Movement patterns and relative abundance of coastal tailed frogs in clearcuts and mature forest stands

Abstract

Age-specific movements, abundance, and capture rates of coastal tailed frogs (Ascaphus truei Stejneger) were compared between clearcuts and mature forests in southwestern British Columbia, Canada, during 1998 and 1999 using pitfall traps and drift-fence arrays. Total frog abundance was similar in both habitat types. More adults were caught in mature stands than in clearcuts, but there was no significant difference for immatures. Analysis of numbers of frogs captured indicated that the direction of movement did not differ between habitat types for any age-class. Frogs were captured at similar frequencies across distance from stream in both habitats. These findings suggest that there are age-specific differences in tailed frog abundance in clearcuts along streams without riparian reserves relative to mature forests. Variation among sites had a greater influence than habitat type on the number of immatures. Low proportions of adults in clearcuts suggested that immatures may be transient or that they incurred high rates of mortality. Age-specific differences in habitat use by tailed frogs indicated that total numbers alone are insufficient to determine the effect of forest management on habitat suitability for tailed frogs.