice feed on clover and
grasses and they may also deface lawns with their runways.

Among the native rodents of direct or indirect value are the
ground-inhabiting squirrels and mice, which play a role in soil
improvement by bringing subsoil to the surface and depositing
humus-forming material below the surface of the ground. Their
burrows hold excess water during wet periods and thus serve
as underground reservoirs during dry periods. These burrows
are frequently used as nests by bumblebees, which help pollinate
the blossoms of some crop plants. Tree squirrels and chipmunks
contribute to forest production by burying tree seeds in the
ground and failing to return for them; some of these buried
seeds sprout and grow. Fox squirrels and gray squirrels provide
food and sport for countless hunters and furnish aesthetic enjoy-
ment for nearly everyone. Some mice feed on insects and may
aid in the control of insect pests more than is realized. Most
species of rodents serve as food for valuable fur-bearing mam-
mals. Woodchucks make and desert numerous burrows that are
used by furbearers as dens for rearing their young and by cotton-
tails as shelter from harsh weather.

The muskrat is the most important fur resource of Illinois.
Each year an estimated 20,000 people in Illinois harvest musk-
rats; the annual value of the furs they take is somewhat under
a million dollars.

Order RODENTIA 125

10.

KEY TO SPECIES
Whole Animals

Hair at mid-length of tail longer than diameter of tail. 2
Hair at mid-length of tail shorter than diameter of tail, or
ePATISETNE AD ok hei eee eyse ti Bieyh hage sos i aR dee eee d otal 9

Tail not more than VAC over-all length of animal; feet black ;
seullomore than -70 mm. (234 in.) long..;.....¢..7. 5...
Ce eee a ee woodchuck, Marmota monax

Tail more than 14 over-all length of animal; feet not
Diack s skull léss: than: 70mm. long... .. sis.105 see... 3

A large, loose fold of skin between front and hind legs,
fig. 83; bush of tail in cross section decidedly flattened
cid gy es eT southern flying squirrel, Glaucomys volans

No loose fold of skin between legs; bush of tail round or
Beate CHOSS SECTION. 6455/2 2%, 2 ceed Seas s SE AL +

Hair at mid-length of tail less than 20 mm. (34 in.) long.. 5

Hair at mid-length of tail more than 35 mm. (13% in.) long. 7

Body without longitudinal stripes, fig. 78... ..........

SS ore Franklin’s ground squirrel, Citellus franklinii

Deis WILBVIONSAEMCINAL, SERIPES x a5. Sloe is sew vereeteh.< © 6

Body with 2 longitudinal light stripes bordered with dark
brown, these stripes represented also on the sides of the
OBER AEE. Sir else's oho. eastern chipmunk, Tamuas striatus

Body with more than 2 longitudinal light stripes bordered
with dark brown, no stripes present on the sides of the
ERT HO Se co ce salt ER ea Oe aoe es

_.thirteen-lined ground squirrel, Citellus tridecemlineatus

Over-all length of animal less than 350 mm. (1334 in.); a

short black stripe bordering the belly color on each side,

BIESENGU ge ty ee Coe: red squirrel, Tamiasciurus hudsonicust
Over-all length of animal more than 350 mm.; no lateral
dark stripe: bordering’ belly color: 2.2.2. s00 2.3 eee 8

Upper parts of animal uniform gray, under parts gray or
white: tail with white-tipped hairs...) .0..70.0..525....-
te, TAN eee eastern gray squirrel, Sciurus carolinensis

Upper parts of animal dappled gray, under parts reddish;
PAroeen CEA -tippem nadine. s...0 202 AlAs. oe UE

Ss a EL eastern fox squirrel, Sciurus niger

Claws on front feet, fig. 85, 3 times as large as claws on hind
feet; each cheek with a pouch that opens by an external,
curved slit starting near the side of the mouth.........
eet Us hen Pe ae plains pocket gopher, Geomys bursarius

Claws on front and hind feet subequal in size; no external
SC OREERICHIGS Path. Fe tet nr PS aa th eee aN OE eee YS Sa ps 10

Tail flattened dorsoventrally, fig. 87, more than 50 mm.
(2 in.) wide; head+body more than 400 mm. (1534 in.)
MORNIN Sy Pieler a id, en Sk ape beaver, Castor canadensis

*This species probably is not now present in Illinois.

126 Order RODENTIA

Tail not flattened dorsoventrally, and less than 25 mm. (1
in.) wide; head+body less than 400 mm. long.........

11. Tail at least 114% times the length of head+body, fig. 102;
upper jaw with 4 cheek teeth on each side ..............

ee ee a hs: meadow jumping mouse, Zapus hudsonius

Tail less than 114% times the length of head-+body; upper
jaw with 3 cheek teeth on each side...............
12. Tail flattened laterally; front feet each with 5 clawed toes

Oh eee ee i ee oe ee muskrat, Ondatra zibethicus

Tail not flattened; front feet each with 4 clawed HOEK ws --
13. ‘Tar*less than’ 3 Tength-of head+bedy? 2 32 a5 3) eee
Tail more than 14 length of head--body ©3222. eee
14. Upper incisors each with shallow longitudinal groove on

face, tie. (47 southern bog lemming, Synaptomys cooperi

Upper incisors not’ grooved... 2. 22°22) 2: - ee eee
15. Tail less than 25 mm. (1 in.) long; hind foot less than 18
mm. (almost 34 in.) long; ears hidden in soft fur........

Rites ats 3. Aa ie ei MEN ney ie pine vole, Pitymys pinetorum

Tail more than 25 mm. long; hind foot usually more than

18 mm. long; ears projecting above coarse fur .........

16. Fur of under parts tipped with white; feet black; each last _
upper molar with 5 or 6 enamel loops, fig. 74d...........

DARE eee BPE in meadow vole, Microtus pennsylvanicus

Fur of under parts ochraceous; feet brown; each last up-
per molar with only 4+ enamel loops, fig. 74e...........

[OKC CO ae ee. se ieee prairie vole, Microtus ochrogaster

17. Upper incisors each with a longitudinal groove ...........
Upper: incisors» not: grooved |... -....0..... 2 a
18. Body having sides washed with fulvous; back brown.......

ba eae western harvest mouse, Reithrodontomys megalotis

Body having sides and back rich brown... -: ::ku) gage. -s

Wave eastern harvest mouse, Reithrodontomys humilis*

19. Over-all length of animal more than 200 mm. (8 in.).....
Over-all length of animal less than 200 mm. ........

20. Fur on throat with each hair white its entire length; upper

cheek teeth with triangles but without distinct cusps,

LIER PED RR ot ag od) te wae eastern wood rat, Neotoma floridana

Fur on throat with each hair white distally but darkened at
base; upper cheek teeth with distinct cusps rather than
triangles, fig.<74¢,) Geotex 2... eas cc oe oh ee

21. Hind foot not more than 34 mm. (134 in.) long; under side
of tail light; cusps on upper cheek teeth in 2 rows. .

Hind foot more than 34 mm. long; under side and upper

side of tail gray; cusps on upper cheek teeth in 3 rows. .
22. Fur long, grizzled buff and black; ears almost hidden in fur

ete er ee ree eee hispid cotton rat, Sigmodon hispidus*

Fur short, brown above and not grizzled; ears projecting

AHGV GubURSe Bee ae Ahaha rice rat, Oryzomys palustris

23... Tail shorter than. length of head+body... .... 02ers

Et ARS Rr SOCAN OR Re Norway rat, Rattus norvegicus

*This species may occur in Illinois, but there are no official records of it here.

Order RODENTIA 127

24.

25.

26.

2.

bo

Tail as long as or longer than head+body................
ok Ae ee AG ule a a roof rat, Rattus rattus
Belly and feet dirty gray or olive. house mouse, Mus musculus
ae GE SS i a a Aen 25
Head, ears, back, and sides of a uniform reddish color.
ho. pi de a aa golden mouse, Peromyscus nuttalli
Head, ears, and back brown or black; sides variable and
PIN CEES et os vo Sly, the aia Kicla ck es Keble es 26
Hind foot 18 mm. (34 in.) or less in length; tail usually
less than 60 mm. (23@ in.) in length; middorsal dark
stripe prominent....... deer mouse, Peromyscus maniculatus
Hind foot more than 18 mm. in length; tail usually more
than 60 mm. in length; middorsal dark stripe present or
Mt. SN, oe Ge aloe ics Wee Dn 27
Hind foot usually less than 23 mm. (7 in.) in length;
head+body usually less than 100 mm. (4 in.) in length. ....
oe ee white-footed mouse, Peromyscus leucopus
Hind foot usually 23 mm. or more in length; head+body
nsually more than 100 mm. in length. =::-..........s.0..
* MAPOA'S Sn SARE eae cotton mouse, Peromyscus gossypinus

Skulls

Each frontal bone with well-developed postorbital process,
eer 44. Rh oem okt. ey oe a ie 2

’ Each frontal bone without postorbital “process... <n... - 25. « )

Postorbital processes large, projecting at right angles to the
longitudinal axis of the skull, fig. 73e¢; incisors whitish
PEE OE ee ere kl 4 G e e woodchuck, Marmota monax

Postorbital processes small and angled backward; incisors
WELLS Th OP Se a Re ea ee ene ee ee ee 3

Interorbital region deeply notched anterior to each post-
orbital process, fig. 747 . Ng lt Ames Geo ke motes
4: ee ee re southern flying squirrel, Glaucomys volans

Interorbital region not deeply notched anterior to each post-

SME MESIMCESS) MIS 7 3.70.21 4 os che os. da) Re a ok hs oe 4
Zygomatic arches tending to converge anteriorly, fig. 73a.. 5
Zygomatic arches nearly parallel, fig. 74k................. 7

masts mare than.17 mm. (5¢ in.) lone... O07. 2.0.0 ss
EE ee a Franklin’s ground squirrel, Citellus franklinii
SUAS CE CELE ES WR ct a 5 oe a a 6
Upper jaw with 5 cheek teeth on each side................
.thirteen-lined ground squirrel, Citellus tridecemlineatus
Upper jaw with 4 cheek teeth on each side............
ES ee ee eastern chipmunk, Tamtias striatus
Upper jaw with series of cheek teeth on each side less
LEU rec eel GEAR Te U0 So a, Sc aii aeee se seas
A gt Re eel te oe squirrel, Tamiasciurus hudsonicust
Upper jaw with series of cheek teeth on each side more than
La WL TLL LA a 5 EI RR ei iP pao he i. 8

{This species probably is not now present in Illinois.

128 Order RODENTIA

8. Upper jaw with 5 cheek teeth on each side; anteriormost
tooth rudimentary. .eastern gray squirrel, Sciurus carolinensis

Upper jaw with 4 cheek teeth on each side...............
eastern fox squirrel, Sciurus niger

9. Upper incisors each with 2 longitudinal grooves, fig. 73c..
J pcticty Wie eerie lnudeagrens plains pocket gopher, Geomys bursarius
Upperincitsors each with 1 or no. groove. 2.25 4s ese ee 10

Fig. 73.—Characters used in the identification of rodents: a, skull
of thirteen-lined ground squirrel, top view; }, portion of skull of
Franklin’s ground squirrel, top view (f, postorbital process); ¢,
front of rostrum of pocket gopher; d, rostrum of beaver, under
side (f, incisive foramen) ; e, skull of woodchuck, top view.

Order RODENTIA 129

10. Skull length more than 90 mm. (31% in.) ; length of incisive
foramen, fig. 73d, shorter than length of grinding sur-
faces of first two upper cheek teeth beaver, Castor canadensis

Skull length less than 75 mm. (3 in.); length of incisive
foramen greater than length of grinding surfaces of first
2 upper PRED eg Fina apt apd eae? dns nee vest . 11

11. Upper jaw with 4 cheek teeth on each side.....

Mia ob: Lees <*, meadow jumping mouse, Zapus hudsomuus
Upper jaw with 3 cheek teeth on each side............. 12

be okallleneth* more. than 45 mm., (134 1m.) .. 6.05.5. 2s ae. 0:

1 Oe ae eee muskrat, Ondatra zibethicus

SUSU) BS 9 EE e000 ae
Pease eneth SOumm. (116 in.) or less..: 0... teks = 55 4
Seuisicneth morethan 30 mm... .:..- 2.20). vege eek ease 23

Fig. 74.—Additional characters used in the identification of ro-
dents: grinding surface of molars of a, rice rat, », eastern wood
rat, c, Norway rat, d, meadow vole, ¢, prairie vole; side view of
rostrum of, f, house mouse, g, golden mouse, /, white-footed mouse ;
i, front of rostrum of southern bog lemming; j, part of skull of
southern flying squirrel, top view; &, skull of fox squirrel, top view.

130

14.

15.

16.

he

18.

12:

ZANE

2s

22.

23.

24.

258

26.

Order RODENTIA

Upper molars with crowns having rows of tubercules or

cusps, fie. 74a, ¢. 0 Wie a Oe ee : 15
Upper molars with crowns having enamel loops, fig. 74d, e¢,
father than tubercules or cusps... .>-2. 0 oases. 20
Upper incisors -with longitudinal groove on front surface or
face of each. -:\s Ge a). harvest mice, Reithrodontomys spp.
Upper incisors without grooves on faces 1 Gey eee 16
Upper incisors, viewed from side, each with a pronounced
terminal notch) fig? J4f 2)... 70>. house mouse, Mus musculus

Upper incisors, viewed from side, without terminal notches 17

Infraorbital plate with anterior margin straight, fig. 74g
Pope ee ee Lab net Bee fe golden mouse, Peromyscus nuttalli

Infraorbital plate with anterior margin bowed forward, as

in’ fig. 7407. <. .6o ves bel ee he © oe eke oer err 18
Beaune width of skull anteriorly less than 12 mm. (1%

(09) eer .deer mouse, Peromyscus maniculatus
Zygomatic . width of skull anteriorly more than 12 mm....... 19

Maxillary tooth rows each 4 mm. long or less.............
Dae SR ee 0S LE white-footed mouse, Peromyscus leucopus
Maxillary tooth rows each usually more than 4+ mm. long .
Pee Oe ME cotton mouse, Peromyscus gossypinus
Upper incisors each with longitudinal groove on face or”
front™:surface,, fig..-742. 01.... Rene... See
BE ak Re ry ee southern bog lemming, Synaptomys cooperi
Upper incisors without grooves on faces. . 734 eee 21
Interorbital region more than 4 mm. wide...............
SEDs Poh. SAS, cate et pine vole, Pitymys pinetorum
Interorbital region less than 4 mm. wide................. 22
Last upper molars each with 5 or 6 enamel loops, fig. 74d. .
Mt Bik Si et. ha a meadow vole, Microtus pennsylvanicus
Last upper molars each with 4 enamel loops, fig. 74e........
Ae ES Be les kt ay 3 prairie vole, Microtus ochrogaster
Upper molars with irregular triangles on crowns, fig. 74). .
WN rees oN kc eR 2 aire eastern wood rat, Neotoma floridana
Upper molars with rows of cusps on crowns, fig. 74a, ¢..... 24
Upper cheek teeth with cusps in 2 rows; skull less than
35mm. (134-in.) dong..°..! 4.2). ae...) ee 25
Upper cheek teeth with cusps in 3 rows; skull more than
35: mm. longi...) 02..%6.. 0. 6. Be es. 2 re 26
Anterior half of rostrum wider than least interorbital space
ete ee eee hispid cotton rat, Sigmodon hispidus*
Anterior half of rostrum narrower than least interorbital
SPaGeerek kta Wicmete e eee eet rice rat, Oryzomys palustris
Length of each parietal, measured along temporal ridge,
less than greatest distance between temporal ridges.....
SAE Wid VEER hiv RB he tee I roof rat, Rattus rattus
Length of each parietal, measured along temporal ridge,
about equal to distance between temporal ridges.........
Norway rat, Rattus norvegicus

Rw © OC ORCL Oe 0.50.0) 0) Ore .ce Genet: 01h) 0, 6).07.8 506

*This species may occur in Illinois, but there are no official records of it here.

Family SCIURIDAE 131

MARMOTA MONAX (Linnaeus)
Woodchuck Groundhog

Description.—The woodchuck, fig. 75, is a stout-bodied,
squirrel-like mammal with short, powerful legs, short ears,
short blunt muzzle, and relatively short furry tail. In most
individuals the upper parts are a grizzled yellowish gray to
dark brown; the under parts are lighter, often with a reddish
wash. The feet are dark brown or black. Occasional wood-
chucks are almost black. The four toes of each front foot and
the five toes of each hind foot have well-developed claws.

Length measurements: head and body 1614-1914 inches
(415-495 mm.); tail 414-6 inches (110-155 mm.); over-all
2014-2514 inches (525-650 mm.); hind foot 3-334 inches
(75-95 mm.). Weight: average about 614 pounds, that of the
male slightly greater than that of the female.

The flat skull, fig. 73e, has well-developed postorbital proc-
esses and is 75-100 mm. (3-4 inches) long. The strong incisors
are cream colored or white. Dental formula: I 1/1, C 0/0,
Pre2/ 1, Mr 3/3.

Life History.—The woodchuck is normally an animal of the
forest edge. It prefers rolling land that is well drained, fig. 2.
In some parts of Illinois, the woodchuck lives along wooded
river bluffs, in other parts in more open country, and in a few
areas in heavy woods. In level countryside, it may make its
burrow in a railroad or highway embankment, fig. 5.

As with most other squirrel-like animals, the woodchuck re-
stricts its activity to daylight hours. It digs innumerable bur-
rows, most of which at some time become the homes of other
mammals. At one of the enlarged entranceways to a burrow
it may be seen dozing in the warm sun, or busily trying to rid
itself of fleas, lice, or ticks, or sitting upright to get a good
view of its surroundings. It may occasionally climb a tree.

The female is occupied during the summer months in rearing
a family. The nest chamber is in the burrow and so situated
as to remain dry. The nest itself consists of only a few leaves
or blades of grass. Two to six (usually three or four) young
per litter are born in April or May. The young, fig. 75, grow
and mature rapidly, and before long are busily feeding on green
plants. Both young and adults commonly feed on clover, alfalfa,
dandelions, wild lettuce, and plantain.

Order RODENTIA
bottom, adult.

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Family SCIURIDAE 133

By late October or thereabouts, when most native herbs and
grasses are dry, when the amount of daylight has greatly de-
creased, and the days as well as the nights are frosty, the wood-
chuck gradually becomes less active above ground and is soon no
longer seen. In its burrow, it sinks into the deep sleep of true
hibernation, in which the heart beat and respiratory rates are
only one-tenth as fast as in normal life. Should a warm spell
occur, the woodchuck may arouse and leave its hibernating cham-
ber for a brief time. Indeed, the groundhog, as the woodchuck
is sometimes called, may even be above ground for a short time
on the second day of February, but not motivated by any desire
to view its shadow.

Signs.—During the growing seasons of the year, woodchuck
tracks, fig. 29, may often be found along creek beds or on dusty
or muddy roads in woods. The four-toed prints of the front feet
and the five-toed prints of the hind feet are closely bunched
when the woodchuck runs; the distance between each set is nor-
mally 12 inches. About 4 inches separate the sets of front and
hind prints when the chuck is walking. Each individual foot-
print is about 11% inches long.

A woodchuck burrow is usually 6 to 12 inches wide at each
of its two or three entrances but soon narrows inside and at
a depth of 2 feet may be only 4 to 7 inches in diameter. Because
the woodchuck keeps its burrow clean by constant enlarging,
there is usually a fresh mound of loose dirt near one or another
of the openings. A burrow deserted by a woodchuck and occu-
pied by a skunk or a rabbit does not have such a fresh mound.
Radiating from the entranceway of a woodchuck burrow are
partially concealed paths or runways which serve as avenues
to food supplies. Closely cropped herbage near the entrance is
an indication that a woodchuck occupies the burrow.

Distribution—The woodchuck, common in many parts of
Illinois, occurs the length and breadth of the state, with the
possible exception of some parts of the level black soil regions of
central Illinois. Only one subspecies, MWarmota monax monax
(Linnaeus), is known in this state. The species ranges from
Labrador westward to central British Columbia, then northward
through Yukon to eastern Alaska; southward as far as northern
Idaho in the western part of the United States and as far as
northeastern Oklahoma and northern Georgia and Alabama in
the central and eastern parts.

134 Order RODENTIA

Fig. 76.—Thirteen-lined ground squirrel.

Family SCIURIDAE 135

CITELLUS TRIDECEMLINEATUS (Mitchill)
Thirteen-Lined Ground Squirrel Striped Gopher

Description.—The thirteen-lined ground squirrel, fig. 76, is
about the size of a chipmunk. The ears are small, the eyes are
large, and the slightly bushy tail is shorter than the body. The
back has approximately 13 longitudinal stripes alternately dark
brown and buft. Each of the brown stripes contains a series of
buff spots. The sides of the body are yellowish or buff, and the
belly is the same color as the light stripes on the back.

Length measurements: head and body 534-734 inches (145-
200 mm.) ; tail 314-414 inches (80-110 mm.); over-all 834-
1214 inches (225-310 mm.); hind foot 114-15%@ inches (32-41
mm.). Weight: about 4 ounces in early summer; nearly 8
ounces in fall prior to hibernation.

The skull, fig. 73a, is 36-43 mm. (about 11% inches) long and
delicate in appearance. In Illinois, only this squirrel, the gray
squirrel, woodchuck, Franklin’s ground squirrel, and the south-
ern flying squirrel have five cheek teeth on each side of the upper
jaw. The skull differs from that of the gray squirrel and the
woodchuck by its decidedly smaller size; from that of Franklin’s
ground squirrel by its smaller size and by its shorter nasal bones
(less than 17 mm. long) ; from that of the southern flying squir-
rel by the absence of deep notches in the interorbital region,
fig. 73a, by incisors that have yellow rather than reddish front
faces, and by smaller auditory bullae. Dental formula: I 1/1,
C070, Pan2/l; M3 /3.

Life History.—In the northern half of Illinois, the thirteen-
lined ground squirrel is seen through casual observations per-
haps more often than any other wild mammal during summer
days. Members of this species attract attention as they dash
across highways or as they stand stiffly erect near the entrances
of their burrows on golf courses, in pastures, in cemeteries, and
on grassy roadsides. The shortness of the grass in areas where
they prefer to live makes them conspicuous, fig. 2. Loud noises
or sudden movements may cause them to run for their burrows.
A ground squirrel may give its shrill, quavering whistle of alarm
before disappearing underground.

So great is its curiosity that a thirteen-liner cannot long re-
main hidden. Soon it will be peering out of the mouth of its
burrow and before much longer it will be back at its usual

136 Order RODENTIA

activities of feeding, gathering grasses for its nest, enlarging its
burrow, cutting paths through the grass, or sunning itself. It is
always alert for a weasel, badger, dog, house cat, man, or hawk.

The thirteen-lined ground squirrel feeds on seeds, on grasses
and other herbs, and on insects. At times during the summer,
nearly half its food may consist of grasshoppers, white grubs,
webworms, cutworms, and other insects.

Young, numbering usually 7 to 10 per litter, are born in late
April or early May in a grass-lined nest below the surface of
the ground. By mid-June, the young have grown from naked,
blind creatures to thin-bodied, big-headed, furred animals able
to clamber out of the burrow and nibble on herbs. By mid-July,
some young have dug simple burrows of their own.

As summer progresses, this ground squirrel lays on quantities
of body fat, and by the time it enters hibernation its early sum-
mer weight has nearly doubled. In the fall when the days get
shorter and colder, this squirrel spends more time below ground
and becomes more and more sluggish. Usually by the time
grasses and seeds have been covered by snow, the ground squir-
rel has sealed the burrow entrance from within and has retired
to a hibernating cell, which is just large enough for the animal
and a little nest material. The cell is to one side of the burrow
proper and so situated as to remain dry. The animal rolls up
in a ball, with its nose tucked against its belly near its hind
legs, and goes into a deep sleep. The rates of breathing and
heart beat are greatly reduced, and the animal’s body tempera-
ture becomes nearly the same as that of its surroundings. When
the animal hibernates, it cannot effectively control or regulate
its temperature and therefore, if the temperature of the hiber-
nating chamber drops below the freezing point, the animal will
die.

If the weather becomes unseasonably warm in winter, the
thirteen-lined ground squirrel may appear above ground for
short periods. Otherwise it remains below ground until March
or April. At this time it is thin, for its stored body fat has been
used during the long period of hibernation.

Signs.—The print of each front foot shows only four toes;
the print of each hind foot shows five toes; that of the hind foot
measures about 114 inches. A burrow entrance is _ usually
slightly less than 2 inches in diameter and without a pile of
dirt at the opening.

Family SCIURIDAE 137

PFRANKLIN'S GROUND
SQUIRREL

Fig. 77—Known distribution, in the United States, of the Illi-
nois ground squirrels.

Distribution—The thirteen-lined ground squirrel is abun-
dant in the northern two-thirds of Illinois, but is unknown
south of an imaginary line connecting Clark and Madison coun-
ties. One subspecies, Citellus tridecemlineatus tridecemlineatus
(Mitchill), occurs in this state. The range of the species ex-
tends from central Ohio and eastern Michigan northward and
westward through Wisconsin and northern Illinois into south-
central Canada, then southward to eastern Arizona, New
Mexico, and south-central Texas, fig. 77.

CITELLUS FRANKLINII (Sabine)
Franklin’s Ground Squirrel Gray Gopher

Description.—Franklin’s ground squirrel, fig. 78, is only
slightly smaller than the arboreal gray squirrel, which it some-
what resembles. Its ears are short and its tail is bushy, but not
so bushy or so long as that of the gray squirrel. The back is
brownish gray, speckled with black, and has an overwash of
yellow. The head and tail are gray, and the under parts are of
a grayish color not much lighter than that of the back.

Length measurements: head and body 812-914 inches (220-
240 mm.) ; tail 514-614 inches (130-160 mm.) ; over-all about
14-16 inches (350-400 mm.) ; hind foot 17-214 inches (48-55

138 Order RODENTIA

Fig. 78.—Franklin’s ground squirrel.

mm.). Adults in early summer weigh slightly more than a
pound (380-490 gm.).

The skull is 52-55 mm. (about 214 inches) long; the rostral
portion or snout of the skull is broad and elongate (nasals more
than 17 mm. long); the postorbital processes are angled Lag
ward, fig. 736. Dental formula: I 1/1, C 0/0, Pm 2/1, M 3

Life History.—The Franklin’s ground squirrel lives in habi.
tats that are similar to those of the thirteen-lined ground squir-
rel except that generally they contain taller and thicker grass and
more brush. It does not often stray as far into the open as does
the thirteen-liner; its shyness and its preference for thicker
cover make it seem relatively scarce, although it is sometimes
seen scurrying across a highway.

Young, usually numbering four or five in a litter, are born
about mid-May. They develop rapidly and by July are foraging
for themselves. Like their parents, they relish grasses, other
herbaceous plants, seeds, and some insects. Members of this
species may sometimes be seen feeding on carcasses of animals
killed on highways. ‘They are said to kill and feed on other
animals, and have been accused of eating eggs occasionally. By
fall, they have stored up great quantities of fat in their bodies
to tide them over the long winter months.

Family SCIURIDAE 139

In its hibernation, this animal is similar to the thirteen-
lined ground squirrel. In October or November, it enters hiber-
nation, usually not to return above ground until March or April.

Hawks, badgers, weasels, dogs, man, and other enemies take
their toll of the Franklin’s ground squirrel; speeding cars on
highways may take the greatest toll.

Signs.—Franklin’s ground squirrel tracks, sometimes seen
along dusty roadsides, are quite similar to those of gray tree
squirrels. The print of a hind foot measures about 2 inches and
shows five toes, but the print of a front foot, which is shorter,
shows only four toes. The location of these tracks, often far
from trees, helps to distinguish them from tracks of the gray
squirrel.

The burrow of this animal is usually in tall grass or a weedy
spot. It is about 3 inches in diameter, and may have a mound of
dirt spread fanwise from it. Usually it is better concealed and
larger than that of the thirteen-lined ground squirrel.

Distribution.—Franklin’s ground squirrel is common in what
was originally prairie regions in about the northern two-thirds
of Lllinois. This ground squirrel is unknown or rare south of
an imaginary line connecting Clark and Madison counties. No
subspecies has been described. “—The known total range extends
from northwestern Indiana and central Illinois northward to
central Manitoba, Saskatchewan, and Alberta, and southward
into Kansas and Missouri, fig. 77. It is known in Wisconsin
from the southern part of the state.

TAMIAS STRIATUS (Linnaeus)
Eastern Chipmunk

Description.—The eastern chipmunk, fig. 79, is one of the
most colorful Illinois mammals. It is russet on the head, flanks,
and rump, and grayish on the sides and back; it has five black
and two light buff stripes on the back. Stripes are present, but
less distinct, on the sides of the face. The under parts are whit-
ish. The tail, which is bushy and about half as long as head
plus body, is about the same color on the upper side as the back
and is russet on the under side. Large pouches are present
within the cheeks.

A characteristic call, consisting of a low-pitched cluck or
chuck, or a shrill chirp, is usually heard before the chipmunk

140 Order RODENTIA

is seen. Frequently this chipmunk twitches its tail in unison
with the call.

Length measurements: head and body 614-7 inches (160-175
mm.) ; tail 314-4% inches (80-110 mm.) ; over-all about 914-
1114 inches (240-285 mm.) ; hind foot 134-114 inches (34-38
mm.). Weight: about 14 pound (100 gm.).

The skull, which is 39-42 mm. (about 15@ inches) long, lacks
an antorbital canal and has only four cheek teeth on each side
of the upper jaw. Dental formula: I 1/1, C 0/0, Pm 1/1,
M 3/3.

Life History.—The eastern chipmunk is usually unsociable
and shy. A chipmunk, at the approach of another of its kind,
may give a few flicks of its tail and then dash out suddenly to
chase the intruder away. This animal inhabits brushy woods,
fig. 1, wooded bluffs, or woods opened by lumbering activities
where there is an abundance of old logs and tumbled stones to
furnish shelter for burrows, nests, and lookout stations. It will
abandon closely pastured woodlands, and its absence from many
wooded parts of Illinois is attributed to overgrazing.

The chipmunk is primarily a ground dweller, living in a bur-
row which it has dug among tree roots or beneath a log, rock,
or building. It may occasionally climb into trees. Its burrow
may be 20 feet long and have one or several storage chambers
in addition to the nest. It feeds chiefly on a variety of fruits
and seeds and on insects. In the summertime when juicy berries
are ripe, tell-tale stains may be seen on its cheeks. The chip-
munk may carry in its cheek pouches a multitude of seeds such
as hazelnuts, acorns, basswood fruits, oats, hickory nuts, grass
seeds, corn, and elm seeds to store in its chambers for the winter
supply of food. It does not grow excessively fat as winter ap-

Fig. 79.—Eastern chipmunk.

Family SCIURIDAE 141

proaches, since it will not need to rely on a reserve supply of fat
for nourishment when food becomes scarce but instead will
retire to a well-filled pantry. It becomes dormant during ex-
cessively cold weather at any time between November and April
but may come above ground during warm periods. It does not
seem to hibernate in the sense that ground squirrels do.

It is possible for a pair of chipmunks to rear two litters of
young each year. The first litter usually arrives in late April
and the second about August. There are five or six young in
each litter. When a month old, the young are nearly two-thirds
grown and appear outside the burrow.

The chipmunk is preyed upon by hawks, weasels, foxes, cats,
and other animals. Probably its greatest enemy is man, who
through his agricultural endeavors has destroyed much of its
natural habitat.

Signs.—Although the chipmunk sometimes emerges in winter
and sets foot in snow, the best places to look for its tracks
are dusty forest paths. The tracks are somewhat like tracks of
squirrels but smaller and with less tendency for the prints of
the front feet to pair.

The burrow is less than 114 inches in diameter. The en-
trance characteristically has no mound when finished and is
usually hidden away under a log, a stone pile, or roots of trees.

Distribution—The eastern chipmunk may occur in all coun-
ties of [llinois but usually it is restricted to unpastured woods
in hilly regions. It is most abundant in rocky, wooded ravines.
Two subspecies are believed to be present in Illinois, T’amuias
striatus ohionensis Bole & Moulthrop in the Wabash and Ohio
river valleys and T. s. griseus Mearns in the remainder of the
state. The range of the species embraces most of southern
Canada from eastern Quebec to southern Manitoba and most
of eastern United States except the far south.

TAMIASCIURUS HUDSONICUS (Erxleben)
Red Squirrel*

Description—The red squirrel, fig. 80, is smaller than the
fox squirrel or the gray squirrel. It is reddish gray on the back
and whitish on the belly; it has a black line on the sides between

*This squirrel should not be confused with the fox squirrel, which is sometimes
called the red squirrel in Illinois.

142 Order RODENTIA

the upper and under parts. The bushy tail is not quite so long
as the body and is reddish gray above, like the back, and yel-
lowish gray below. In the winter pelage, ear tufts are apparent.
Length measurements: head and body 714-814 inches (186-
210 mm.) ; tail 414-514 inches (104-130 mm.) ; over-all 1114-
1314 inches (290-340 mm.) ; hind foot 134-214 inches (44-53
mm.). Weight: approximately % pound (140-220 gm.).

Fig. 80.—Red_ squirrel.

Family SCIURIDAE 143

The skull is 43-49 mm. (about 134 inches) long. The third
upper premolar, if present, is very small, and the upper cheek
teeth are less than 10 mm. long. Dental formula: I 1/1, C 0/0,
pue2/ser 1/1; M 3/3.

Life History.—In former years, the red squirrel probably
frequented the hardwood and coniferous forests of northern
Illinois.

This squirrel does not hibernate, although it becomes inactive
during periods of extreme cold. It sometimes makes long bur-
rows in snow, probably in search of food. Usually it makes its
nest of grasses and leaves in a cavity of a tree, but sometimes
it makes a leaf nest among the branches.

Distribution.—Although it almost certainly no longer inhab-
its Illinois, the red squirrel formerly occurred in scattered col-
onies in the northern part of the state. There are four au-
thentic records of this squirrel for the state: Lake Forest and
Fox Lake in Lake County, Lawnridge in Marshall County, and
Hennepin in Putnam County. The specimens on which these
records are based (all collected before 1912) belong to the sub-
species Tamiasciurus hudsonicus loquax (Bangs). The species
occurs throughout most of Canada and Alaska; in western
United States in mountainous areas as far south as southeast-
ern Arizona; in eastern United States as far south as southern
Iowa, central Indiana, and western North Carolina.

SCIURUS CAROLINENSIS Gmelin
Eastern Gray Squirrel

Description.—The eastern gray squirrel, fig. 81, generally
is grayish on the back and sides and has a wash or overlay of
fulvous or yellow on the sides and legs. The belly is white or
light gray, and the bushy tail is gray, tipped with white. Tufts
of white hair behind the ears and a ring of white around each
eye are characteristic.

Melanistic (“black”) or albinistic (“white”) individuals or
colonies of this species are occasionally seen. In former years,
melanistic individuals were frequently found, especially in the
northern part of Illinois. In the middle 1800’s, an entire group,
numbering nearly 50 individuals, near the Rock River con-
sisted of “blacks.” At present, there is a sizable colony of
albinistic individuals established in and near Olney.

144 Order RODENTIA

Length measurements: head and body 814-1014 inches (210—
270 mm.) ; tail 714-914 inches (190-240 mm.) ; over-all 16-20
inches (400-510 mm.), males averaging about 1814 inches
(464 mm.), females 1714 inches (439 mm.); hind foot 234-3
inches (60-75 mm.). Average weight: about 114 pounds.

The skull is 59-64 mm. (about 23% inches) long. The third
upper premolar on each side is small and peglike. Dental for-
mulaca 1/0/00; Pm 2/1 eM 3/3.

Life History.—The gray squirrel is commonly seen in trees
bordering city streets, in parks, on lawns, near wooded streams
and heavy stands of timber, and in areas where there is abun-
dant ground cover and brush not greatly disturbed by ax or live-
stock. Probably it spends more time in trees and less time on
the ground than does the fox squirrel; it is more adept and
graceful in moving through trees.

The gray squirrel lives in a leaf nest or in a hollow within
the main trunk of a tree. A litter of three to five young is
brought forth in the nest about the middle of February in south-

Fig. 81—Young of eastern gray squirrel.

Family SCIURIDAE 145

ern Illinois and about the middle of March in northern Illinois.
A second breeding period begins about June 15 in southern IIli-
nois, about June 25 in central Illinois, and about July 5 in
northern Illinois. About 45 days later, the second litter is born.

Food of the gray squirrel consists chiefly of buds, seeds,
acorns, nuts, and other fruits of nearly all trees in the habitat
where the animal lives. It consists also of fungi, corn kernels,
soybeans, berries, and grapes. This squirrel stores quantities of
food for winter use, as it does not hibernate. It may, however,
become inactive and remain within its nest during severe cold
spells.

Early in the settlement of Illinois, grays were apparently
much more abundant than they are today. In some years, the
production of nuts and seeds was especially good, and ample
food resulted in a large number of squirrels. In those years in
which the nut crop was a failure, grays in large numbers would
move as a group across country, surmounting many barriers
en route. This forced migration resulted in their being called
“migratory squirrels” by some people.

The gray squirrel and the fox squirrel usually do not live
together in Illinois. In some towns there are only grays and in
other towns only fox squirrels. In some timber, usually open
timber, there are only fox squirrels; in other timber, usually
that with ample undercover, there are only grays. These two
species do not cross or interbreed in nature, despite stories to
the contrary.

Signs.—Prints of the hind feet of the gray squirrel measure
a little less than 2 inches each over-all, and prints of the front
feet are shorter. Tracks of the gray squirrel resemble those of
the fox squirrel, fig. 34. Gnawed remains of nuts and depres-
sions an inch or so deep and about as wide among fallen leaves
in brushy woodlands are signs of the gray squirrel.

Leaf nests, situated well up in trees, in a type of habitat de-
scribed above, indicate the presence of gray squirrels; a single
squirrel may be the owner of more than one leaf nest.

Distribution.—The gray squirrel is fairly common in wooded
areas of Illinois. Individuals in the northern two-thirds of the
state are of the subspecies Sciurus carolinensis pennsylvanicus
Ord, those in the southern third 8. c. carolinensis Gmelin. The
species occurs in most of the eastern half of the United States
and in southern Ontario.

146 Order RODENTIA

SCIURUS NIGER Linnaeus
Eastern Fox Squirrel

Description.—The eastern fox squirrel, fig. 82, generally is
rusty-yellow, with a mixture of gray, on the upper parts and
reddish yellow on the under parts. The cheeks, the fur behind
the ears, and the feet are a light reddish yellow. The bushy
tail is bordered with reddish.

Length measurements: head and body 11-1134 inches (280-
300 mm.) ; tail 834-1014 inches (220-260 mm.) ; over-all 1914-
22 inches (500-560 mm.) ; hind foot 23-3 inches (60-78 mm.).
Weight: average approximately 134 pounds, about half a pound
more than that of the gray squirrel.

The skull is 60-70 mm. (about 214 inches) long; there are
only four cheek teeth on each side of the upper jaw (usually
five in gray squirrel). The zygomatic arches are nearly parallel,

fig. 74k. Dental formula: I 1/1, C 0/0, Pm 1/1, M 37/3.

Fig. 82.—Eastern fox squirrel.

Family SCIURIDAE 147

Life History.— The fox squirrel is familiar to most people
in Illinois, for it occurs in many of the city parks and farm
wood lots of the state. Since it prefers woods with openings, the
removal of timber for lumber or the grazing of woodlands by
cattle has not adversely affected the fox squirrel so much as the
gray squirrel. Wood lots of even a few acres provide suitable
habitat if they are connected by hedgerows or scattered trees,
and if they have trees with cavities and trees that produce nuts
or other seeds.

The fox squirrel lives in a leaf nest, fig. 9, or in the cavity of
a hollow tree. It has two periods of mating and breeding, one
in midwinter (December or January) and another in early sum-
mer (May in southern, June in northern Illinois). Young num-
bering two to five per litter are born in February or March and
in July or August. A female of 2 years or older may have two
litters a year, but a yearling has only one litter.

The fox squirrel feeds on nuts, fruits of the oak, elm, and
beech, corn, tree buds, mushrooms, and even birds’ eggs. Mast
is important in fall and winter; fleshy fruits, buds, and left-over
mast in spring; many items in summer. Nuts for winter use are
individually buried in small. pits the animal digs in the ground.
The fox squirrel does not hibernate; it hunts out, actually
smells out, these food reserves when winter comes. Because of
its habit of burying food, the fox squirrel spends much time on
the ground and frequently moves considerable distances from
trees.

Signs.—Fox squirrel tracks, fig. 34, average slightly larger
than gray squirrel tracks, and the small prints of the front feet
are more often paired. ‘Their location helps to distinguish
tracks of the two species. If the tracks are along hedgerows,
along narrow strips of timber, or among widely scattered trees
in pastures or cultivated fields, they generally belong to the fox
squirrel. If they are in very dense stands of brushy timber, they
are likely to belong to the gray squirrel. The leaf nest of the
fox squirrel resembles that of the gray squirrel.

Distribution.—The iox squirrel occurs throughout Illinois.
Individuals in this state are of the subspecies Sciurus niger
rufiventer Geoffroy. The range of the species extends from
Delaware and southern Pennsylvania westward through south-
ern Minnesota, Nebraska, and much of Texas, and southward

to the Gulf of Mexico.

Order RODENTIA

83.—Southern flying squirrel.

Family SCIURIDAE 149

Fig. 84—Southern flying squirrel in “flight.”

GLAUCOMYS VOLANS (Linnaeus)
Southern Flying Squirrel

Description.—The southern flying squirrel, fig. 83, is about
the size of the eastern chipmunk but appears larger than it
really is because of its “flying” membranes, thick fur, and broad
tail. Its eyes are especially large and its ears project only a
short distance above the fur. The “flying’’ membrane on each
side of the body consists of a loose fold of skin extending from
wrist to ankle. The glossy fur on the back and sides of the body
is gray, drab, or pinkish cinnamon; the under parts are pure
white. The feet are a dusky color. The flattened tail is about
the same color as the back.

Length measurements: head and body 514-514 inches (130-
140 mm.) ; tail 314-414 inches (90-110 mm.) ; over-all 854-934
inches (220-250 mm.) ; hind foot about 114 inches (27-33 mm.).
Weight about 2 ounces (40-70 gm.).

The skull is 33-36 mm. (about 13¢ inches) long. The inter-
orbital region is deeply notched, fig. 74j, and the postorbital
processes are large. Dental formula: I 1/1, C 0/0, Pm 2/1,
M 3/3.

Life History—The flying squirrel is abroad only at night
and sleeps by day in a cavity within a tree. It is a very in-
triguing animal, for it has perfected the art of gliding (loosely

150 Order RODENTIA

referred to as flying). To get from one tree to another, per-
haps 30 or more yards away, a flying squirrel does not need to
go to the ground and expose itself to dangers there, fig. 1. In-
stead, it leaps, spreads its legs so that the fold of skin on each
side of the body is fully extended, fig. 84, and, aided by the flat-
tened tail, glides to the trunk of a distant tree. The direction
of the glide can be controlled somewhat by movement of the
tail and the membrane. The squirrel does not fly in the sense
that it flaps the membrane, nor is its point of landing ever higher
than its point of departure.

The southern flying squirrel is found in areas that are heavily
wooded, but*not so heavily wooded as to prevent gliding, and
that. have trees with ample woodpecker holes or similar cavities
in which to make nests. In one of these cavities a female may
have one or two litters of two to six young each year. The first
litter is born in late March or early April and the second in
August. The flying squirrel feeds on nuts, seeds, tree buds,
fruits, insects, and birds’ eggs. :

This is the commonest squirrel in much of the heavy timber
of Illinois. Noisy taps on a hollow tree or on a tree with wood-
pecker holes may cause a sleepy flying squirrel to poke its head
out of one of the cavities. Several individuals may occupy one
cavity, for these animals are quite sociable. They make ideal
pets.

Signs.—Tracks of the flying squirrel are rarely seen. The
footprints are like those of other tree squirrels. Prints of the
hind feet are each about 114 inches long. Opened nuts beneath
an old woodpecker hole in a tree may indicate the presence of
one or more flying squirrels. Nuts opened by a flying squirrel
have a roughly circular opening and are not largely gnawed
away, as are those opened by the gray squirrel or the fox squir-
rel. Tooth marks of the flying squirrel are finer than those of
the other tree squirrels common in Illinois.

Distribution.—The southern flying squirrel occurs in mature
woodlands of Illinois, and probably it is common in such habi-
tats. Individuals in this state are of the subspecies Glaucomys
volans volans.(Linnaeus). The species has a disjunct. range;
one population occupies approximately the eastern half of the
United States (except northern New England); one occurs in
the central part of the Central American countries; a third
occurs in the central part of the Mexican Plateau.

Family GEOMYIDAE 151

GEOMYS BURSARIUS (Shaw)
Plains Pocket Gopher*

Description.—The plains pocket gopher, fig. 85, in Illinois
usually is slate gray to black on the back, light gray on the under
parts, and white on the nose, feet, and terminal half of the tail.
In other parts of its range, this gopher is principally brown or
tawny, but in Illinois only rarely is one found that is chocolate
brown on the back. The eyes are small, and the ears are round
and extremely short. The front legs are stout, and the claws of
the front feet are long. ‘The tail is about one-third the length

Fig. 85.—Plains pocket gopher.

of the head plus body and sparsely covered with short hairs. An
external pocket or pouch is present on each side of the mouth.
The lips can be closed behind the long, heavy upper incisors.

Length measurements: head and body of males 734-834
inches (200-222 mm.), of females 7-814 inches (180-210 mm.) ;
tail 214-4 inches (65-100 mm.) ; over-all for males 1014-1234
inches (265-322 mm.), for females 914-1214 inches (245-311
mm.) ; hind foot about 134 inches (30-37 mm.). Weight: about
34 pound (300-400 gm.).

The skull is strongly ridged for muscle attachments and is
49-59 mm. (about 21% inches) long in males, 46-56 mm. (about
2 inches) in females. The rostrum is heavy and broad. The
incisors are strong, and each upper incisor has at least two
grooves on its front surface, fig. 73c. Dental formula: I 1/1,

ee Pea 171 WV 3/3.

*Not to be confused with the ground squirrels, sometimes called gophers.

152 Order RODENTIA

Life History.—The plains pocket gopher lives continuously,
or nearly so, below ground and comes to the surface only to
dump earth from its burrow or to make very short forays in
quest of food. Normally, it breeds, nests, feeds, and carries on
all other activities below ground. Its burrow system is several
hundred feet long, and each animal throws up many mounds or
piles of dirt as it digs its burrow system.

Except for a short time during the breeding season, each bur-
row system is occupied by a single individual. The tunnels usu-
ally are not deeper than 4 feet; they have a main nest, and pos-
sibly subsidiary nests, and several storage chambers of food.
In the storage chambers, the gopher stores roots, stems, and
leaves of sweet clover, alfalfa, dandelion, plantain, and other
herbs, as well as roots of shrubby plants. It digs innumerable
side tunnels to the roots of likely food plants. The gopher cuts
the roots in appropriate lengths, stuffs the pieces adeptly into its
cheek pouches, and carries them to its storage chamber.

This gopher has certain adaptations for a lifetime within a
narrow, dark tunnel. The tip of the tail, which is highly sensi-
tive, is employed as a guide when the animal is backing. With the
tail projecting straight back, except for a little crook at the end
which causes the tip to touch the wall or floor of the tunnel, the
gopher can run backward almost as swiftly and surely as it can
run forward. The skin of the gopher is loose and easily stretched,
allowing the animal to reverse itself readily within a narrow
tunnel. The lips are modified in such a way that they can be
closed behind the incisors and thus keep dirt out of the mouth
while the animal is gouging out soil or cutting roots. The long,
curved claws aid in digging and pushing dirt from the tunnel.

The pocket gopher in Illinois probably has only one litter a
year, born some time between early March and early May.
There may be as many as six young in a litter, but the usual
number is four. The mother, having driven the male from her
burrow system soon after the breeding season is over, raises the
young by herself.

Weasels, badgers, and snakes, particularly bull snakes, are
the principal enemies of the pocket gopher. The tunnel en-
trances are kept solidly blocked with dirt at almost all times
and this may discourage enemies from entering.

Signs.—Mounds of dirt in grasslands, in hayfields, or along
grassy roadsides in central Illinois may be signs of the pocket

Family GEOMYIDAE 153

gopher. At a distance, gopher mounds may be mistaken for those
ot the mole. The gopher produces a mound, figs. 2 and 7, by
pushing the dirt from the mouth of the sloping entranceway in
such a manner that this dirt forms a relatively low, fan-shaped
mound. The mouth of the entranceway, which is on the low side
of the mound, is plugged by the last “load” of dirt; the “plug”
is a distinguishing characteristic of a recently constructed pocket
gopher mound. The mole produces a mound, fig. 6, by pushing
the dirt straight up from beneath the surface of the ground;
the loosened dirt cascades down evenly to form a cone with
relatively steep sides, like those of a volcano. In weathered
mounds, these differences are difficult to detect. A gopher
mound is 12 or more inches across, and a mole mound is about
10 inches. The pocket gopher never has subsurface runs that
hump up the dirt radiating out from the mound as does the mole.

Distribution.—The pocket gopher is abundant in the sandy
and black soils east and south of the Illinois and Kankakee
rivers, and in Madison County, fig. 86. In Illinois is the sub-
species Geomys bursarius illinoensis Komarek & Spencer.
The range of the species includes an irregular area in the center
of the North American continent, fig. 86.

PLAINS POCKET
GOPHER

Fig. 86.—Known distribution, in the United States, of plains
pocket gopher.

154 Order RODENTIA

CASTOR CANADENSIS Kuhl
. Beaver

Description.—The beaver, fig. 87, is a large, dark brown,
semiaquatic mammal with a flat, paddle-shaped, scaly tail,
webbed hind feet, and small ears.

Length measurements: head and body 26-31 inches (660-790
mm.); tail 914-1014 inches (240-260 mm.); over-all about
35-41 inches (900—1,050 mm.) ; hind foot 614-7 inches (165-180
mm.): Weight: usually 25-50 pounds; a weight of 7814 pounds
is recorded for a specimen taken on the Mississippi River near
Meyer, Adams County.

The skull is massive and about 120 mm. (434 inches) long.
The large, red-orange incisors are well suited for gnawing, and
the back cheek teeth well suited for grinding, fig. 73d. Dental
formula: t/1,°C:0/0, Pmilyt, Mes /3.

Life History—vThe beaver needs a continuous supply of
water and a supply of suitable food near water. For food it
prefers poplar, maple, birch, and willow; it may eat other kinds
of trees, as well as cattails and other aquatic plants. The trees
and branches cut by a colony of beavers and transported to their
dam serve not only as a means of retaining the water but also

as a pantry for food.
A colony of beavers consists usually of an adult male and fe-
male and their offspring of the year and the previous year. Since

~

Fig. 87.—Beaver.

Family CASTORIDAE 155

the usual number in each litter is four, there may be as many as
10 beavers in a colony. As the older litter approaches the age of
2 years, it is driven from the colony. This forced dispersion
results in the continuous establishment of new colonies, some
nearby, others far removed. During this dispersion, adult
beavers may be killed by dogs, men, or cars. Young beavers
may be killed by minks or by extreme fluctuations in water level.
By and large, beavers have few natural enemies in Illinois.

Some beavers live in burrows in banks of lakes or streams.
Many others live in lodges behind their dams. Their dams may
be as much as 6 feet in height and 200 feet in length and so con-
structed as to withstand heavy floodwaters. They are made of
tree branches, sticks, mud, and stones, and are plastered with
mud on the upstream side. Their great lodges, fig. 11, built of
similar material, often extend 6 feet above water and are several
times as wide as high. From dusk to daylight, beavers work on
their dams or lodges—adding branches, replacing mud, or felling
nearby trees. Each member of a colony except the young of the
year is ‘busy as a beaver.”

Signs.—Some of the most dramatic wildlife signs in Illinois
are those of the beaver. In addition to their dams and lodges,
beavers leave such signs as felled trees, sometimes more than a
foot in diameter, gnawed down for food, or the stumps of trees
showing the characteristic wide tooth marks, fig. 28e; great piles
of branches stored near the lodges for food; canals several feet
deep and several feet wide down which they float timber; large
burrows 12 to 18 inches in diameter dug in stream banks; and
footprints, chips, droppings, nibbled cornstalks, and a host of
lesser signs. Branches cut into sections several feet long with
bark peeled from them may indicate the presence of beavers.

Beaver droppings are loosely packed, 1-114 inches in length,
and composed principally of wood fiber. They are light and float
on the surface of the water only a brief time before disinte-
grating. They are not deposited on stones or logs in or near
water, as are the droppings of muskrats.

The print of a hind foot of the beaver, fig. 28+, measures 6
inches in length and 5 inches across, and it shows the web con-
necting the toes. The print of a front foot, fig. 28a, roughly
half as long as that of a hind foot, shows long claw marks.

Distribution.—In former times, the native beaver was abun-
dant in Illinois. Probably Castor canadensis michiganensis

156 Order RODENTIA

Bailey occurred over most of the state, and C. c. carolinensis
Rhoads inhabited the extreme southern part. By the middle
1800’s beavers had been reduced to the point of being rare in the
state, and during the late 1800's or early 1900's the native popu-
lation was exterminated. In 1935, beavers brought from Wis-
consin were released in Illinois; subsequently there were inva-
sions of beavers from Iowa and Indiana. These animals in-
creased in numbers and extended their range until by 1954
beavers were present in nearly half the counties of Illinois;
through transplantations or natural movements there were
nearly 600 colonies. All members of the species occurring in
Illinois at present probably belong to the subspecies C. c. michti-
ganensis. The natural range of the species occupies most of
Alaska, Canada, and the United States except parts of the
southeastern and Gulf Coast states and the arid parts of the
southwestern states.

REITHRODONTOMYS MEGALOTIS (Baird) f
Western Harvest Mouse

Description——The western harvest mouse, fig. 4, smaller
than the white-footed mouse, is similar to the house mouse except
in color. Its back and sides are brown, and its under parts are
silvery gray; the under side of its tail is whitish, and the upper
sides of its hind feet are white. Each upper front tooth (incisor)
has a groove down its face. The only other rodents now reported
in Illinois with such grooves are the plains pocket gopher, the
meadow jumping mouse, and the bog lemming.

Length measurements: head and body 214-3 inches (66-77
mm.); tail 214-25¢ inches (57-68 mm.); over-all 434-534
inches (123-145 mm.) ; hind foot about 5¢ inch (16-18 mm.) ;
ear from notch about 14 inch (12-14 mm.).

The skull averages 20.3 mm. (about 34 inch) in length; in
width across the zygomatic arches it averages 10.4 mm. (about
¥ inch). Dental formula: I 1/1, C 0/0, Pm 0/0, M 3/3.

Life History.—Western harvest mice taken in_ Illinois
near Mount Carroll were found living among brome-grass,
goldenrod, blackberry, ragweed, and bluegrass. The vegetation
was tall but not thick. Harvest mice were quite rare in this
habitat and were associated with masked shrews, short-tailed
shrews, white-footed mice, and bog lemmings.

Family CRICETIDAE 157

Little is known about the life history of the harvest mouse
in Illinois. In some other states, this species is known to build
a globular nest in dense grasses or weeds, rather than under
logs or below the surface of the ground. It feeds on seeds, is a
good climber, and frequently crawls far up into plants in search
of food. Breeding begins in the spring. Young may appear by
late April and when 3 weeks old are able to feed by them-
selves.

GOLDEN MOUSE

COTTON MOUSE

Fig. 88.—Known distribution, in the United States, of some mice
with a limited range in Illinois.

158 Order RODENTIA

Signs.—T racks or droppings of the western harvest mouse
cannot easily be differentiated trom those of other mice. A grassy
nest above the ground in a weedy or grassy field may be that of
a harvest mouse. —

Distribution.—In Illinois the western harvest mouse has
been taken in Carroll County. Elsewhere east of the Mississippi
River, it has been recorded from southern Wisconsin. It is
found in much of the United States west of the Mississippi and
in Mexico, fig. 88. Animals of this species in Illinois have been
referred to the subspecies Reithrodontomys megalotis dychei

Allen.

REITHRODONTOMYS HUMILIS (Audubon & Bachman)
Eastern Harvest Mouse

Although specimens or records of this species are lacking for
Illinois, an eastern harvest mouse was caught recently across the
Ohio River near Paducah, Kentucky. Because of this proximity,
the species might be expected in brome-grass and savanna-like
habitats in extreme southeastern Illinois.

‘The combination of grooved incisors and moderately long tail
will serve to identify the genus. Differences in their geographic
ranges can be used as a provisional means of distinction between
the eastern harvest mouse and the paler but similar western
harvest mouse, Reithrodontomys megalotts.

PEROMYSCUS MANICULATUS (Wagner) *
Deer Mouse Prairie Deer Mouse

Description.—The smallest Illinois Peromyscus, the deer
mouse, fig. 89, usually is grayish brown (rarely ochraceous) on
the upper parts, with a blackish area, more or less concentrated
in a band, down the middle of the back. The tail, except for a
narrow stripe of grayish brown on top, the feet, and the under
parts are whitish. The ears are grayish brown, margined with
cream or white. The hind feet are unusually small, and the tail
is relatively short.

Length measurements: head and body 314-314 inches (81-90
mm.) ; tail 134-23¢ inches (44-60 mm.) ; sD. 5-6 inches

*As used here, the name white-footed mouse is restricted to the species Peromyscus
le ucopus.

Family CRICETIDAE 159

(125-150 mm.) ; hind foot 54-34 inch (15-18 mm.) ; ear from
notch about 14 inch (11-14 mm.).

The skull is 22.0-24.5 mm. (about 74-1 inch) long; its width
across the zygomatic arches just behind the infraorbital plate is
less than 12 mm. Dental formula: I 1/1, C 0/0, Pm 0/9,
M 3/3.

The deer mouse may usually be distinguished from the more
abundant white-footed mouse on the basis of the following com-
bination of characters: hind foot less than 19 mm. long, rather
than 19 mm. or more as in the white-footed mouse; tail less
than 60 mm. long, rather than more than 60 mm.; total length

Fig. 89.—Deer mouse.

of adults less than 155 mm., rather than more; width of skull
across zygomatic arches just behind the infraorbital plate less
than 12 mm., rather than more; length of skull 14.5 mm. or less,
rather than more.

Life History—The deer mouse is an inhabitant of the
prairie and is most abundant in areas of ungrazed and uncut
grass and forbs, such as grow along railroad and highway rights-
of-way, in extensive weedy fields, and along fencerows, fig. 2.
It is at home under a haystack or a corn shock, among dry
weeds along a fence, or under a rock or board.

The nest, usually underground, is approximately the size of a
man’s two cupped hands. It is formed of a coarse outer frame-

Order RODENTIA

90.—White-footed mouse.

Family CRICETIDAE 161

work of stems, roots, and leaves, and holds a soft inner lining
of plant down, fur, or feathers.

Young may be produced in nearly any month of the year. An
adult female may have several litters (potentially a dozen, but
probably only four or five) each year, and there are usually four
young in each litter. The young, blind and naked at birth, grow
rapidly. Females can start breeding when only 5 to 10 weeks
old.

The deer mouse feeds on seeds of grasses and weeds, and on
berries, buds, insects, and possibly some green plants. It does
not hibernate. Probably it hoards some seeds in burrows or
tunnels near its nest for winter use. This mouse is preyed upon
by owls, snakes, weasels, foxes, and nearly all other Illinois fur
bearers. In the wild, it probably never lives for more than 2
years before it meets an untimely end; it may live as long as 9
years in captivity.

Signs.—It is difficult to tell the footprints and droppings of
the various kinds of Peromyscus apart. The location of signs
may aid in determining the kind of mouse that made the signs,
as habitats of the various species differ considerably.

Prints of the hind feet of the deer mouse are paired and those
of the front feet are nearly so. The sets, fig. 31, are about 3
inches apart when made by a mouse bounding at an ordinary
gait; much farther apart when made by a speeding mouse. Drop-
pings are brown or black and between 14 and 3% inch long.

Distribution—The deer mouse may be locally abundant,
particularly in sand prairies. Colonies probably occur through-
out the state. The subspecies in Illinois is Peromyscus manicu-
latus bairdii (Hoy & Kennicott). The main range of the spe-
cies extends from Labrador to central Alaska and southward to
southern Mexico in the west and Tennessee in the east; the
range also extends down the Appalachians to northeastern
Georgia.

PEROMYSCUS LEUCOPUS (Rafinesque)
White-Footed Mouse Woodland White-Footed Mouse

Description.—The white-footed mouse, fig. 90, has the same
proportions as the house mouse, but is larger. In the adult, the
upper parts are bright brown or fulvous, the under parts white.
The ears are dusky brown, with whitish edges. All four feet

162 Order RODENTIA

are white. The tail is bicolored, dark on the upper part, whit-
ish on the under part. In the immature mouse, the upper parts
are a dull brown or gray, the under parts white.

Length measurements: head and body 3-4 inches (78—100
mm.); tail 23-33 inches (60-85 mm.); over-all 534-714
inches (138-185 mm.) ; hind foot 34-78 inch (18-22 mm.) ; ear
from notch 54-34 inch (15-19 mm.).

The skull is 24.5-28.0 mm. (about 1-114 inches) long; the
width across the zygomatic arches just behind the infraorbital
plate is more than 12 mm. Part of the skull is shown in fig.
74h. Dental formula: I 1/1, C 0/0, Pm 0/0, M 3/3.

The white-footed mouse closely resembles the deer mouse
and the cotton mouse.

Life History.—The white-footed mouse lives in forests, fig.
1, brushlands, river bottoms, forest edges, and even in brushy
areas extending out into prairies. Probably 3 to 12 mice, some-
times even more, per acre occur in these habitats. A white-
footed mouse may be found under a log, within a stump, in a
once-abandoned bird’s nest, or in a shallow burrow. It may make
its nest in, on, or above the ground. If a home in a burrow
proves too damp, the white-footed mouse may move into a de-
caying log or into a tree stump. In the fall, it may move to an
unused bird’s nest, such as that of the goldfinch, after working
diligently a few nights to build a dome over it and arrange a
soft lining. It may nest in a woodpecker hole or a bird box near
timber; it rarely enters inhabited buildings.

Breeding may take place in all except the very coldest months
of the year, but the majority of young are produced in spring,
early summer, and fall. The white-footed mouse is probably as
prolific as the deer mouse. A mature female gives birth yearly
to at least four litters, with four or five young in each litter.
The young are hairless and blind at birth. They grow rapidly
and become independent of family ties probably when they are
scarcely more than a month old.

The white-footed mouse is nearly omnivorous. It normally
feeds on seeds of wild herbaceous plants, nuts, buds, fruits, and
insects; if given an opportunity it eats grains and pantry items.

Signs.—Tracks and droppings of the white-footed mouse
resemble those of the deer mouse, fig. 31, but they are slightly
larger. ‘The home of the white-footed mouse is described above
under life history.

Family CRICETIDAE 163

Distribution.—The white-footed mouse is abundant through-
out Illinois. The subspecies in northern and central Illinois. is
Peromyscus leucopus noveboracensis (Fischer) ; that in southern
\llinois is probably P. /. leucopus (Rafinesque). The range of
the species extends from southern Maine to southern Alberta
and southward to southern Mexico. Its western limits are
marked by northeastern Wyoming, northwestern Kansas, and
south-central Arizona. The range does not include the extreme
southeastern United States.

PEROMYSCUS GOSSYPINUS (Le Conte)
Cotton Mouse

Description.—The adult of the cotton mouse is dark reddish
brown on the upper parts and white on the under parts. An
immature may be gray or grayish brown on the upper parts.
The adult closely resembles the white-footed mouse but usually
can be distinguished from it by the longer body and hind feet and
the larger skull.

Length measurements: head and body +-414 inches (100-107
mm.); tail 3-314 inches (78-88 mm.) ; over-all 7—75¢ inches
(178-195 mm.) ; hind foot about | inch (23-26 mm.) ; ear from
notch 5¢ inch (15-16 mm.) in dry study skins.

The skull is 28-30 mm. (about 11% inches) long. The upper
molar tooth row is 3.6-4.0 mm. (about 14 inch) long. Dental
formula: J 1/1, C. 0/0; Pm 0/0, M. 3/3.

Life History.—The cotton mouse lives in swamps and bot-
tomlands, and in forests adjacent to them, fig. 3. Apparently
it picks the driest spot beneath a fallen log or stump to place
its nest.

Little is known about the cotton mouse in IIlinois. Probably
its breeding habits are similar to those of the white-footed
mouse. Both species may occupy the same swampy woodlands.

It is not clear how the common name for this mouse was
derived; in southern states where it is abundant it usually is
found in areas not far removed from cotton fields.

Signs.—Tracks and nests of the cotton mouse are like those
of the white-footed mouse.

Distribution.—The cotton mouse is uncommon in IIlinois and
is known in the state only in the southern tip south of the Ozark
Plateau and the Shawnee Hills. The subspecies in this state is

164 Order RODENTIA

Peromyscus gossypinus megacephalus (Rhoads). The range of
the species is an irregular area that embraces most of the south-
eastern states, fig. 88. It includes northward extensions into
northeastern Virginia and southern Illinois. Its westward limit
is eastern Texas.

PEROMYSCUS NUTTALLI (Harlan)
Golden Mouse

Description—The golden mouse, fig. 91, is reddish brown
or golden on the upper parts and white or cream colored on the
lower parts. The ears are red and the feet are white. The
eyes are large and conspicuous, the cheek pouches are thin and
inconspicuous, and the tail is slightly shorter than the body.

Length measurements: head and body 314-314 inches (83-89
mm.); tail 254-314 inches (67-83 mm.); over-all 57-634
inches (150-172 mm.); hind foot 34 inch (18-20 mm.) ; ear
from notch about 34 inch (16-18 mm.).

The skull is 25-27 mm. (about 1 inch) long. The infraorbital
plate is straight along its front margin, fig. 74g. Dental for-
mula: I 1/1, C 0/0, Pm 0/0, M 3/3.

The following combination of characters serves to distinguish
the golden mouse from all other species of Peromyscus in Illi-
nois: reddish brown or golden color of both young and adults,
red ears, thin cheek pouches, and straight infraorbital plate.

Life History.—The bright-colored golden mouse is as much
at home in trees, vines, or bushes as it is on the ground. It con-
structs its home in a thicket of honeysuckle, greenbrier, or poison
ivy, or in the crotch or branches of a tree or bush, fig. 3. In
Illinois, it apparently prefers the thick timber bordering cypress
swamps.

Its nest, fig. 91, is about 8 inches in diameter and globular in
shape; the single entrance is closed except when the mouse is
entering or leaving the nest. The inner lining is of soft, finely
shredded material. Several golden mice, probably a family
group, may occupy a single nest at the same time. Young may
be brought forth in a nest at any time between March and
October. A female may have more than one litter each year,
with two or three young in each litter.

The golden mouse spends much of its time in vines and trees,
and it is, as might be expected, an adept, sure-footed climber.

-Family CRICETIDAE 165

ge >

~

Fig. 91.—Golden mouse and its nest.

Its tail, used as a fifth appendage, is frequently wrapped around
twigs to aid the animal in balancing and maneuvering. ‘The
golden mouse is a seed eater; it feasts on the soft inner parts of
the seeds of sumac, greenbrier, wild cherry, dogwood, poke-
weed, clover, bittersweet, and oak. The mouse fills its small
cheek pouches with these seeds and carries them to a nestlike
feeding platform situated above the ground. Here it may eat
the seeds immediately or store them for future use.

The beautifully colored golden mouse makes a docile pet. A
few days of confinement and gentle handling will usually result
in its complete adjustment and conditioning to man.

Signs.—A globular nest or feeding platform in a thicket or
tree may belong to a mouse of this species. However, in many
parts of Illinois, such a nest may belong to a white-footed
mouse.

Distribution.—The golden mouse, evidently uncommon in
Illinois, has been taken only in Alexander and Johnson counties.
The Illinois subspecies is Peromyscus nuttalli aureolus (Audubon
& Bachman). The range of the species extends from southern
Virginia west to southern Missouri and eastern Oklahoma and
southward to the Gulf Coast and to central Florida, fig. 88.

166 Order RODENTIA

ORYZOMYS PALUSTRIS (Harlan)
Rice Rat

Description.— The rice rat, fig. 92, is a third to half the size
of the Norway rat and has a tail slightly shorter than the body.
It is grayish brown on the upper parts and silvery gray on the

Fig. 92.—Rice rat.

under parts. The upper side of the tail is the same color as the
back of the animal and the lower side is only slightly lighter.
The fur of the under parts of the-animal is soft and woolly. In
general, the rice rat closely resembles the Norway rat, but the
light color of the under parts, including the under side of the
tail, is distinctive.

Length measurements: head and body 434-514 inches (120-
140 mm.) ; tail 414-514 inches (110-140 mm.) ; over-all 9-11
inches (230-280 mm.) ; hind foot 114 inches (30-33 mm.).

The skull of the rice rat is 30-33 mm. (about 114 inches) long
and has supraorbital ridges along the lateral margins of the
braincase. In this rat, the cusps on the upper cheek teeth are

Family CRICETIDAE 167

arranged in two longitudinal rows, whereas in the Norway rat
they are arranged in three rows, fig. 74a, c. Dental formula:
ieiy ty, 20/0; Pm 0/0, M 3/3.

Life History.—The rice rat is nearly as much at home in the
water as the muskrat and almost as good a trail-maker as the
meadow vole; its runways thread the dense vegetation of
marshes and swamp margins, fig. 3. The rice rat readily takes
to water when disturbed, and in many cases it is necessary for
it to go through water to reach its nest.

The nest of the rice rat is a globular structure of dry grasses
and leaves. It may be constructed in an oval chamber at the
end of a burrow, in one of the highest, driest objects in a swamp
or bottomland, such as a stump or hollow log or a pile of debris,
or on the top of a fence post which is well covered with vines;
or it may be suspended on a bunch of interlaced marsh grass or
embedded in a tangled mass of blue flags or marsh grasses.

Breeding may extend from March to October. Three to
eight young are produced in a single litter. The young are help-
less at birth but grow and mature rapidly. Females may begin
bearing young when they are about 2 months old.

The rice rat is active during daylight hours as well as at
night. In this regard, it resembles the meadow vole. It feeds
principally on green plants, but also on young turtles, snails,
and crayfish. Apparently this rat acquired its currently used
common name because, in parts of its range, individuals of this
species were found invading rice fields to feed on newly planted
and also maturing grain. Each rat normally eats approximately
25 per cent of its own weight in food every day. The rice rat
is fed upon by swampland predators, including snakes, owls,
hawks, minks, and raccoons.

Signs—The runways of the rice rat resemble those of the
meadow vole but they are more open and without the numerous
cut sections of vegetation lying in them. Feeding platforms of
freshly cut grass stems near such runways are almost certain
signs of the rice rat. These may be as large as dinner plates, but
smaller than those of the muskrat. The burrow of the rice rat
is seldom more than a foot deep, and the entrance is commonly
a few inches above the high water level usual for the area in
which it is located.

Footprints in soft mud near water may be those of a rice rat,
especially if they lead to a nest or a feeding platform. The

168 Order RODENTIA

print of a hind foot is more than 28 mm. (about 11% inches) long
and may be confused with that of the Norway rat.
Distribution.—The rice rat is little known in Illinois, having
been collected only-in some of the southernmost counties. The
subspecies in Illinois is Oryzomys palustris palustris (Harlan).
The range of the species includes an area that extends from
southern New Jersey westward to northwestern Arkansas and

EASTERN WOOD § *
RAT

Fig. 93.—Known distribution, in the United States, of some ro-
dents with a restricted range in Illinois.

Family CRICETIDAE 169

southward to extreme northeastern Mexico and Florida, fig. 93.
It also includes an extension into southeastern Kansas.

SIGMODON HISPIDUS Say & Ord
Hispid Cotton Rat

The cotton rat is known no closer to Illinois than Reelfoot
Lake in western Tennessee. The species is included in the key
because of the possibility, although remote, that it may occur in
southern Illinois.

NEOTOMA FLORIDANA (Ord)
Eastern Wood Rat

Description—The eastern wood rat, fig. 94, is about the
size of a large Norway rat. The back and head are a brownish
gray or buffy gray, mixed with black, the under parts are white,
and the tail is blackish above and dull white below. The eyes
are large and black. The sides of the face may be grayer and
the legs more brownish than the back. The ears are large and
thin, and the tail is nearly as long as the body.

Length measurements: head and body 8-814 inches (203-209
mm.) ; tail 73g-8 inches (187-203 mm.) ; over-all 1514-1614
inches (390-412 mm.) ; hind foot about 114 inches (36-40 mm.) ;
ear from notch 114 inches (28 mm.).

The skull is 39-42 mm. (about 114 inches) long, has a long
rostrum, and has high cheek teeth, each of which has a smooth
grinding surface consisting of a series of triangles, fig. 746.
Dental formula: I 1/1, C 0/0, Pm 0/0, M 37/3.

Life History.—The wood rat in southern II]linois is an inhab-
itant of the cliffs and rocky bluffs, fig. 95, overlooking the bot-
tomlands of the Mississippi River. It lives in the crevices and
fissures within the cliffs and bluffs and among the rocky litter
at the base of these. It packs quantities of materials—sticks,
leaves, corncobs, cans, jar lids, empty shotgun shells, dung, or
almost anything else it can carry—to the nest. Buried within
this mass of rubble is the nest itself, measuring about 9 inches in
diameter and composed of masses of soft material.

Little is known about the life history of the wood rat in IIli-
nois. Fifty miles south, in Tennessee, it is known to breed in
March and give birth to two or three young per litter in April.

170 Order RODENTIA

There may be litters at other times of the year, also. This rat
in Tennessee feeds on acorns, honey locust beans, beechnuts,
mint, and probably many other items.

Signs.— Tracks of the wood rat are similar to those of the
Norway rat. They may be found in fine dust on sheltered ledges
of rocky bluffs. The tracks converge near the nest and form
well-beaten pathways several inches wide. The prints of the
front feet are more handlike than those of the Norway rat and
have longer marks of the little toe.

An odd assortment of debris on a ledge or in a narrow
crevice of a limestone cliff may indicate a wood rat house.

Fig. 94.—Eastern wood rat.

Family CRICETIDAE 171

Usually there is a urinating station nearby, as well as numerous
droppings, each about 34 inch long. The nest of the wood rat
is described in the section on life history.

Distribution.— The wood rat is known from very few locali-
ties in Illinois but is common where present. In this state, it has
been collected only on the Mississippi River bluffs in Jackson
and Union counties. The subspecies occurring in Illinois is
Neotoma floridana illinoensis Howell. The range of the species
covers an area of irregular shape, principally in the south-

Fig. 95.—Habitat of eastern wood rat in Illinois: rocky bluffs
along the Mississippi River near Wolf Lake, Union County.

172 - Order RODENTIA

eastern quarter of the United States, fig. 93. It is unknown on
the Eastern Piedmont Plateau.

SYNAPTOMYS COOPERI Baird
Southern Bog Lemming - Lemming Mouse

Description.—The southern bog lemming is-a mote with an
exceptionally short tail and long, fine fur, which is rich brown
or almost chocolate bf6wn on the back and silvery gray on the
belly. The short ears are almost concealed in the long fur.

Length measurements: head and body 4434 inches (100-119
mm.) ; tail 54-34 inch (15-21 mm.); over-all 414-514 inches
(115-140 mm.); hind foot about 34 inch (18-20 mm.). The
ratio of hind foot to tail varies from individual to individual,
but in most specimens it is 1:1. The foot may vary in length
from 3 mm. shorter to 3 mm. longer than the tail.

The skull is 24.5-27.5 mm. (about 1 inch) long. It has
orange-colored, broad, and grooved upper incisors, fig. 744.
Dental formula: I 1/1, C 0/0, Pm 0/0, M 373.

The short tail, long fur, and broad, bright orange, grooved
upper incisors distinguish this mouse from all others in Illinois.

Life History.—The bog lemming occurs in wet meadows and
bogs, usually where there is a thick stand of bluegrass or similar
ground cover. Within this cover, bog lemmings make a series
of interconnecting runways on the surface of the ground but en-
tirely hidden beneath the vegetation. ‘This series of miniature
highways provides avenues to food supplies and to the several
holes leading to underground burrows. The lemmings construct
these highways by clipping away the grass with their incisor
teeth and keep them smooth by constant use. The runs are no
wider than the body of a lemming.

This lemming is active during daylight hours as well as at
night. Most of the runs are quite dark during the daytime, for
each is rather effectively roofed by a mat of grass.

The number of bog lemmings fluctuates markedly from year
to year. In one year these lemmings may be overrunning a bog
or meadow; in the next year few, if any, may be present. Ap-
parently they breed from March until late fall. For rearing
young, they build nests in chambers that join the underground
burrows not far below the surface of the ground, or sometimes
in thick mats of dry bluegrass on the surface of the ground.

Family CRICETIDAE 173

The bog lemming is preyed upon by foxes, as well as hawks,
owls, weasels, and most other Illinois predators. When lem-
mings are at the peak of their population cycle, there may be 30
or 40 per acre in suitable habitat, but, at the bottom of the
cycle, there may be only 2 or 3 per acre.

Signs.—F resh piles of grass, cut in pieces about an inch long,
and bright green droppings in small, grass-covered runways
may indicate the presence of bog lemmings. Only when other
voles feed as exclusively on bluegrass as do lemmings, and this
is rarely the case, are their droppings bright green. When there
are many bog lemmings present, the greenish fecal pellets form
a solid mass on the floor of much of the runway network.

Distribution—The bog lemming, sporadic in occurrence and
usually not abundant in Illinois, has been taken in only the
southern two-thirds of the state. The subspecies in Illinois is
Synaptomys cooperi gossti (Coues). The range of the species
extends from eastern Quebec to southwestern Ontario, and
southward to northern Arkansas and the southern Appalachian
Mountains, with an extension into western Kansas.

MICROTUS PENNSYLVANICUS (Ord)
Meadow Vole Meadow Mouse

Description—The meadow vole, fig. 96, is a stout-bodied,
short-tailed, dark-colored mouse that lives in meadow-like
places. Its back is dark brown or chestnut -brown; the under
parts are grayish, tipped with silver (never tipped or washed
with fulvous or ochraceous) ; the under side of the tail is nearly
the same color as the belly. The hind foot usually has six pads
or tubercles. The tail is nearly twice as long as the hind foot.
‘The female has four pairs of mammary glands.

Length measurements: head and body 35¢-434 inches (93-120
mm.) ; tail 13g-15¢ inches (35-42 mm.) ; over-all 5—63¢ inches
(128-162 mm.) ; hind foot about 34 inch (18-22 mm.).

The skull is 25-29 mm. (1-114 inches) long. The front sur-
face of each upper incisor is not grooved, and each of the last
upper molars has five or six enamel triangles or loops, fig. 74d,
not four as in the prairie vole, fig. 74e. Dental formula: I 1/1,
C 0/0, Pm 0/0, M 3/3.

Life History—The meadow vole lives in damp, grassy
places. If the dense vegetation of such places is parted, surface

174 Order RODENTIA

Fig. 96.—Meadow vole.

runways of this mouse may be discovered. The first runway
that is found may lead to a network of other runs. Along these
runs, voles cut off the grass; they may feed on it immediately,
or store it for future use in chambers below ground. Side runs
lead to new sources of grasses, weeds, tuberous roots, or the
bark of trees.

Underground tunnels, nearly as intricate and complex as those
aboveground, serve as refuges and breeding places for the
meadow vole. The nest of this vole is a globular mass, chiefly
of dry grass, about 5 inches in diameter. It is usually in a
chamber about 4 inches underground but it may be in a mass
of herbage aboveground.

The meadow vole can breed throughout the year. Seventeen
litters were produced by one captive female in a year. Probably
in nature, a mature female rarely produces more than six or
eight litters a year, and in some years perhaps only one or two.
A litter may consist of as many as eight young. The young are

Family CRICETIDAE 175

weaned at 2 or 3 weeks of age. Because of their great fecun-
dity, meadow voles may overrun fields during favorable years
with as many as 100 or 200 individuals per acre. A disease epi-
demic or a food shortage may reduce the population within a
year to as small a number as 2 to 10 per acre.

Signs.— Tracks, burrows, runways, and nests of the meadow
vole are like those of the prairie vole. When the meadow vole
walks, its footprints are paired; the prints of the hind feet fall
just a little short of those of the front feet. When it runs, its
footprints occur in groups of four; prints of the hind feet lie
opposite one another and those of the front feet lie behind them,
generally one not so far behind as the other. This pattern of
footprints, and the fact that a tail mark is seldom present, may
help to distinguish tracks of the meadow vole from those of
the deer mouse.

Occasionally, meadow vole tracks, fig. 30, may be seen on the
surface of snow, but usually voles keep to their maze of run-
ways beneath it. The abundance and complexity of these run-
ways show best after the snow has melted.

Piles of grass cut about an inch long and small dark brown
or black droppings in surface runways are signs of the meadow
vole or the prairie vole. The nest of the meadow vole is de-
scribed in a paragraph on the life history of the animal.

Distribution—The meadow vole is fairly common in ex-
treme northern Illinois and is known to occur as far south as
an imaginary line drawn between Kankakee and Havana. The
subspecies in Illinois is Microtus pennsylvanicus pennsylvanicus
(Ord). The range of the species includes all of Canada except
the west coast; it extends westward into Alaska and south-
ward in the United States as far as northern New Mexico,
northern Missouri, northern Illinois, eastern Kentucky, northern
Georgia, and South Carolina, fig. 93.

MICROTUS OCHROGASTER (Wagner)
Prairie Vole Prairie Meadow Mouse

Description.—The prairie vole, fig. 4, is a short-tailed, me-
dium-sized mouse that is common in Illinois fencerows, open
grasslands, and meadows. The upper parts are a brownish gray,
with a grizzled appearance resulting from a mixture of yellow-
ish brown and black hairs. The under parts, particularly the

176 Order RODENTIA

breast and anterior part of the belly, are washed with yellow
or rust. The tail is short, and the under side of it is somewhat
lighter in color than the upper side. Each hind foot has five pads
or tubercles. The female has three pairs of mammary glands.

Length measurements: head and body 37-45% inches (99-117
mm.); tail 1-136 inches (26-36 mm.) ; over-all 47-6 inches
(125-153 mm.) ; hind foot about 34 inch (16-20 mm.).

The skull of this vole resembles that of the meadow vole
except that each of the last upper molars has four enamel
triangles or loops, fig. 74e, instead of six. Dental formula:
E1100; Pm. 070; M373:

The prairie vole can be distinguished from the meadow vole
by the following characteristics: rusty or yellowish wash on
under parts rather than silvery, each of the last upper molars
with four rather than five or six triangles, each hind foot with
five rather than six pads, length of tail usually 35 mm. or less
rather than over 35 mm., and three pairs of mammae rather
than four.

Life History.—The prairie vole lives in a variety of grassy
places throughout most of Illinois. In the grassy shoulders of
roads, grassy pastures that are not heavily grazed, clover fields,
grassy forest edges, and lush meadows, several prairie voles will
usually be found in each acre. Their surface runways, figs. 2
and 14, about the diameter of a garden hose, can be found by
parting the grass. These lead eventually to holes which open
into complex underground burrow systems. A small plot about
16 feet square may have as many as 160 feet of surface runs
and 10 to 40 feet of underground burrows. The prairie vole
obtains grasses, seeds, and various herbs for food from along
surface runways. It finds refuge, feeds on roots, and nests in
the underground burrows.

Storage chambers for food, fig. 2, and usually the nest of the
prairie vole are located in an enlarged portion of an under-
ground burrow. The nest consists of grass—in some cases the
equivalent of several pints of it. If the grass in which this vole
lives is very dense and tall, the nest may be placed aboveground
among the roots of the grass. Young are produced throughout
most of the year except in the coldest winter months. There
are three to six young in each litter. The young develop as rap-
idly as do those of the meadow vole. A female of the prairie
vole is sexually mature when only 3 or + weeks old.

Family CRICETIDAE 177

The prairie vole may be active day and night, winter and
summer, but is probably most active at night. In winter it makes
burrows through the snow at the surface of the ground. Under
the protective mantle of snow, it may make runs to the trunks
of trees, where it feeds on the bark.

When conditions are ideal, prairie voles may increase rap-
idly, and a population peak of 100 or more per acre may result.
Usually within’a year or two after the peak has been reached,
there will be @ rather rapid and marked decrease in the number
of voles. Later, the population may build up to another peak.
Increases and decreases in population follow a rather definite
time pattern or cycle. Biologists believe that the cycle is com-
pleted about every 4 years.

Signs.—The runways and nests described above are signs of
the presence of the prairie vole. Other signs are tooth marks,
beginning immediately above ground, on the trunks of trees,
fig. 37. Tracks of the prairie vole are like those of the meadow
vole.

Distribution—The prairie vole is most abundant in central
and southern IlIlinois but is known to occur in suitable habitats
throughout the state. The Illinois subspecies is Microtus ochro-
gaster ochrogaster (Wagner). The range of the species covers
an area from western West Virginia to southeastern Alberta
and southward to central Oklahoma and western Tennessee.

PITYMYS PINETORUM (Le Conte)
Pine Vole Pine Mouse

Description.—The pine vole, fig. 97, is a short-tailed mouse
with small eyes. The fur on the back and sides is chestnut or
bright brown, with a gloss or sheen, and is dense, almost like
that of a mole. The under parts are gray and may be washed
with buff. The tail is brown, lighter on the under than on the
upper side. The hind foot is usually 1 to 3 mm. shorter than the
tail. There are four (two pairs of) mammary glands.

Length measurements: head an body 334-414 inches (95-108
mm.) ; tail about 34 inch (15-22 mm.) ; over-all 414-514 inches
(110-130 mm.) ; hind foot about 5¢ inch (16-18 mm.).

The skull is much like that of other voles but is broader
through the interorbital region (more than + mm., or more
than 14 inch) and the posterior border of the palate has a

178 Order RODENTIA

~

ig

5%
¥

ie 4 P

Fig. 97.—Pine vole.

median projection. Dental formula: I 1/1, C 0/0, Pm 0/0,
WI S/S

The pine vole, fig. 4, differs from other voles in having ~a
shorter tail, glossy, velvety fur, two pairs of mammary glands,
and a broad interorbital region of the skull. It differs from the
bog lemming in possessing ungrooved and narrower upper
incisors and glossy brown hair that is velvety like that of a mole.

Life History.—The pine vole occurs in woods, orchards, and
even in grassy fields some distance from woods. It lives in leat
litter or grassy mats. It makes an extensive network of under-
ground burrows, which it uses in searching for food, in resting
or nesting, and in rearing its young. Along these underground
burrows, fig. 1, it feeds on tubers and succulent roots, grasses,
seeds, and roots of trees. The pine vole spends much less time
in surface runways than do other Illinois voles. It makes a
globular nest of dead leaves and grasses in a burrow a few
inches below the surface of the ground, under the roots or the
stump of a tree, or in a log.

Breeding of the pine vole extends from March to November.
Usually there are three or four young in a litter. Although
helpless at birth, the young can gather food for themselves at
about 2 weeks of age.

The pine vole is preyed upon by foxes, minks, skunks, rac-
coons, and owls.

Signs.—T racks of the pine vole are similar to those of other
voles but are rarely seen because this mouse prefers to remain
underground. Its burrows, however, are common in some wood-

Family CRICETIDAE 179

lands and orchards. ‘These burrows may be just beneath a thick
carpet of leaves or deeper in the soil. ‘They vary in diameter
from somewhat less than 114 inches to as much as 2 inches.
Some of them may surface beneath well-rotted logs. In orchards
they may lead to fallen apples, on which the vole may feed from
beneath. Pine vole burrows are often appropriated by shrews.

Distribution—The pine vole is state-wide but sporadic in
occurrence and usually uncommon. ‘There are two subspecies
in Illinois, Pitymys pinetorum auricularis (Bailey) in the south-
ern third of the state and P. p. scalopsoides (Audubon & Bach-
man) elsewhere. The species occurs from Massachusetts and
Vermont to central Wisconsin and south to central Texas and
northern Florida.

ONDATRA ZIBETHICUS (Linnaeus)
Muskrat

Description.— The muskrat, fig. 98, is a large vole, nearly
the size of a cottontail rabbit, that is adapted to a life in and
near water. Its body is a dark or chocolate brown, darkest on
the back where long glistening guard hairs are thickest. The
eyes and ears are small. The hind feet are large and webbed.
The blackish, nearly naked tail is laterally flattened, long, and
scaly.

Length measurements: head and body 11-1234 inches (280-
25 mm.) ; tail 814-1034 inches (210-275 mm.) ; over-all 1914-
314 inches (490-600 mm.) ; hind foot 27-33 inches (73-85
mm.). Weight: about 21% pounds.

The skull is more than 60 mm. (238 inches) long; the grind-
ing or cheek teeth, fig. 40c, are long and flat surfaced, each con-
sisting of a series of upright prisms or columns; the incisors are
not grooved. Dental formula: I 1/1, C 0/0, Pm 0/0, M 3/3.

Life History—The muskrat lives along or in the many
rivers, streams, drainage ditches, marshes, lakes, ponds, and
water-filled strip mine areas of Illinois. Usable habitat for the
muskrat has been increased by construction of drainage ditches
and strip mine areas and by protection of stream and ditch-
banks from overgrazing and erosion.

The muskrat is at home in water, on land, and below the sur-
face of the ground. Muskrats that live in marshes, ponds, and
strip mine areas usually build houses, figs. 3 and 11, some for

“= ame | ¢

180 Order RODENTIA

Fig. 98.—Muskrat.

dwelling and some for feeding, from materials that are readily
available, such as bulrushes, smartweed, and cattails. A dwelling
house usually is dome shaped, several feet in diameter at the base,
and the walls are 1 to 2 feet thick. The entrances (usually
two) are below the surface of the water. Within the house the
muskrat makes its nest, which is above the normal high-water
level and usually remains dry. Perhaps half or more of the
houses are feeding houses. These are without nests, are smaller
than the dwelling houses, and have thinner walls.

Muskrats that live along rivers and ditches build no houses
like those described above but extend burrows back into the
banks. The nest chambers are above the surface of the water
at its normally highest level, and thus the nests usually remain
dry. Entrances are normally below the surface of the water,
but at times of low water some of them may be exposed. Run-
ways or paths lead from the exposed burrow entrances to the
water. Trails visible in shallow parts of a stream may indicate
usual routes of travel.

The muskrat may breed from April to September. A female
usually has two litters, occasionally three, per year, and litters
average about four young each. At about a month of age, the
young are sufhciently grown to shift for themselves. Sometimes
there may be room within the parental marsh or along the home
bank for these new muskrats to settle down, for an acre of suit-
able marsh may accommodate 20 to 40 rats, or a mile of un-

Family MURIDAE 181

grazed ditchbank more than a hundred. At other times, some
of the young may have to move long distances to establish homes,
and it is during forced migrations overland that many are killed
hy motor vehicles on highways or by dogs or other predators.
Once established in their new homes, the young muskrats may
be preyed upon by minks. Extreme fluctuations in water level
can be destructive to an entire population of muskrats.

The muskrat is active during all months of the year. -It feeds
on roots, tubers, and green material, including cattails, bul-
rushes, sedges, pickerelweeds, corn, alfalfa, - wal¢ parsnips, wil-
lows, and clovers. 3 Soak?

Signs.—Houses in ponds or marshes; fig. 11, runways from
water to burrows in the banks, of Streams or ditches, fig. 12,
and feeding platforms amongy. the vegetation in shallow Waiter
fig. 38, are telltale signs of wiluskrats. Footprints and tail marks,
fig. 21, may be evident at the water's edge. The print of a hind
foot is about 314. inches leng; the print of a front foot shows
only four toes and‘ is about 114 inches long. Droppings, fig. 21,
are dark brown, oval-shaped, and each a little more than ly
inch long; they are frequently deposited on stones and logs pro-
jecting above water.

Distribution—The muskrat, found in suitable habitats
throughout Illinois, is most common in the northern portion of
the state. The Illinois subspecies is Ondatra zibethicus zibethi-
cus (Linnaeus). The range of the species includes most of
Canada, Alaska, and the United States. It does not include
south-central Oregon, most of California, south-central Nevada,
southern Arizona, south-central Texas, or the extreme south-
eastern United States.

RATTUS RATTUS (Linnaeus)

Roof Rat Black Rat

Description.—The roof rat, fig. 99, generally is a grayish
brown on the upper parts and a creamy color on the under parts.
The tail is brown all around and longer than the body. The
upper sides of the feet are light brown. Occasionally black indi-
viduals or families occur. This rat differs from the Norway rat
in that it has a slimmer body and a more uniformly colored
tail that is longer, rather than shorter, than its head and body.
Its ears are larger, more delicate, and less hairy.

182 Order RODENTIA

Length measurements of one specimen from Illinois: head
and body 634 inches (171 mm.) ; tail 1014 inches (266 mm.) ;
over-all 1714 inches (437 mm.) ; hind foot 114 inches (37 mm.).

The skull has the temporal ridges on the lateral margins of
the braincase bowed slightly outward, and the length of a parie-
tal measured along a temporal ridge is noticeably less than the
distance between these ridges; otherwise the skull is like that
of the Norway rat. Dental formula: I 1/1, C 0/0, Pm 0/0,
Mi3/3:

Life History.—In many places in the United States the roof
rat has been driven out of favored habitats by its larger cousin,

Fig. 99.—Roof rat.

the Norway rat. As a result it often makes its home in the
upper parts of buildings and in trees, for it is a better climber
than the Norway rat. It is slightly less prolific.
Distribution.—In Illinois, the roof rat is known from one
specimen taken in Urbana, but it may occur from time to time
in other cities over the state through accidental introductions
from the South. The one known Illinois specimen, a black-
haired individual, belongs to the subspecies or variety Rattus
rattus rattus (Linnaeus). The roof rat, introduced from the
Old World, commonly occurs along the Atlantic and Gulf
Coast states from New York to Texas and southwest through-
out central Mexico. It occurs also along the Pacific Coast
from southern British Columbia southward into Mexico and
occasionally in interior parts of the United States. A colony

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Family MURIDAE

184 Order RODENTIA

of the brown variety, R. r. alexandrinus (E. Geoftroy-Saint-
Hilaire), inhabited some warehouses at St. Louis, Missouri, in
1945 but it was soon exterminated.

RATTUS NORVEGICUS (Berkenhout)
Norway Rat Barn Rat House Rat Sewer Rat

Description.—The Norway rat, fig. 100, generally is grayish
brown on the upper parts and gray on the under parts. The
fur is coarse. The gray or brown tail is slightly but noticeably
lighter below than above, is scaly, nearly devoid of hair, and
slightly shorter than the head and body.

Length measurements: head and body 714-934 inches (187-
250 mm.); tail 514-714 inches (138-185 mm.) ; over-all 13-17
inches (325-435 mm.) ; hind foot 114-134 inches (38-44 mm.).
Weight: average about 24 pound, but there is much individual
variation. 4

The skull is 41.5-45.0 mm. (nearly 134 inches) long; the ros-
trum is long; ridges may be present on the lateral margins of
the braincase; the cusps on the cheek teeth of the upper jaw
are in three longitudinal rows, fig. 74c. Dental formula: I 1/1,
C 0/0, Pm 0/0, M 3/3.

Life History—The Norway rat, an Old World species acci-
dentally introduced into the New World, is at home not only in
dwellings, warehouses, stores, and sewers of American cities
but around garbage dumps, along ditchbanks, under straw
piles, and in cornfields, feed lots, and barns. Usually it chooses
a protective shelter from which it can burrow into the ground,
fig. 8. It is a sociable animal, and usually several of its kind
live together.

This rat reproduces at a rapid rate. Litters are made up of
2 to 15 young and average about 7. The young are weaned at
3 weeks and are capable of breeding when about 3 months old.
The gestation period is 21 to 23 days. Litters may be produced
almost continuously throughout the year if adequate food is
available. Theoretically, one pair of Norway rats and their
progeny can produce more than 3,000 rats in a single year.

In some years, Norway rats become excessively abundant. In
1903, hordes of rats were found migrating over several counties
in western Illinois. In 1939, rats were again very abundant in
this state.

Family MURIDAE 185

The Norway rat is truly omnivorous. It eats the kinds of
foods consumed by man and many other things besides. An adult
rat usually requires a minimum of 34 ounce of dry food and
14 to 1 ounce of water daily.

This rat is able to enter buildings by climbing wires or faces
of rough walls, by gnawing through wood, or by burrowing
under masonry foundations.

In most years the citizens of Illinois are the custodians of
about one Norway rat per person. A rat that lives near sup-
plies of food for man or livestock eats, fouls, or otherwise
wastes more than 20 pounds of food or feed each year. Also it
undermines foundations and damages wooden structures by its
burrowing and gnawing.

In the wild, the Norway rat is preyed upon by foxes, weasels,
minks, owls, hawks, snakes, and other animals. In urban dis-
tricts and around farm buildings, man can be its worst enemy.

Signs.—The Norway rat makes tracks, fig. 22, that are like
those of a tree squirrel, but the prints of the front feet are
smaller and less often paired; also, a tail mark often shows.
Droppings are oblong and usually up to 34 inch long. A dark
smudge along a baseboard molding or around a hole in a wall or
floor is indicative of a frequently used path of a rat. A burrow
of this rat has piles of dirt and often corncobs or pieces of junk
at the entrance. Gnawed doorways, fig. 100, are common in
poorly sanitated sections of cities.

Distribution—The Norway rat is abundant throughout
Illinois. Only the subspecies Rattus norvegicus norvegicus
(Berkenhout) is known in the United States. “The Norway rat
occurs in southern Canada, along the Pacific Coast to northern
Alaska, and throughout the United States and Mexico.

MUS MUSCULUS Linnaeus
House Mouse

Description.—The house mouse, fig. 101, is grayish brown
to dark gray on the upper parts and gray or buff on the under
parts. Its practically hairless tail is uniformly brownish gray.

Albinos of this species are the “white mice” of laboratories.

Length measurements: head and body 234-33 inches (70-85
mm.); tail 23g-334 inches (60-95 mm.); over-all 5—7 inches
(130-180 mm.) ; hind foot 54-34 inch (16-19 mm.).

186 Order RODENTIA

The skull is readily recognizable by a distinct notch in the
tip of each upper incisor as viewed from the side, fig. 74f, and
by three longitudinal rows of cusps in each of the upper cheek
teeth. Dental formula: I 1/1, C 0/0, Pox 0/0, Basse:

This is the only mouse in Illinois that has gray or buffy
under parts, a long, naked tail that is almost the same color al!
around, and a peculiar notch at the tip of each upper incisor.

Life History.—The house mouse, like the Norway rat, is an
accidentally introduced pest. It lives in dwellings, office build-
ings, stores, factories, barns, poultry houses, and sheds, and in
the runways of native mice and voles. Frequently, mice of this
species move out of houses into yards, gardens, and fields in the
spring and back into houses in the fall. They usually dominate
native mice, and may forcibly drive them out of an area.

The house mouse produces litters throughout the year, except
for the cold winter months. The female has five or six young
per litter. The young can run about at 21 days of age and
breed at 42 days.

In eating habits, this mouse is truly omnivorous.

Signs.—Gnawed paper, black droppings about 14 inch long,
or small tracks in the dust beside a building may be evidence of
the presence of this mouse. In fields, it is difficult to distinguish
between signs of the house mouse, fig. 32, and those of some
of the native mice.

Distribution—The house mouse, like the Norway rat, is
abundant throughout southern Canada and along the Pacific
Coast to northern Alaska, the United States, and Mexico. The

Fig. 101.—House mouse.

Family ZAPODIDAE 187

subspecies in Illinois is probably Mus musculus domesticus
Rutty.

ZAPUS HUDSONIUS (Zimmermann)
Meadow Jumping Mouse

Description—The meadow jumping mouse, fig. 102, has
large hind feet and a tail that is considerably longer than the
body. It has no cheek pouches. The fur of this animal is dark
olive-brown on top of the back, finely streaked with dark brown
hairs on the sides, and white on the under parts.

Length measurements: head and body about 3 inches (about
77 mm.) ; tail 414-514 inches (108-135 mm.) ; over-all 714-814
inches (185-212 mm.); hind foot 1-114 inches (25-31 mm.) ;
ear from notch about 14 inch (11.0-15.5 mm.).

AS =
Fig. 102—Meadow jumping mouse.

The skull is about 22 mm. (7% inch) long and has a large
infraorbital foramen. There are four cheek teeth on each side
of the upper jaw. The upper incisors are grooved. Dental for-
met Wh, COO, Pu 1/0," M373:

Life History.—The meadow jumping mouse may be found at
night on a grassy or vine-covered bank of a stream or pond,
usually where there are a few trees. It seldom runs but travels
rapidly by making a series of jumps, each nearly a yard in length.
if pursued, it may take refuge among roots and debris or it may
dive into water without hesitation. It swims well and dives fre-
quently to avoid capture, but in water it tires rather quickly.

This mouse makes its home in a globular nest of grass, other
herbs, or moss. The female gives birth to young between May
and August. This mouse feeds most extensively on grass seeds,
berries, nuts, and insects. The stored fat in the body prepares

oe?

188 Order LAGOMORPHA

it for the winter sleep. It hibernates, probably from November
until early April, far enough underground to be well-below
the frost line. _

Signs.—Because it is in hibernation when snow is on the
ground, and because it is too light to make visible tracks in mud,
the meadow jumping mouse seldom leaves tracks that can be
detected.

In areas where this mouse is common, little crisscross piles of
slender grass and weed stems may be found; the stems have been
cut into 2- to 3-inch sections in attempts of the animal to reach
the seed heads. The piles are as much as 6 or 7 inches across.
The sections of stems may be in little bundles and are not to be
mistaken for the shorter sections, averaging about 112 inches
long, left by the meadow vole.

Summer nests of this mouse are in open meadows: on the
surface, in a tussock of grass, or a few inches below the surface
of the ground, covered by a protecting log. They are made of
material found nearby, often entirely of the dead leaves of
herbs, bits of grass, or dry moss.

Distribution—The meadow jumping mouse, although not
abundant, is of state-wide occurrence in Illinois. The sub-
species in this state is Zapus hudsonius intermedius Krutzsch.
The range of the species extends westward from Labrador
across most of Canada and Alaska, and southward to northeast-
ern Colorado, northern Oklahoma, northeastern Georgia, and
northern South Carolina.

ORDER LAGOMORPHA
Hares and Rabbits

Members of the order Lagomorpha—hares, rabbits, and
pikas—resemble the rodents in having a pair of large, chisel-
shaped upper incisor teeth, but differ from them in having an
additional small, inconspicuous incisor directly behind each of
these teeth, fig. 40d. They also differ from the rodents in having
short tails that, in most species, resemble small tufts of cotton.
All lagomorphs are herbivorous.

Only three species of lagomorphs, all of which belong in the
family Leporidae, occur in Illinois. Of these, the eastern cot-
tontail is the most abundant and widely distributed. It is prob-
ably the most important game animal in the state, being taken

Order LAGOMORPHA 189

by more than three-fourths of the hunters and making up nearly
half of the total bag of game. The other two species are re-
stricted in range and are of little importance from a hunter's
standpoint.

Economic Status.—In some years cottontail rabbits do con-
siderable damage in orchards and nurseries in Illinois by eating »
the bark of young trees, fig. 37. Also, at times they are trouble-
some in truck and home gardens.

Rabbits are the source of most cases of human tularemia in
the United States. In 1939, in a period of particularly heavy
outbreaks among rabbits, 485 human cases of this serious dis-
ease were reported in Illinois. In most years since then, the
number of human cases in this state has been less than 100 an-
nually. More than half of the cases in Illinois in the 1936-1949
period were from the southern third of the state (Yeatter &
Thompson (1952:357). The tick that is the chief vector of this
disease feeds on its rabbit host from about the end of winter
until after the return of freezing weather in autumn, when the
tick becomes immobile and drops off its host. In about a week
after the onset of freezing weather, most of the infected rabbits
will have died and any rabbits not then infected will be free of
the disease for about 2 months. Sickly or sluggish rabbits and
rabbits found dead should be avoided as possible sources of the
disease.

The domestic rabbit, Oryctolagus cuniculus, has been included
in the key for the identification of skulls because occasionally a
skull of this animal may be found. Not only have individuals
of this species been known to escape from captivity, but efforts
have been made to establish the species as a game animal in
Illinois. ‘The domestic species and native species do not cross.

KEY TO SPECIES
Whole Animals

1. Ear from notch more than 75 mm. (3 in.) jong hind foot
more than 120 mm. (434 in.) long. .... Ln wt oe ee
ents Pecan es white-tailed jackrabbit, Lepus townsendii

Ear from notch less than 75 mm. long; hind foot less than

OG by Aiba, oh pon lume ens eee 2
2. Hind foot less than 90 mm. (314 in.) long; back ‘of animal
grayish brown ..... eastern cottontail, Sylvilagus floridanus

Hind foot more than 90 mm. long; back of animal reddish,
with much black........ swamp rabbit, Sy/vilagus aquaticus

190 Order LAGOMORPHA

Fig. 103.—Characters used in the identification of lagomorphs:
a, skull of domestic rabbit, top view; », portion of skull of jack-
rabbit, top view; c, skull of cottontail, top view; d, skull of swamp
rabbit, top view.

Family LEPORIDAE 191

Skulls

1. Supraorbital processes each with the posterior projection
well separated from the braincase, fig. 103a, 6; base of
IMMER SEPRILEC 5 getce 210 7 duc ave alee: tsk! ugy as w:% Gre, 9 dee oev'w Bod a 2

Supraorbital processes each with the posterior projection or
extension partly or completely fused to braincase, fig. 103c,
Mame ar Skull not tenestrated. «%. 2... . cs. es. ees Aes 3

2. Nasals gradually narrowed from base to near apex; pos-
terior projection of each supraorbital process narrow, fig.
US Oo Sa sane er domestic rabbit, Oryctolagus cuniculus

Nasals almost parallel from base to near apex; posterior pro-
jection of each supraorbital process broad, fig. 103b......
Lo ak ee white-tailed jackrabbit, Lepus townsendii

3. Each supraorbital process with part of posterior projection
fused to braincase, leaving a distinct slitlike opening,
Pipi PGES. ayes Soi bs eastern cottontail, Sylvilagus floridanus

Each supraorbital process with posterior extension almost
entirely fused to braincase, leaving only a small pore, fig.
LIS 2 ee swamp rabbit, Sylvilagus aquaticus

LEPUS TOWNSENDII Bachman
White-Tailed Jackrabbit

Description.—The white-tailed jackrabbit, fig. 104, is much
larger than either the eastern cottontail or the swamp rabbit.
The upper parts in summer are buffy or brownish gray, in
winter white; the under parts are white, except for the throat,
which is buff. The ears are long and tipped with black. The
tail is white. The hind legs are long, and the feet are well
furred.

Length measurements: head and body 19-20 inches (475-505
mm.); tail 4414 inches (100-115 mm.); over-all about 24
inches (575-620 mm.) ; hind foot 53g-6 inches (138-153 mm.) ;
ear from notch 4414 inches or about 334 inches dry (96-113
mm.). Average weight: about 7 pounds.

The skull is about 95 mm. (334 inches) long; the rostrum is
greatly fenestrated. The bullae are comparatively large; the
interparietal is fused with the parietals (unfused in Sylvilagus) ;
and the posterior projection of each supraorbital process is free
(not fused to the braincase), fig. 1034. Dental formula: I 2/1,
C 0/0, Pm 3/2, M 3/3.

Life History.—The white-tailed jackrabbit makes its home
in open country, where with its large ears it can hear approach-
ing trouble from a considerable distance and with its long legs

192 Order LAGOMORPHA

Fig. 104.—White-tailed jackrabbit in winter pelage.

it can usually outrun its enemies. Many a dog has pursued a
white-tailed jackrabbit only to become exhausted while the hare
was still fresh and several hundred feet in the lead.

This animal rests in forms, which are body-sized depressions
either in thick vegetation or in soft soil. Usually it feeds on
grasses, Clovers, and other herbs, and on grains. In winter, it
may be forced to feed on buds, bark, and twigs of woody
plants.

The white-tailed jackrabbit is really a hare and not a true
rabbit. Its precocious young are fully furred and have their
eyes wide open at the time of birth. Probably it breeds in April,
and young, three to six in a litter, are born in June. The young
may nibble on grasses when only a few days old and in less than
5 or 6 weeks are ready to shift for themselves.

Signs.—Prints left by the hind feet of a jackrabbit, fig. 16c,
are much larger than those of the cottontail, the length of one
print varying from 4 to 614 inches as compared with 4 inches
or less for that of the cottontail. The tracks of the front feet
are also correspondingly larger than those of the cottontail. The
patterns of the tracks of the two animals are much alike. The
long prints of the hind feet lie approximately side by side and

Family LEPORIDAE 193

WHITE-TAILED JACKRABBIT

SWAMP. RABBIT

Fig. 105.—Known distribution, in the United States, of two lago-
morphs with a restricted range in IIlinois.

a little ahead of the small prints of the front feet, one of which
trails the other when the animal hops, fig. 16c.

Droppings of the jackrabbit average larger than those of the
cottontail but are otherwise like them.

Jackrabbit forms, or resting places, are about 15 inches long
and half as wide; cottontail forms are about 10 inches long. A
form found in a plowed field, fig. 10, almost certainly belongs
to a jack rather than a cottontail or a swamp rabbit.

Distribution—The white-tailed jackrabbit occurs in Illinois
only in the extreme northwestern counties. It is common in the
sand prairie at the Savanna Ordnance Depot in Jo Daviess
County. The subspecies in Illinois is Lepus townsendii cam-
panius Hollister. The range of the species extends from north-
western Illinois north and west to central Saskatchewan and
central Oregon and south to east-central California and north-
ern New Mexico, fig. 105.

SYLVILAGUS FLORIDANUS (Allen)
Eastern Cottontail

Description—The eastern cottontail, frontispiece and fig.
106, is the common rabbit of Illinois. The upper parts of the

194 Order LAGOMORPHA

body are buff or rusty brown, and the under parts, except for
the buff throat, are white. The ears are darker than the back,
the nape of the neck is reddish, and the under side of the tail
is white. ~

Length measurements: head and body 1334-1514 inches (350-
395 mm.); tail 134-214 inches (45-65 mm.) ; over-all 1514-18
inches (395-460 mm.) ; hind foot 334-414 inches (85-110 mm.) ;
ear from notch, about 21% inches (50-60 mm.). Weight: usu-
ally 2-3 pounds.

The skull, figs. 40d, 103c, is about 70 mm. (234 inches) long
and, except for the distinct interparietal bone, is not unlike that

of the jackrabbit. Other characters are noted in the key to
skulls. Dental formula: I 2/1, C 0/0, Pm 3/2, M 3/3.

Fig. 106.— Young of eastern cottontail.

Life History—The eastern cottontail makes its home in
brushy or weedy fields, fig. 2, thickets along fencerows and mar-
gins of wood lots, forest edges, and dry bottomlands. It is un-
common in pastured woodland, fig. 116. It frequently forages
in intensively cultivated fields that are situated near permanent
cover. At dawn and at dusk it is often seen feeding in such
fields and in open grassy areas.

In central Illinois, the male reaches breeding condition in
mid-February, the female in late February. The breeding sea-
son attains its peak during the first 2 weeks of March and con-
tinues into September. Usually the female produces annually
three litters of five or six young each. The nest is placed in a
depression in the soil. It has an outer lining of grasses and
leaves and an inner lining of hair, which the female has pulled
from her breast and abdomen. ‘The nest is completely covered
while the young are alone in it. At birth the young have short
fur and are blind but capable of creeping about. In about a

Family LEPORIDAE 195

week, their fur is considerably longer and their eyes are open.
At about 2 weeks of age the young nibble on grasses.

The cottontail feeds preferably on grasses and broad-leaved
weeds, but eats other vegetation also. It commonly feeds on
bluegrass, clover, dandelion, plantain, alfalfa, and soybean plants.
In winter, it may be forced to turn to buds, bark, and twigs,
particularly of dogwood, elm, rose, and apple.

A multitude of enemies harass the cottontail. Among these
are dogs, foxes, owls, weasels, and minks, as well as men and
their guns. The cottontail attempts to avoid predators by run-
ning away or by freezing. It will remain quiet and still as if
frozen to a spot until danger approaches too close; then, with
an explosive burst of speed, it will bounce to another spot sufh-
ciently far away, and where cover is available, and again freeze.

Signs.—Footprints of the cottontail in snow, dusty paths,
or soft damp ground are easily recognized. When this animal
travels at its usual gait, which is a hop, prints of the hind feet
lie side by side and in front of those of the front feet, one of
which trails the other, fig. 16. The print of each hind foot is
2 to 4 inches long. When the rabbit is hopping slowly, the
prints of the front and hind feet may lie side by side but, when
it is feeding, the front feet are placed in front of the hind feet.
Each print is pointed like the tip of an arrowhead. The spherical
droppings are each about 10 mm., or somewhat less than 14 inch,
in diameter.

Distribution.—The eastern cottontail, common throughout
Illinois, fluctuates in abundance from year to year. —T’wo sub-
species occur in this state, Sy/vilagus floridanus alacer (Bangs)
south of the Shawnee Hills and 8S. f. mearnsii (Allen) in the
rest of Illinois. The range of the species includes the eastern
United States as far north as northeastern Connecticut and
central New York, westward through southern Ontario to
southern Manitoba, and southward through parts of Colorado,
Texas, New Mexico, and Arizona into Mexico.

SYLVILAGUS AQUATICUS (Bachman)
Swamp Rabbit

Description—The swamp rabbit is similar to the eastern
cottontail, but it is larger, is darker on the upper parts, and has
more reddish brown on the body.

196 Order PERISSODACTYLA

Length measurements: head and body 18-1814 inches (455-
468 mm.) ; tail 214-234 inches (65-72 mm.) ; over-all 2014-2114
inches (520-540 mm.); hind foot about 414 inches (105-112
mm.); ear from notch about 214 inches dry (63-68 mm.).
Weight: 3-514 pounds.

The skull, about 85 mm. (33% inches) long, has a minute hole
between the postorbital process and frontal bone on each side,
fig. 103d. Dental formula: I 2/1, C 0/0, Pm 3/2, M 3/3.

Life History.—In southern Illinois the swamp rabbit lives in
cane thickets or dense woods and brush bordering swamps. It
is never far from water, and, being a good swimmer, does not
hesitate to take to water. It swims with little more than the
top ot its head exposed and with its ears straight back, fig. 3.
The denseness of the thickets in which it lives and its ability
to swim are valuable protective features.

This rabbit feeds on a variety of green herbs, bark, and
leaves; its fondness for giant cane is indicated by one of its
popular names, “cane-cutter.” Its nest resembles that of the
cottontail, but it is larger and frequently is in thickets with
stalks pulled down to form a protective covering. The young
are produced between March and November, usually four at a
time; a female may have more than one litter in a year. At
birth, the young have very short fur and are blind.

Signs.—Footprints of the swamp rabbit are similar to buz
usually larger than those ot the cottontail (print of hind foot
3-414 inches). Droppings are like those of the cottontail but
are deposited on logs or mounds near water, fig. 3.

Distribution—The swamp rabbit occurs in the southern
third of Illinois. “The subspecies in this state is Sy/vilagus aquat-
icus aquaticus (Bachman). The range of the species extends
from northwestern South Carolina to eastern Texas and in-
cludes two narrow northward projections, one into southern
Illinois and southwestern Indiana and the other into southeast-
ern Kansas, fig. 105.

ORDER PERISSODACTYLA
Odd-Toed Hoofed Mammals

Members of the order Perissodactyla have on each foot an odd
number of hoofed toes; the middle (third) toe is distinctly
larger than the others and forms the principal support of the

Order ARTIODACTYLA 197

foot. The order includes the horse, tapir, and the rhinoceros,
each known from only a few species. There are no living native
North American representatives of the order in Illinois, but the
domestic horse, of Old World origin, is familiar to all.

The horse is mentioned in this Fieldbook not because anyone
would have any difficulty in identifying the whole animal, but
because a collector might find a horse skull or tooth, which is
not readily identified. The skull and molar tooth of a horse are
illustrated in figs. 40f and 109c, and identifying features are
given in the key to orders, beginning on page 41.

ORDER ARTIODACTYLA
Even-Toed Hoofed Mammals

Mammals of the order Artiodactyla have a large, hard hoof on
the third and another on the fourth toe of each foot, and the
principal support for the foot is shared by these two toes. The
result is the forming of the familiar so-called “cloven hoof.”
The other toes may be represented by smaller hoofs or by
vestigial structures. The order is a large one, representatives
of which are distributed all over the world. It contains many
strange animals, such as the hippopotamus, camel, and giraffe.
North American representatives include members of the deer
(Cervidae), sheep and bovine (Bovidae), pronghorn (Antilocap-
ridae), and pig (Suidae) familes.

When white men first arrived in the Illinois country, three
species of these artiodactyls occurred wild in the area—the
bison, the elk or wapiti, and the white-tailed deer. Land settle-
ment and intensive farming caused all three to disappear from
Illinois in the previous century, but in recent years the white-
tailed deer has been successfully reintroduced. ‘This species is
the only wild representative of the order Artiodactyla in the
state.

Several domestic animals belong to this order—the cow, sheep,
goat, and pig. These are well known, and no key is needed for
identification of the whole animal. There is a good possibility,
however, that if skulls of these animals, figs. 107a, 108a, b, c,
are found they will be confused with deer, elk, or bison skulls
that may be unearthed. A key has been added for the identifi-
cation of these skulls. Some of the molar teeth of the cow are
illustrated in fig. 109a, b.

198

Order ARTIODACTYLA

KEY FOR SKULLS OF THE ARTIODACTYLA
(Domestic species included)

Each eye socket incompletely encircled by bone, fig. 1074;

upper Jaw Jwith ifcisOts... .... 22 4; . see pig, Sus scrofa
Each eye socket completely encircled by bone, fig. 1074; up-

per jaw. withoiit incisors: 02)... <5. 22 2
Upper jaw with canine teeth, fig. 1070. .2. 5.52 voee es - 9
Upper jaw ‘without! canine. teeth. .../. .-.c3 yee eee - 3
Skull more than 1214 inches (313 mm.) long............ 4
Skull ‘less than, 12174 imches long: -...; :2:, 72 =. oe oe 6
Open space present between lacrymal and nasal bones, fig.

LOUD Rots ee oo Baek ee elk, Cervus canadensis

Fig. 107.—Characters used in the identification of ungulates:
a, skull of pig, side view; 4, skull of American elk, side view, but
without lower jaw.

Order ARTIODACTYLA 199

No open space between lacrymal and nasal bones, fig.
AME oe <6 MOKED OR ORR Goh BARRIER EEN, 5
5. Skull elongate, fig. 1084; prominent ridge at top of skull be-

Fig. 108.—Dorsal views of skulls of ungulates: a, goat; b, cow;
c, sheep; d, bison.

200 Order ARTIODACTYLA

Skull subtriangular in frontal view, fig. 108d; no prominent
ridge between horns or horn bases... .... bison, Bison bison

6. Top of skull with a groove extending from the inner side of

the base of each horn (or knob) and meeting on the fore-

head to form~a V or U, fig. 108a; horns usually present,

subparallel, and directed posteriorly........ goat, Capra sp.
Top of skull without such grooves, fig. 108c; horns absent,
or diverging and downwardly curved.................. 7

7. Skull relatively long and narrow; posterior narial aperture
completely divided by a vertical vomerine partition; ant-
léts present’ or absent 25: .Yo.2/)en 2. Se
TE J ...s+......White-tailed deer, Odocoileus virginianus

Skull relatively short and wide; posterior narial aperture
without complete vertical septum; antlers never present.. 8

8. Skull with sides behind eyes converging sharply, fig. 108c;
bony eye sockets strongly protuberant....... ..........
Raat. > NES 5 ey orl ae eee domestic sheep, Owis sp.

Skull with sides behind eyes rounded; bony eye sockets not
strongly protuberant:....2... 4.2.1 domestic calf, Bos taurus

9. Skull more than 1214 inehes long (313 mm)". --) 2.
sh eterno WAR, 28 BD en ty elk, Cervus canadensis

Skull less than\1214 inchés long: .)...7. 2. oS epee 7
af Oars loos CO ae white-tailed deer, Odocoileus virginianus

agit Dy S a os
/, oa TA
= =n \

a ae Wve dgn dette
mr,

Fig. 109.—Teeth of ungulates: a, grinding surface of teeth of
cow; J, outer side of teeth of cow; c, tooth of horse.

Family CERVIDAE 201

CERVUS CANADENSIS Erxleben
Elk Wapiti

Description.—The elk is the largest member of the deer
family ever known to occur in Illinois. It weighs about 650
pounds (females smaller than males) and stands nearly 5 feet
high at the withers (shoulders). The back and sides of the
body are grayish brown, and a large patch on the rump is buff
or yellow. An old male may have antlers several feet long and
nearly 2 inches in diameter at the base. The branches of antlers
are directed forward. The two canines are knoblike, fig. 107d.

Former Distribution—The elk was once found along the
wooded streams and in the open woods of Illinois. Some au-
thorities believe that it was at home on the prairies also. Ani-
mals of this species are gregarious; they gather in large herds
in winter, small herds in summer. They browse on twigs and
leaves of trees and graze on many different kinds of green plants.

The elk or wapiti once occurred over most of Illinois. By
the early 1800's it was becoming uncommon, and by the mid-
1800’s it had disappeared from the state. Available Illinois rec-
ords for the elk are for Cook County in the northeastern, Kas-
kaskia in the southwestern, near Peoria in the central, and near
Mount Carmel in the southeastern parts of the state.

ODOCOILEUS VIRGINIANUS (Zimmermann)
White-Tailed Deer Virginia Deer

Description.—The white-tailed deer, figs. 110 and 111, in
Illinois can be confused with no other animal. Its large size,
long legs, thick, stubby but conspicuous white tail, and ornate
antlers in males distinguish it from other mammals. In winter,
the coat is gray or grayish brown, in summer reddish brown.
The under parts of the body and the under side of the tail are
white. The hoofs are narrow and pointed, and a metatarsal
gland, indicated by a tuft of white hairs, is present on the hock.

The height at the shoulder is 3 to 314 feet, and the weight
ranges from 150 to 300 pounds in males and 100 to 150 pounds
in females.

The skull is large (more than 10 inches in length). A pit is
present in the lacrimal bone, and the posterior nares are sep-
arated by the median vomer bone. The male in season is ant-

202 Order ARTIODACTYLA

lered, and each antler has one main beam, with supplemental
branches or spikes, when present, directed backward. Dental
formula: 1 0/3,°C 0/1, Pur 3/3,5 M373.

Life History.—The white-tailed deer is most at home in
woods and thickets, particularly where wooded areas alternate
with open glades, fig. 1. By opening up the forests, early Illinois
settlers increased the area favorable to the white-tail, and for
a few years in the first half of the last century the deer popula-
tion of the state increased. Later, more extensive destruction
of forests, intensive agriculture, and hunting combined to exter-
minate the white-tail from Illinois. Reintroduced into this
state, the white-tail has found suitable habitat in reforested
areas and in other areas that are not cultivated.

Each white-tail buck annually grows a set of antlers, which
start to develop late in April or early in May and are covered
with velvety skin until it is rubbed off in August or September.
It is beneath this “velvet” that bone-forming materials produce
the hard antlers. During the mating or rutting season, the
antlers are at their strongest, the neck of the male swells, and

Fig. 110.—Fawn of white-tailed deer.

Family CERVIDAE 203

the mature and vigorous bucks may take unto themselves a
harem of several does. Breeding takes place in November or
December. Later, in December or in January, there is a re-
sorption of the bony material of each antler near the skull, and
the antlers are shed.

Fawns are born in May or early June after a gestation period
of 7 months. A doe may produce one, two, or three young at a
birth. In Minnesota the average number of young per preg-
nant female is about 1.3. The young are protectively colored
with a reddish coat, dotted with white, fig. 110, and are nearly
free of scent. Throughout the summer, males and females usu-
ally remain separate.

Fig. 111—Male and female adults of white-tailed deer.

204 Order ARTIODACTYLA

The white-tail feeds on a variety of plants, including trees,
nibbling or browsing a little on one and then on another item.
If the deer are too numerous in an area, they will remove all of
the available food-they can reach, and some of them may starve
to death. In some places, deer do damage to gardens and to
orchards.

Signs.—Prints, fig. 15, of both front and hind feet of adult
deer are relatively sharp pointed and usually register well when
the animal is walking or trotting. Tracks of running deer show
prints of the clots or short hind toes on each foot, especially
in mud. Tracks of fawns or immature animals usually can be
distinguished from tracks of pigs, sheep, and goats by the more
acute pointedness of the footprints.

Deer droppings are long, oval objects, commonly varying
from one-half to more than an inch long; generally one end is
tipped with a cone-shaped projection. There are usually 50 to
100 pellets in each set. A

Distribution.—The white-tailed deer was once common in
Illinois, but the native stock was exterminated during the last
century. In the 1930's, a concerted program of re-establishing
the species was undertaken, and in the winter of 1950-51 game
biologists estimated that there were more than 3,075 deer in 68
of the 102 counties of the state (Pietsch 1954:12). The intro-
duced deer apparently belong to the subspecies Odocoileus vir-
ginianus borealis Miller. The natural range of the white-tailed
deer includes most of North America south of an imaginary

line extending from Nova Scotia to southeastern British Colum-
bia.

BISON BISON (Linnaeus)

Bison Buffalo*

Description.—The bison is the only member of the bovine
family which was native to Illinois within historic times. This
animal is about the size of domestic cattle, but it appears larger
because of its woolly, shaggy fur, its shaggy “beard,” and the
hump between its shoulders. The short horns and split hoofs
are black. The horns, fig. 108d, are ever-growing and not shed.
A bull weighs nearly a ton, a cow about half a ton.

*Bison is preferable to buffalo to distinguish this mammal from the water buffalo
and other buffaloes of Africa and Asia.

MAMMALS OF PREHISTORIC TIMES 205

Former Distribution.—The bison, or buffalo as it is more
frequently called, once occurred throughout the prairies ot
Illinois, but probably never so abundantly as on the plains west
of the Mississippi River. Early explorers record the bison mostly
from along river banks, probably because these men usually trav-
eled by way of water courses. They referred to “extraordinary”
numbers of this animal and wrote of the prairies “abounding”’ in
buffaloes. Large herds to these explorers apparently were made
up of 200 to 300 individuals, not of several thousands, as in the
West.

Numerous buffalo trails crossed and recrossed the prairies
of the Illinois country. Perhaps the best known were those from
Vincennes, Indiana, which invaded the lush central prairies
from the east and continued on almost directly westward toward
the Mississippi River.

By 1814, the bison had entirely disappeared from the Illinois
territory, leaving behind their countless well-trodden paths.

At present, bison are kept in a semidomesticated condition
on a few farms in Illinois.

~ SOME MAMMALS OF PREHISTORIC TIMES

Many thousands of years ago, there lived in the region of
what is now known as Illinois certain kinds of mammals that
became extinct long before the white man arrived in the Amer-
icas. These were the strange mammals of the Ice Age, or Pleis-
tocene. Some flourished when the climate was cold, others when

Fig. 112.—Tooth of a mastodon, a; tooth of a mammoth, b.

206 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

it was warm. Most notable of these animals were the elephant-
like mammoths and mastodon, the musk-ox, the giant beaver, and
the giant ground sloth. Their fossilized bones and teeth have

Fig. 113.—A restoration of the American mastodon.

Fig. 114.—A restoration of the mammoth.

MAMMALS OF PREHISTORIC TIMES 207

been found in Illinois, and it is only through such evidence that
their former presence in this area is known. Teeth of two of
these prehistoric mammals, the mastodon and the mammoth,
are pictured in fig. 112.

MEGALONYX JEFFERSONII Desmarest
Giant Ground Sloth

The most bizarre of all of the extinct mammals of the IIli-
nois region was the giant ground sloth, which was nearly as
large as a present-day elephant, but looked somewhat like a
bear with a long neck and with a very broad, blunt tail. It ap-
parently fed on leaves and twigs. Since sloths of today live in
tropical America, it is usually assumed that the giant ground
sloth occurred in the Illinois region during the warm inter-
glacial periods. There are few fossil records of this prehistoric
species for I[Ilinois.

CASTOROIDES OHIOENSIS Foster
Giant Beaver

A gigantic beaver, as large as a bear, once frequented the
waterways of the present-day Illinois area. One can surmise
that the giant beaver constructed enormous dams and was capa-
ble of felling large trees. It became extinct at the close of the
Ice Age. Several fossilized bones of this animal have been dis-
covered in [Ilinois.

MAMMUT AMERICANUS (Kerr)
American Mastodon

The American mastodon, fig. 113, was about the size of an
average elephant of present-day India, but the body was coy-
ered with long, coarse hair. The upper tusks were more or
less parallel and either straight or curved upward. In the male,
a single, short lower tusk was present, presumably completely
concealed in the lower lip. The mastodon was probably a brow-
ser, feeding heavily upon leaves, for it lived in forested areas
and had teeth for grinding food, fig. 112. Remains of this spe-
cies have been found in a number of widely scattered localities
in Illinois.

208 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

MAMMUTHUS JEFFERSONI (Osborn) and
MAMMUTHUS PRIMIGENIUS (Blumenbach)

Mammoth

These mammoths, fig. 114, were similar to but larger than
present-day elephants. hey stood approximately 11 feet high
and had huge tusks, as long as 16 feet, bowed outward in the
middle and curved inward at the tips. Their woolly fur, pro-
tected by long guard hairs, equipped them to withstand cold
weather, and it is probable that they were in the Illinois region
during periods of glaciation. Since their teeth, fig. 112, are so
similar to those of present-day elephants, it is assumed that their
food habits were much the same. Remains of two species of
mammoths have been taken at scattered localities in Illinois.

EQUUS sp.
Horse :

A few remains of a horse that was apparently somewhat like
our present-day horse have been found in Illinois. Teeth of this
prehistoric horse resemble those of our present-day horse, fig.
109c, but they can be distinguished by experts.

PLATYGONUS COMPRESSUS Le Conte
Peccary

The remains of a piglike animal, known as a peccary, have
been taken near Galena and Alton, Illinois. The nearest rela-
tives of this animal now live in southwestern United States and
Mexico.

SYMBOS CAVIFRONS (Leidy)
Musk-Ox

During glacial periods the musk-ox occurred in what is now
Tllinois, and as far southward as Arkansas. Closely related
musk-oxen are presently known from the barren Arctic of
North America. The extinct musk-ox undoubtedly had long,
shaggy fur, as do the living kinds. The horns were united over
the head and extended downward before curving outward.
There are very few records of this species in I[lIlinois.

MAMMAL HABITATS AND THE FUTURE 209

BISON sp.
Giant Bison Royal Bison

A bison, fig. 115, much larger than the one that now exists,
is known from skeletal remains found near Alton.

Fig. 115.—A restoration of the giant or royal bison.

RANGIFER sp.
Caribou

A kind of caribou is known from fossil remains found in Ken-
tucky and near Alton, Illinois. Iwo kinds of caribou now occur
in northern North America.

MAMMAL HABITATS AND THE FUTURE

Most of the mammalian species in the Illinois country when
its settlement began are still with us. But, with few exceptions,
they are here despite a lack of favorable attention paid to them.
Some, like the thirteen-lined ground squirrel, have been inad-
vertently favored by agricultural practices, in this case excessive
pasturing; some, like the cottontail rabbit, have been able to
“take it’; others, like certain bats, have not been adversely
affected by civilization; and a few, like the bobcat, have been
able to survive because agriculture has by-passed habitats of
varying sizes in which they can live.

210 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

The red squirrel, so far as we know, is the species most re-
cently eliminated from the state. Nearer the center of its range,
in cooler climates, this squirrel can tolerate a wide variety of
habitats, some of them marginal. As far south as Illinois, only
the better habitats are tolerable and, to be tolerable, they must
be extensive.

Species other than the red squirrel have felt the pressure of
Illinois agriculture. They have yielded ground as their habitats
have been narrowed or eliminated. Most Illinois counties at one
time had many species, widely distributed. Some counties now
lack one or more species found in other parts of the state, and
the species still present generally are restricted to a few small
habitats. Gray squirrels, once widely distributed in all counties,
now occcur only in a few choice habitats in most of those counties
in which they are still present.

The loss of any one or several species may not, in itself, be
of great consequence, but, when a species becomes rare or dis-
appears, it serves as a signal that there has disappeared with it
a vast and real, though often intangible, set of natural conditions
which supported it. When bison disappeared from Illinois, they
signaled the disappearance of extensive prairie, which was com-
posed of native grasses, forbs, vines, and bushes.

We can now hardly afford in Illinois the extensive space re-
quired to maintain bison on natural habitats; elimination of bison
from this state was a calculated procedure. Probably most
people do not need the occasional solitude that a sojourn on the
primitive prairie would afford; they experience sufficient contact
with nature when they fish on a nearby lake, hunt on a farm,
play a round of golf on a well-kept course, or attend a picnic
in a public park. We are, however, in danger of letting too
much of the natural habitat disappear, of crowding our satis-
factions into too little out-of-door space.

In spite of decades of progressive soil conservation, too many
Illinois pastures are still so heavily grazed that they not only do
not support wildlife but they do not support the number of cattle
they could if efficiently managed. Too many woodlands have
cattle turned into them and thus lose many of their wild mam-
mals and birds, and also their value as woods without attaining
value as pastures, fig. 116. In 1949, two-thirds of the privately
owned Illinois woodland was still being pastured: the equiva-
lent of six counties going to waste! In such woodland, cattle

MAMMAL HABITATS AND THE FUTURE 211

use most of their energy in getting food; there is not enough
food value in the meager grass to produce much milk and beef.

Too many ditchbanks, stream sides, and slopes are still
farmed so severely that soil washes downstream with every rain.
Too much water is allowed to run to sea—water that should
sink deep into our soils to form a continuous store for human
use. Too many brooks and rivers are fouled by oil and sewage,
chemical waste and soil. Modern science can use or dispose
of stream pollutants in harmless ways. Contour farming on
slopes, restoration of plant cover to gullies and ravines, can hold

Fig. 116.—Left, managed, unpastured woodland; right, pastured
woodland. Pastured woodland is uneconomical because it produces
poor forage and little or no replacement timber.

212 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

soil in place and support game besides. What multiple rewards
for small corrections!
Too much wildlife cover and too much wildlife have been

destroyed by careless use of herbicides and insecticides; proper —

use of these materials requires experience, planning, and expert
supervision.

Some corrections in the conservation situation have been
made; they are bright pilots for the future. About a quarter
century ago. a national forest was established in southern IIli-
nois. In many parts of Illinois, state parks and county forests
have been established. In heavily populated Cook County, a
large forest preserve has for many years given reasonable op-
portunity for people to enjoy a soothing day in prairie and wood-
land areas. There are now in I]linois about 55 square miles of
land in 64 state-owned parks and conservation areas, all of which
serve as habitats for many species of wildlife. Railroad and high-
way rights-of-way harbor more species, usually the kinds that re-
quire grass or forb-covered habitats. These areas can be altered
to harbor many more kinds of wildlife. In southern Illinois
much of the land which was despoiled by ruinous farming is so
poor that now, ironically, it is allowed, even helped, to produce
timber without interference by grazing.

Mammalian populations renew themselves in such favorable
centers and extend their ranges as more habitats become avail-
able. Within the past half century we have seen beavers and
white-tailed deer restored in considerable numbers to Illinois,
and furbearing mammals, with the possible exception of musk-
rats, are now more numerous in the state than they were 25
years ago. This favorable trend only indicates the possibility
for the future. We can have more productive land and more
wildlife. But there still is a long way to go.

GLOSSARY

albinistic. Whitish, having less than normal amount of pigment.

alveolar. Pertaining to the alveoli, as those of the jaws.

alveolus (pl. alveoli). A pit or socket, as for a tooth.

anterior. At or toward the head or front end; opposed to posterior.

antorbital canal. Canal in the skull having a small opening (infra-
orbital foramen) to the outside in front of and usually slightly
below the eye socket, fig. 117 (dark area above third premolar
of upper jaw).

auditory bulla (pl., auditory bullae). Bony capsule (bulblike struc-
ture), fig. 117, at base of braincase surrounding the bones of the
inner ear.

ball pad. A cushion-like thickening of the ball of the foot: corre-
sponds to the ball of the human foot.

Infraorbital Frontal Parietal

Sagittal

Auditory
Bulla

Premolar Molar

Canine Teeth Teeth Foramen
Tgoth en Der | Magnum
T i
By Shy,
Mandible

Fig. 117.—Side view of skull and lower jaw of dog. This and
he following two figures are labeled to illustrate the diagnostic
varts referred to in the keys and descriptions.

213

214 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

basioccipital bone. Bone at the base of the cranium (braincase)
immediately in front of the foramen magnum (large opening
at the base of the skull through which the spinal cord passes).

bony palate. See hard palate.

braincase. Part of the skull enclosing the brain, fig. 118.

bulla (pl., bullae). A hollow, thin-walled, bony prominence of
rounded form, fig. 117.

calcar. In bats, a bony process (extension) from the heel; it par-
tially supports the tail membrane, fig. 39.

canine or canine tooth. The tooth between the incisors (front cut-
ting teeth) and the premolars; figs. 117, 119; eyetooth.

carnassial or carnassial tooth. Shearing tooth found in Carnivora;
last upper premolar and first lower molar, figs. 117, 119.

Interparietal Bone:

Braincase Parietal

}
Rostrum
\\

Incisor Teeth

Nasal Bone

remaxillary Bone

Maxillory Bone

Narial Aperture

Fig. 118.—Top view of skull of dog.

GLOSSARY 215

carnivore. A mammal belonging to the order Carnivora.

carnivorous. Flesh-eating.

cheek pouch. Pouch either just inside or outside the mouth for the
temporary storing of food.

cheek teeth. The premolar and molar teeth, fig. 119.

cranial. Of or pertaining to the skull, or to the cranium (brain-
case) only.

cranium. Braincase, fig. 118.

crown. Part of tooth not covered by the gum in living animal.

cusps. Prominences or points on the grinding surface of the crown
of a tooth, fig. 112a.

dental formula. The arrangement of the teeth (for different spe-
cies) written as a formula; example: I 3/3, C 1/1, Pm 4/4,
M 2/3. The example should be interpreted as follows: To the

Occipital Bone
Zygomatic
Arch
Molar Teetn[ WES
Carnassial Cheek
Tooth Teeth

Premolor Teeth

Canine Tooth

Premaxillary Bone

Incisor Teeth

Fig. 119.—Under side of skull of dog.

216 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

left of each diagonal line is indicated the number of a certain
kind of tooth in each half of the upper jaw, to the right the num-
ber of the same kind of tooth in each half of the lower jaw. The
total number of teeth in each half of the upper jaw is 10, in
each half of the lower jaw 11. Therefore, there are 20 upper
teeth and 22 lower teeth and 42 teeth altogether. In each half
of the upper jaw in this example there are three incisors (I),
one canine (C), four premolars (Pm), and two molars (M).

dentary bone. One of a pair of membranous bones of the distal
(farthest from hinge) part of the lower jaw.

diastema. A distinct space or gap between two teeth, as shown in
fig. 40f.

digitigrade. Walking primarily on the toes, as in horses and dogs.

dorsal. Pertaining to the back or upper parts; opposed to ventral.

dorsoventrally. Between the dorsal (upper) and ventral (lower)
sides of an animal. For example, a body or part flattened dorso-
ventrally would be unusually broad for its depth, i.e., vertically
compressed as opposed to laterally compressed.

enamel loop. Loop formed by convolutions of enamel of tooth as
seen on the grinding surface, fig. 74a—e.

enamel triangle. Triangle formed by convolutions of enamel of
tooth as seen on the grinding surface, fig. 746, d, e.

fenestrated. Having numerous openings, as in skull of a cotton-
tail, fig. 40d.

flange. A rim or rimlike extension.

foramen. An opening, as found in the skull, through which nerves
or blood vessels pass, fig. 119.

foramen magnum. Large opening in skull at posterior (rear) end,
figs 1L7,

forb. Any herbaceous plant other than a grass.

frontal or frontal bone. One of a pair of bones forming the roof
of the braincase, figs. 117, 118.

fulvous. A dull yellowish gray or brownish color.

gestation period. The period of carrying of young normally in the
uterus, from conception to delivery; period of pregnancy.

guard hairs. Long hairs of the pelt that protect the shorter and
finer textured fur.

habitat. The natural abode in which a species of plant or animal
grows or lives.

hard palate. Portion of palate, fig. 119, supported by bone; that
part of palate covering the palatal bone.

herbivore. A mammal that feeds on plant material.

herbivorous. Plant eating.

hibernate. To pass the winter in close quarters in a torpid or in-
active state.

incisive foramen. One of a pair of openings in the anterior palate,
sometimes called anterior palatine foramen, figs. 73d(f), 119,

incisor. One of the front teeth between the canines; found in the
premaxillary or dentary bones, figs. 118, 119.

inferior. Lower, as opposed to superior or upper.

GLOSSARY 217

infraorbital foramen. A small opening or pore in the skull in front
of, or anterior to, and usually slightly below the eye socket, fig.
117 (dark area above the third premolar of upper jaw).

infraorbital plate. Also called zygomatic plate; expanded anterior
or front portion of the zygomatic arch, fig. 117.

insectivore. A mammal belonging to the order Insectivora (shrews
and moles).

insectivorous. Insect eating.

interorbital region. Area between orbits or eye sockets in the skull.

interorbital space. Area across skull at the widest part of frontal
bone.

interparietal or interparietal bone. Part of the top of the brain-
case; bone at the rear of the skull with the front extension
wedged between the parietal bones, fig. 118.

lacrimal or lacrimal bone. Small bone at anterior (front) angle
of eye socket.

lateral or laterally. Pertaining to the sides of an animal.

longitudinal or longitudinally. Lengthwise, along the long axis of
an animal.

mandible. One of the halves of the lower jaw, fig. 117.

marsupial. Mammal belonging to the order Marsupialia; pertaining
to an animal having a pouch for carrying the young.

maxilla (pl. maxillae) or maxillary bone. One of a pair of bones
that bear the molar and premolar teeth, figs. 117, 118.

maxillary. Pertaining to the maxilla; maxillary bone.

melanistic. Black or blackish, having more than the normal amount
of dark pigment.

metatarsal gland. A gland situated on the inside of the hind leg
between the toes and the heel.

milk tooth. A temporary (deciduous) tooth; “baby” tooth.

molar or molar tooth. One of the posteriormost or back teeth
of the upper or the lower jaw, figs. 74a-e, 117, 119.

molar tooth row. The group or row of molar teeth.

nares. Bones of the nose.

narial aperture. Internal nares; nasal opening through the roof of
the mouth, fig. 118.

nasal or nasal bone. One of a pair of bones in the region of the
nose, figs. 117, 118.

nosepad. The bare part of the nose of a mammal.

occipital or occipital bone. Pertaining to, or one of, the bones
which surround the foramen magnum (large opening) at the
posterior (rear) end of the skull, fig. 119.

ochraceous (ocherous). Pertaining to a color similar to ocher;
referring to a yellowish or yellowish tan color.

omnivorous. Eating both animal and vegetable food.

orbit. Socket in the skull in which one of the eyes is located.

orbital region. Pertaining to the area near one of the orbits or eye
sockets or between the eye sockets.

over-all length. Measurement from tip of the nose to tip of the
tail, excluding terminal hairs; total length.

218 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

palatal width. Width of palate between teeth of the two sides of
upper jaw, fig. 61c, d.

palate. Bony roof of the mouth, figs. 61c, d, 119.

parietal or parietal bone. One of a pair of bones of the brain-
case, figs. 117, 118.

pelage. The hair (fur or wool) covering the body of a mammal.

placenta. Organ of the developing embryo to provide for its nour-
ishment and the elimination of waste products by interchange
through the membranes of the uterus of the mother.

placental. Pertaining to an animal having a placenta.

plantigrade. Walking on the sole of the foot with the heel touching
the ground, as in bears and man.

posterior. At or toward the hind end; opposed to anterior.

postorbital. Area situated behind the eye and usually referring to
the postorbital process.

postorbital process. A projection of the frontal bone directly be-
hind the orbit, fig. 73b(p).

predator. An animal that lives by preying upon other animals.

prehensile. Adapted for seizing or grasping.

premaxilla (pl. premaxillae). One of a pair of bones in the skull;
these bones, between the nasal and maxillary bones, bear the
upper incisor teeth, fig. 117; premaxillary bone, figs. 118, 119.

premaxillary. Pertaining to the premaxilla.

premolar. One of a series of teeth on each side of upper jaw and
of lower jaw in front of the true molars, figs. 117, 119. When a
canine tooth is present, the premolars are between it and the first
molar, and in the upper jaw are confined to the maxillary bone.
Premolars replace the milk (deciduous) molars.

process. A prominence or projecting part; an extension.

protuberant. Bulged beyond the surrounding or adjacent surface.

retractile. Capable of being drawn back or in, as with the claws of
cats.

rostral. Pertaining to the rostrum or snout.

rostrum. The projecting front part of the skull, in the snout or
nose region, figs. 40c-d, 44, 73c-d, 74f-i, 117, 118.

rudimentary. Not fully developed, or represented only by a ves-
tige.

sagittal crest. Raised ridge of bone on top of and extending from
front to back of braincase, fig. 117.

scat. A dropping of excrement.

septum. A partition.

Keen’s Eastern Red
Bat Pipistrel Bat

GLOSSARY 219

skull length. Length of the skull as measured from the posterior-
most portion to the anteriormost portion, fig. 118.

skull width. Width of the skull, usually the width across the zygo-
matic arches, fig. 118.

sonar system. A means of locating objects by producing sound
waves and then receiving the reflected vibrations or sound waves.

supersonic. Pertaining to vibrations and waves whose frequencies
are greater than those that affect the human ear.

supraorbital process. A process on the top rim of each orbit (eye
socket), as in fig. 103.

supraorbital ridge. A lateral, longitudinal ridge of the skull situ-
ated above each eye socket.

suture. A line of union between bones of the skull.

tarsus. Part of the foot immediately below the long leg bones; the
ankle.

temporal ridge. One of ridges on top of braincase, as in fig. 60a, b.

tentacle. An elongate, flexible, single or branched process (struc-
ture) usually tactile in function.

thoracic. Pertaining to the chest region.

tine. Any of the branches which come off the main beam of an
antler.

tooth triangle. Same as enamel triangle.

tragus. Projection of skin near the bottom of the external ear
opening in bats, fig. 51.

tubercle. A small knotlike prominence either soft or hard.

underfur. Thick, soft fur lying beneath the longer and coarser hair
of a mammal.

ungulate. Hoofed; a hoofed animal.

unicuspid. A tooth with a single cusp, as in certain teeth of shrews,
fig. 44a, b, c.

venter. Abdomen or belly.

ventral. Pertaining to the lower side, as opposed to dorsal.

vestigial. Pertaining to a structure or organ that in the adult is
degenerate or imperfectly developed.

vomer or vomer bone. Bone forming part of the nasal septum
(partition) and dividing the nasal cavities.

vomerine partition. Same as vomer.

zygomatic arch. An arch of bone forming the outside of each orbit
(eye socket), figs. 118, 119.

zygomatic width. Width of skull across the zygomatic arches at
the widest point.

Evening Silver-Haired
Bat Bat

BIBLIOGRAPHY
Some Literature on Illinois Mammals

Anderson, Elsie P.
1951. The mammals of Fulton County, Illinois. Chicago Acad.
Sci. Bul. 9(9) : 153-88.
Anonymous
1837. Illinois in 1837; a sketch descriptive of the situation,
boundaries, face of the country, prominent districts, prai-
ries, rivers, minerals, animlas [sic], agricultural produc-
tions, public lands, places of internal improvement, manu-
factures, &c. of the State of Illinois. S. Augustus Mitch-
ell, Philadelphia. 143 pp.
Brown, Louis G., and Lee E. Yeager
1943. Survey of the Illinois fur resource. Il]. Nat. Hist. Surv.
Bul. 22(6) :435-504.
Cory, Charles B.
1912. The mammals of Illinois and Wisconsin. Field Mus. Nat.
Hist. Pub. 153, Zool. Ser., 11:1—505.
Gregory, Tappan
1936. Mammals of the Chicago region. Chicago Acad. Sci.
Prog. Act. 7(2-3) : 13-75.
Kennicott, Robert
1855. Catalogue of animals observed in Cook County, Illinois.
Ill. State Ag. Soc. Trans. 1:577—95.
1857— The quadrupeds of Illinois injurious and beneficial to the
1859. farmer. U. S. Commr. Patents Rep. (Ag.) for 1856:52—110;
1857:72-107; 1858:241—-56.
Mohr, Carl O.
1943. Illinois furbearer distribution and income. Ill. Nat. Hist.
Surv. Bul. 22(7) :505-37.
Necker, Walter L., and Donald M. Hatfield
1941. Mammals of Illinois. Chicago Acad. Sci. Bul. 6(3):17-60.
Pietsch, Lysle R.
1954. White-tailed deer populations in Illinois. Ill. Nat. Hist.
Surv. Biol. Notes 34. 24 pp.
Sanborn, Colin C.
1925. Mammals of the Chicago area. Field Mus. Nat. Hist.
Teaflet 8:129-51.
Sanborn, Colin Campbell, and Douglas Tibbitts
1949. Hoy’s pygmy shrew in Illinois. Chicago Acad. Sci., Nat.
Hist. Misc. 36. 2 pp.
Scott, Thomas G.
1955. An evaluation of the red fox. Ill. Nat. Hist. Surv. Biol.
Notes 35. 16 pp.
Thomas, Cyrus
1861. Mammals of Illinois. Catalogue. Ill. State Ag. Soc. Trans.
(for 1859-60) 4:651-61.

220

BIBLIOGRAPHY 221

West, James A.
1910. A study of the food of moles in Illinois. Ill. Lab. Nat.
Hist. Bul. 9(2) :14—22.
Wood, Frank Elmer
1910. A study of the mammals of Champaign County, Illinois.
Ill. Lab. Nat. Hist. Bul. 8:501-613.
Yeager, Lee E.
1945. Capacity of Illinois land types to produce furs. N. Am.
Wildlife Conf. Trans. 10: 79-86.
Yeatter, Ralph E., and David H. Thompson
1952. Tularemia, weather, and rabbit populations. Ill. Nat.
Hist. Surv. Bul. 25 (6) :351-82.

Some Handbooks on Mammals of the United States

Anthony, H. E.
1928. Field book of North American mammals. G. P. Putnam’s
Sons, New York and London. xxvi-+ 674 pp.
Burt, William Henry
1952. <A field guide to the mammals. Houghton Mifflin Com-
_ pany, Boston. xxi-+ 200 pp.
Hamilton, William J., Jr.
1943. The mammals of eastern United States. Comstock Pub-
, lishing Co., Inc., Ithaca, New York. 432 pp.
Murie, Olaus J.
1954. A field guide to animal tracks. Houghton MifHin Com-
pany, Boston. xxii + 374 pp.
Palmer, Ralph S.
1954. The mammal guide. Doubleday & Company, Inc., Garden
City, New York. 384 pp.

Some Literature on Mammals of States Near Illinois

Barger, N. R.
1951. Wisconsin mammals. Wis. Cons. Dept. Pub. 351-51. 54 pp.
Bennitt, Rudolf, and Werner O. Nagel
1937. A survey of the resident game and furbearers of Mis-
souri. Mo. Univ. Studies 12(2) :1-215.
Burt, William H.
1946. The mammals of Michigan. University of Michigan
Press, Ann Arbor. xv + 288 pp.
Funkhouser, W. D.
1925. Wild life in Kentucky. Ky. Geol. Surv., Ser. 6, 16:1-385.
Gunderson, Harvey L., and James R. Beer
1953. The mammals of Minnesota. University of Minnesota
Press, Minneapolis. xii + 190 pp.
Hahn, Walter Louis
1907. Notes on mammals of the Kankakee Valley. U. S. Natl.
Mus. Proc. 32:455-64.
1909. The mammals of Indiana. Ind. Dept. Geol. and Nat.
Res. Ann. Rep. 33:417-654.

222 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

Hicks, Ellis A., and George O. Hendrickson
1940. Fur-bearers and game mammals of Iowa. Iowa State Col.
Ag. Exp. Sta. Bul. P3(n.s.) :113-47.
Lyon, Marcus Ward, Jr.
1936. Mammals of Indiana. Am. Midland Nat. 17(1) :1—384.
Scott, Thos. G.
1937. Mammals of Iowa. Iowa State Col. Jour. Sci. 12(1) :43-98.
Scott, Thomas G., and Willard D. Klimstra
1955. Red foxes and a declining prey population. So. Ill. Univ.
Monog. Ser. 1. 123 pp.
Seagears, Clayton B.
1945. The fox in New York (second printing). New York State
Conservation Department, Albany. 85 pp.
Swanson, Gustav, Thaddeus Surber, and Thomas S. Roberts
1945. The mammals of Minnesota. Minn. Dept. Cons. Tech.
Bul. 2. 108 pp.

INDEX

Page entries in boldface type refer to principal treatments of

items listed; those in italic type refer to illustrations.

Names of

orders and families are in CAPITAL letters; those of genera and
species are in italic type. All names of animals and certain other
words are listed in the index in the singular, as mouse for mice,
tooth for teeth, regardless of the way in which they appear in the
text. For complete reference to an animal, pages under both scien-
tific and common names should be consulted.

A
alacer, Sylvoilagus floridanus, 195
alexandrinus, Rattus rattus, 184
allegheniensis, Mustela rixosa, 98
americana, Martes, 87, 90, 95
americanus
Mammut, 207
Ursus, 87,90, 92
ANTILOCAPRIDAE, 197
aquaticus
Scalopus, 39, 50, 51, 51
Sylvilagus, 40, 189, 191, 195
armadillo, 38
ARTIODACTYLA, 41, 43, 44,
197
aureolus, Peromyscus nuttall1,
165
auricularis, Pitymys pinetorum,
179
austroriparius, Myotis, 39, 67,
70
avia, Mephitis mephitis, 108

B

badger, 1, 7, 16, 26, 32, 39, 85,
86, 87,91, 91,109, 109, 112,
£4. 1367439; 152

bairdit, Peromyscus maniculatus,
161

Bat vy 9,95, 38,39, 41, 41, 42,
44, 63, 65, 66, 67, 68, 70, 75,
78, 79, 80, 82, 83, 108, 209

big brown, 39, 66, 68, 74, 77,

78, 82, 83

223

big-eared, 7

eastern pipistrel, 7, 39, 66, 68,
69, 75, 76, 218

evening, 7, 39, 65, 67, 68, 69,
70, 82, 219

flying fox, 63

fruit, 63

gray, 7,39, 65,66; 68, 69, 71.
218

hoary, 39, 64, 66, 74, 79, 80,
219

Indiana, 7, 39, 65, 68, 69, 73,
78

Keen's; 39;:67,.67, 68:9. 72>
218

little brown, 4, 39, 67, 67, 68,
69; IV 42,13; 783,83

ted, 39, 64, 66, 74, 755-80, 87,
218

silver-haired, 2, 39, 64, 66, 68,
74, 75, 80, 219

small-footed brown, 67, 74

southeastern, 7, 39, 65, 67, 68,
69, 70

southeastern big-eared, 39,
65, 66, 68, 83, 84

vampire, 63

western big-eared, 83

bear, 1, 85, 207
black, 85, 87, 90, 92
beaver, 1, 3, 6, 20, 21, 26, 30, 35,

40, 123, 124, 125, 128, 129,
154... 254,207, 212

giant, 206, 207

224

bison, 15°22, 120,197; 1995200,
204, 209, 210
giant, 209, 209
royal, 209, 209
Bison
bison, 200, 204
sp., 209
Blarina
brevicauda, 39, Si, 59,62
brevicauda brevicauda, 61
brevicauda carolinensis, 61
bobeat, 5, 19, 20; 28, 39, 58, 88,
89, 121, 122, 209
borealis
Lasiurus, 39, 66, 80
Odocotleus virginianus, 204
Bos taurus, 199, 200
BOVIDAE, 197
bovine, 197, 204
brevicauda, Blarina, 39, 51, 59,
62
buffalo, 204; see also bison
bull, 199
burrows,.3, 14, 16,..17,-20, 21,
22; see also species accounts
bursarius, Geomys, 40, 125, 128,
151

C
cache, food, 35; see also food
signs and species accounts
calf 25,200
camel, 197
campantius, Lepus townsendit,
193
canadensis
Castor, 40, 125, 129, 154
Cervus, 198, 200, 201
Lutra, 39, 87, 90, 104
CANIDAE, 39
Canis
Ffamiliaris, 88, 90
latrans, 39, 88, 90, 116
latrans frustror, 119
latrans thamnos, 119
lupus, 88, 90, 119
lupus lycaon, 120

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

niger, 88, 90, 120
niger gregory1, 120
Capra sp., 200
caribou, 209
CARNIVORA, 39, 43, 44, 85,
101, 109
carnivore, 32, 85, 86, 89, 91, 97,
100, 107
carolinensis
Blarina brevicauda, 61
Castor canadensis, 156
Sciurus, 40, 125, 128, 143
Castor
canadensis, 40, 125, 129,
154
canadensis carolinensis, 156
canadensis michiganensis,
155, 156
CASTORIDAE, 40
Castoroides ohioensis, 207
cat, 13,26, 26,39; 45) 54556085,
88, 90, Of, 206, 125, *F22-
123, 136; 141
bobcat, 5,.19,..20, 2a 39. 5a,
88, 89, 121, 122, 209
cougar, 88, 89, 121; see also
mountain lion
mountain lion, 1, 85, 121; see
also cougar
cattle, 43, 204, 210; see also cow
cavifrons, Symbos, 208
CERVIDAE, 4i5i3¥
Cerous canadensis, 198, 200, 201
CETACEA, 38
chipmunk, 2, 3, 6, 8, 16, 20, 35,
124-135
eastern, 40, 125, 127, 139,
140, 149
CHIROPTERA, 39, 41, 44, 63
chuck, see woodchuck
cinereoargenteus, Urocyon, 39, 88,
90, 114
cinereus
Lasiurus, 39, 66, 79
Sorex, 39;51, 3%
Citellus
franklinii, 40, 125, 127, 137

INDEX

tridecemlineatus, 40, 125, 127,
135
tridecemlineatus tridecemline-
atus, 137
civet cat, 108; see a/so skunk,
spotted
compressus, Platygonus, 208
concolor, Felis, 88, 89, 121
Condylura cristata, 50, 51, 54
coon, 92; see a/so raccoon
cooperi, Synaptomys, 40, 126,
130, 172
Corynorhinus
macrotis, 84
rafinesquii, 39, 66, 68, 83
townsendi1, 83
eertentan, 3,4,°6,°9) "13, 28, 32,
fo, 79, 18959190, 1972,
193, 196, 209
eastern, frontis., 40, 188, 189,
19t 193, 794, 195
cougar, 88, 89, 121; see also
‘mountain lion
couguar, Felis concolor, 121
paw, 25, 497;°199, 199; 200; see
also cattle
goyote, 3, 16, 20, 22, 26, 29, 35,
39,49, 86, 88,90, 1196, 1168,
119, 120
coyote-dog hybrid, 117, 118, 120
CRICETIDAE, 40
cristata, Condylura, 50, 51, 54
Cry ptotis
parva, 39, 51, 61
parva harlani, 63
parva parva, 63
cuniculus, Oryctolagus, 189, 191

D
deer, 15 @)-22,'25, 27, 38; 41, 43,
120, 197, 201
Virginia, 201; see also white-
tailed next below
white-tailed, 6, 41, 197, 200,
201, 202, 203, 212
den, 16, 20; see also spectes ac-
counts

225

dental formula, 36; see also
Glossary and species ac-
counts
DIDELPHIDAE, 38
Didelphis
marsuptalis, 38, 45
marsupialis virginiana, 49
distribution, 6, 36; see also
species accounts
dog, 26,.495,85788, 90/91/95;
LOS) 110; 14 ATT 7 as;
120; 1363 1399S t55 5 TSE, 21972,
195, 213, 214, 215
fox terrier, 93
German “shepherd’’ (police),
116
hybrid, covote-dog, 117, 118,
T20r.
domestica, Felis, 88, 90
domesticus, Mus musculus, 187
droppings, 5, 8, 13, 2¢, 28, 29,
31; see also scats and species
accounts
dychei, Reithrodontomys mega-
lotis, 158

E
EDENTATA, 38
elephant, 38, 207, 208
elk, 1, 120, 197, 198, 200,
201

American, 198
Eptesicus

fuscus, 39, 66, 68, 77

fuscus fuscus, 79
Equus sp., 208
erminea, Mustela, 88, 92, 101
EUTHERIA, 38

even-toed hoofed mammals, 197

F

familiaris, Canis, 88, 90

feeding platform, 34, 35; see also
Species accounts

feeding station, 8; see also
species accounts

FELIDAE, 39

226

Felis
concolor, 88, 89, 121
concolor couguar, 121
fisher, 87, 90, 96
flesh eaters, 43, 44, 85
floridana, Neotoma, 40, 126, 130,
169
floridanus, Sylvilagus, 40, 189,
191, 193
flying fox, 63
food signs, 13, 35; see also
species accounts
cache, 35
fragments, 8, 13, 16, 25, 29,
SHS)
remains, 8, 36
stores, 13
footprints, 25, 26; see also
prints, tracks, and species
accounts
form, 20, 20; see also species
accounts
fox;als 3416.)20; -26..35,.39) 49,
85. 86, 94,) 103, 141161,
LS, Ah 78s. LS 5s 195
splacke-s LL
Pcross,, 11)
gray, 2, 19, 20, 30, 39, 88,69,
90, Lily, 113, 114, 115
Teds ots ale, (235.305 539> 35.
88, 69, 90, 111, 172, 114,
115,.116
“silver,” 111
franklinii, Citellus, 40, 125, 127,
137
frenata, Mustela, 39, 88, 92, 98
frustror, Cants latrans, 119
fulva, Vulpes, 39, 88, 90, 111
fuscus, Eptesicus, 39, 66, 68, 77

G
geographical distribution, 6;
see also range and Distribu-
tion in species accounts
GEOMYIDAE, 40

Geomys
bursarius, 40, 125, 128, 151

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

bursarius illinoensis, 153
giraffe, 197
Glaucomys
volans, 40, 125, 127, 149
volans volans, 150
gnawing animals, 123
goat, 25, 197, 199, 200, 204
gopher, 16, 151, 152, 153
gray, 137; see also ground
squirrel, Franklin’s |
plains pocket, 7, 17, 40, 125.
128, 151, 25 ieee S56 )
pocket, 4, 13, 19, 40, 54, 124,
128, 152, 153 )
striped, 135; see also ground |
squirrel, thirteen-lined
gossit, Synaptomys cooperi, 173
gossypinus, Peromyscus, 40,127,
130, 163
gregory1, Canis niger, 120
grisescens, Myotis, 39, 66, 71
griseus, Tamias striatus, 141
groundhog, 131; see also wood-
chuck
ground squirrel, 8, 13, 16, 94,
100, 107, 108, 110, 124,
137,158
Franklin’s, 7, 40, 125, 127,
128, 135, 137, 137, 138
gray gopher, 137; see also
Franklin’s next above
striped gopher, 135; see also
thirteen-lined next delow
thirteen-lined, 3, 4, 7, 19, 40,
125, 127, 128, 134, 135, 1374
138, 139, 209

H
habitat, 3, 6; 9, 11, 13, 16, 22,
36, 209; see also species
accounts
hare, 20, 40, 188, 192; see also
jackrabbit and rabbit
harlani, Cryptotis parva, 63
herbivores, 32
high trails, 20, 23
hippopotamus, 197

INDEX

hirtus, Procyon lotor, 95

hispidus, Sigmodon, 126, 130,
169

hog, see pig

homes, 8, 9, 13, 16; see also
Species accounts

horse, 25, 42, 43, 44, 120, 197,
200, 208

hoyt, Microsorex, 39, 51, 58

hudsonicus, Tamiasciurus, 125,
127, 141

hudsonius, Zapus, 40, 126, 129,
187

humeralis, Nycticeius, 39, 67, 68,
82

humilis, Reithrodontomys, 126,
158

I
illinoensis
Géomys bursarius, 153
Neotoma floridana, 171
INSECTIVORA, 39, 43, 44, 49
insectivore, 48, 49, 50, 54
intermedius, Zapus hudsonius,

188

J
jackrabbit, 28, 190, 194
white-tailed, 7, 20, 40, 189,
191, 191, 192, 193
Jeffersoni, Mammuthus, 208
Jeffersoniit, Megalonyx, 207
jumping mouse, 35, 40
meadow, 40, 126, 129, 156,
187, 187

K
kangaroo, 44
keenti, Myotis, 39, 67, 72
keys, 36
skulls, 43, 51, 68, 89, 127,
191, 198
tracks, 25
whole animals, 41, 50, 66, 87,
125, 189
koala, 45

227

L
lagomorph, 188, 190, 193
LAGOMORPHA, 40, 43, 44,
188
Lasionycteris noctivagans,
39, 66, 68, 74
Lasiurus, 68
borealis, 39, 66, 80
borealis borealis, 82
cinereus, 39, 66, 79
cinereus cinereus, 80
latrans, Canis, 39, 88, 90, 116
lemming
bop, 24,35, 156,172, 123-178
southern bog, 40, 126, 129,
OS 872
lemming mouse, 172; see also
lemming, southern bog
LEPORIDAE, 40, 188
Lepus
townsendit, 40, 189, 191, 191
townsendii campanius, 193
lesueurti, Sorex cinereus, 56
letifera, Mustela vison, 104
leucopus, Peromyscus, 40, 127,
130, 158, 161
lodge, 20, 21; see also species
accounts
longirostris, Sorex, 39, 51, 56
loquax, Tamiasciurus hudsonicus,
143
lotor, Procyon, 39, 87, 90, 92
lucifugus, Myotis, 39, 67, 68
lupus, Canis, 88, 90, 119
Lutra
canadensis, 39, 87, 90, 104
canadensis canadensis, 106
lycaon, Canis lupus, 120
Lynx
rufus, 39, 88, 89, 121
rufus rufus, 123

M
machrinus, Scalopus aquaticus,
54

macrotis, Corynorhinus, 84

MAMMALIA, 37

228 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

mammoth, 205, 206, 206, 207,
208 +
Mammut americanus, 207
Mammuthus
Jeffersoni, 208
primigenius, 208
maniculatus, Peromyscus, 40,
127, 1305 158
Marmota
monax, 40, 125, 127, 131
monax monax, 133
marsupial, 44
MARSUPIALIA, 38, 43, 44,
44
marsuptalis, Didelphis, 38, 45
Inartense yO. 96
pine, 87; °90, 95
Martes
americana, 87, 90, 95
americana americana, 96
pennanti, 87, 90, 96
pennanti pennanti, 97
mastodon, 205, 206, 207
American, 206, 207
mearnsi1, Syluilagus floridanus,
195
megacephalus, Peromyscus
gossypinus, 164
Megalonyx jeffersonii, 207
megalotis, Reithrodontomys,
40, 126, 156, 158
Mephitis
me phitis, 39, 87, 91, 106
mephitis avia, 108
mephitis nigra, 108
michiganensis, Castor cana-
densis, 155, 156
Microsorex
hoyi, 39, 51, 58
hoyi hoyi, 58
Microtus
ochrogaster, 40, 126, 130, 175
ochregaster ochrogaster, 177
pennsylvanicus, 40, 126, 130,
173
pennsylvanicus pennsylvani-

ta 175

mink, 1; 3,578 mop oo, 21, 2a
26, 30, 35, 39, 49, 85, 86, 87,
91, 92, 95, 99, 100, 101, 101,
102, 104, 167, 178, 181, 185,
195
mink, Mustela vison, 104
mole, 2, 3, 6, 16, 17,19, 39, 420
44, 49, 53, 54, 59; 113,153)
177, 178
eastern, 15; 39; 43, 50:50; Sit
51 a2
prairie, 54
star-nosed, 50, 50, 51, 54
monax, Marmota, 40, 125, 127,
131
MONOTREMATA, 38
mound, 4, 15, 17, 17, 19, 24;
see also species accounts
mountain lion, 1, 85, 121; see
also cougar
mouse, 15°35, 6570-50, eee, ae
33, 38, 40, 48, 54, 59, 60, 97,
98, 100, 101, 103, 108, 113,
114, 116, 118, 122; 123, 1244
157, 172, 473, 4 eae, 1
cotton, 5; 7, 19, 40; 127, 130)
157, 162,065
deer, 3, 4, 24, 31, 35, 40, 127,
130, 15835959) 2625-879
eastern harvest, 126, 158
golden, 5, 7, 19, 40, 127, 129,
130, 157, 164, 165
harvest, 130
house, 1, 6, 31, 35, 40, 47, 124,
127, 129, 130, 156, 161, 185,
186
jumping, 35, 40
lemming, 172; see also lem-
ming, southern bog
meadow, 53, 62, 103, 110,
173: see also vole, meadow
meadow jumping, 40, 126,
129, 156, 187, 187
Old World, 40
pine, 24, 35, 53, 177; see also
vole, pine
prairie deer, 158

INDEX

prairie meadow, 175; see also
vole, prairie
western harvest, 7, 10, 40,
23-9926, 956,°757, 158
“white,” 185
white-footed, 2, 3, 19, 20, 24,
Bo, 40956,5, 100; 103; 127,
129; 180, 156, 158, 159, 160,
1615.163, 165
woodland white-footed, 161
mumfordi, Myotis austroriparius,
Ht
MURIDAE, 40
Mus
musculus, 40, 127, 130, 185
musculus domesticus, 187
musculus, Mus, 40, 127, 130,
185
musk-ox, 206, 208
musenae, yi, 2, 9,13; 20,21,
Oi 22 25 L26,29,, 325 34,35;
40, 42, 85, 94,.95, 102;°103,
104, 124, 126, 129, 155, 167,
£79, 150,212
Mustela
erminea, 88, 92, 101
frenata, 39, 88,:92, 98
frenata noveboracensts,
101
Fixosa, 39,°88, 92,°97
rixosa alleghentensis, 98
vison, 39, 87, 92, 101
vison letifera, 104
vison mink, 104
MUSTELIDAE, 39
Myotis, 68, 70, 71, 72, 73, 74,
83
austroriparius, 39, 67, 70
austroriparius mumfordi,
a
grisescens, 39, 66, 71
keenit, 39, 67, 72
keenii septentrionalis, 73
lucifugus, 39, 67, 68
lucifugus lucifugus, 70
sodalis, 39, 68, 73
subulatus, 67, 74

229

N
Neotoma
floridana, 40, 126, 130, 169
floridana tllinoensis, 171
neste 3; 5, 8,9 1G 18, 19220795;
36; see also Species accounts
niger
Canis, 88, 90, 120
Sciurus, 40, 125, 128, 146
nigra, Mephitis mephitis, 108
noctivagans, Lastonycteris, 39,
66, 68, 74
norvegicus, Rattus, 40, 126, 130,
184
noveboracensts
Mustela frenata, 101
Peromyscus leucopus, 163
nuttall1, Peromyscus, 40, 127,
130, 164
Nycticeius
humeralis, 39, 67, 68, 82

Aumeralis humeralts, 83

0
obscurus, Piptstrellus subflavus,
ie;
ochrogaster, Microtus, 40, 126,
1302 475
odd-toed hoofed mammals,
196
Odocoileus
virginianus, 41, 200, 261
virginianus borealis, 204
ohioensis, Castoroides, 207
ohionensis, Tamtias striatus, 141
Ondatra
zibethicus, 40, 126, 129, 179
zibethicus zibethicus, 181
opossum. 2, .5,° 9, 16, -19 928;
OL 256 deg SE Fen Soy
44, 45, 45, 46, 49, 95
Oryctolagus cuniculus, 189, 191
Oryzomys
palustris, 40, 126, 130, 166
palustris palustris, 168
otter, 16, 25, 85, 105
river, 29, 39, 87, 90, 104, 104

230

Ovis, 200
ox, 199
P —
palustris, Oryzomys, 40, 126,
130, 166

panther, 121; see a/so cougar
and mountain lion
parva, Cryptotis, 39, 51, 61
peccary, 208
pennanti, Martes, 87, 90, 96
pennsylvanicus
Microtus, 40, 126, 130, 173
Sciurus carolinensis, 145
PERISSODACTYLA, 43, 44,
196
Peromyscus, 158, 161, 164
gossypinus, 40, 127, 130, 163
gossypinus megacephalus, 164
leucopus, 40, 127, 130, 158,
161
leucopus leucopus, 163
leucopus noveboracensis, 163
maniculatus, 40, 127, 130, 158
maniculatus bairdit, 161
nuttalli, 40, 127, 130, 164
nuttalli aureolus, 165
pig, 25, 27, 44, 197; 198,198,
204
pika, 188
pinetorum, Pitymys, 40, 126,
130, 177
pipistrel, eastern, 7, 39, 66, 68,
75; 76, 218.
Pipistrellus
subflavus, 39, 66, 68, 75
subflavus obscurus, 77
subflavus subflavus, 77
Pitymys
pinetorum, 40, 126, 130, 177
pinetorum auricularis, 179
pinetorum scalopsoides, 179
platform, feeding, 34, 35; see
also species accounts
Platygonus compressus, 208
porcupine, 97
porpoise, 38

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

possum, 45; see also opossum
primigenius, Mammuthus, 208
prints, 26, 27-32; see also foot-
prints, tracks, and species
accounts
Procyon
lotor, 39, 87, 90, 92
lotor hirtus, 95
lotor lotor, 95
PROCYONIDAE, 39
pronghorn, 197
putorius, Spilogale, 87, 91, 108

R
rabbit; 1; 16; 20,;22,925, 26. Sa
33, 35, 40, 43, 44, 85, 10@
103, 110, 113, 114, 116, 118,
122, 133, 188, 192, 193
“cane-cutter,’” 196
cottontail, 3, 4, 6, 9, 13,"@83
32, 42, 124, 179, 189, 190,
192, 1935 196.5209
domestic [hare], 189, 190, 191
eastern cottontail, frontis., 40,
188, 189, 191, 193, 194, 195
jackrabbit [hare], 28, 190, 194
swamp, 5, 7, 32, 40, 189, 190,
191, 193,00 93eaee
white-tailed jackrabbit [hare],
7, 20, 40, 189, 191, 191, 192,
193
raccoon, 2; 3,'3, 95, 16,-39, 208
21, 26, 28; 35,395 25, Ges
87, 90, 92, 93, 167, 178
rafinesquii, Corynorhinus, 39,
66, 68, 83
range, 6, 7, 16, 36; see also
geographical distribution
Rangifer sp., 209
rat, 9; 13, 20, 26, 33,40) 108
123
barn, 16, 184; see also Norway
next below
black, 181; see also roof next
below
eastern wood, 40, 126, 129,
130, 168, 169, 170, 171

INDEX

hispid cotton, 126, 130, 169
house, 184; see a/so Norway
next below
Worway, 1,17, 19, 29, 35, 40,
Gear, 223,124, 126; 129,
130, 166, 167, 168, 169, 170,
181, 182, 183, 184, 186
Old World, 40
fice5, 7,.16,.19,.34, 35,40,
126, 129, 130, 166, 166, 168
mar whe 7,.40./127,-130;.181,
182
sewer, 184; see also Norway
next above
wood, 7, 20,35
Rattus
norvegicus, 40, 126, 130,
184
norvegicus norvegicus, 185
rattus, 40, 127, 130, 181
rattus alexandrinus, 184
rattus rattus, 182
regalis, Vulpes fulva, 114
Retthrodontomys, 130
humilis, 126, 158
megalotis, 40, 126, 156, 158
megalotis dychet, 158
rhinoceros, 197
rixosa, Mustela, 39, 88, 92, 97
rodent, 43, 44, 85, 100, 118, 123,
128, 129, 156, 168, 188
RODENTIA, 40, 43, 44, 85,
123
rufiventer, Sciurus niger, 147
rufus, Lynx, 39, 88, 89, 121
runs, 17; see a/so runways
Fuuways, 6, 13515. 16, 20, 22,
24, 33, 36; see also runs and
Species accounts

a
scalopsoides, Pitymys pinetorum,
179
Scalopus

aquaticus, 39, 50, 51, 51
aquaticus machrinus, 54
scats, 13, 24, 26, 36; see also

231

droppings and species ac-
counts
SCIURIDAE, 40
Sciurus
carolinensis, 40, 125, 128,
143
carolinensis carolinensis, 145
carolinensis pennsylvanicus,
145
niger, 40, 125, 128, 146
niger rufiventer, 147
scrofa, Sus, 198
sea cow, 38
season, 16
septentrionalis, Myotis keenii, 73
sheep, 25,27, 197, 199, 200, 204
shrews d,-33 8, 16; 20; 22 94 26,
SO}. G9 43,6 447 49° SO Fi.
53, 56,60, 62,. 113.9179
Bachman’s, 56; see also
southeastern next below
least, 33,45. 10; 39:50. 51.61,
62
masked’ 2327/5 3946-50251;
54,55,.56, 57; 58; 61, 156

mole, 59

old-field, 61; see also least
next above

pigmiy,./52359,796,-40; 51, 55,
575 15S,61

short-tailed, 2, 10, 31, 39, 50,
51,56; 59; 59. 6h, 639156
southeastern, 7, 39, 48, 50, 51,
5556. 57, 58:61
Sigmodon hispidus, 126, 130,
169
signs, 8, 13, 15, 28-32, 36; see
also species accounts
SIRENIA, 38
skunlen3; 45 16.20; 26; 353,39,
4}, 85, 86, 102; 103, 133.
178
“black,”’ 107
civet cat, 108; see also
spotted next below
spotted, 87, 91, 91, 108
“star, >. 107

232

skunk—continued
striped, 3, 92, 39,07, 91, £06,
106
slide, 20; see also species ac-
counts
sloth, 38, 207
giant ground, 206, 207
sodalis, Myotis, 39, 68, 73
Sorex, 58
cinereus, 39, 51, 54
cinereus lesueurti, 56
longirostris, 39, 51, 56
longirostris longirostris, 57
SORICIDAE, 39, 49, 50, 51
Spilogale putorius, 87, 91, 108
equintel, ol. 5,9, 26, 35, 40,189,
122; 423, 124,141, 150
chipmunk, 2, 3, 6, 8, 16, 20,
35,124,135
eastern chipmunk, 40, 125,
1272 139. 140 49
eastern fox, 18, 40, 125, 128,
146, 146
eastern gray, 40, 125, 128,
143, 144
flying, 2, 3,19; 149, 150
fomgitgs 1S 19S Sie See les,
129, 141, 144, 145, 150
Franklin’s ground, 7, 40, 125,
N27 DROSS ST, dod SO
Grave lost le Moke NaS, ike,
139, 141, 144, 145, 146, 147,
150, 210
gray gopher, 137; see also
Franklin’s ground next
above
ground, 8, 13, 16, 94, 100, 107,
TOSe 10s 24. 137, tou
migratory, 145
fed, / Vo, i2o,.12/, Sel e942,
210
southern flying, 40, 125, 127,
129, 135, 148, 149, 149
striped gopher, 135; see also
thirteen-lined ground next
below
thirteen-lined ground, 3, 4, 7,

ILLINOIS NATURAL HISTORY SURVEY MANUAL 4

19, 40, 125,127, 128, 134,
135, 137; 13m, 847, 209
tree, 3, 19, 124, 150, 185
woodchuck, 3, 4, 13, 14, 16,
20, 22, 26,:30, 40;°47, 9%
104, 105, 107, 108, 110, 112,
114, 124, 125, 127, 128, 131,

132, 135

striatus, Tamias, 40, 125, 127,
139

subflavus, Pipistrellus, 39, 66,
68, 75

subulatus, Myotis, 67, 74
SUIDAE, 197
Sylvilagus, 191
aquaticus, 40, 189, 191, 195
aquaticus aquaticus, 196
floridanus, 40, 189, 191, 193
floridanus alacer, 195
floridanus mearnsii, 195
Symbos cavifrons, 208
Synaptomys
cooperi, 40, 126, 130, 172
cooperi gossii, 173

.
TALPIDAE, 39, 49, 50, 51
Tamias
striatus, 40, 125, 127, 139
striatus griseus, 141
striatus ohtonensis, 141
Tamiasciurus
hudsonicus, 125, 127, 141
hudsonicus loquax, 143
tapir, 197
taurus, Bos, 199, 200
Taxidea
taxus, 39, 87, 91, 109
taxus taxus, 111
taxus, Taxidea, 39, 87, 91, 109
thamnos, Canis latrans, 119
tooth, 35, 36, 200, 205
tooth marks, 13, 30, 32, 35; see
also species accounts
townsendii
Corynorhinus, 83
Lepus, 40, 189, 191, 191

INDEX

tenems. 6, 13, 16, 21, 25, 26,
27-32; see also spectes
accounts

trails, 8; 13, 20, 21, 22; see also
Species accounts

high, 20, 23

tridecemlineatus, Citellus, 40, 125,

127, 135

tunnels, 22

U
ungulates, 198, 199, 200
Urocyon
cinereoargenteus, 39, 88, 90,
114
cinereoargenteus cinereoargen-
teus, 116
Ursus
americanus, 87, 90, 92
americanus americanus, 92

Vv
VESPERTILIONIDAE, 39,
64
virginiana, Didelphis marsuptia-
lis, 49
virginianus, Odocotleus, 41, 200
201
vison, Mustela, 39, 87, 92, 101
volans, Glaucomys, 40, 125, 127
149
Poles; S06. 215.22. 24.32.33,
soe oe AAS 177: 4-78, 1:79;
186
lemming, see lemming, south-
ern bog
meadow, 7, 31, 35, 40, 98, 126,
129, 130, 167, 173, 174, 176,
177, 188; see also mouse,
meadow
pine, 2, 3, 10, 40, 126, 130,
177, 178; see also mouse,
pine

bd

’

233

prairie, 3, 4, 10, 24, 40, 126,
129 430, L/Sy Dio; VTS
Vulpes
fulva, 39, 88, 90, 111
fulva fulva, 114
fulva regalis, 114

WwW
wapiti, 197, 201; see also elk
water-weasel, 101
weasel: 3) U3. 16.°26, 35.39.0835,
$6, 102, 103; 104, 113; 136,
(39: 141. 152-168 175, 185.
195
least, 7,39, 85, 66, 33,92, 97,
97, 100, 101
long-tailed, 20, 39, 88, 92, 98,

98, 99, 101
short-tailed, 88, 92, 101
whale, 38

wolf, 1, 385 39, 119; 120
black, 119

brush, 118

gray, 117, 119; see also timber
next below

prairie, 116, 120; see also
coyote

red, 85, 88, 90, 120
timber, 85, 88, 90, 117, 119,
120
woodchuck, 3, 4, 13, 14, 16, 20,
22, 26,.30, 40, 47,94, 104,
105, 107, 10S 410. It?) aie,
12451295, 327, 126; 131, 132,

135
Z
ZAPODIDAE, 40
Zapus

hudsonius, 40, 126, 129, 187
hudsonius intermedius, 188
zibethicus, Ondatra, 40, 126, 129,

179

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