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Response of Western Pond Turtles to Drought

Photo of A western pond turtle at the San Joaquin Experimental Range in California. USDA Forest ServiceA western pond turtle at the San Joaquin Experimental Range in California. USDA Forest ServiceSnapshot : Western pond turtles (Actinemys marmorata) are declining throughout most of their range. The population studied at the San Joaquin Experimental Range in central California appeared to be rebounding following control efforts on introduced bullfrogs (Lithobates catesbianus), which eat hatchlings and juvenile turtles. Unfortunately, following four years of record low precipitation in California, western pond turtle populations at the San Joaquin Experimental Range have suffered high levels of mortality. Drought appears to negatively impact pond turtle populations.

Principal Investigators(s) :
Purcell, Kathryn L. 
Research Location : San Joaquin Experimental Range (California)
Research Station : Pacific Southwest Research Station (PSW)
Year : 2015
Highlight ID : 794


The western pond turtle (Actinemys marmorata) is a Species of Special Concern in California and a candidate for federal listing. In 2006 the pond turtle population at the San Joaquin Experimental Range in Madera County, Calif., was estimated at only 10-12 individuals and consisted entirely of individuals greater than 12 years of age. Following the initiation of bullfrog (Lithobates catesbianus) control efforts, juvenile turtles appeared to be rebounding. Four years of drought have caused the stock pond that serves as their primary water source to dry up in late summer (2012 and 2013) or to not form at all (2014 and 2015). Forest Service scientists observed high levels of turtle mortality during this period, which was negatively correlated with precipitation. The scientists observed extensive terrestrial movements and movement into new areas, both which of which make them vulnerable to predation are considered risky behavior. The scientists concluded low precipitation and drought are likely to negatively impact the already imperiled pond turtle populations in California. ?

Forest Service Partners

External Partners

  • Brian Todd, Department of Wildlife and Conservation Biology, University of California, Davis