Plains Leopard Frog
Rana blairi
Summary: This grassland species barely enters the southwestern part of the Chicago region, with records from Will, Kankakee, and Grundy Counties. A series of juveniles collected in southwest Cook County may represent a release, since subsequent searches have not located the species there.
Description: The plains leopard frog is of medium size, 2.0 to 4.0 inches (5.1 to 10.2 cm), often brown or tan above, less often dark green. There is a light line on the upper jaw, and usually a small light spot on each tympanum. The underside is whitish, sometimes with a wash of pale yellow in the groin area. It differs from the northern leopard frog primarily in its round or oval dark spots without distinct light borders; and in the dorsolateral folds, which are broken and offset slightly to the inside at the very rear.
The Plains Leopard Frog was described as a species only in 1975.
Distribution and Status: This is a great plains grassland frog, which barely extends into the southwestern periphery of our region. The only valid records are from Will, Kankakee, and Grundy Counties, Illinois. Two old Indiana records are from south of our limits. A few juvenile specimens from Cook County reported by Brown and Morris (1990) are of this species, but I attribute the record to an intentional or accidental release. The locality is heavily used by the public and has been thoroughly inventoried by many workers over several decades, but there heve been no other specimens reported there. The northernmost recent record in the Chicago region is near Monee.
Habitat: This is a species of the former prairies, although most current localities are at disturbed sites. Because of the limited number of populations in our area not much specific habitat information is available. Will County populations are mostly within non-native grassland near water. A little to the southwest where the plains leopard frog is more common, breeding occurs in marshes and in man-made ponds, with many adults remaining in the general vicinity of the water throughout the active season. Near St. Louis open portions of floodplains along major rivers are frequented.
Voice: Two or three fast and short notes, delivered within a second or so, described as "chuck, chuck."
Phenology: No breeding information is available for our region; in central Illinois I have heard calling activity in late March and April. In more arid regions to the west breeding is opportunistic and associated with storm events. In Kansas I have seen recently transformed juveniles in mid-August.
Literature Cited:
Brown, L. E., and M. A. Morris. 1990. Distribution, habitat, and zoogeography of the plains leopard frog (Rana blairi) in Illinois. Illinois Natural History Survey Biological Notes 136:1-6.
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| Updated: October 9, 2007
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