Massachusetts mammal reference

Common Mammals of Massachusetts

Use the pictures to narrow an identification, then compare body shape, tail, habitat, range and behavior. The 28 detailed profiles focus on mammals Massachusetts residents are most likely to notice, plus a few native species that are important to recognize.
28 mammal profiles
Massachusetts range notes
Look-alikes & tracks
State contacts
Identification
Pictures, range, habitat and behavior
Coverage
Common and notable Massachusetts mammals
Massachusetts mammals range from familiar backyard species to coyotes, bobcats, black bears, deer and moose. Use body shape, tail, habitat and range together for identification.
What this page covers. The detailed profiles focus on mammals people are most likely to see around homes, roads, trails, woods, fields and inland waterways in Massachusetts. A few less-common native species are included because they are often confused with other mammals or have important conservation status. Additional bats, small mammals, marine mammals and historical records are summarized farther down the page.

Identify 28 common and notable Massachusetts mammals

Pictures are a starting point, not the whole identification. Size, tail shape, habitat, range and movement often separate species more reliably than color alone.

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Backyards & neighborhoods

Virginia opossum

Didelphis virginiana

Quick ID: Gray body, white face, naked ears and a long, nearly hairless tail. Adults are about house-cat size.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Often turns up after dark around yards, sheds, compost, roadsides and wooded edges.

If it is near your home: If it is simply passing through, give it room. Secure pet food, trash and accessible crawl spaces rather than trying to catch or move the animal.

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Backyards & neighborhoods

Eastern gray squirrel

Sciurus carolinensis

Quick ID: Gray-brown upperparts, pale belly and a large bushy tail edged with lighter hairs. Black individuals occur in some populations.

Massachusetts: Statewide; also established on Nantucket.

Where you may see it: Very common in towns, suburbs, parks and hardwood woodland.

If it is near your home: Roofline activity, chewing or repeated trips into one opening may point to an attic entry. Do not seal an active opening until you know whether young are present.

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Backyards & neighborhoods

American red squirrel

Tamiasciurus hudsonicus

Quick ID: Smaller than a gray squirrel, with reddish or rusty upperparts, a pale belly and a compact bushy tail.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Most often associated with conifers, mixed woods and wooded neighborhoods.

If it is near your home: Red squirrels can use wall voids, garages and attics. Repeated daytime travel to one gap is more useful than a single sighting when locating an entry point.

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Backyards & neighborhoods

Southern flying squirrel

Glaucomys volans

Quick ID: Small, soft gray-brown squirrel with very large dark eyes and a fold of skin between front and hind legs.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Woodlands and mature neighborhoods; almost entirely nocturnal, so many residents never see one.

If it is near your home: Scratching high in walls or attics at night can be consistent with flying squirrels, but mice and bats can sound similar. Confirm the animal before exclusion work.

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Backyards & neighborhoods

Eastern chipmunk

Tamias striatus

Quick ID: Small ground squirrel with bold dark and pale stripes running along the back and sides.

Massachusetts: Statewide except Nantucket County.

Where you may see it: Stone walls, woodland edges, gardens, brush piles and yards with cover.

If it is near your home: Burrows near foundations are common and do not automatically mean the animal is inside the house. Remove food sources and repair structural gaps rather than disturbing an occupied burrow without a reason.

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Backyards & neighborhoods

Woodchuck (groundhog)

Marmota monax

Quick ID: Heavy-bodied brown rodent with short ears, strong digging claws and a relatively short, dark tail.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Fields, road edges, gardens, embankments and the edges of woods.

If it is near your home: A woodchuck burrow beside a shed may cause little trouble, while one beneath steps or a foundation deserves closer attention. Watch where the animal enters and what the burrow is affecting before deciding whether control is needed.

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Wetlands & waterways

American beaver

Castor canadensis

Quick ID: Large aquatic rodent with a broad flat tail, compact ears and a blunt head.

Massachusetts: Most established in northeastern, central and western Massachusetts; occasional in the southeast.

Where you may see it: Ponds, streams, marshes and impoundments where woody vegetation is available.

If it is near your home: Cut trees and rising water are more reliable clues than a brief swimming sighting. Water-level or dam conflicts can involve state and local rules, so large alterations should not be improvised.

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Wetlands & waterways

Muskrat

Ondatra zibethicus

Quick ID: Medium-sized aquatic rodent with a narrow, vertically flattened tail rather than the broad paddle of a beaver.

Massachusetts: Statewide except Nantucket County.

Where you may see it: Marshes, ponds, slow streams and drainage systems with emergent vegetation.

If it is near your home: Bankside holes or vegetation lodges can reveal activity. If burrowing is affecting a dam, retaining structure or drainage feature, get the site assessed before filling entrances.

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Woodlands & larger wildlife

North American porcupine

Erethizon dorsatum

Quick ID: Stocky, slow-moving mammal with dark fur mixed with pale-tipped quills.

Massachusetts: Northeastern, central and western Massachusetts; unusual farther southeast.

Where you may see it: Forests, rocky areas and wooded edges; individuals also climb trees to feed.

If it is near your home: Give the animal space and keep dogs leashed. Porcupines do not shoot quills, but direct contact can leave a dog with a serious mouth or face injury.

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Rabbits & hares

Eastern cottontail

Sylvilagus floridanus

Quick ID: Brown-gray rabbit with a bright white underside to the tail and relatively large ears.

Massachusetts: Introduced and now widespread statewide.

Where you may see it: Lawns, gardens, fields, thickets and suburban edges.

If it is near your home: A shallow nest in a lawn can look abandoned even when the mother is caring for the young. Keep pets away and avoid moving a nest unless there is an immediate hazard.

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Rabbits & hares

New England cottontail

Sylvilagus transitionalis

Quick ID: Very similar to the eastern cottontail. A small black ear edge or dark forehead mark can occur, but photographs are not enough for a certain field identification.

Massachusetts: Now limited to parts of southeastern Massachusetts, including Nantucket, and southern Berkshire County; it is a native conservation-priority species.

Where you may see it: Dense thickets, young forest and shrublands rather than open lawns.

If it is near your home: Treat a possible New England cottontail conservatively. Exact identification often needs expert review, skull features or genetic evidence, not a quick visual guess.

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Rabbits & hares

Snowshoe hare

Lepus americanus

Quick ID: Long-legged hare with very large hind feet. Many individuals turn white in winter and brown in summer, though coat change can vary.

Massachusetts: Found more or less statewide, including southeastern Massachusetts, Cape Cod and Nantucket; abundance is generally highest where young forest and reliable winter cover remain.

Where you may see it: Young forest, dense thickets, conifer cover, bog edges and brushy wetlands.

If it is near your home: Usually not a home-conflict species. A white hare on bare ground in a mild winter can be normal seasonal coat timing rather than evidence of illness.

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Bats

Big brown bat

Eptesicus fuscus

Quick ID: One of the largest Massachusetts bats, with glossy brown fur, dark face and broad dark wings.

Massachusetts: Statewide.

Where you may see it: Suburban and rural areas; maternity colonies and winter roosts can occur in buildings.

If it is near your home: Never pick up a bat bare-handed. If a bat was in a room with a sleeping person, unattended child, or someone who cannot reliably rule out contact, seek public-health advice before releasing it.

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Bats

Little brown bat

Myotis lucifugus

Quick ID: Small glossy brown bat; much smaller than a big brown bat and difficult to separate from several other Myotis species at a glance.

Massachusetts: Statewide but now much less abundant; endangered in Massachusetts.

Where you may see it: Summer colonies have historically used barns and buildings; winter hibernation occurs in caves and mines.

If it is near your home: White-nose syndrome caused a severe decline. Avoid disturbing colonies, and do not assume a small brown bat in a house can be identified safely from a phone photo.

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Bats

Northern long-eared bat

Myotis septentrionalis

Quick ID: Small brown bat with noticeably long ears that extend well past the nose when laid forward; difficult to confirm from an ordinary distant photo.

Massachusetts: Statewide, but now uncommon; endangered in Massachusetts and federally endangered after severe declines associated with white-nose syndrome.

Where you may see it: Forested habitat in summer, with winter hibernation in caves and mines. It is now much less frequently encountered than before white-nose syndrome.

If it is near your home: Do not handle the bat or disturb a roost. Because this species is protected and hard to identify visually, a suspected record is best documented with a clear photo from a safe distance and referred to wildlife professionals.

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Predators

Eastern coyote

Canis latrans

Quick ID: Long-legged wild canid with pointed ears, a narrow muzzle and a bushy tail usually carried low.

Massachusetts: Established across mainland Massachusetts; absent from Nantucket and not established on Martha’s Vineyard.

Where you may see it: Forest edges, farmland, suburbs and cities, especially where food and cover overlap.

If it is near your home: Remove attractants, feed pets indoors and supervise small pets. A coyote crossing a yard is usually a very different situation from one that repeatedly approaches people or behaves aggressively.

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Predators

Red fox

Vulpes vulpes

Quick ID: Usually rusty red with black lower legs, pointed ears and a long bushy tail commonly tipped in white.

Massachusetts: Widespread on mainland Massachusetts; absent from Nantucket and not established on Martha’s Vineyard.

Where you may see it: Fields, suburban edges, farms, dunes and mixed woodland.

If it is near your home: Daytime activity alone is not proof of rabies. Give foxes space, secure food sources and pay attention to abnormal neurologic behavior, unprovoked aggression or inability to move normally.

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Predators

Gray fox

Urocyon cinereoargenteus

Quick ID: Grizzled gray coat with rusty areas on the neck and sides and a black stripe along the top of the tail.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Wooded and brushy habitat, often with thicker cover than red foxes use.

If it is near your home: Gray foxes can climb trees. If one is using a quiet part of a property without approaching people, space and attractant control are usually more useful than pursuit.

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Predators

Raccoon

Procyon lotor

Quick ID: Black facial mask, gray body and a tail marked with dark rings.

Massachusetts: Statewide except Nantucket County.

Where you may see it: Nearly any habitat with food, water and shelter, including dense urban neighborhoods.

If it is near your home: Chimneys, soffits and attics can become den sites. Do not close an entry until you know whether dependent young are inside. Avoid direct handling because raccoons can carry rabies and other diseases.

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Woodlands & larger wildlife

American black bear

Ursus americanus

Quick ID: Large black-bodied bear with rounded ears, a short tail and a brownish muzzle; some have a small pale chest patch.

Massachusetts: Breeding range is strongest from Worcester County and northern Middlesex west to the Berkshires; dispersers increasingly appear farther east.

Where you may see it: Forested landscapes and increasingly suburban areas where food is available.

If it is near your home: Do not approach for a photograph. Bring in bird feeders when bears are active, secure trash and pet food, and give the animal an open route away from people.

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Predators

Bobcat

Lynx rufus

Quick ID: Medium-sized wild cat with a short “bobbed” tail, spotted or mottled coat, facial ruff and pointed ears.

Massachusetts: Most common in northeastern, central and western Massachusetts; also occurs in the southeast.

Where you may see it: Forests, swamps, rocky areas and quiet suburban edges with cover.

If it is near your home: Massachusetts has no resident wild cougar population; many “mountain lion” reports turn out to be bobcats, coyotes or domestic animals. A clear photo with scale is much more useful than a distant silhouette.

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Predators

Fisher

Pekania pennanti

Quick ID: Long, low, dark-brown mustelid with a bushy tail and rounded ears; larger and heavier than a mink or weasel.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Forests, wooded suburbs and areas with connected tree cover.

If it is near your home: The common name “fisher cat” is misleading: fishers are members of the weasel family. Keep small pets supervised, but do not assume every nighttime scream is a fisher; foxes and other animals can make striking calls.

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Wetlands & waterways

American mink

Neogale vison

Quick ID: Slender, dark brown mustelid with short legs, a pointed face and a long tail; smaller and slimmer than a fisher.

Massachusetts: Widespread statewide except Nantucket; present again on Martha’s Vineyard.

Where you may see it: Streams, ponds, marshes, saltmarsh edges and shorelines.

If it is near your home: Fast movement along a bank can make mink look larger than they are. Check body shape and habitat before assuming a fisher or otter.

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Predators

Long-tailed weasel

Neogale frenata

Quick ID: Very slender body, short legs and a long tail with a black tip. Coat is brown above and pale below in summer; northern animals may become whiter in winter.

Massachusetts: Statewide except Dukes and Nantucket counties.

Where you may see it: Fields, stone walls, brushy edges, farms and woodland margins.

If it is near your home: Weasels may follow mice into sheds or outbuildings. Their presence can point to a rodent food source, so sealing prey access is often part of the solution.

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Wetlands & waterways

North American river otter

Lontra canadensis

Quick ID: Sleek aquatic mammal with a broad head, small ears, thick tapering tail and smooth dark coat.

Massachusetts: Found throughout Massachusetts in lakes, rivers, wetlands and coastal habitats.

Where you may see it: Rivers, ponds, marshes, reservoirs and coastal waters with connected habitat.

If it is near your home: Otters move over land between water bodies and may leave slides on muddy or snowy banks. A brief land crossing is normal behavior.

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Backyards & neighborhoods

Striped skunk

Mephitis mephitis

Quick ID: Black mammal with one or two bold white stripes running from the head toward the tail; pattern varies between individuals.

Massachusetts: Found throughout most of Massachusetts, except Nantucket and the Elizabeth Islands; reintroduced to Martha’s Vineyard.

Where you may see it: Suburbs, farms, forest edges and lawns where insects and grubs are available.

If it is near your home: If a skunk raises its tail, stamps or turns its rear toward you, back away slowly. Close access under decks only after confirming the space is no longer being used.

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Woodlands & larger wildlife

White-tailed deer

Odocoileus virginianus

Quick ID: Long-legged deer with a brown coat and a large tail that flashes white when alarmed. Adult males grow antlers seasonally.

Massachusetts: Statewide.

Where you may see it: Forests, fields, coastal scrub, suburbs and city-edge open space.

If it is near your home: The largest everyday risk is often on the road. Slow down where deer are active at dawn and dusk, and remember that one deer crossing can be followed by another.

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Woodlands & larger wildlife

Moose

Alces americanus

Quick ID: By far the largest deer in the state, with very long legs, a heavy muzzle and, in adult males, broad antlers.

Massachusetts: Found mainly in western and central Massachusetts, with occasional sightings in eastern Massachusetts.

Where you may see it: Forested landscapes, wetlands and young forest, with occasional appearances on roads and in suburban areas.

If it is near your home: Give a moose much more room than you would give a deer. On roads, slow well before the animal; its height means a collision can be especially severe.

Common Massachusetts look-alikes

Most wrong IDs come from a few predictable pairs. Before relying on color alone, compare size, tail shape, habitat and the way the animal moves.

Bobcat vs. cougar

A bobcat has a short tail, compact body and often visible spotting or mottling. A cougar would have a very long heavy tail. Cougars are not a resident Massachusetts population, so a distant “large cat” needs unusually strong evidence before that identification makes sense.

Fisher vs. mink vs. otter

Fishers are larger and dark, with a bushier tail and a strong woodland association. Mink are slimmer and commonly hug shorelines. River otters are heavier-bodied aquatic mammals with a thick tapering tail and are often seen swimming or moving between water bodies.

Eastern vs. New England cottontail

These two rabbits overlap in appearance. Habitat can help: New England cottontails depend strongly on dense thickets and young forest. A photograph may suggest one species, but a confident separation can require expert examination or genetic evidence.

Coyote vs. fox

Coyotes are taller and longer-legged, with a proportionally smaller-looking bushy tail carried low. Red foxes are smaller, often rusty red and commonly show a white tail tip. Gray foxes are grizzled gray with a dark stripe along the top of the tail.

Tracks can narrow the list

Tracks are useful when the animal itself is gone. Substrate can distort a print, so use the pattern as a clue rather than a stand-alone identification.

Two main toe impressions

Think hoofed mammals first. White-tailed deer are widespread; a moose track is much larger and is more plausible in northern, central and western parts of the state.

Four-toed walking prints

Cats and canids commonly leave four main toe marks. Bobcat prints are rounder and usually lack obvious claw marks; fox and coyote tracks are more oval and often show claws.

Small paired bounds

Squirrels and rabbits often register as repeating groups rather than a simple walking line. Hind feet can land ahead of the front feet when the animal bounds.

Five-toed hand-like or mustelid prints

Raccoons can leave remarkably hand-like front prints. Skunks, otters, mink, fishers, opossums and beavers also have five-toed patterns, but size, webbing, gait and habitat separate them.

Other mammals recorded in Massachusetts

Massachusetts also has many smaller mammals and marine species that are less likely to be identified from a casual sighting. The groups below round out the statewide picture.

Other Massachusetts bats

Massachusetts recognizes nine bat species. In addition to the three profiles above, the state list includes the Indiana bat, eastern small-footed bat, tricolored bat, eastern red bat, silver-haired bat and hoary bat. Several are endangered or species of special concern, and visual identification often requires close anatomical or acoustic evidence.

Shrews, moles, mice and voles

The official list also includes masked, smoky, northern short-tailed, least and water shrews; hairy-tailed, star-nosed and eastern moles; jumping mice; meadow and woodland voles; deer mice; the southern red-backed vole; southern bog lemming; and introduced house mice and rats. Many are best confirmed through measurements or expert examination rather than a distant photograph.

Marine mammals

Massachusetts waters support seals, porpoises, dolphins and whales. Harbor and gray seals are familiar coastal mammals, while the state list also records harp, hooded, bearded and rare ringed seals. Offshore records include right, humpback, fin, minke and other whales as well as dolphins and harbor porpoises. Marine-stranding response is a different system from terrestrial wildlife control.

Historical, accidental and extirpated records

The statewide record includes mammals that are no longer resident, were introduced and disappeared, or occur only as unusual visitors. Examples include cougar, Canada lynx, gray wolf, American marten, wolverine, elk, black-tailed jackrabbit and West Indian manatee. A modern Massachusetts sighting should not be identified as one of these species simply because a historic record exists.

Taxonomy note: wildlife agencies do not always update scientific names at the same time. Some Massachusetts materials still use older genera such as Martes, Mustela or Neovison for species that are now commonly placed in Pekania or Neogale. Common names and Massachusetts distribution are given priority here, with current widely used scientific names in the detailed profiles.

If the animal is in or around a house

Identification is only the first step. The safest response depends on whether the animal is outdoors and passing through, trapped inside, denning with young, injured, or involved in possible human or pet exposure.

Start with distance. Keep children and pets back. Do not corner, chase or handle a wild mammal just to obtain a better photograph.
Work out whether it is actually inside. A squirrel on a roof or a skunk beside a deck is not proof that the animal has entered the structure. Look for repeated use of one opening, sounds, droppings or nesting material.
Do not seal first and investigate later. Closing an active entry can trap an adult or separate a mother from young. This is especially important around attics, chimneys, crawl spaces and decks.
Do not relocate wildlife off your property on your own. Massachusetts restricts capture and relocation. If removal is needed, use the correct legal route and a licensed professional when required.
Treat possible rabies exposure separately. A bite, scratch, direct bare-skin contact with a bat, or a bat found in a room where contact cannot be ruled out needs prompt public-health or medical advice rather than routine wildlife exclusion.
Escalate unusual behavior. Severe injury, inability to move normally, unprovoked aggression, an animal trapped in a dangerous location, or a large animal creating an immediate traffic hazard may need professional or emergency response.

Who to call when the sighting is more than an ID question

Most wildlife sightings need no intervention. These contacts are for situations where there is a safety issue, a wildlife-law question, or an active conflict that cannot be solved by simply leaving the animal alone.

Immediate danger

For a human medical emergency, fire, immediate threat to life, or another emergency requiring police, fire or EMS.

Call 911

MassWildlife

State wildlife questions, species guidance and help understanding what kind of wildlife professional may be appropriate. Open Monday–Friday, 8 a.m.–4 p.m.

(508) 389-6300

Environmental Police

For an environmental or wildlife-law violation in progress. Massachusetts Environmental Police maintains statewide emergency dispatch 24 hours a day.

(800) 632-8075

Property damage or a nuisance animal? Massachusetts licenses Problem Animal Control (PAC) agents who may be hired for wildlife conflicts. There is no single statewide PAC service number. If you are unsure whether you need a PAC agent, a municipal Animal Control Officer, a wildlife rehabilitator, or another professional, identify the situation first rather than calling the first removal company you find.

About this Massachusetts mammal reference

Range, status and contact information were checked against current Massachusetts wildlife information. Where a visual identification is uncertain—especially for small bats and cottontails—the text says so.

Range and status

Distribution notes follow current Massachusetts wildlife information. Profiles distinguish statewide species from those with restricted, expanding, migratory or conservation-sensitive ranges.

Identification

Each profile emphasizes traits that can be seen at ordinary viewing distance. For cottontails, small bats and similar mustelids, range, habitat and body proportions often matter more than coat color alone.

What the profiles cover

The 28 detailed profiles concentrate on mammals residents are most likely to notice around homes, roads, trails, woods, fields and inland waters, with several conservation-important species included for comparison.

Current-status notes

Range, conservation status and contact information follow current Massachusetts wildlife guidance. Time-sensitive details should be rechecked when a decision depends on them.