2001 Frog and Toad Survey Isle Royale National Park, Michigan

Isle Royale National Park; Goodwin, Katy; Egan, Alexander

Isle Royale National Park, Michigan established a survey of frogs and toads in 1996 to monitor anuran populations on the island, as well as to integrate these findings with those of the Frog and Toad Survey Program conducted by the Michigan Department of Natural Resources. Four survey transects were established along park trails. In 2001. surveys were conducted in the early spring, late spring, and summer on all four transects. Each transect has 10 survey points, for a total of 40 survey points per run. The survey is based upon the calls given by the male frogs and toads during the various mating seasons. Call indexes were used to indicate the relative abundance of frogs and toads calling. These indexes were averaged and compared to those recorded in previous years. During the 2001 survey, all six species were heard on survey routes. The abundance of each species was similar to previous Isle Royale surveys and also agrees with regional population trends which indicate relatively low abundance for mink frogs, high abundance for spring peepers, and intermediate abundance for the other four species. Species richness varied with habitat type, and comparisons between mean call index and rainfall have shown a close correlation for four of the six species. Mean call index was also shown to be somewhat related to temperature.