Plains Leopard Frog Lithobates blairi

Description: Adult Morphology: A medium-sized, brown to olive-green frog with irregular dorsal spots. In this species, the spots have no light borders and there is usually a spot on the snout. The dorsolateral folds on plains leopard frogs are broken and inset posteriorly (near the hind legs), a key feature distinguishing them from other Indiana leopard frogs. The tympanum has an obvious light center and a distinct line along the upper jaw is present (as it is in other leopard frogs).

Size: Most adults reach lengths of around 2-2.5 in (45-65 mm), but in western populations some frogs grow to nearly 4 in (100 mm).

Larvae: Tadpoles are difficult to distinguish from other Indiana leopard frogs. Plains leopard frog tadpoles have been noted as being generally more slender and rounded with a noticeably more subterminal mouth than the larvae of the northern leopard frog (L. pipiens). They grow to approximately 2 in (~60 mm) in length.

Eggs: Eggs are similar to those of other leopard frogs and are deposited in globular masses attached to vegetation or sticks.

Similar Species: Both northern (Lithobates pipiens) and southern (L. sphenocephalus) leopard frogs are very similar in appearance to this species. In general, other leopard frog species tend to have more green coloration whereas plains leopard frogs are often uniformly brown. While plains leopard frogs lack the light borders around their spots that northern leopard frogs have, both species tend to have a spot on their snout (which southern leopard frogs usually lack). The dorsolateral folds of this species are broken and inset near the hind legs, separating it from all other frogs in the state. The vocalizations of plains leopard frogs superficially resemble those of southern leopard frogs and the two could be confused. This species has been found alongside both northern and southern leopard frogs in Indiana, though all three species are not known to co-exist anywhere in the state. The pickerel frog (L. palustris) is similar in appearance, but has rectangular blotches running down the back in organized rows and a bright yellow wash on the groin and rear legs. Crawfish frogs (L. areolatus) are much larger and have a blunt, rounded snout and a more reticulated pattern between its dorsal spots.

Distribution: This frog is a species of the Great Plains and occurs throughout the central United States. They are found from New Mexico and Texas, north into South Dakota and east into Illinois and the western half of Indiana.

The range of this species in Indiana is not well-understood. There are only a few records scattered along the western (primarily northwestern) part of the state with the exception of a single Tipton County record. The range of this frog coincides roughly with the eastern extent of the prairie peninsula which reached its easternmost limit in northwestern Indiana. Where they have been found in Indiana, plains leopard frogs occur alongside either northern or southern leopard frogs which may partially account for its lack of documentation in the state. The only recent records for this species are from Vigo and Newton Counties. In Vigo County, the frogs are sympatric with southern leopard frogs while they are sympatric with northern leopard frogs in Newton County.

Activity: Plains leopard frogs are generally active from March to October. However, nothing is known of its activity patterns in Indiana.

Breeding Season: In other states, plains leopard frogs breed from late March to early May. They will also occasionally breed in the fall. Due to the paucity of records, virtually nothing is known about its breeding season in Indiana.

Taxonomy: Plains leopard frogs (Lithobates blairi) are in the family ranidae which includes eight species of frogs in Indiana. All Indiana ranids were formerly placed in the genus Rana, but have since been moved to the genus Lithobates. They belong to a species complex that includes northern leopard frogs (L. pipiens) and southern leopard frogs (L. sphenocephalus) which were formerly considered to comprise a single species (Rana pipiens). Occasionally, plains leopard frogs will hybridize with other leopard frogs, but this appears to be relatively rare, despite the extensive range in which they are sympatric. Even though multiple leopard frog species may be found utilizing the same habitat, their calls are distinctive which likely accounts for the low rate of hybridization.

Ecology: Habitat: In other states, plains leopard frogs are found in association with open habitats such as old fields, grassland, marshes, and along the margins of highways and agricultural areas. They apparently avoid forested areas and are scarce in and around plowed fields. They require wetlands or ponds in which to breed and are rarely found far from water. Morphological evidence suggests that this species is more adapted for breeding in streams than the other leopard frogs in the state. Historically, this species was almost certainly a prairie inhabitant, but has adapted to more disturbed environs following the loss of most native prairie habitat. In Indiana, frogs have been collected in open habitat near streams and in low-lying wetlands.

Diet: Plains leopard frogs prey on crickets and earthworms, among other invertebrates.

Reproduction and Life History: Plains leopard frogs breed from March to May in still water. They begin to breed with the first warm, spring rains. While they may be found near streams, they are primarily a wetland breeder and will utilize marshes, ponds, and low flooded areas.

Call: The call of this frog has been described as a "chuck-chuck-chuck", lasting about a second.

Conservation: Because records for plains leopard frogs are few and scattered in Indiana, virtually nothing is known about its conservation status. This frog may have experienced population declines associated with the loss of Indiana's native grasslands, however, since Indiana lies on the eastern periphery of the species’ range it is possible that the frog was never a common resident in the state. In Indiana, it is sympatric with other leopard frog species and will occasionally hybridize with them. Plains leopard frogs are considered a state endangered species in Indiana due to a scarcity of records.

Literature

Burris, J. and A. Hoffman 2014. Lithobates blairi. Plains Leopard Frog. Geographic distribution (Newton County). Herpetological Review 45:87.

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.

Conant, R. and J. T . Collins. 1998. Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin, New York, New York.

Engbrecht, N. E., J. A. Crawford, and M. J. Lannoo. 2009. Lithobates (=Rana) blairi (Plains Leopard Frog)County Record. Herpetological Review 40.4:446.

Frost, J. S. and J. T. Bagnara. 1977. Sympatry Between Rana blairi and the Southern Form of Leopard Frog in Southeastern Arizona (Anura:Ranidae). Southwestern Naturalist 22.4:443-453.

Hillis, D. M. and T. P. Wilcox. 2005. Phylogeny of the New World true frogs (Rana). Molecular Phylogenetics and Evolution 34.2:299-314.

Hillis, D. M., J. S. Frost, and D. A. Wright. 1983. Phylogeny and Biogeography of the Rana Pipiens Complex: A Biochemical Evaluation. Systematic Biology 32.2:132-143.

Hillis, D. M. 1982. Morphological Differentiation and Adaptation of the Larvae of Rana berlandieri and Rana sphenocephala (Rana pipiens Complex) in Sympatry. Copeia 1:168-174.

Korky, J. K. 1978. Differentiation of the Larvae of Members of the Rana pipiens Complex in Nebraska. Copeia 3:455-459.

Kruse, K. C. 1981. Phonotactic Responses of Female Northern Leopard Frogs (Rana pipiens) to Rana blairi, a Presumed Hybrid, and Conspecific Mating Trills. Journal of Herpetology 15.2:145-150.

Lynch, J. D. 1978. The Distribution of Leopard Frogs (Rana blairi and Rana pipiens) (Amphibia, Anura, Ranidae) in Nebraska. Journal of Herpetology 12.2:157-162.

Minton, S. A. Jr. 2001. Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN.

Transeau, E. N. 1935. The Prairie Peninsula. Ecology 16:423–437.

Distribution Map
Distribution map of Plains Leopard Frog (Lithobates blairi)
Photographs