Harmless · Native to the United States · Kept as a pet

Eastern rat snake

Pantherophis alleghaniensis

Also called black rat snake, eastern ratsnake, central ratsnake
Data updated October 2026

Adult eastern rat snake, shiny black with faint white flecks, stretched along a tree trunk
Fig. 1 — Adult climbing a tree trunk. Adults are glossy black, often with flecks of white between the scales.
Young eastern rat snake, pale gray with dark brown blotches
Fig. 2 — Juveniles are pale gray with dark blotches and look nothing like the adults.

At a glance

A large, glossy black constrictor of eastern woods, farms and backyards, and one of the region’s best climbers. It eats mostly rodents and often turns up in barns and attics. It is harmless to people, and its scientific name is in the middle of a taxonomic shuffle.

01

Identification

Adults are big, heavy-bodied and shiny black, often with white showing between the scales. The chin and throat are plain white, and the belly has a black-and-white checkerboard that turns grayer toward the tail. The scales along the back are weakly keeled, and the body is squared-off in cross-section with a fairly thin neck. Young snakes are a different animal to look at: pale gray with dark brown or black blotches.

  1. 01White chin, checkered belly. A clean white throat leading into a black-and-white checkerboard underneath.
  2. 02Square-shaped body. A heavy, squared-off body with a fairly thin neck.
  3. 03Weakly keeled scales. A faint ridge on the back scales gives a less polished look than a racer.

A note on the name. This snake was long called the black rat snake, a subspecies of one wide-ranging rat snake. Genetic studies around 2000 split that species into eastern (P. alleghaniensis), central or gray (P. spiloides) and western (P. obsoletus) rat snakes. A 2021 revision then argued that the name P. alleghaniensis belongs to the central group, the one formerly called the gray rat snake, so P. spiloides becomes a synonym, and that the rat snakes of the southeastern coastal plain should be P. quadrivittatus. Agencies have not all caught up. Connecticut and Massachusetts still say eastern ratsnake, while New York now says central (formerly eastern) ratsnake. In practice, the black rat snakes of New England, New York and Pennsylvania are P. alleghaniensis under either system, and those are the snakes this page covers.

Commonly confused with

Racers are slimmer, have smooth satiny scales and a plain dark belly, and bolt when disturbed. Blotched young rat snakes are easy to mistake for milk snakes.

02

Size

01 ft2 ft3 ft4 ft5 ft6 ft Typical adult · about 5 ft (152 cm)

Most adults measure about 46 to 68 inches (117–173 cm), and it is the largest snake in Massachusetts. Some individuals grow longer still. Hatchlings are about a foot long.

03

Range & habitat

Eastern rat snake basking on a rocky ledge at the edge of a forest
Fig. 3 — Rocky ledges next to woodland give rat snakes both basking spots and winter dens.

In the Northeast this rat snake reaches its limit in western Vermont, central Massachusetts and eastern Rhode Island, and ranges south and west through Connecticut, south-central New York and Pennsylvania into the Midwest. New York places the species it now calls the central ratsnake east of the Mississippi River and inland of the Atlantic Fall Line in Virginia. In New York it lives south of the Tug Hill Plateau and the Adirondacks.

It favors rough wooded country with ledges and rock outcrops, along with small meadows, field edges and thickets next to forest. It does well in a patchwork of woods, farmland and houses, and regularly turns up in barns, haylofts, sheds and attics while hunting rodents.

04

Diet & predators

Rat snakes are active hunters that kill by constriction. Small mammals make up most of the diet: deer mice, voles, rats, moles, chipmunks, squirrels and even young cottontails. They also climb to raid bird nests for eggs and nestlings, and take frogs, other reptiles and insects. Their habit of following rodents indoors is what brings them into contact with people most often.

Feeds on

  • Mice, voles and rats
  • Chipmunks, squirrels and moles
  • Small birds and bird eggs
  • Frogs, lizards and insects

Preyed on by

  • Hawks and other large birds of prey
  • Mink
  • Larger mammal predators
Deer mouse on the forest floor
Prey — mice and other rodents.
Red-tailed hawk perched on a branch
Predator — large birds of prey.

05

Behavior & seasons

Eastern rat snakes are mostly active by day, sometimes at night, and are excellent climbers that go high into trees and buildings. When approached they often freeze and rely on blending in. If pushed, they may vibrate the tail in dry leaves so it sounds like a rattle, strike, coil around an arm, and smear a foul-smelling musk on whatever grabs them. They are not venomous.

In New England they head to winter dens in early to mid-November and come out in mid to late April. Dens are usually south-facing rock crevices or old burrows used year after year, and they are often shared with racers, copperheads and timber rattlesnakes. Tracked snakes in Massachusetts rarely moved more than about a mile from their den.

06

Reproduction

Mating starts soon after the snakes leave their dens and runs through May. Females lay their eggs in June, usually 8 to 12 of them, in rotting leaf piles, compost or mulch, old burrows, or under stumps and inside hollow logs. The eggs hatch in August or September, and the young get no care from either parent.

07

Conservation

The species is not listed under the US Endangered Species Act and is still common across much of its range. At the northern edge it is a different story: Massachusetts lists it as endangered, and taking one from the wild or keeping one from any source is illegal there. New York lists it as a Species of Greatest Conservation Need, though its populations there appear stable. The main threats are road deaths, building on ridgelines and rocky outcrops, quarrying of den sites, and illegal collection for the pet trade. Endangered US reptiles

08

In captivity

Their size and fairly docile nature have made black rat snakes popular pets. They are active, climbing snakes, so space and height matter more than with many pet snakes. Keep one snake per enclosure. A common minimum for an adult is about 6 × 3 × 3 feet, with sturdy branches for climbing and secure lids, since they are strong escape artists.

  • Heat and light. A basking area of about 85–90°F, a cool side around 72–77°F, heat off at night, and about 12 hours of light a day. Low-level UVB is recommended but not strictly required.
  • Humidity. Moderate, roughly 50–70%.
  • Food. Whole prey, usually frozen-thawed rodents, sized to the snake’s thickest point. Young snakes eat more often than adults.
  • Lifespan. 15 years or more with good care.
  • Legality. Buy captive-bred animals, do not collect wild snakes, and never release a pet. Massachusetts bans possession entirely.

See a reptile vet if your snake refuses food for a long stretch, sheds in patches or has bubbling or wheezing breathing. More pet care guides

Keep reading

Sources

Data updated October 2026 · How we build these pages