Mammals of Delaware

32 established wild species in Delaware. Plus 19 range-listed species with few or no digitized records.

All species A-Z →

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

American Beaver

Castor canadensis

Common in Delaware 202 sightings
Size 60–90 cm2–3 ft Weight 11–32 kg24.3–70.5 lb active day & night river

Sightings by month

Norka amerykańska (neovison vison)

American Mink

Neogale vison

Occasional in Delaware 21 sightings
Size 33–45.7 cm13–18 in Weight 0.5–1.4 kg1–3 lb active day & night lake

Sightings by month

Tamiasciurus hudsonicus James Gardens

American Red Squirrel

Tamiasciurus hudsonicus

Common in Delaware 36 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

Occasional in Delaware 14 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

Range-listed · no digitized records yet
Size 16–24 cm6.3–9.4 in Weight 75–230 g2.6–8.1 oz active by night agricultural
Common Bottlenose Dolphin (Tursiops truncatus)

Common Bottlenose Dolphin

Tursiops truncatus

Common in Delaware 66 sightings
Size 2–4 m6.6–13.1 ft Weight 150–650 kg330.7–1433 lb active by day coastal

Sightings by month

Small group of common dolphins surfacing in choppy water, pale hourglass flank patch visible

Common Dolphin

Delphinus delphis

Marginal occurrence · 2 records
Size 1.6–2.6 m5.2–8.5 ft Weight 70–110 kg154.3–242.5 lb active by night coastal

Sightings by month

Common Raccoon in Hugh Taylor Birch State Park

Common Raccoon

Procyon lotor

Common in Delaware 427 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

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

Coyote

Canis latrans

Common in Delaware 54 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

Range-listed · no digitized records yet
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 Delaware 195 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 Delaware 954 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 Delaware 999 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

Occasional in Delaware 16 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

Occasional in Delaware 30 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

Range-listed · no digitized records yet
Size 7.5–8.5 cm3–3.3 in Weight 5 g0.2 oz active by night cave
Evening bat resting, brown fur and dark ears and wings visible, not restrained

Evening Bat

Nycticeius humeralis

Range-listed · no digitized records yet
Size 5 cm2 in Weight 7–15 g0.2–0.5 oz active by night agricultural
Fin whale from air

Fin Whale

Balaenoptera physalus

Marginal occurrence · 3 records
Size 17–22 m55.8–72.2 ft Weight 40000–80000 kg88185–176370 lb active by day coastal
Sciurus niger

Fox Squirrel

Sciurus niger

Marginal occurrence · 2 records
Size 25.4–38.1 cm10–15 in Weight 804 g1.8 lb active by day river

Sightings by month

Gray fox standing in dappled woodland

Gray Fox

Urocyon cinereoargenteus

Occasional in Delaware 11 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 Delaware 239 sightings
Size 50.6 cm19.9 in Weight 3.4 kg7.5 lb active by day woodland

Sightings by month

Common seal (Phoca vitulina) 2

Harbor Seal

Phoca vitulina

Common in Delaware 119 sightings
Size 1.4–1.9 m4.6–6.2 ft Weight 55–170 kg121.3–374.8 lb active by day coastal

Sightings by month

Phocoena phocoena.2

Harbour Porpoise

Phocoena phocoena

Occasional in Delaware 12 sightings
Size 1.4–1.9 m4.6–6.2 ft Weight 45–70 kg99.2–154.3 lb active by night coastal

Sightings by month

Harp Seal (Pagophilus groenlandicus), Greenland Sea IMG 5032

Harp Seal

Pagophilus groenlandicus

Marginal occurrence · 2 records
Size 1.8 m5.8 ft Weight 141.1 kg311.1 lb active by day coastal
House mouse in dry plant litter

House Mouse

Mus musculus

Occasional in Delaware 19 sightings
Size 5–10 cm2–3.9 in Weight 12–30 g0.4–1.1 oz active by night agricultural

Sightings by month

Humpback whale (Megaptera novaeangliae) with calf Moorea 2

Humpback Whale

Megaptera novaeangliae

Occasional in Delaware 12 sightings
Size 12–17 m39.4–55.8 ft Weight 25000–40000 kg55115.6–88185 lb active by day marine

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

Marginal occurrence · 1 record
Size 24.8 cm9.8 in Weight 170 g6 oz active day & night wetland
Sorex cinereus, Harwich, Chatham, Ontario, Canada 1

Masked Shrew

Sorex cinereus

Marginal occurrence · 9 records
Size 6.9 cm2.7 in Weight 5 g0.2 oz active day & night grassland

Sightings by month

Muskrats resting on a floating log in open water

Muskrat

Ondatra zibethicus

Common in Delaware 241 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

North American least shrew moving through short grass

North American Least Shrew

Cryptotis parvus

Occasional in Delaware 26 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

Common in Delaware 52 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

Common in Delaware 32 sightings
Size 14.2 cm5.6 in Weight 50 g1.8 oz active day & night wetland

Sightings by month

Hoary bat in flight against blue sky, wings spread to show its yellow throat patch and heavily frosted fur

Northern Hoary Bat

Lasiurus cinereus

Range-listed · no digitized records yet
Size 13–15 cm5.1–5.9 in Weight 26 g0.9 oz active by night cave
Northern myotis hanging head-down from a rock ceiling, long ears and tan fur visible

Northern Myotis

Myotis septentrionalis

Range-listed · no digitized records yet
Size 8.6 cm3.4 in Weight 6 g0.2 oz active by night coniferous forest
Northern Short-tailed Shrew (Blarina brevicauda)

Northern Short-tailed Shrew

Blarina brevicauda

Common in Delaware 148 sightings
Size 11.1 cm4.4 in Weight 21 g0.7 oz active day & night riparian

Sightings by month

Live Norway rat beside shallow water

Norway Rat

Rattus norvegicus

Occasional in Delaware 25 sightings
Size 15–28 cm5.9–11 in Weight 140–500 g0.3–1.1 lb active by night urban

Sightings by month

Red Fox (Vulpes vulpes)

Red Fox

Vulpes vulpes

Common in Delaware 1,377 sightings
Size 43 cm16.9 in Weight 5–10 kg11–22 lb active day & night desert

Sightings by month

Short-finned Pilot Whale off Tenerife

Short-finned Pilot Whale

Globicephala macrorhynchus

Marginal occurrence · 8 records
Size 6.1 m20 ft Weight 726 kg1600.6 lb active by night coastal
Sika Deer (Cervus nippon)

Sika Deer

Cervus nippon

Marginal occurrence · 1 record
Size 1.1–1.7 m3.6–5.6 ft Weight 30–90 kg66.1–198.4 lb active by night urban
Silver-haired bat tucked into loose bark

Silver-haired Bat

Lasionycteris noctivagans

Marginal occurrence · 6 records
Size 9.5–11.5 cm3.7–4.5 in Weight 11 g0.4 oz active by night river
Southern Flying Squirrel-27527-1

Southern Flying Squirrel

Glaucomys volans

Occasional in Delaware 23 sightings
Size 17.1 cm6.7 in Weight 65 g2.3 oz active by night deciduous forest

Sightings by month

Star-nosed mole's fleshy 22-ray nose organ fanned out, close-up macro

Star-nosed mole

Condylura cristata

Marginal occurrence · 3 records
Size 12.1 cm4.8 in Weight 52 g1.8 oz active day & night urban
Small group of striped dolphins swimming at the surface in open blue ocean

Striped Dolphin

Stenella coeruleoalba

Occasional in Delaware 18 sightings
Size 1.8–2.6 m5.9–8.5 ft Weight 100–160 kg220.5–352.7 lb active day & night urban

Sightings by month

Mephitis mephitis in Dierenpark Zie-ZOO

Striped Skunk

Mephitis mephitis

Common in Delaware 58 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

Two Tamanend's bottlenose dolphins surfacing together, an adult with a smaller paler calf alongside

Tamanend's Bottlenose Dolphin

Tursiops erebennus

Common in Delaware 216 sightings
Size 2.3–2.9 m7.6–9.4 ft coastal

Sightings by month

Tricolored Bat hibernating on a limestone mine wall

Tricolored Bat

Perimyotis subflavus

Range-listed · no digitized records yet
Size 7.7–8.9 cm3–3.5 in Weight 5–8 g0.2–0.3 oz active by night cave
Virginia Opossum clinging to a tree branch in a snowy winter woodland

Virginia Opossum

Didelphis virginiana

Common in Delaware 119 sightings
Size 40.8 cm16.1 in Weight 1.1–1.6 kg2.5–3.6 lb active by night river

Sightings by month

Little brown myotis roosting alertly on a wooden beam

Western Little Brown Myotis

Myotis lucifugus

Marginal occurrence · 1 record
Size 8–9.5 cm3.1–3.7 in Weight 6–13 g0.2–0.5 oz active by night cave
White-footed mouse on a fallen log in leaf litter

White-footed Mouse

Peromyscus leucopus

Common in Delaware 55 sightings
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 Delaware 1,470 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

Microtus pinetorum - crlevy - 550023152

Woodland Vole

Microtus pinetorum

Marginal occurrence · 11 records
Size 10.3 cm4.1 in Weight 26 g0.9 oz active day & night woodland