We were happy to learn that a few days ago the California Fish and Game Commission voted unanimously to designate two species of native yellow legged frogs inhabiting high-elevation lakes in the Sierra Nevada and Southern California mountain ranges as threatened and endangered species under the state’s Endangered Species Act. The commission acted after the Center for Biological Diversity filed a petition outlining the decline.
According to the Center, the population of Sierra Yellow legged frogs has decreased by 75% in recent decades. Reading about these frogs, we were struck by how they are a symbol of the challenges that frogs face worldwide. But they aren’t facing one challenge—they seem to be facing almost all of them:
Introduction of nonnative species: Stocking of nonnative trout in high-elevation Sierra lakes has been the main cause of the species’ decline. The trout eat tadpoles and juvenile frogs and alter the food web of the aquatic ecosystems on which the native frogs depend. The Department is recommending no trout stocking in the state without a fish management plan, and no further stocking of trout in areas that would conflict with protecting yellow-legged frogs.
Pesticides: Recent research has linked pesticides that drift from agricultural areas in the Central Valley to declines of native amphibians in the Sierra Nevada. Pesticides and other pollutants can directly kill frogs and also act as environmental stressors that render amphibians more susceptible to diseases, including a chytrid fungus that has recently ravaged many yellow-legged frog populations.
Loss and degradation of habitat: Grazing, logging, water diversions, off-road vehicles and recreational activity are allowed in frog habitat.
Climate change: Climate change has brought warmer temperatures, decreases in runoff, shifts in winter precipitation in the Sierra from snow to rain, and habitat changes that are rendering frog populations more vulnerable to drought-related extinction events.
A recent settlement agreement with the Center for Biological Diversity, which will also speed protection decisions for 756 other species, requires the U.S. Fish and Wildlife Service in 2013 to make a decision about whether to add the Sierra frog to the federal endangered list.
See the Center for Biological Diversity for more information about these frogs and about the other endangered species they are working to protect.