Snakes in Pennsylvania: 21 Native Species and 3 Venomous Ones

How many snakes live in Pennsylvania?

The Pennsylvania Fish and Boat Commission, which manages the state’s reptiles and amphibians, recognizes 21 native snake species. They range from the eastern ratsnake, which can be longer than an adult is tall, to the red-bellied snake, which rarely grows longer than 25 cm (10 in). The list includes three gartersnakes (counting the eastern ribbonsnake), two green snakes and three venomous pit vipers.

Pennsylvania’s snakes are active from about April to October. They spend the winter below the frost line in rock crevices, rodent burrows, old foundations and other sheltered spots, often sharing dens with other snakes. For more on how they survive the cold, see do snakes hibernate?.

Lengths follow the Pennsylvania Fish and Boat Commission; larger individuals occur.

Eastern copperhead

The copperhead (Agkistrodon contortrix) is the venomous snake Pennsylvanians are most likely to meet. It is a stout, medium-sized snake with a plain coppery head and a tan to pinkish-brown body crossed by darker hourglass-shaped bands that are narrow on the back and wide on the sides. Its belly is mottled. Young copperheads have a yellow tail tip that they twitch to lure frogs and lizards within reach.

Copperheads favor rocky, wooded hillsides, stone walls, old farm buildings and the edges of fields and forests, and they are most common in the southern and central parts of the state. They hunt mice, voles, frogs, lizards and cicadas. A copperhead’s first defense is to lie still and rely on its camouflage, which is why most bites happen when people step on one or reach under a log or rock. Bites are painful and need hospital treatment, but they are very rarely fatal.

Timber rattlesnake

The timber rattlesnake (Crotalus horridus) is Pennsylvania’s largest venomous snake, usually 91–137 cm (36–54 in) long. It has dark, V-shaped crossbands, a black tail and a rattle made of interlocking segments of keratin. Pennsylvania timber rattlesnakes come in two main color phases: a yellow phase, with dark bands on a yellow to tan background, and a black phase, which is so dark that the pattern can be hard to see.

Timber rattlesnakes live mainly in large, unbroken forests in the mountains of central and northern Pennsylvania. They are absent from the far southwest and from the urban southeast, including Pittsburgh and Philadelphia. In fall they return to communal dens, usually rocky outcrops on sunny, south-facing slopes, where dozens of snakes may spend the winter together; read more in where do timber rattlesnakes spend the winter?. Pregnant females often bask together on open rocks in summer and give birth to live young in late summer.

These snakes are slow to reproduce. Females in the north often do not breed until they are several years old and then usually breed only every two years or more, so the loss of even a few adults can harm a population. The state regulates it closely, and the Fish and Boat Commission treats it as a species of conservation concern.

Eastern massasauga

The eastern massasauga (Sistrurus catenatus) is Pennsylvania’s smallest and rarest venomous snake. It is usually 51–76 cm (20–30 in) long, gray to brownish gray with a row of large dark brown blotches down the back, and has nine large plates on top of its head, unlike the many small scales of the timber rattlesnake. Its rattle is small and its buzz is easy to miss.

Massasaugas live in wet meadows, old fields, shrubby wetlands and prairie-like openings, and they often spend the winter in crayfish burrows below the water table. They once occupied several northwestern counties, but draining of wetlands and the regrowth of forest on open land have reduced them to a few sites in western Pennsylvania. The species is listed as endangered in Pennsylvania, and since 2016 it has been listed as threatened under the US Endangered Species Act.

Common harmless snakes

Most snakes found in Pennsylvania yards, parks and farms are harmless to people:

• Eastern gartersnake (Thamnophis sirtalis): the most familiar snake in the state, usually 46–66 cm (18–26 in) long, dark green to black with three yellowish stripes. It lives statewide, from city lots to mountain meadows. See our common garter snake profile.
• Eastern ratsnake (Pantherophis alleghaniensis): the largest snake in Pennsylvania, glossy black and usually 1.1–1.8 m (3.5–6 ft) long. It climbs trees and barn walls to reach rodents, birds and eggs. The Fish and Boat Commission also calls it the central ratsnake.
• Northern watersnake (Nerodia sipedon): the largest of the state’s water snakes and the one seen most often in streams, ponds and lakes. It is brown or gray with dark crossbands that break into blotches toward the tail. It is not venomous but bites readily if handled.
• Northern black racer (Coluber constrictor): a slim, fast, satin-black snake with a white chin, usually 0.9–1.5 m (3–5 ft) long, that hunts by day.
• Eastern milksnake (Lampropeltis triangulum): gray or tan with reddish-brown blotches and a black-and-white checkered belly.
• Small snakes: the northern ring-necked snake with its yellow collar, the brown DeKay’s brownsnake and the red-bellied snake are often found under logs, stones and garden debris.

The smooth greensnake, a bright green snake of meadows and grassy hillsides, eats mainly insects and spiders. The eastern hognose snake is famous for its bluff: it flattens its neck like a cobra, hisses and, if that fails, rolls over and plays dead.

Rare and protected species

Besides the massasauga, two harmless snakes are listed as endangered in Pennsylvania. Kirtland’s snake is a small, reddish-bellied snake of wet meadows found only in western Pennsylvania. The northern rough greensnake is a slender, pale green climber that reaches the northern edge of its range in southern Pennsylvania. Several other species, such as the queensnake, the eastern ribbonsnake and the short-headed gartersnake, are considered species of special concern. The short-headed gartersnake has one of the smallest ranges of any North American snake, centered on northwestern Pennsylvania and southwestern New York.

How to tell Pennsylvania’s venomous snakes from harmless ones

All three venomous species are pit vipers. Up close, they have a heat-sensing pit between the eye and nostril and vertical, cat-like pupils, while Pennsylvania’s harmless snakes have round pupils and no facial pit. These features are useful in photos, but they can only be seen at very close range, so they should never be checked in person.

Easier clues are the overall pattern and where the snake is found:

• Hourglass bands that are narrow on the back and wide on the sides point to a copperhead. Harmless milksnakes and young ratsnakes have separate blotches instead.
• A rattle and a black tail mean a timber rattlesnake. A massasauga has a rattle too, but it is smaller and blotched.
• A banded snake in or beside water is almost always a northern watersnake. Pennsylvania has no cottonmouths, so reports of water moccasins in the state are cases of mistaken identity.
• Snakes that vibrate their tails are not necessarily rattlesnakes. Racers, ratsnakes and milksnakes often shake their tails in dry leaves, producing a convincing buzz.

Staying safe around snakes

Venomous snakebites in Pennsylvania are rare, and deaths are rarer still. Across the whole United States, the CDC estimates that about 7,000–8,000 people are bitten by venomous snakes each year and about five die. Most bites happen when someone tries to handle, move or kill a snake.

• Leave snakes alone and give them room to move away. Watch from a distance with binoculars or a camera.
• Watch where you put your hands and feet when climbing rocky ledges, moving firewood or walking at night.
• If someone is bitten, call 911 immediately and get the person to emergency medical care as quickly as possible.