Snakes are a natural part of Pennsylvania’s diverse ecosystems, and encounters are possible when exploring the state’s natural areas. A total of 21 native snake species inhabit Pennsylvania, but only three pose a threat to human safety. Understanding the difference between harmless and dangerous species is the most effective way to ensure a safe outdoor experience. This guide provides information for identifying Pennsylvania’s snakes and outlines protocols for safe encounters.
Common Non-Venomous Snakes
Non-venomous species contribute significantly to controlling local rodent and insect populations. The Eastern Garter Snake is one of the most frequently seen, identifiable by the three light-colored longitudinal stripes running along its dark body. These snakes are active during the day and can be found in nearly every habitat, including gardens and grassy areas near homes.
The Black Rat Snake is a long, black snake that can reach lengths of over four feet. This species is an adept climber and is often found in wooded areas, barns, or old buildings where it hunts for rodents. A third common species is the Eastern Milk Snake, which is often mistakenly killed due to a superficial resemblance to the venomous Copperhead. The Milk Snake features reddish-brown blotches bordered in black, set against a lighter gray or tan body.
The Milk Snake’s head is light-colored and marked, unlike the uniformly coppery head of a Copperhead. The Northern Water Snake is frequently observed near rivers, ponds, and streams, and is sometimes misidentified as the Southern Water Moccasin, a species not found in Pennsylvania. Non-venomous snakes are docile and only bite if threatened or handled.
Identifying the Venomous Species
Only three of Pennsylvania’s native snakes are venomous: the Northern Copperhead, the Timber Rattlesnake, and the Eastern Massasauga. All three belong to the pit viper family, sharing distinct physical characteristics. Venomous snakes possess vertically elliptical pupils, which resemble a cat’s eye, while non-venomous species have round pupils.
These pit vipers also have a facial pit, a heat-sensitive organ located between the eye and the nostril, which is absent in non-venomous snakes. The Northern Copperhead is the most common venomous snake, recognized by its light tan or gray body covered in distinctive, dark reddish-brown, hourglass-shaped crossbands. Its head often has a coppery-red tint, lacking the markings found on similar non-venomous snakes.
The Timber Rattlesnake is large and heavy-bodied, growing 3 to 5 feet long, and is found in two color phases: a dark form that is almost entirely black, and a yellow form. Its most definitive feature is the segmented rattle at the end of its tail, though it does not always sound a warning before striking. The Eastern Massasauga is the smallest of the three (18 to 40 inches) and is considered threatened and rare, found only in specific western wetlands. It has a light gray or brown body with dark blotches and a small, segmented rattle that can be difficult to hear.
Understanding Snake Habitats and Distribution
Snakes are found across Pennsylvania, utilizing a variety of natural environments to regulate their body temperature and find prey. Habitats vary by species, but common locations for encounters include rocky outcrops, forested hillsides, and areas near water, such as riverbanks and marshy fields. The most significant factor leading to human encounters is the search for shelter and food sources like rodents.
Snakes are ectothermic, meaning they rely on external heat, and are most active during the warmer months from late April or May through September. During this period, they can often be found basking in sunny spots in the morning or evening to warm up. They also seek cover under logs, rocks, or debris piles, which offer warmth and protection. The movement of snakes to and from communal hibernation sites in the fall and spring increases the likelihood of them crossing roads or trails.
Guidelines for Safe Encounters
The safest rule when encountering any snake is to leave it alone and observe it from a distance. Snakes are not aggressive and only bite if provoked, handled, or accidentally stepped on. For those hiking in areas known for venomous species, wearing high-topped boots and long pants can offer protection against an accidental bite.
To prevent attracting snakes near a home, remove potential hiding spots like rock piles, wood stacks, and construction debris, and keep grass trimmed near buildings. Sealing any cracks or openings near ground level in foundations, sheds, and garages will prevent snakes from seeking shelter inside a structure. All snakes in Pennsylvania are protected by state regulations, so killing them is prohibited. Should a snake find its way into a dwelling, contact a local wildlife control professional for removal.