The Distribution of Leopard Frogs (Rana blairi and Rana pipiens) (Amphibia, Anura, Ranidae) in Nebraska

Extensive collecting of leopard frogs (Rana blairi and R. pipiens) in Nebraska reveals that the large zone of sympatry heretofore recognized in central and eastern Nebraska is fragmented. Rana pipiens occurs as disjunct populations on the isolated Sandhills formations in south-central Nebraska. Within the largest zone of sympatry (in northeast Nebraska) hybridization is infrequent (hybrids comprise usually less than 5% of the pooled populations). Ecologic isolation is in part effected by selection of different substrates by the two species. Rana blairi occurs in loess soil areas whereas R,. pipiens predominates in areas of sandy soils.