Pennsylvania’s diverse landscape, stretching from the Appalachian Mountains to the Delaware River, creates a mosaic of habitats supporting a vast array of wildlife. The state’s geography includes dense forests, extensive river systems, and pockets of wetlands, all of which contribute to a remarkable level of biodiversity. These environments allow for the survival of over 60 native mammal species, hundreds of bird species, and dozens of reptiles and amphibians. The distribution of these animals is directly tied to the specific ecological niches provided by the state’s terrain and abundant water sources.
Large and Common Mammals of Pennsylvania
The most recognizable large mammal in Pennsylvania is the White-tailed Deer, which holds the distinction of being the state’s official animal. This adaptable herbivore thrives across all regions, often leading to high population densities that impact forest regeneration through over-browsing. The American Black Bear, the state’s largest predator, is widespread, particularly in the forested northcentral and northeastern counties. Black bears enter a state of shallow torpor during winter, unlike true hibernators.
The Eastern Coyote has expanded its range to every township, filling the predatory niche left by the historical extirpation of the wolf. This secretive canine is primarily nocturnal and generally avoids human contact. However, coyotes have successfully adapted to suburban and urban areas, preying on small game and deer, and scavenging from human food sources.
Smaller, highly adaptable mammals are most commonly encountered in developed areas. The Gray Squirrel is Pennsylvania’s most common squirrel, reaching high densities in prime woodland habitat. Raccoons also display high population densities in suburban and urban environments, utilizing human structures for denning and exploiting available food waste.
State’s Extensive Avian Populations
Pennsylvania is situated along the Atlantic Flyway, making it a temporary home for a wide variety of migratory species. The state’s ridge lines, part of the Appalachian chain, function as a natural highway for migrating raptors like the Bald Eagle and Red-tailed Hawk. Successful conservation efforts for the Bald Eagle have resulted in a strong recovery of its population across the state’s major waterways.
The Ruffed Grouse, the official state bird, is a non-migratory game bird found primarily in the state’s mixed-oak and northern hardwood forests. Common backyard birds, such as the Northern Cardinal and Black-capped Chickadee, remain year-round residents, relying on local food sources. Forest-interior songbirds, including the Scarlet Tanager and Wood Thrush, also rely heavily on Pennsylvania’s extensive forest cover for breeding.
Herpetofauna: Reptiles and Amphibians
Pennsylvania is home to over 50 species of herpetofauna. Amphibians, like the tiny Spring Peeper and the larger American Bullfrog, have smooth, permeable skin and rely on water or moist environments to complete their life cycle. Salamanders, with 22 species present, also depend on moisture, with many migrating nocturnally to breeding pools in the spring.
Reptiles, including the state’s 13 turtle species, have scaly skin and are largely terrestrial or semi-aquatic. The Common Snapping Turtle is a powerful aquatic species that spends most of its time walking along the bottom of lakes and ponds. The Eastern Box Turtle is a common terrestrial species, known for its hinged lower shell that allows it to fully enclose itself for protection.
Safety concerns revolve around the state’s three venomous snake species: the Timber Rattlesnake, the Eastern Copperhead, and the rare Eastern Massasauga Rattlesnake. Non-venomous species, such as the Eastern Garter Snake and the Black Rat Snake, play a significant role in controlling rodent populations. Distinguishing the venomous snakes involves recognizing features like elliptical pupils and heat-sensing facial pits, which are absent in non-venomous varieties.
Aquatic Life in Pennsylvania’s Waterways
The state’s rivers, streams, and lakes support a rich aquatic ecosystem. The native Brook Trout serves as an indicator species, requiring cold, highly oxygenated water with temperatures consistently below 65 degrees Fahrenheit. Conversely, popular warm-water sport fish like Largemouth Bass and Smallmouth Bass thrive in the state’s numerous lakes and slower-moving rivers.
Channel Catfish, which can reach up to 15 pounds, are common in clear, warm lakes and large rivers, typically foraging in deeper pools. The health of these aquatic habitats is directly linked to the presence of other species, including freshwater mussels, which act as natural filter feeders. Macroinvertebrates, such as crayfish and stonefly larvae, function as bio-indicators, with their presence or absence reflecting the overall quality of the water.
The North American River Otter and the Beaver are two semi-aquatic mammals that have rebounded in the state following reintroduction programs. The Beaver, an ecosystem engineer, creates ponds that slow water flow and increase aquatic biodiversity. This benefits the otter, a top predator of fish, amphibians, and crayfish.