Abstract

Movement ecology and seasonal distribution of mountain yellow-legged frogs (Rana muscosa) in Dusy Basin (3470 m), Kings Canyon National Park, California, were characterized using passive integrated transponder (PIT) surveys and visual encounter surveys. We individually PIT-tagged 500 frogs during the summers of 1997 and 1998 and monitored these individuals during seven recapture surveys in 1997 and 15 recapture surveys in 1998 from the time they emerged from overwintering in July until the lakes froze for the winter in October. Probability of movement between lakes was associated with abundance of Hyla regilla larvae in the different lakes of origin, activity of the frogs (overwintering, breeding, feeding), and time of year. Overland movements exceeding 66 m were observed in 17% of the tagged frogs. Movement between lakes 1 km apart was detected. Site fidelity from 1997 to 1998 was high, and 97% of the tagged frogs recaptured in October of both years were found in the same overwintering lakes. Frogs were more narrowly distributed in spring and fall than in summer. Summer frog densities (number per meter of shoreline) were positively related to water temperature, air temperature, maximum lake depth, and presence of H. regilla larvae and negatively related to presence of trout. Mountain yellow-legged frogs use a range of aquatic sites throughout their activity period, and basins with a variety of deep lakes and shallow ponds may be the most appropriate reserves for this declining species.