When discussing reptiles that deliver toxins through a bite, the correct term is “venomous,” not “poisonous.” Pennsylvania is home to 21 native snake species, but only three of these possess venom, all of which belong to the pit viper subfamily. Understanding the appearance and habits of these three native venomous snakes is important for anyone who spends time outdoors. The distribution and risk level vary significantly among the species, with two being common and one being exceedingly rare. Learning to identify these species and knowing the proper safety protocols can help ensure safe outdoor experiences.
The Two Widespread Venomous Species of Pennsylvania
The Eastern Copperhead (Agkistrodon contortrix) is the most widely distributed and numerous of Pennsylvania’s three venomous species. Adults are medium-sized, typically ranging from 20 to 42 inches in length, and possess a heavy body build. Their most recognizable feature is a pattern of dark brown, hourglass-shaped crossbands set against a lighter background. The head is often a solid copper or bronze color, giving the snake its common name.
Copperheads are habitat generalists, thriving in environments from deciduous forests to rocky outcroppings and areas near human development. They are often found in wood piles, rock piles, and brush piles for shelter and foraging. During the hottest summer months, copperheads tend to become nocturnal. Juvenile copperheads are born with the same body pattern but have a distinct yellow-tipped tail, which they use to lure prey.
The Timber Rattlesnake (Crotalus horridus) is Pennsylvania’s largest venomous snake, often reaching lengths of up to 5 feet. This species is stout-bodied and its coloration is highly variable, often appearing as brown or black chevron-like bands on a background that can be bright yellow or black. The tail is almost always completely black, ending in a distinct keratinized rattle.
Timber rattlesnakes are primarily found in the mountainous and forested regions of the state, including the Ridge and Valley Province, the Laurel Highlands, and the Allegheny Plateau. They prefer upland forested areas with rocky outcroppings, steep ledges, and talus slopes, which provide ideal basking and den sites. Overwintering dens, known as hibernacula, are typically located on south-facing rocky slopes. Males may travel several miles from the den during the summer, while pregnant females generally remain nearby for gestation.
General Identification Features of PA Venomous Snakes
All three native venomous snakes in Pennsylvania belong to the pit viper group, sharing several distinguishing physical characteristics. A primary feature is the presence of loreal pits, which are deep, heat-sensing depressions located on each side of the head between the eye and the nostril. These organs allow the snake to detect warm-blooded prey, aiding in hunting, especially in low-light conditions.
Pit vipers also possess vertically elliptical pupils, resembling a cat’s eye, while non-venomous Pennsylvania snakes generally have round pupils. All pit vipers naturally have a broad, triangular head shape that is noticeably wider than their neck, though many non-venomous snakes can flatten their heads when threatened. Another element is that venomous species have a single row of scales on the underside of the tail, whereas non-venomous snakes have a double row.
The Restricted Eastern Massasauga
The Eastern Massasauga Rattlesnake (Sistrurus catenatus) is the state’s third venomous species, but encounters are rare due to its highly restricted range. This snake is smaller than the Timber Rattlesnake, typically averaging 20 to 30 inches in length. It is characterized by large, dark brown blotches running down the middle of its back, with smaller blotches along the sides, all set on a gray or tan background.
The Massasauga is classified as a federally Threatened and state Endangered species, with only a few isolated populations remaining. Its remaining habitat is confined to specific low-lying wetlands and wet grasslands in western and northwestern Pennsylvania. Though it possesses a rattle, it is noticeably smaller and creates a quiet, barely audible buzz, which is why it is sometimes called the “swamp rattlesnake.”
Prevention and Emergency Response
The most effective way to avoid snake bites is through simple preventative measures that minimize the chance of a surprise encounter. When hiking or walking in wooded areas, wearing protective footwear like thick boots and long pants can provide a barrier against an accidental strike. It is important to watch where you place your hands and feet, particularly when stepping over logs, gathering firewood, or climbing on rocky ledges. If you see any snake, give it a wide berth and never attempt to handle, harass, or provoke it.
In the event a bite occurs, immediate action is necessary to ensure the best outcome. The first step is to call 911 or the Poison Control Center’s National Hotline at 1-800-222-1222, and then move the victim away from the snake. Keep the person calm and still, which helps to slow the spread of venom through the lymphatic system. Remove any constricting items like rings, watches, or tight clothing from the affected limb before swelling begins.
Certain actions can cause more harm and must be avoided:
- Never apply a tourniquet.
- Never cut the wound.
- Never attempt to suck out the venom.
- Avoid applying ice or cold compresses, as this can worsen local tissue damage.
The wound may be gently washed with soap and water, but seeking professional medical attention for antivenom administration is the only proper treatment.