STATUS OF THE CALIFORNIA RED-LEGGED FROG (RANA DRAYTONII) IN THE STATE OF BAJA CALIFORNIA, MEXICO

Abstract/Summary

The California Red-legged Frog (Rana draytonii) is a threatened species in the United States that has undergone population declines, especially in southern California. Due to the lack of information on the status of Mexican populations, we surveyed for the presence of R. draytonii in Baja California and assessed possible threats to population persistence. The two-year study (2013−2014) extended from the U.S.-Mexican border to the southern end of the species distribution in the Sierra San Pedro Mártir. We found R. draytonii at six of 15 historical sites, none of five proxy sites and four of 24 additional sites sites. All 10 occupied sites are confined to three watersheds within the Sierra San Pedro Mártir (two sites at Arroyo San Rafael, two sites at Arroyo San Telmo, and six sites at Arroyo Santo Domingo). Capture rates ranged from 1–11 individuals per visit, with the exception of La Grulla, where the average was 68. Rana draytonii was absent from 9 historical sites, including the highest elevation site at La Encantada and numerous drainages in low-lying coastal areas, suggesting the species is in decline in Baja California. The main threats identified across the study area include presence of exotic animal species, water diversion, and cattle grazing. Management of the remaining populations and local education is needed to prevent further declines.

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