SEASONAL MIGRATION AND EARLY-STAGE DISPERSAL PATTERNS IN ADULT AND JUVENILE RED-LEGGED FROGS (RANA DRAYTONII)

Hale V Garcia-Dean; Sonoma State University; garciadean@sonoma.edu; Jennaca Hajek, Jeffery T. Wilcox, Derek J. Girman

We examined the patterns of dispersal and seasonal migration in the California Red-legged frog (Rana draytonii), a federally threatened species. We used radio telemetry techniques to examine the movement patterns and habitat use of post-breeding adults and metamorphs migrating away from an established breeding pond in a grassland and oak-savannah habitat in Sonoma County, CA. By sampling one to three times per 24-hour period, we were able to evaluate the effects of weather, canopy cover, ground moisture, and time of day on migration, forays, and rate of movement across these age classes. We found significant patterns of movement with respect to time of day, precipitation, wind, canopy cover and location relative to known moisture corridors (inundated waterways and wetlands). Patterns of humidity also impacted movements of non-migrating frogs making frequent forays between the pond and adjacent wetlands. Both experienced adults and naïve metamorphs demonstrated a non-random orientation away from the pond, suggesting a preference for specific landscape features. Finally, preliminary results suggest that short-term survivorship of first year metamorphs may be highly dependent on microhabitat use and dispersal timing.

Ecology and Conservation of Amphibians and Reptiles   Student Paper