Smith, Brian E. 1996. A Problem with Amphibian Calling Surveys: Not All Species are Equally Observable. 10 p.

Abstract

Sites in and around the Black Hills of western South Dakota were surveyed for reptiles and amphibians during the summer of 1996. On the basis of observations of tadpoles or metamorphs, several reproducing populations of northern leopard frogs (Rana pipiens) were discovered relatively late in the active season, whereas chorusing groups of this species were never found. A case history of one such population is given, and data from the literature and anecdotal sources are presented which suggest that calling amphibians surveys may be inadequate for quickly and accurately detecting the presence of this species. The inability of an herpetological field crew to detect chorusing populations of northern leopard frogs, peculiarities of the natural history of this species, and anecdotal evidence from several sources leads to the conclusion that calling amphibian surveys may be inadequate to assess population trends of northern leopard frogs, at least in certain areas. Lack of knowledge of natural history and chorusing behavior could hamper efforts to monitor other species as well.