Michigan Bluff California Red-Legged Frog (Rana draytonii) Habitat Assessment, Surveys and Population Estimate

ECORP Consulting, Inc. performed a habitat assessment and protocol-level surveys for the federally threatened California red-legged frog (Rana draytonii; CRF) at a recently discovered site in the Sierra Nevada foothills near Foresthill. The primary purpose of the surveys was to develop an estimate of the CRF adult/sub-adult population at the site. Diurnal and nocturnal surveys were conducted according to the Revised Guidance on Site Assessments and Field Surveys for the California Red-Legged Frog (USFWS 2005). The overall habitat assessment also included a preliminary evaluation of other aquatic features within five-miles of the site to evaluate potential connectivity with other possible CRF breeding habitats. This task was accomplished using aerial photography, USGS/Forest Service maps, and other remote sources, and site visits where possible.


Both habitat assessment and survey results were compiled in formal reports for the client and for submittal to the U.S. Fish and Wildlife Service. Based on habitat and survey information, each aquatic habitat was assessed relative to its overall quality for CRF breeding, larval development through metamorphosis, and juvenile/adult summer refugia, including a preliminary evaluation the stability of the habitat over time. In addition, potential issues that could negatively impact CRF either at a breeding site or within the site itself was identified and discussed. Recommendations for resolving existing habitat issues, enhancing aquatic and terrestrial conditions, and/or creating new habitat were also provided in the final report.

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