Mammals of Massachusetts

68 established wild species in Massachusetts. Plus 13 range-listed species with few or no digitized records.

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

American Beaver

Castor canadensis

Common in Massachusetts 2,948 sightings
Size 60–90 cm2–3 ft Weight 11–32 kg24.3–70.5 lb active day & night river

Sightings by month

Oso negro (Ursus americanus), Parque natural provincial Tatshenshini-Alsek, Yukón, Canadá, 2017-08-25, DD 85

American Black Bear

Ursus americanus

Common in Massachusetts 856 sightings
Size 1.2–2 m3.9–6.6 ft Weight 40–250 kg88.2–551.2 lb active by night conifer forest

Sightings by month

Mustela Erminea head

American Ermine

Mustela erminea

Occasional in Massachusetts 153 sightings
Size 17–33 cm6.7–13 in Weight 70–260 g2.5–9.2 oz active by night coniferous forest

Sightings by month

Norka amerykańska (neovison vison)

American Mink

Neogale vison

Common in Massachusetts 332 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

Range-listed · no digitized records yet
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

Common in Massachusetts 2,433 sightings
Size 17–23 cm6.7–9.1 in Weight 140–310 g4.9–10.9 oz active by day wetland

Sightings by month

American water shrew swimming at the surface of a stream, seen from above

American water shrew

Sorex palustris

Marginal occurrence · 7 records
Size 8 cm3.1 in Weight 8–18 g0.3–0.6 oz active day & night river
Atlantic white-sided dolphin leaping clear of the water at Stellwagen Bank, showing the yellow blaze on its tail stock

Atlantic White-sided Dolphin

Leucopleurus acutus

Occasional in Massachusetts 84 sightings
Size 2.1–2.8 m6.9–9.2 ft Weight 180–230 g6.3–8.1 oz active day & night continental shelf

Sightings by month

Big Brown Bats (Eptesicus fuscus)

Big Brown Bat

Eptesicus fuscus

Occasional in Massachusetts 254 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

Occasional in Massachusetts 50 sightings
Size 16–24 cm6.3–9.4 in Weight 75–230 g2.6–8.1 oz active by night agricultural

Sightings by month

Black-tailed jackrabbit (6785302534)

Black-tailed Jackrabbit

Lepus californicus

Marginal occurrence · 2 records
Size 47–63 cm1.5–2.1 ft Weight 1.3–3.6 kg2.9–7.9 lb active by night open desert
Live blue whale surfacing with a tall bushy blow spray rising from its blowhole in sunlit open ocean

Blue Whale

Balaenoptera musculus

Marginal occurrence · 1 record
Size 21–30.5 m68.9–100.1 ft Weight 70000–200000 kg154323.7–440924.9 lb active by day estuary
Bobcat (Lynx rufus)

Bobcat

Lynx rufus

Common in Massachusetts 645 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 Bottlenose Dolphin (Tursiops truncatus)

Common Bottlenose Dolphin

Tursiops truncatus

Rarely seen in Massachusetts 12 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

Common in Massachusetts 293 sightings
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 Massachusetts 3,447 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 Massachusetts 2,935 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

Ziphius cavirostris Mar Ligure

Cuvier's beaked whale

Ziphius cavirostris

Size 5–7 m16.4–23 ft Weight 2000–3500 kg4409.2–7716.2 lb active day & night coastal
Eastern Chipmunk (Tamias striatus)

Eastern Chipmunk

Tamias striatus

Common in Massachusetts 6,695 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 Massachusetts 15,082 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 Massachusetts 19,269 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 Massachusetts 13 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 Massachusetts 44 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
Fallow deer in field

European Fallow Deer

Dama dama

Marginal occurrence · 7 records
Size 1.3–1.8 m4.3–5.9 ft Weight 30–100 kg66.1–220.5 lb active day & night mixed forest
European rabbit feeding in dry vegetation

European Rabbit

Oryctolagus cuniculus

Rarely seen in Massachusetts 8 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

Fin whale from air

Fin Whale

Balaenoptera physalus

Occasional in Massachusetts 154 sightings
Size 17–22 m55.8–72.2 ft Weight 40000–80000 kg88185–176370 lb active by day coastal

Sightings by month

Martes Pennanti

Fisher

Pekania pennanti

Common in Massachusetts 625 sightings
Size 75–95 cm2.5–3.1 ft Weight 3.5–6 kg7.7–13.2 lb active dawn & dusk wetland

Sightings by month

Gray fox standing in dappled woodland

Gray Fox

Urocyon cinereoargenteus

Common in Massachusetts 496 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

Silver-gray wolf walking along a gravel bank in Alaska

Gray Wolf

Canis lupus

Occasional in Massachusetts 46 sightings
Size 1.1–1.6 m3.4–5.2 ft Weight 23–80 kg50.7–176.4 lb active day & night cave

Sightings by month

Groundhog (Marmota monax)

Groundhog

Marmota monax

Common in Massachusetts 1,908 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 Massachusetts 857 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 Massachusetts 47 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

Occasional in Massachusetts 57 sightings
Size 1.8 m5.8 ft Weight 141.1 kg311.1 lb active by day coastal

Sightings by month

House mouse in dry plant litter

House Mouse

Mus musculus

Occasional in Massachusetts 166 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

Common in Massachusetts 699 sightings
Size 12–17 m39.4–55.8 ft Weight 25000–40000 kg55115.6–88185 lb active by day marine

Sightings by month

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

Indiana bat

Myotis sodalis

Range-listed · no digitized records yet
Size 5.5 cm2.2 in Weight 5–10 g0.2–0.4 oz active by night agricultural
Long-finned pilot whale spyhopping at the surface, showing its bulbous forehead

Long-finned Pilot Whale

Globicephala melas

Occasional in Massachusetts 21 sightings
Size 7.1 m23.3 ft Weight 1060 kg2336.9 lb active by night urban

Sightings by month

AI-generated image: Long-tailed Shrew in side profile on moss-covered wet rocks. 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

Long-tailed Shrew

Sorex dispar

Marginal occurrence · 3 records
Size 6.6 cm2.6 in Weight 3–8 g0.1–0.3 oz active day & night river
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 Massachusetts 183 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

Occasional in Massachusetts 124 sightings
Size 6.9 cm2.7 in Weight 5 g0.2 oz active day & night grassland

Sightings by month

Common minke whale (Balaenoptera acutorostrata). Teriberka

Minke Whale

Balaenoptera acutorostrata

Occasional in Massachusetts 86 sightings
Size 7–10 m23–32.8 ft Weight 5000–10000 kg11023.1–22046.2 lb active by day wetland

Sightings by month

Cow moose standing in a marshy Alaska wetland

Moose

Alces alces

Common in Massachusetts 342 sightings
Size 2.4–3.1 m7.9–10.2 ft Weight 200–490 kg440.9–1080.3 lb active day & night wetland

Sightings by month

Muskrats resting on a floating log in open water

Muskrat

Ondatra zibethicus

Common in Massachusetts 1,614 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

New England cottontail

New England Cottontail

Sylvilagus transitionalis

Occasional in Massachusetts 14 sightings
Size 38–43 cm15–16.9 in Weight 1–1.5 kg2.2–3.3 lb active dawn & dusk shrubland

Sightings by month

Deer Mouse (Peromyscus maniculatus) (9310532204)

North American Deermouse

Peromyscus maniculatus

Common in Massachusetts 1,030 sightings
Size 8–10 cm3.1–3.9 in Weight 21 g0.7 oz active by night river

Sightings by month

Erethizontidae Erethizon dorsatum 3.2

North American Porcupine

Erethizon dorsatus

Common in Massachusetts 953 sightings
Size 60–90 cm2–3 ft Weight 3.5–12 kg7.7–26.5 lb active by night mixed forest

Sightings by month

River Otter (Lontra canadensis)

North American River Otter

Lontra canadensis

Common in Massachusetts 646 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 North Atlantic right whale head at the surface, rough pale callosity patches visible on the rostrum

North Atlantic right whale

Eubalaena glacialis

Occasional in Massachusetts 191 sightings
Size 17.6 m57.8 ft Weight 23000 kg50706.4 lb active day & night coastal

Sightings by month

Hyperoodon ampullatus fin

Northern Bottlenose Whale

Hyperoodon ampullatus

Size 7–9.8 m23–32.2 ft Weight 5–7.5 kg11–16.5 lb active day & night deep ocean
Northern Flying Squirrel (Glaucomys sabrinus)

Northern Flying Squirrel

Glaucomys sabrinus

Occasional in Massachusetts 48 sightings
Size 25–37 cm9.8–14.6 in Weight 148 g5.2 oz active by night mixed conifer

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

Marginal occurrence · 7 records
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

Rarely seen in Massachusetts 11 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

Common in Massachusetts 791 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

Common in Massachusetts 644 sightings
Size 15–28 cm5.9–11 in Weight 140–500 g0.3–1.1 lb active by night urban

Sightings by month

Killer Whales Hunting a Seal

Orca

Orcinus orca

Rarely seen in Massachusetts 12 sightings
Size 5–9.8 m16.4–32.2 ft Weight 2600–10000 kg5732–22046.2 lb active day & night coastal

Sightings by month

Live pygmy sperm whales logging at the sea surface, backs and dorsal fins exposed

Pygmy Sperm Whale

Kogia breviceps

Rarely seen in Massachusetts 12 sightings
Size 2.7–4 m8.9–13.1 ft Weight 320–450 kg705.5–992.1 lb active day & night urban

Sightings by month

Red Fox (Vulpes vulpes)

Red Fox

Vulpes vulpes

Common in Massachusetts 2,013 sightings
Size 43 cm16.9 in Weight 5–10 kg11–22 lb active day & night desert

Sightings by month

Risso s Dolphin (Grampus griseus) Catalina (3)

Risso's Dolphin

Grampus griseus

Occasional in Massachusetts 16 sightings
Size 2.6–4 m8.5–13.1 ft Weight 342.5–460 kg755.1–1014.1 lb active by night coastal

Sightings by month

Sei whale surfacing in deep blue ocean water, small curved dorsal fin visible with a splash at the blowhole

Sei Whale

Balaenoptera borealis

Occasional in Massachusetts 20 sightings
Size 12–20 m39.4–65.6 ft Weight 14000–30000 kg30864.7–66138.7 lb active by day urban

Sightings by month

Short-finned Pilot Whale off Tenerife

Short-finned Pilot Whale

Globicephala macrorhynchus

Marginal occurrence · 4 records
Size 6.1 m20 ft Weight 726 kg1600.6 lb active by night coastal
Silver-haired bat tucked into loose bark

Silver-haired Bat

Lasionycteris noctivagans

Occasional in Massachusetts 19 sightings
Size 9.5–11.5 cm3.7–4.5 in Weight 11 g0.4 oz active by night river

Sightings by month

Smoky shrew moving through dense green grass

Smoky Shrew

Sorex fumeus

Rarely seen in Massachusetts 9 sightings
Size 7.4 cm2.9 in Weight 8 g0.3 oz active day & night river

Sightings by month

Lepus americanus 5459 cropped

Snowshoe Hare

Lepus americanus

Occasional in Massachusetts 19 sightings
Size 41–52 cm16.1–20.5 in Weight 1.4–1.6 kg3.2–3.4 lb active by night coniferous forest

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

Marginal occurrence · 7 records
Size 11.8 cm4.6 in Weight 35 g1.2 oz active day & night mixed conifer
Southern Flying Squirrel-27527-1

Southern Flying Squirrel

Glaucomys volans

Occasional in Massachusetts 177 sightings
Size 17.1 cm6.7 in Weight 65 g2.3 oz active by night deciduous forest

Sightings by month

Southern red-backed vole feeding among sunflower seeds on snow

Southern Red-backed Vole

Clethrionomys gapperi

Common in Massachusetts 542 sightings
Size 12–16.5 cm4.7–6.5 in Weight 6–42 g0.2–1.5 oz active by night mixed forest

Sightings by month

Sperm whale pod recolored

Sperm Whale

Physeter macrocephalus

Rarely seen in Massachusetts 6 sightings
Size 10.7–11 m35–36 ft Weight 13500–57000 kg29762.4–125663.6 lb active day & night urban

Sightings by month

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

Star-nosed mole

Condylura cristata

Occasional in Massachusetts 81 sightings
Size 12.1 cm4.8 in Weight 52 g1.8 oz active day & night urban

Sightings by month

Small group of striped dolphins swimming at the surface in open blue ocean

Striped Dolphin

Stenella coeruleoalba

Occasional in Massachusetts 30 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 Massachusetts 1,002 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

Marginal occurrence · 2 records
Size 2.3–2.9 m7.6–9.4 ft coastal
Tricolored Bat hibernating on a limestone mine wall

Tricolored Bat

Perimyotis subflavus

Rarely seen in Massachusetts 8 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 Massachusetts 1,048 sightings
Size 40.8 cm16.1 in Weight 1.1–1.6 kg2.5–3.6 lb active by night river

Sightings by month

Manatee with calf.PD - colour corrected

West Indian Manatee

Trichechus manatus

Marginal occurrence · 1 record
Size 4 m13.1 ft Weight 387.5 kg854.3 lb active day & night coastal
Little brown myotis roosting alertly on a wooden beam

Western Little Brown Myotis

Myotis lucifugus

Occasional in Massachusetts 82 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

White-beaked dolphin porpoising beside a boat, showing its pale flank and short beak

White-beaked dolphin

Lagenorhynchus albirostris

Occasional in Massachusetts 27 sightings
Size 2.3–3.2 m7.5–10.5 ft Weight 180–350 kg396.8–771.6 lb active day & night river

Sightings by month

White-footed mouse on a fallen log in leaf litter

White-footed Mouse

Peromyscus leucopus

Common in Massachusetts 5,209 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 Massachusetts 8,808 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 Massachusetts 5 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 Massachusetts 27 sightings
Size 10.3 cm4.1 in Weight 26 g0.9 oz active day & night woodland

Sightings by month