Sympatry in Bufo horeas and Bufo canorus and Additional Evidence of Natural Hybridization

Abstract

The second case of sympatry and hybridization between Bufo boreas and B. canorus in the Sierra Nevada Mountains is reported. The location of contact is Frog Lakes, a group of tarns at 3,170 m elevation in Mono County, California. Specimens of both species were collected in late summer of 1976. General appearance, amount of ventral pigmentation, and particularly measurements of parotoid gland width and of hind foot web length indicate that several of the specimens are actually hybrids.