Rana boylii Plasticity and Management Under Dam-controlled Flows in the Northern West-slope Sierra Nevada

Ryan Peek

Stillwater Sciences

Berkeley, CA

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ABSTRACT

PEEK, RYAN*, and SAPNA B. KHANDWALA
Stillwater Sciences, Berkeley, CA 94705, ryan@stillwatersci.com

Rana boylii Plasticity and Management Under Dam-controlled Flows in the Northern West-slope Sierra Nevada

Rana boylii (foothill yellow-legged frog) populations are found throughout the foothills of the Sierra Nevada, often occurring downstream of large dams that control flows for much of the year. Renewal of hydroelectric project licenses generally requires studies of project-related effects on surrounding ecosystems, to help inform the design of flow schedules that are consistent with species conservation and management.
Focused studies conducted in support of hydro-relicensing generally occur in two phases and are designed to fill gaps in our understanding of species ecology and potential responses to altered flows. The first phase is focused on local distribution and basic life history timing of R. boylii. The second phase focuses on a specific analysis of how the hydroelectric project may potentially affect the species, including habitat connectivity and the effects of regulated flows on breeding habitat. Based on case studies on the South Fork Feather and South Fork American rivers, results of first phase investigations have validated current research on R. boylii habitat use and local distribution in similar watersheds. In addition, our observations suggest R. boylii can occur in atypical habitats (man-made tunnels over a mile from the main channel, within roadside culverts, and along the banks of reservoirs).
Studies in the second phase, however, are generally more complex and ask more detailed ecological questions. We need an integrated, efficient approach that can maximize our understanding of flow effects on R. boylii (within the hydroelectric project relicensing time frame), that furthers both scientific research and overall species management goals.