Post-breeding dispersal and summer home range of female American toads (Bufo americanus)

Abstract

While many amphibians have complex life cycles involving a primarily terrestrial adult phase and an aquatic larval phase, use of terrestrial habits by adult forms remains poorly understood. We used radiotelemetry to track the post-breeding dispersals of 16 female Bufo americanus during the summer and fall of 2001 to determine the extent of upland habitat use by females of this species. Female toads dispersed a minimum of 250 m and up to 1000 m from the breeding pond with the majority (97%) of relocations occurring more than 400 m from the breeding site. Typically dispersal paths were non-random and linear, punctuated by periods of sedentary behavior. During periods of sedentary behavior females confined their activities to an area of several m2. Females employed 24-h movements of up to several hundred m when moving between activity centers. For 8 toads with > 22 recaptures, total area of upland habitat utilization ranged from 434 to 1305 m2 (mean = 717.7 m 2). All 16 toads were lost prior to entering winter torpor, including 10 confirmed cases of predation. Our study of post-breeding dispersal by female American Toads suggests terrestrial habitat use extending up to 1 km from the breeding site is common, and emphasizes the need for consideration of terrestrial as well as aquatic habitats in the development of conservation plans.