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Learn about eastern ratsnakes

Learn more about the Bay State's largest snake, which is listed as endangered in Massachusetts.
Eastern ratsnake

Fast facts

Common name(s): Eastern ratsnake, eastern rat snake
Scientific name: Pantherophis alleghaniensis
Size: 3–8.5 feet
Range: Central Georgia, north to Vermont and southern Ontario, west to Louisiana and Illinois
Conservation status: Listed as endangered in Massachusetts
Fun fact: Can climb sheer cliffs

Description

Eastern ratsnakes are large, black, and shiny. Some adults also have traces of white patterning, caused by pigmented skin exposed between their scale rows. Their chins and throats are white and un-patterned. Their underside is mottled and becomes uniformly gray towards the tail. The length of this mottled pattern varies by individual. Their eyes have a black pupil, which is sometimes surrounded by a distinctly white margin. Body scales are weakly keeled.

Juveniles are pale gray in color, with a distinct diamond pattern. The undersides are white, similar to adults. Juvenile colors change to all black by the time they reach three feet long. The pupils of juveniles are distinct, with a prominent white margin. 

Similar species: Eastern ratsnakes can sometimes be confused with milk snakes (Lampropeltis triangulum), North American racers (Coluber constrictor), and timber rattlesnakes (Crotalus horridus).

Population status

Massachusetts populations are found in a few widely scattered locations of the Connecticut River Valley, southern Worcester County, and Bristol County. Eastern ratsnakes are listed as endangered on the Massachusetts Endangered Species List. 

Conservation

Eastern ratsnake populations are threatened mainly by:

  • habitat alteration
  • collection from the wild for the pet trade
  • roads as barriers to migration
  • roads as sources of vehicular mortality

Due to their relatively docile nature and large size, eastern ratsnakes are popular in the pet trade. In Massachusetts, it is illegal to capture a wild eastern ratsnake, and it is illegal to possess one from any other source, including from out of state.

Habitat

Massachusetts is restricted by the availability of hibernating sites. New England is the northern limit of this animal's range, and its hibernacula (areas where snakes overwinter) are in areas with southern exposure that receive maximum thermal benefit from the sun in winter and provide basking areas in early spring and late fall. Eastern ratsnakes may share hibernacula with other snakes such as North American racers, copperheads, and timber rattlesnakes.

Other than their need for specialized sites for hibernation, eastern ratsnakes live in a variety of woods and forest, as well as in adjacent fields, thickets, and other early successional habitats that support populations of its prey species.

Life history

Eastern ratsnakes can live to be at least 20 years old. They emerge from hibernacula in spring and disperse into adjacent woodlands to feed and mate. They can climb trees and can enter rodent holes in the ground to find food during spring and early summer. Research suggests eastern ratsnakes do not venture more than one mile from their overwintering locations. 

Eastern ratsnakes lay 8–12 eggs in June, in piles of decaying leaves and other rotting vegetation, stumps, or hollow logs or trees. Foot-long young hatch in August or September.

Their diets consist mainly of small mammals like deer mice, voles, eastern chipmunks, squirrels, and small cottontails. They will opportunistically feed on birds, amphibians, and other reptiles. Eastern ratsnakes are constrictors, squeezing to subdue or kill prey. 

Predators include mink, large carnivores, and large birds of prey.

More information

Learn more about eastern ratsnakes with our fact sheet (PDF).

See an overview of the Massachusetts Endangered Species Act.

Support conservation efforts for eastern ratsnake and other rare species.

 

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