This list of mammals of Connecticut includes both native and nonnative species (introduced or invasive) found in the U.S. state of Connecticut now or in the past, but not domesticated or farm animals.
Many mammals formerly extirpated in the state have returned, sometimes with active human projects and sometimes through a natural expansion from neighboring states as Connecticut's natural environment has become more welcoming to them.
Many mammal species were removed from Connecticut or almost became extinct within the state through hunting and clearing forests to create farmland, starting in the 17th century with European colonization and continuing until the 19th century, when most of the state's forest covering had been replaced with farmland. Populations of moose, turkeys, black bears and mountain lions lost their habitats and were greatly reduced or eliminated in Connecticut. Pollution in the 19th and 20th centuries also played a role in either greatly reducing or extirpating some species, such as the bald eagle.
With the collapse of farming in the 19th century and its continued decline in the state in the 20th century, forests spread back over much of the land. They are not the same forests, however: Chestnut trees, for instance, wiped out by a disease, are not nearly as prevalent as they once were, and the lack of their nuts affects the populations of various mammals. Stone walls, built largely in the 19th century, provide more welcoming homes to certain species; and mammals from Europe, including the house mouse and Norway rat, and from elsewhere (such as the coyote) can create a different competitive environment for some species and a different food source for some (the American barn owl, for instance, can now feed on Norway rats).
To some extent, deforestation and fragmentation of forests has occurred in recent decades with expanded residential development. Some improvements have come with the removal of certain industries from Connecticut since the mid-20th century and the installation of more sewage treatment plants and improvements in their functioning. Residual industrial pollution remains, however, and prevailing winds keep Connecticut on the receiving end of pollution from the New York City metropolitan area and other areas south and west of the state, Connecticut also continues to produce some of its own pollution.Hammerson, Geoffrey, Connecticut Wildlife: Biodiversity, Natural History, and Conservation, University Press of New England: Hanover, New Hampshire, and London, 2004, , Chapter 1: "The Landacape", pp 1–10
Dead animals killed by cars on the state's roads are one of the primary ways state residents see diverse varieties of local mammals. The more common roadkill in Connecticut consists of striped skunks, opossums, raccoons, and gray squirrels.Hammerson, Geoffrey, Connecticut Wildlife: Biodiversity, Natural History, and Conservation, University Press of New England: Hanover, New Hampshire, and London, 2004, , Chapter 21: "Mammals", pp 379–404
Species
(This list of species concentrates on the habitats in the state in which they can be found, how prevalent they are or have been in the state, history of their prevalence in Connecticut and any other information directly related to the mammals' existence in the state — including laws and regulations, state-sponsored re-introductions, and notable sitings. Descriptions of the species or other, more general information not related to Connecticut can be found by following the links to Wikipedia articles on the individual species.)
Opossums (Order Didelphimorphia, Family Didelphidae) Virginia opossum (Didelphis virginiana) — common in wooded areas, farmland, drier areas of wetlands, rural areas and in some other habitats in the state; came to Connecticut from the south in the early 20th century, a movement likely helped by its attraction to human-created food sources such as crops and trash, although it eats just about anything, including carrion. Many are run over on Connecticut roads.
Shrews and moles
Shrews (Order Eulipotyphla, Family Soricidae) Northern short-tailed shrew (Blarina brevicauda) — very common in leafy or grassy ground (usually in wooded areas) Smoky shrew (Sorex fumeus) — common, especially in moist, shady spots Masked shrew (Sorex cinereus) — plentiful in the state,Desmarais, Paul, "Photo Journal: Wilds of Suburbia" photograph (of a masked shrew in Bethel, Connecticut) with long caption, The Advocate of Stamford, Connecticut, October 30, 2007, page A11, Norwalk edition especially in moist, shady spots. Water shrew (Sorex palustris) — uncommon; found near water Least shrew (Cryptotis parva) — rare in Connecticut, where the species reaches its eastern limit and close to its northern limit (it is also in central New York state); in this state, only found in coastal areas with high beach dunes and neighboring brackish marshes;ct.gov Web page titled "Least Shrew", at the Connecticut Department of Environmental Protection Web site, retrieved December 30, 2007 all other shrews in the state have much longer tails (at least as long as the rest of their bodies). As of late 2007, the species was the only mammal listed on the Connecticut endangered species list,ct.gov Web page titled "Endangered and Threatened Species Fact Sheets", at the Connecticut Department of Environmental Protection Web site, retrieved December 30, 2007 and it was the first mammal ever put on the list. The greatest threat facing least shrews in the state is land development along the coast, which limits the land available for the species and isolates breeding populations. Other threats are pesticides and pollutants contaminating food and habitat. The animal was first identified in Darien, Connecticut, in 1840 by Reverend James H. Linsley, but not seen again for 100 years. In 1941, George Goodwin, assistant curator of mammals at the American Museum of Natural History, in New York City, found one in Westbrook at the edge of a saltgrass meadow. The animal again went without documented sightings until it was found in 1989 in coastal Middlesex County in 1989. As of 2007, this is the only documented Connecticut location of the species.
Moles (Order Eulipotyphla, Family Talpidae) Eastern mole (Scalopus aquaticus) — common in the state; usually found in fields, lawns and wooded areas that aren't too wet; much less prevalent in higher elevations in the northern parts of the state Star-nosed mole (Condylura cristata) — common in wet or moist soils near water, less common in upland areas that are moist; apparently active at ground level during the night (when wildlife expert Geoffrey A. Hammerson found 583 samples of food items in a sample of barn owl pellets in central Connecticut, 24 of them were star-nosed moles; none were eastern moles) Hairy-tailed mole (Parascalops breweri) — somewhat common in well-drained areas in northwestern part of the state
Bats Bats (Order Chiroptera, Family Vespertilionidae)
The state has eight extant species of bats, plus at least one which may now be extirpated from the state.
Because some bats have rabies, the state Department of Environmental Protection (now DEEP) advises on its Web site: "If a bat has bitten or scratched a person or a pet, or is found in a situation where exposure cannot be ruled out, contact the DEP Wildlife Division at (860) 424-3011 or DEP Emergency Dispatch at (860) 424-3333 for advice. An example of a situation where exposure cannot be ruled out is when a bat is found in the same room as a sleeping individual or a very young child."ct.gov Web page titled "Dealing with Distressed Bats" at the Connecticut Department of Environmental Protection Web site, retrieved December 30, 2007
Bats that occupy buildings: Little brown bat (Myotis lucifugus) — common and widespread in the state; this and the big brown bat are the two most common bat species in the statect.gov Web page titled "Bats" at the Connecticut Department of Environmental Protection Web site, retrieved December 30, 2007 Big brown bat (Eptesicus fuscus) — winters in the state, often hibernating in buildings, occasionally caves; a bat seen in winter is probably this species; in summer it often roosts in attics; it breeds in the state.
Bats that roost in trees in summer: Silver-haired bat (Lasionycteris noctivagans) — uncommon; usually seen near water; listed as a Connecticut species of special concern Red bat (Lasiurus borealis) — usually found at lower elevations; seldom seen and listed as a Connecticut species of special concern Hoary bat (Lasiurus cinereus) — seldom seen and listed as a Connecticut species of special concern Northern long-eared myotis or long-eared bat (Myotis septentrionalis)
Bats that hibernate in caves and tunnels: Northern long-eared myotis (see above) Little brown bat (see above) Eastern small-footed bat (Myotis leibii) — believed to have been extirpated in the state, and it was probably always scarce; no confirmed sightings have been recorded in the state for several decades; listed by the state as a "species of special concern" Indiana bat (Myotis sodalis) — in the several decades up to 2004, only one was ever found in the state; the bat is on both state and federal lists of endangered species Tricolored bat (Perimyotis subflavus or Pipistrellus subflavus)
Rabbits and hares
Rabbits and hares (Order Lagomorpha, Family Leporidae) Eastern cottontail (Sylvilagus floridanus) — introduced to New England in the late 1800s and has expanded its range at the expense of the native New England cottontail.Desmarais, Paul, "Photo Journal: Wilds of Suburbia" photograph (of an Eastern cottontail rabbit) with long caption, The Advocate of Stamford, Connecticut, October 2, 2007, page A11, Norwalk edition, caption states: "Sources: Nature Works (a Web site), Texas Tech University's online guide and Connecticut Department of Environmental Protection" The species originally came from the south. By the 1930s, New England cottontails were still considered more numerous than the eastern cottontail, but both species were declining as farms reverted to forests;[ ]Web page titled "Cottontail Rabbits" at the Connecticut Department of Environmental Protection Web site, retrieved December 30, 2007 found in shrubby and open areas, often in disturbed areas. Hammonasset Beach State Park has many of them; in the early evening, 30 to 40 can be found along the entrance road. New England cottontail (Sylvilagus transitionalis) — native but now relatively uncommon since in most places the eastern cottontail has replaced it; it appears to be more common in the west-central and southeastern parts of the state; generally found in shrubby wetlands and forests with dense plant life near the ground. Another possible reason for the decline of this species could be the loss of areas with suitable ground cover, which protects the animals from predators. Loss of farmland to forests is thought to have reduced the population since the 1930s, when New England cottontails were still thought to outnumber eastern cottontails. Snowshoe hare (Lepus americanus) — common in the northern part of the state, usually where there are dense thickets; the population in Connecticut doesn't soar cyclically, as the species does farther north
Rodents
Squirrel family (Order Rodentia, Family Sciuridae)
Groundhog, woodchuck or whistle pig (Marmota monax) — scarce when Europeans first came to North America, but they have thrived since then.Desmarais, Paul, "Photo Journal: Wilds of Suburbia" photograph (of a groundhog in Stamford, Connecticut) with long caption, The Advocate of Stamford, Connecticut, September 4, 2007, page A11, Norwalk and Stamford editions