Abstract

Studies of resource selection at multiple scales are critical to understanding ecological and evolutionary attributes of a species. We analyzed relative abundance, habitat use, and oviposition site selection of Foothill Yellow-Legged Frogs (Rana boylii) at 11 localities across two geographic regions in California (northern Coast Range and Sierra Nevada) over 16 yr. We found narrow ranges for oviposition microhabitat characteristics (water depth, water velocity, and stream substrate) among study localities. At the Main and South forks of the Trinity River, variances of the habitat traits were lower for oviposition microsites than for random points within breeding areas, indicating fine-scale selection. On the South Fork Trinity, egg mass relative abundances were negatively associated with water depth and positively associated with distance from the shoreline, suggesting that breeding areas with high egg mass relative abundances generally occurred in wide shallow areas. We observed long-term repeated use of breeding sites. At the South Fork Trinity, 63% of potentially suitable breeding areas were used consecutively for 3 yr, and at Hurdygurdy Creek several areas were used in ≥11 yr. Oviposition site selection and microhabitat specificity may result in population stability even within the substantial temporal and spatial variability of stream environments. Management of stream environments and conservation plans for R. boylii could benefit by preserving hydrologic processes that produce these specific habitats and identifying and protecting high-use breeding areas.