Pennsylvania’s wetlands, forests, and backyards host an incredible diversity of frog species—from giants weighing over a pound to tiny amphibians smaller than your thumb.
Whether you’re listening to the first spring chorus echoing across a vernal pool or spotting movement near your garden pond, you’re experiencing one of nature’s most adaptable creatures.
This guide reveals how to identify each of Pennsylvania’s 11 most common frog species by sight and sound, including where to find them and what makes each one unique in the Keystone State’s amphibian community.
1. American Bullfrog
The American Bullfrog reigns as Pennsylvania’s largest frog species, with adults reaching impressive lengths between 3.6 and 6 inches.
You’ll recognize these powerful amphibians by their olive green coloration, though some individuals display gray or brown mottling across their backs. Their fully webbed back feet make them exceptional swimmers, and mature males develop distinctive bright yellow throats during breeding season.
Key Identification Features:
- Dorsal ridge wraps around the tympanum (eardrum) rather than extending down the back
- Can weigh up to 1.5 pounds
- Large, prominent eyes positioned on top of the head
- Lack of distinct dorsolateral ridges running down the back
You’ll find Bullfrogs near permanent water bodies throughout Pennsylvania, including large ponds, lakes, streams, and swamps.
During breeding season, males establish territories in shallow water and defend them aggressively. Their call sounds remarkably like a bull bellowing—a deep “jug-o-rum” that carries across the water on warm summer nights.
Pro Tip: Bullfrogs are voracious predators that consume anything fitting in their mouth, including insects, fish, small snakes, birds, and even other frogs. Their opportunistic feeding behavior makes them fascinating to observe near pond edges.
2. Green Frog
Green Frogs rank as medium to large-sized amphibians, displaying coloration ranging from bright green to greenish brown. Once males reach sexual maturity, their throats turn bright yellow—a reliable identification marker during breeding season. These common Pennsylvania residents adapt to various aquatic habitats.
The most reliable way to distinguish Green Frogs from Bullfrogs involves examining their dorsal ridges. Green Frogs have prominent ridges that start at the eye and run partway down the back, stopping before reaching the hind legs. In contrast, Bullfrogs have ridges that wrap around the tympanum without extending down the back.
You can spot Green Frogs near virtually any water body in Pennsylvania:
- Ponds and lakes with vegetated shorelines
- Streams with slow-moving sections
- Marshes and wetlands
- Beaver ponds with dense aquatic vegetation
Their call resembles a plucked banjo string—a single, distinctive note often repeated several times. Green Frogs use a “sit and wait” hunting approach, making them opportunistic feeders that consume spiders, insects, fish, crayfish, snails, slugs, and even small snakes.
Common Mistake: Don’t confuse young Bullfrogs with Green Frogs. Always check the dorsal ridge pattern—it’s the most reliable identification feature between these two similar-looking species.
3. Pickerel Frog
Pickerel Frogs measure between 2 and 2.5 inches as adults, with females typically larger than males. These distinctive amphibians feature two parallel rows of rectangular (squarish) spots running down their backs between the dorsolateral folds. The spots’ square shape immediately separates them from the rounded spots of Northern Leopard Frogs.
Distinctive Characteristics:
- Bright yellow or orange coloration on inner thighs
- Two rows of neatly arranged rectangular spots
- Light-colored dorsolateral ridges extending down the back
- Tan to light brown base coloration
Pickerel Frogs thrive near beaver ponds and wetlands with dense vegetation throughout Pennsylvania. What makes this species truly unique is its defense mechanism—the skin produces a toxic substance that makes them unappealing to most predators. This secretion protects them from being eaten and can even be irritating to human skin.
Their call sounds like a finger running over the tines of a comb—shorter and faster than the Northern Leopard Frog’s snoring sound. During breeding season, males use paired vocal sacs (visible only when calling) to amplify their distinctive call.
Important Note: Pickerel Frogs are the only poisonous frog species native to Pennsylvania. While their toxin won’t seriously harm humans, it’s best to wash your hands after handling them and avoid touching your eyes or mouth.
4. Northern Leopard Frog
Northern Leopard Frogs range from 2 to 4 inches in length, with females generally larger than males. These semi-aquatic frogs vary dramatically in color—from dark brown to brilliant green—adorned with fairly large, rounded spots distributed across their bodies. Light-colored dorsolateral ridges run the entire length of their backs, extending all the way to the groin.
You’ll encounter Northern Leopard Frogs near slow-moving water bodies with abundant vegetation throughout Pennsylvania (except the far eastern edge of the state). Look for them in these habitats:
- Ponds and lakes with vegetated shorelines
- Streams and marshes
- Meadows and fields near water sources
- Floodplains during breeding season
Key Insight: Northern Leopard Frogs require three distinct habitat types to complete their life cycle—permanent water for overwintering, floodplains and marshes for breeding, and meadows and fields for foraging. This habitat complexity makes them vulnerable to landscape changes.
These opportunistic feeders consume an impressive variety of prey, including worms, crickets, flies, smaller frogs (even their own species), small snakes, and birds. Males produce a low, rumbling snore-like call during spring breeding season while floating in shallow pools. When captured or startled, they may emit a high, loud screaming call.
Northern Leopard Frog populations are declining across many areas due to a combination of factors including habitat loss, drought, introduced fish, environmental contaminants, and disease. Conservation efforts focus on protecting their diverse habitat requirements.
5. Wood Frog
Wood Frogs measure between 1.4 and 2.8 inches in length, displaying coloration that varies from brown and tan to red or copper tones. Their most distinctive feature is a dark mask extending across their eyes—often called a “robber’s mask”—that makes identification unmistakable. Females tend to be more brightly colored than males.
As their name suggests, Wood Frogs inhabit moist woodland areas throughout Pennsylvania, including forested swamps, ravines, and bogs. After breeding season ends, they travel widely and may be found far from water sources, exploring the forest floor.
Remarkable Adaptation: Wood Frogs possess one of nature’s most incredible survival mechanisms. During winter, they can freeze completely solid—their breathing and heartbeat stop entirely. Their bodies produce glucose that acts as natural antifreeze, preventing cell damage during freezing. When spring arrives, they thaw and resume normal activities.
These are among the first amphibians to emerge after snow melts, gathering at vernal pools and small water bodies. Their call sounds remarkably like a clucking chicken or duck quacking. Interestingly, Wood Frog tadpoles can recognize their siblings and will seek each other out to group together—a rare social behavior among amphibians.
Pro Tip: Listen for Wood Frog choruses on the first warm, rainy nights of early spring. Their duck-like calls can lead you to ephemeral breeding pools that you might otherwise never notice.
6. Spring Peeper
Spring Peepers rank among Pennsylvania’s smallest frogs, measuring just 1 to 1.5 inches long. They’re typically tan or brown, with females displaying lighter coloration than males. The key identification feature is a dark cross or “X” pattern across their backs, making them easy to distinguish from other chorus frogs.
Despite their tiny size, Spring Peepers have large toe pads that enable them to climb trees. You’ll typically find them on the forest floor among leaves, though they venture into trees more than you might expect for such small amphibians.
Where to Find Them:
- Forest floors in wooded areas
- Swamps and marshlands
- Meadows near water sources
- Ponds and small water bodies during spring breeding season
Spring Peepers are nocturnal hunters that pursue ants, spiders, and other small insects during evening hours. Like most tree frogs, they spend most of their time on land, only returning to water for breeding and egg laying.
Their call is unmistakable—a high-pitched, single “peep” that can be heard up to half a mile away when multiple males chorus together. These calls are often the first sign of spring in Pennsylvania, beginning as early as February and continuing through May. Their vocal sacs inflate like shiny bubbles during calling.
Key Insight: Spring Peepers are the most common frog in Pennsylvania. Despite being one of the smallest vertebrates in the state, they can jump over 3 feet in a single leap to escape predators.
7. Eastern Gray Treefrog
Eastern Gray Treefrogs measure between 1.5 and 2 inches in length, displaying remarkable color-changing abilities. Their mottled gray, green, and brown coloring shifts slowly to match their surroundings—similar to chameleons. A whitish spot beneath each eye and bright orange coloration on the undersides of their legs provide reliable identification markers.
Distinguishing Features:
- Bumpy, pebbly-looking skin texture
- Short snout
- Large toe pads for climbing
- Dark irregular blotch pattern on the back
- Bright yellow skin on inner thighs
Gray Treefrogs inhabit wooded areas throughout Pennsylvania, from suburban backyards to dense forests and swamps. They spend most of their time in the treetops, descending only to breed. During breeding season, they prefer woodland ponds without fish, though they’ll also use swamps and garden water features.
Their call is a high trill lasting about one second, commonly heard during spring and summer evenings. Males call to establish territories and attract females. The species is nocturnal and rarely seen during daylight hours unless you happen upon one camouflaged against tree bark.
Important Note: Eastern Gray Treefrogs can survive freezing temperatures during winter by producing natural antifreeze in their bodies, similar to Wood Frogs. This adaptation allows them to overwinter in leaf litter and shallow burrows.
8. Cope’s Gray Treefrog
Cope’s Gray Treefrog is essentially identical to the Eastern Gray Treefrog in appearance, size, and habitat preference. Both species measure 1.5 to 2 inches, display the same mottled coloring, and feature the characteristic bright orange on their legs’ undersides. The two species can only be reliably distinguished by their breeding calls and chromosome numbers.
Call Differences:
- Eastern Gray Treefrog: Slower, more melodic trill
- Cope’s Gray Treefrog: Faster, harsher-sounding trill
Both species are found statewide in Pennsylvania, inhabiting the same wooded environments. They possess identical color-changing abilities, using their bumpy skin to blend perfectly with tree bark, lichens, and leaves. Large toe pads enable them to climb vertical surfaces with ease.
Like their Eastern relatives, Cope’s Gray Treefrogs are nocturnal and spend most of their lives in the treetops. They descend during breeding season to mate and lay eggs in fish-free woodland ponds. Both species are excellent climbers and can be found on house siding, windows, and trees.
Pro Tip: If you’re trying to identify which gray treefrog species you’ve encountered, record the call during breeding season. The faster, harsher sound indicates Cope’s Gray Treefrog, while the slower, more musical trill belongs to the Eastern Gray Treefrog.
9. Mountain Chorus Frog
Mountain Chorus Frogs are small species ranging from 0.75 to 1.5 inches in length. They display tan to light brown coloration with dark brown mottling patterns across their backs. Unlike other chorus frogs that frequent wetlands, this species is typically found near woodlands and is not strongly associated with water bodies.
Identification Features:
- Three dark longitudinal stripes (often broken or faint)
- Small size (under 1.5 inches)
- Light brown base coloration
- Dark mottling pattern
- Found primarily in woodland areas
Mountain Chorus Frogs occur in the mid and southcentral counties of Pennsylvania, with more limited distribution than other chorus frog species. The species is listed as a species of special concern by Pennsylvania wildlife authorities due to habitat loss and restricted range.
These small frogs face conservation challenges due to their specialized habitat requirements. They prefer areas near woodlands with appropriate moisture levels but without permanent water bodies. Their breeding occurs in temporary pools and seasonal wetlands.
Common Mistake: Don’t confuse Mountain Chorus Frogs with Spring Peepers. While both are small, Spring Peepers have a distinctive X pattern on their backs, while Mountain Chorus Frogs show three stripes (though these may be broken).
10. Upland Chorus Frog
Upland Chorus Frogs measure slightly over 1 inch in length, making them one of Pennsylvania’s smallest amphibian species. They feature three thin, dark longitudinal stripes running down their backs, though these stripes are often broken or incomplete. Base coloration ranges from tan to brown.
Range and Habitat: The Upland Chorus Frog occurs primarily in the mid and southcentral counties of Pennsylvania. They inhabit:
- Temporary pools and seasonal wetlands
- Areas near vernal pools
- Moist grasslands and meadows
- Woodland edges
Pro Tip: The best way to distinguish the three chorus frog species in Pennsylvania is by geographic location. Western Chorus Frogs occur in the westernmost counties, Upland Chorus Frogs in the mid and southcentral regions, and New Jersey Chorus Frogs (also called Coastal Plain Chorus Frogs) only in the southeastern corner.
Like other chorus frogs, this species is named for its vocal nature. Males call in large choruses during breeding season, creating a loud, distinctive sound that carries across wetlands. They’re much easier to hear than see due to their small size and secretive nature.
Upland Chorus Frogs are among the first amphibians to call in early spring, sometimes beginning as early as late February. Their breeding season coincides with the first warm rains, when males gather at temporary pools to attract females.
11. Eastern Cricket Frog
Eastern Cricket Frogs (also called Northern Cricket Frogs) measure between 0.75 and 1.5 inches long, making them one of Pennsylvania’s smallest frog species.
They display highly variable coloration—green, brown, gray, or combinations thereof—with a warty texture to their skin. A dark triangular spot between the eyes and dark banding on the legs provide reliable identification markers.
Key Features:
- Blunt snout
- Irregular color patterns (no distinct markings on back)
- Warty skin texture
- Small size (under 1.5 inches)
- Limited to eastern corner of Pennsylvania
Unlike most other small frogs in Pennsylvania, Eastern Cricket Frogs lack distinct markings or patterns on their backs. This absence of clear markings, combined with their warty appearance, makes them unique among the state’s small frog species.
You’ll find Eastern Cricket Frogs only in the eastern corner of Pennsylvania, where they inhabit ponds and small water bodies. Despite belonging to the tree frog family (Hylidae), they’re not particularly arboreal and spend most of their time on the ground near water.
Key Insight: Eastern Cricket Frogs get their name from their breeding call, which sounds exactly like the repeating chirp of a cricket. Once you learn this distinctive sound, you’ll never confuse them with actual crickets again.
These tiny frogs are excellent swimmers despite their small size. They can jump impressive distances relative to their body size—over 3 feet in a single leap—helping them escape predators. They’re active during the day, unlike many other small frog species, making them easier to observe.
Conclusion
The best time to find frogs in Pennsylvania runs from March through August, with peak activity during the spring breeding season. Visit wetlands, ponds, and vernal pools after sunset on warm, rainy nights for the most reliable frog encounters.
Learning their calls provides the most effective identification method since many species are more easily heard than seen.
Seasonal Timing:
- Late February to April: Wood Frogs and chorus frogs emerge first
- April to May: Spring Peepers at peak calling
- May to July: Bullfrogs, Green Frogs, and treefrogs actively breeding
- Late summer: Cricket Frogs most active
Pennsylvania’s 11 common frog species represent just a portion of the state’s amphibian diversity. Each species plays a vital role in controlling insect populations and serving as prey for larger animals.
By learning to identify these fascinating amphibians, you’re connecting with creatures that have adapted to survive Pennsylvania’s seasons through remarkable strategies—from freezing solid in winter to producing antifreeze in their cells.
Remember that frog populations face numerous conservation challenges, including habitat loss, pollution, climate change, and disease.
You can help by preserving wetland areas, avoiding pesticide use near water bodies, and reporting your frog sightings to the Pennsylvania Amphibian and Reptile Survey (PARS). Every observation contributes to conservation efforts protecting these incredible amphibians for future generations.
