Pickerel Frog
Rana palustris
Summary: Probably always rare in the region, the current status of this species is uncertain. The only relatively recent valid reports are from Walworth County. Old historical records are available for McHenry, Kane, and Porter Counties. Graminoid fens and fast flowing streams with bordering dense vegetation are the preferred habitats.
Description: A medium-sized frog, 1.75 to 3.0 inches (4.4-7.5cm). Two regular rows of rectangular dark brown blotches down the back, between a pair of raised light dorsolateral folds. Additional smaller brown blotches on the sides. The ground color is tan to light brown. The underside is white.
Pickerel frogs and leopard frogs are similar in appearance and easily confused. The best field character for the pickerel frog is the presence of bright yellow-orange flash colors under the hind legs; however, it is usually necessary to capture the frog to see these. The regular rows of rectangular spots usually are reliable, but occasional leopard frogs mimic this pattern. Pickerel frogs also have wider dorsolateral folds and a more rounded snout, but these last characters are subtle and are usually of use only to more experienced observers.
Distribution and Status: The pickerel frog has always been rare in the Chicago region, and there have been no verified records in many years. Redmer and Mierzwa (1994) summarized the Illinois distribution. Two McHenry County specimens date from 1926 and 1930. Two 1949 specimens are available from near Dundee in Kane County. There are a number of recently verified populations in northwestern Illinois, but none approach our area.
In Indiana, the only record from within the region is old and is from the dunes area. A population was verified just to the east in St. Joseph County, Indiana in the late 1970s. There are also two reports from Walworth County, Wisconsin.
Good pickerel frog habitat still exists in several places, and additional searches should be encouraged. Because of the past frequency of misidentification -- including errors by at least one prominent herpetologist -- a photograph or voucher specimen for any new locality is strongly recommended.
Habitat: In northwestern Illinois, pickerel frogs occur in two situations: along the margins of high-gradient streams in dense, low vegetation, usually in sunlit patches but near tree cover; and in cool, seepage-fed graminoid fens. In both habitats, frogs would often attempt to escape by leaping into water and then back into bordering vegetation.
In Indiana, pickerel frogs occur along the margins of sunlit ponds and low shrub fens within mostly forested sites.
Voice: The call is a low-pitched snore similar to that of the northern leopard frog, but more regular. It is difficult to hear at any distance.
Phenology: Breeding apparently begins in early April and continues into early May. In Wisconsin the larval period is 60 to 80 days (Vogt, 1981). Juveniles which had recently completed metamorphosis were found in northwestern Illinois on July 2, 1988 (Redmer and Mierzwa, 1994).
Field Notes
May 14, 1988. Lee County, Illinois. Sunny and warmer, low 80s. Lots of Rana palustris, 10 - 20, along a wooded stream and the adjacent fen, two or three more by a beaver dam.
Literature Cited
Redmer, M., and K. S. Mierzwa. 1994. A review of the distribution and zoogeography of the pickerel frog, Rana palustris, in northern Illinois. Bulletin of the Chicago Herpetological Society 29:21-30.
Vogt, R. C. 1981. Natural History of Amphibians and Reptiles of Wisconsin. Milwaukee Public Museum.
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| Updated: October 9, 2007
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