Pickerel frog (Lithobates palustris)
|Size||Male length: 4 - 5.8 cm (2)|
Female length: 5.5 - 7.2 cm (2)
Male weight: 6.2 - 17.6 g (2)
Female weight: 19.7 - 45.7 g (2)
The pickerel frog is classified as Least Concern (LC) on the IUCN Red List (1).
A relatively common, medium-sized amphibian found in North America (2), the pickerel frog (Lithobates palustris) is characterised by squarish or rectangular-shaped spots or blotches which run in two parallel lines along its back. The pickerel frog is often mistaken for the northern leopard frog (Lithobates pipiens), but the shape of the distinctive blotches can be used to distinguish the two species, with the northern leopard frog having more oval-shaped spots (2) (3) (4).
Generally, the pickerel frog is tan, bronze, light brown or greenish-grey above, and the dark spots are rusty brown with black borders (2) (4) (5). In some parts of the pickerel frog’s range, the spots on the back may merge, forming bars or stripes (3). The underside of this species is usually white (2) (4), although this also varies across its range, being white in some regions and mottled with brown in others (3). The legs of the pickerel frog have bold dark bands (2), and the underside of the hind leg is yellow or orange. There is a light-coloured stripe running along the jaw (3), while the back has a thick yellow, white or cream stripe running from the ear to the pelvis (2) (3) (4).
The female pickerel frog is usually larger and darker than the male. The male may also be distinguished during the breeding season by an internal vocal sac found between the tympanum and the foreleg, and by its swollen thumbs (2). Tadpoles of the pickerel frog are yellowish to yellowish-brown, becoming more olive-green to grey-brown above and creamy white below as they grow (5) (6).
The call of the pickerel frog resembles the sound of tearing cloth or a quiet, long, drawn-out snore (2) (5).
The pickerel frog occurs throughout the eastern United States, ranging from Wisconsin south to South Carolina and northern Georgia, and west to Texas. This species also occurs in southern Canada (1) (2).
The pickerel frog is absent from the extreme south-eastern part of the country (1) (2), including most of the Gulf Coast and Florida, as well as central Illinois and northwest Ohio (2).
The pickerel frog is usually found in habitats with slow-moving water and low, dense vegetation. This species lays its eggs in standing water, in a woodland pond, stream pool or flooded ditch, where there are few or no fish (1).
After breeding, the pickerel frog will disperse from the breeding sites and move to a nearby wetland or upland area, such as a swamp, marsh, stream, meadow or damp wood (2) (1) (3). It is often found near cool, clear streams and ponds in the more northern parts of its range, while in the south it may inhabit warm, turbid swamps (1).
During the winter, the pickerel frog hibernates in the mud in the bottom of ponds, or in ravines, springs or under rocks. In some areas it may hibernate in caves (1) (2).
The pickerel frog is primarily terrestrial, spending most of its time on land even during the breeding season. It will, however, take to the water to thermoregulate. The pickerel frog will also enter the water to avoid predators, such as birds and snakes (2). Like many amphibians, the pickerel frog can protect itself further by producing toxic, irritating skin secretions which are distasteful to many predators (2) (3). (2).
The majority of the pickerel frog’s prey is captured on land, with its diet consisting of small invertebrates, such as beetles, caterpillars, ants and spiders. In the water, the pickerel frog will forage for a variety of prey, including snails, crayfish and small amphibians (2).
The pickerel frog hibernates from October to March or April. The breeding season begins once the pickerel frog emerges in early spring, usually after heavy rainfall. At its breeding sites, this species is usually gregarious, gathering in large groups in the water. The male pickerel frog initiates courtship by giving a series of low-pitched calls, often while submerged (2).
The female pickerel frog lays a cluster of 2,000 to 3,000 eggs, which are attached to submerged aquatic vegetation. The eggs hatch after about 2 weeks, and the tadpoles complete metamorphosis and develop into young frogs within 8 to 11 weeks (5) (6). This species become reproductively mature at between two and three years old (5) (6).
There are currently no major threats to the pickerel frog. However, this species has undergone local population declines in some areas due to habitat modification, clear-cutting of woods and forests, and increasing urbanisation (1).
The pickerel frog is found over a wide geographic range and has a large, stable population. It also occurs in many protected areas across North America, and there are therefore currently no specific conservation measures in place for this species (1).
Find out more about the pickerel frog:
Rhode Island Vernal Pools - Pickerel frog:
Find out more about amphibian conservation:
IUCN/SSC Amphibian Specialist Group:
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- Hibernation: a winter survival strategy in which an animal’s metabolic rate slows down and a state of deep sleep is attained. While hibernating, animals survive on stored reserves of fat that they have accumulated in summer.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.
- Metamorphosis: abrupt physical change from the larval to the adult form.
- Thermoregulate: to control the body temperature.
- Turbid: cloudy or muddy; not clear.
- Tympanum: also known as the eardrum. A thin membrane that transmits sounds from the air to the middle ear.
IUCN Red List (September, 2011)
Rhode Island Vernal Pools - Pickerel frog (September, 2011)
- King, W. and Behler, J.L. (1988) The Audubon Society Field Guide to North American Reptiles and Amphibians. Random House USA, Inc., New York.
Yale Peabody Museum of Natural History - Pickerel frog (September, 2011)
Minnesota Department of Natural Resources - Pickerel frog (September, 2011)
- Beane, J.C., Braswell, A.L., Mitchell, J.C., Palmer, W.M. and Harrison, J.R. (2010) Amphibians and Reptiles of the Carolinas and Virginia, Second Edition. University of North Carolina Press, Chapel Hill, North Carolina.