Mammals of Illinois

61 established wild species in Illinois. Plus 10 range-listed species with few or no digitized records.

All species A-Z →

AmericanBadger

American Badger

Taxidea taxus

Occasional in Illinois 45 sightings
Size 63.9 cm2.1 ft Weight 4–12 kg8.8–26.5 lb active by night grassland

Sightings by month

Beaver swimming low in murky green pond water with only its wet head and back above the surface

American Beaver

Castor canadensis

Common in Illinois 1,473 sightings
Size 60–90 cm2–3 ft Weight 11–32 kg24.3–70.5 lb active day & night river

Sightings by month

Image-American bison rests at hot spring in yellowstone national park 1

American Bison

Bison bison

Occasional in Illinois 14 sightings
Size 1.9–2 m6.1–6.6 ft Weight 360–1000 kg793.7–2204.6 lb active day & night grassland

Sightings by month

Mustela Erminea head

American Ermine

Mustela erminea

Occasional in Illinois 26 sightings
Size 17–33 cm6.7–13 in Weight 70–260 g2.5–9.2 oz active by night coniferous forest

Sightings by month

Marten in a tree

American marten

Martes americana

Range-listed · no digitized records yet
Size 32–45 cm12.6–17.7 in Weight 0.5–1.4 kg1.1–3.1 lb active by night lake
Norka amerykańska (neovison vison)

American Mink

Neogale vison

Common in Illinois 485 sightings
Size 33–45.7 cm13–18 in Weight 0.5–1.4 kg1–3 lb active day & night lake

Sightings by month

American pygmy shrew crossing an asphalt path

American pygmy shrew

Sorex hoyi

Marginal occurrence · 6 records
Size 5–7 cm2–2.8 in Weight 2–5 g0.1–0.2 oz active day & night deciduous forest
Tamiasciurus hudsonicus James Gardens

American Red Squirrel

Tamiasciurus hudsonicus

Occasional in Illinois 82 sightings
Size 17–23 cm6.7–9.1 in Weight 140–310 g4.9–10.9 oz active by day wetland

Sightings by month

Big Brown Bats (Eptesicus fuscus)

Big Brown Bat

Eptesicus fuscus

Common in Illinois 205 sightings
Size 7.5 cm3 in Weight 17 g0.6 oz active by night agricultural

Sightings by month

Live black rat climbing through branches

Black Rat

Rattus rattus

Marginal occurrence · 1 record
Size 16–24 cm6.3–9.4 in Weight 75–230 g2.6–8.1 oz active by night agricultural
Bobcat (Lynx rufus)

Bobcat

Lynx rufus

Common in Illinois 130 sightings
Size 30–60 cm11.8–23.6 in Weight 4–18 kg8.8–39.7 lb active by night forest edge

Sightings by month

Common Raccoon in Hugh Taylor Birch State Park

Common Raccoon

Procyon lotor

Common in Illinois 3,892 sightings
Size 40–70 cm1.3–2.3 ft Weight 3.5–9 kg7.7–19.8 lb active by night mixed forest

Sightings by month

Hisbid Cotton Mouse Mission TX 2018-03-12 08-18-23 (27112942988)

Cotton Mouse

Peromyscus gossypinus

Occasional in Illinois 15 sightings
Size 10.3 cm4.1 in Weight 34–51 g1.2–1.8 oz active by night woodland

Sightings by month

Mother Coyote Sitting, Watching Over Den, Photo 1 of 2 (47924154788)

Coyote

Canis latrans

Common in Illinois 2,310 sightings
Size 0.8–1 m2.5–3.3 ft Weight 7–21 kg15.4–46.3 lb active day & night urban

Sightings by month

Coypus

Coypu

Myocastor coypus

Marginal occurrence · 1 record
Size 40–60 cm15.7–23.6 in Weight 4–10 kg8.8–22 lb active by night river
Eastern Chipmunk (Tamias striatus)

Eastern Chipmunk

Tamias striatus

Common in Illinois 4,526 sightings
Size 16.6 cm6.5 in Weight 93 g3.3 oz active by day urban

Sightings by month

Blacklick Woods - Eastern cottontail feeding 1

Eastern Cottontail

Sylvilagus floridanus

Common in Illinois 8,477 sightings
Size 36–43 cm14.2–16.9 in Weight 0.8–1.5 kg1.8–3.3 lb active day & night lake

Sightings by month

Grey squirrel (Sciurus carolinensis) 01

Eastern Gray Squirrel

Sciurus carolinensis

Common in Illinois 13,688 sightings
Size 23–30 cm9.1–11.8 in Weight 400–710 g0.9–1.6 lb active by day wetland

Sightings by month

Eastern Mole (Scalopus aquaticus)

Eastern Mole

Scalopus aquaticus

Common in Illinois 191 sightings
Size 14.8 cm5.8 in Weight 75 g2.6 oz active day & night river

Sightings by month

Eastern red bat roosting among green leaves, disguised as a dead leaf

Eastern Red Bat

Lasiurus borealis

Common in Illinois 272 sightings
Size 9.3–11.7 cm3.7–4.6 in Weight 7–13 g0.2–0.5 oz active by night desert

Sightings by month

Eastern small-footed myotis clinging to a weathered wooden post in daylight, unhandled and alert

Eastern Small-footed Myotis

Myotis leibii

Marginal occurrence · 1 record
Size 7.5–8.5 cm3–3.3 in Weight 5 g0.2 oz active by night cave
Eastern woodrat climbing in a shrub

Eastern Woodrat

Neotoma floridana

Rarely seen in Illinois 5 sightings
Size 21.4 cm8.4 in Weight 208 g7.3 oz active by night coastal

Sightings by month

Fallow deer in field

European Fallow Deer

Dama dama

Marginal occurrence · 3 records
Size 1.3–1.8 m4.3–5.9 ft Weight 30–100 kg66.1–220.5 lb active day & night mixed forest

Sightings by month

European rabbit feeding in dry vegetation

European Rabbit

Oryctolagus cuniculus

Occasional in Illinois 14 sightings
Size 34–50 cm13.4–19.7 in Weight 1–2.5 kg2.2–5.5 lb active by night grassland

Sightings by month

Evening bat resting, brown fur and dark ears and wings visible, not restrained

Evening Bat

Nycticeius humeralis

Rarely seen in Illinois 8 sightings
Size 5 cm2 in Weight 7–15 g0.2–0.5 oz active by night agricultural

Sightings by month

Sciurus niger

Fox Squirrel

Sciurus niger

Common in Illinois 3,435 sightings
Size 25.4–38.1 cm10–15 in Weight 804 g1.8 lb active by day river

Sightings by month

Franklin's Ground Squirrel in Nebraska

Franklin's Ground Squirrel

Poliocitellus franklinii

Rarely seen in Illinois 5 sightings
Size 36–41 cm14.2–16.1 in Weight 370 g13.1 oz active by day grassland

Sightings by month

Golden Mouse (Ochrotomys nuttalli)

Golden Mouse

Ochrotomys nuttalli

Occasional in Illinois 13 sightings
Size 9.7 cm3.8 in Weight 22 g0.8 oz active dawn & dusk woodland

Sightings by month

Myotis grisescens colony

Gray Bat

Myotis grisescens

Occasional in Illinois 47 sightings
Size 7.5–10.1 cm3–4 in Weight 10 g0.4 oz active by night cave

Sightings by month

Gray fox standing in dappled woodland

Gray Fox

Urocyon cinereoargenteus

Rarely seen in Illinois 9 sightings
Size 0.8–1.1 m2.5–3.7 ft Weight 3–9 kg6.6–19.8 lb active day & night brushy woodland

Sightings by month

Groundhog (Marmota monax)

Groundhog

Marmota monax

Common in Illinois 1,402 sightings
Size 50.6 cm19.9 in Weight 3.4 kg7.5 lb active by day woodland

Sightings by month

House mouse in dry plant litter

House Mouse

Mus musculus

Common in Illinois 117 sightings
Size 5–10 cm2–3.9 in Weight 12–30 g0.4–1.1 oz active by night agricultural

Sightings by month

Indiana bats roosting in a dense cluster on a cave ceiling with several individuals in flight below

Indiana bat

Myotis sodalis

Occasional in Illinois 25 sightings
Size 5.5 cm2.2 in Weight 5–10 g0.2–0.4 oz active by night agricultural

Sightings by month

Least Weasel (Mustela nivalis)

Least Weasel

Mustela nivalis

Occasional in Illinois 19 sightings
Size 26 cm10.2 in Weight 50 g1.8 oz active by night grassland

Sightings by month

Long-tailed weasel standing alert in grass with its black-tipped tail curled behind it, Sonoma County, California

Long-tailed Weasel

Neogale frenata

Occasional in Illinois 32 sightings
Size 24.8 cm9.8 in Weight 170 g6 oz active day & night wetland

Sightings by month

Sorex cinereus, Harwich, Chatham, Ontario, Canada 1

Masked Shrew

Sorex cinereus

Size 6.9 cm2.7 in Weight 5 g0.2 oz active day & night grassland

Sightings by month

Tadarida brasiliensis - Bahamas - Long Island (sic) - Cartwright Cave - March 2006 - 2

Mexican Free-tailed Bat

Tadarida brasiliensis

Marginal occurrence · 1 record
Size 3.1–4.1 cm1.2–1.6 in Weight 7–12 g0.2–0.4 oz active by night cave

Sightings by month

Meriones unguiculatus (wild)

Mongolian gerbil

Meriones unguiculatus

Marginal occurrence · 2 records
Size 10–13 cm3.9–5.1 in Weight 50–130 g1.8–4.6 oz grassland

Sightings by month

Muskrats resting on a floating log in open water

Muskrat

Ondatra zibethicus

Common in Illinois 1,948 sightings
Size 25–36 cm9.8–14.2 in Weight 0.6–2 kg1.3–4.4 lb active day & night wetland

Sightings by month

Nine-banded Armadillo

Nine-banded Armadillo

Dasypus mexicanus

Size 60–90 cm2–3 ft Weight 3–8 kg6.6–17.6 lb active by night forest

Sightings by month

Deer Mouse (Peromyscus maniculatus) (9310532204)

North American Deermouse

Peromyscus maniculatus

Occasional in Illinois 65 sightings
Size 8–10 cm3.1–3.9 in Weight 21 g0.7 oz active by night river

Sightings by month

North American least shrew moving through short grass

North American Least Shrew

Cryptotis parvus

Rarely seen in Illinois 10 sightings
Size 5–8 cm2–3.1 in Weight 6 g0.2 oz active by night grassland

Sightings by month

River Otter (Lontra canadensis)

North American River Otter

Lontra canadensis

Occasional in Illinois 112 sightings
Size 0.7–1.1 m2.2–3.5 ft Weight 5–15 kg11–33.1 lb active day & night river

Sightings by month

Live northeastern marsh rice rat peering out from dense dry grass and green shoots

Northeastern Marsh Rice Rat

Oryzomys palustris

Marginal occurrence · 3 records
Size 14.2 cm5.6 in Weight 50 g1.8 oz active day & night wetland
Hoary bat in flight against blue sky, wings spread to show its yellow throat patch and heavily frosted fur

Northern Hoary Bat

Lasiurus cinereus

Occasional in Illinois 47 sightings
Size 13–15 cm5.1–5.9 in Weight 26 g0.9 oz active by night cave

Sightings by month

Northern myotis hanging head-down from a rock ceiling, long ears and tan fur visible

Northern Myotis

Myotis septentrionalis

Rarely seen in Illinois 5 sightings
Size 8.6 cm3.4 in Weight 6 g0.2 oz active by night coniferous forest

Sightings by month

Northern Short-tailed Shrew (Blarina brevicauda)

Northern Short-tailed Shrew

Blarina brevicauda

Size 11.1 cm4.4 in Weight 21 g0.7 oz active day & night riparian

Sightings by month

Northwestern marsh rice rat on a bare soil bank, unrestrained

Northwestern Marsh Rice Rat

Oryzomys texensis

Rarely seen in Illinois 3 sightings
Size 22.6–30.5 cm8.9–12 in Weight 40–80 g1.4–2.8 oz active by night wetland
Live Norway rat beside shallow water

Norway Rat

Rattus norvegicus

Common in Illinois 365 sightings
Size 15–28 cm5.9–11 in Weight 140–500 g0.3–1.1 lb active by night urban

Sightings by month

Plains pocket gopher emerging from a burrow in reddish soil

Plains Pocket Gopher

Geomys bursarius

Occasional in Illinois 105 sightings
Size 25–35 cm9.8–13.8 in Weight 187 g6.6 oz active day & night grassland

Sightings by month

AI-generated image: Prairie Vole alert in a grassy meadow, stocky grizzled brown-gray body and short tail. No public-domain photograph of this species exists. This image was generated with AI from verified reference material and reviewed by our editorial team for accuracy

Prairie Vole

Microtus ochrogaster

Occasional in Illinois 16 sightings
Size 12.4 cm4.9 in Weight 47 g1.7 oz active day & night grassland

Sightings by month

Rafinesques big-eared bat (5494435840)

Rafinesque's Big-eared Bat

Corynorhinus rafinesquii

Marginal occurrence · 7 records
Size 10.5 cm4.1 in Weight 9–11 g0.3–0.4 oz active by night cave
Red Fox (Vulpes vulpes)

Red Fox

Vulpes vulpes

Common in Illinois 929 sightings
Size 43 cm16.9 in Weight 5–10 kg11–22 lb active day & night desert

Sightings by month

Canis rufus running

Red Wolf

Canis rufus

Occasional in Illinois 72 sightings
Size 1.4–1.6 m4.5–5.4 ft Weight 20–39 kg44.1–86 lb active by night river

Sightings by month

Silver-haired bat tucked into loose bark

Silver-haired Bat

Lasionycteris noctivagans

Common in Illinois 233 sightings
Size 9.5–11.5 cm3.7–4.5 in Weight 11 g0.4 oz active by night river

Sightings by month

Southeastern Myotis (Myotis austroriparius)

Southeastern Myotis

Myotis austroriparius

Occasional in Illinois 23 sightings
Size 7.7–8.9 cm3–3.5 in Weight 6–7 g0.2 oz active by night coastal

Sightings by month

AI-generated image: Southern bog lemming alert among wet sedges and sphagnum at a bog edge. No public-domain photograph of this species exists. This image was generated with AI from verified reference material and reviewed by our editorial team for accuracy

Southern Bog Lemming

Synaptomys cooperi

Occasional in Illinois 73 sightings
Size 11.8 cm4.6 in Weight 35 g1.2 oz active day & night mixed conifer

Sightings by month

Southern Flying Squirrel-27527-1

Southern Flying Squirrel

Glaucomys volans

Common in Illinois 160 sightings
Size 17.1 cm6.7 in Weight 65 g2.3 oz active by night deciduous forest

Sightings by month

Southern short-tailed shrew walking through moss and leaf litter beside green plant shoots

Southern Short-tailed Shrew

Blarina carolinensis

Rarely seen in Illinois 7 sightings
Size 10.2 cm4 in Weight 20 g0.7 oz active day & night agricultural

Sightings by month

Mephitis mephitis in Dierenpark Zie-ZOO

Striped Skunk

Mephitis mephitis

Common in Illinois 676 sightings
Size 46.5–81.5 cm1.5–2.7 ft Weight 0.6–6.3 kg1.3–13.9 lb active by night grassland

Sightings by month

Sylvilagus aquaticus - Sumpfkaninchen 193808230

Swamp Rabbit

Sylvilagus aquaticus

Occasional in Illinois 11 sightings
Size 40–55 cm15.7–21.7 in Weight 1.5–2.7 kg3.3–6 lb active day & night wetland

Sightings by month

Thirteen-lined ground squirrel crouched beside short grass

Thirteen-lined ground squirrel

Ictidomys tridecemlineatus

Common in Illinois 498 sightings
Size 17–30 cm6.7–11.8 in Weight 173 g6.1 oz active by day grassland

Sightings by month

Tricolored Bat hibernating on a limestone mine wall

Tricolored Bat

Perimyotis subflavus

Occasional in Illinois 44 sightings
Size 7.7–8.9 cm3–3.5 in Weight 5–8 g0.2–0.3 oz active by night cave

Sightings by month

Virginia Opossum clinging to a tree branch in a snowy winter woodland

Virginia Opossum

Didelphis virginiana

Common in Illinois 2,181 sightings
Size 40.8 cm16.1 in Weight 1.1–1.6 kg2.5–3.6 lb active by night river

Sightings by month

Western harvest mouse moving through dry stems and gravel

Western Harvest Mouse

Reithrodontomys megalotis

Occasional in Illinois 27 sightings
Size 11.8–17 cm4.6–6.7 in Weight 11 g0.4 oz active by night wetland

Sightings by month

Little brown myotis roosting alertly on a wooden beam

Western Little Brown Myotis

Myotis lucifugus

Rarely seen in Illinois 7 sightings
Size 8–9.5 cm3.1–3.7 in Weight 6–13 g0.2–0.5 oz active by night cave

Sightings by month

Western meadow vole Talkeetna alaska

Western Meadow Vole

Microtus drummondii

Common in Illinois 132 sightings
Size 13–20 cm5.1–7.9 in Weight 39 g1.4 oz active day & night river

Sightings by month

White-footed mouse on a fallen log in leaf litter

White-footed Mouse

Peromyscus leucopus

Size 10.1 cm4 in Weight 20–30 g0.7–1.1 oz active by night urban

Sightings by month

White-tailed Deer (Odocoileus virginianus)

White-tailed Deer

Odocoileus virginianus

Common in Illinois 9,776 sightings
Size 0.9–2.2 m3.1–7.2 ft Weight 68–136 kg149.9–299.8 lb active day & night mixed forest

Sightings by month

Adult wild boar foraging in grass

Wild Boar

Sus scrofa

Rarely seen in Illinois 8 sightings
Size 85–90 cm2.8–3 ft Weight 40–50 kg88.2–110.2 lb active day & night lake

Sightings by month

Microtus pinetorum - crlevy - 550023152

Woodland Vole

Microtus pinetorum

Occasional in Illinois 16 sightings
Size 10.3 cm4.1 in Weight 26 g0.9 oz active day & night woodland

Sightings by month