Pickerel Frog (Lithobates palustris)
Order: Anura; Family: Ranidae (True Frogs); Genus: Lithobates; Species: L. palustris. They are North American 'true frogs' characterized by dorsolateral folds and smooth skin.
Species
Pickerel Frog (Lithobates palustris)
Family
Order: Anura; Family: Ranidae (True Frogs); Genus: Lithobates; Species: L. palustris. They are North American 'true frogs' characterized by dorsolateral folds and smooth skin.
Size
Adults typically range from 1.75 to 3.5 inches (4.4 to 8.9 cm) SVL. Females are generally larger and more robust than males. They are slightly smaller on average than the closely related Northern Leopard Frog.
Conservation
Listed as Least Concern by the IUCN, but populations can be localized and are sensitive to water pollution and siltation. They are often used as bioindicators of healthy, unpolluted stream systems.
Description
The Pickerel Frog appears as a master of geometry in the amphibian world, adorned with precise rows of rectangular spots that look almost human-painted. Often found near cool, flowing water, this frog is a stunning inhabitant of the Appalachian streams and eastern meadows. Its most surprising secret is the hidden fire of yellow under its legs, revealed only when it leaps away.
Key Features
Two rows of rectangular dark spots between the ridges; light-colored dorsolateral folds; bright yellow/orange coloration on the hidden surfaces of the hind legs.
Physical Description
A medium-sized frog with a relatively slender, acrobatic body. It features a pointed snout, large eyes with gold/yellow irises, and prominent, light-colored dorsolateral ridges extending from the eye to the groin. The tympanum (eardrum) is smaller than the eye.
Skin Texture & Coloration
Skin is smooth. The dorsal color is tan to light brown, marked by two parallel rows of distinct, dark chocolate-brown, squarish or rectangular spots. A key feature is the bright yellow or orange 'flash' coloration on the inner thighs (groin area), which is a diagnostic marker for this species.
Distinguishing Features
The presence of two rows of hand-drawn looking square/rectangular spots between the dorsolateral folds, whereas look-alikes have rounded spots. Also, the bright yellow or orange wash on the inner surface of the hind legs is the most definitive field mark.
Habitat
Found in cool, clear waters such as rocky ravines, meadow streams, and brook edges. They are more terrestrial in summer, wandering into damp fields or grassy meadows far from permanent water. They prefer higher water quality than many other ranids.
Geographic Range
Common throughout the eastern United States and southeast Canada, ranging from the Maritime Provinces down to the Carolinas and west into the Mississippi Valley and eastern Texas.
Behavior
Nocturnal and crepuscular, though they can be seen during the day in high-quality habitats. They are strong jumpers and will leap into the water or tall grass to escape predators. If captured, they secrete a skin toxin that can be fatal to other frogs.
Diet & Feeding
An opportunistic carnivore eating various invertebrates including beetles, ants, spiders, sawflies, and snails. They use a sit-and-wait ambush strategy near the water's edge or in moist vegetation.
Reproduction
Breeding occurs from March to May depending on latitude. High-pitched, low-frequency 'snoring' calls are made underwater or at the surface. Amplexus is axillary. Females lay globular egg masses attached to submerged vegetation, containing 700 to 3,000 eggs.
Vocalizations
The call is a low-pitched, grating 'snore' that lasts about 1-2 seconds. It sounds somewhat like a low-pitched groan or a rusty door hinge creaking. It is often described as a 'descending snore' and lacks the 'chuckle' pulses of leopard frogs.
Life Cycle
Eggs hatch in 1-2 weeks. Tadpoles are greenish or brownish with dark spots and typically metamorphose into froglets in 60-90 days during the late summer. Sexual maturity is reached in about 2 years.
Conservation Status
Listed as Least Concern by the IUCN, but populations can be localized and are sensitive to water pollution and siltation. They are often used as bioindicators of healthy, unpolluted stream systems.
Toxicity & Defense
Specifically unique among North American frogs for producing toxic skin secretions (palustritoxin) that can irritate human skin and kill other frogs if kept in the same container. This serves as a potent deterrent against snakes and mammals.
Ecological Role
Functions as both a predator of terrestrial and aquatic insects and prey for birds and larger mammals. Their presence indicates high dissolved oxygen and low pollution in freshwater ecosystems.
Similar Species
Northern Leopard Frog (L. pipiens) has rounder spots that are irregularly placed and lacks the yellow groin wash. Mink Frog (L. septentrionalis) has more mottling and a musky odor.
Observation Tips
Listen for their 'snoring' calls during spring rains near slow-moving streams. During summer, look in tall, damp grass near water. Using a flashlight to spot eye-shine on brook banks at night is particularly effective.
Handling & Safety
Warning: Do not handle this frog and then touch your eyes or mouth, as their secretions can cause severe irritation. If you must handle, use wet hands and wash them thoroughly afterward. Never house them with other frog species.
Seasonal Activity
Active from early spring through autumn. During winter, they hibernate underwater in the muddy bottoms of springs and streams, often staying active under ice in very oxygen-rich water.
Cultural Significance
Commonly cited in North American nature literature as a sign of spring. Their sensitivity to pollution makes them culturally symbolic of environmental purity and the health of local watersheds.
Interesting Facts
The Pickerel Frog is the only endemic poisonous frog in the United States. Its name comes from the fact that it was frequently used as bait for pickerel and other fish, although its toxicity makes it unpalatable to some predators.