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For Immediate Release, January 25, 2010

Contact: Jeff Miller, Center for Biological Diversity, (510) 499-9185

California Endangered Species Act Protection Sought to Save Mountain Yellow-legged Frog
From Exotic Trout, Habitat Destruction, and Disease

SAN FRANCISCO  The Center for Biological Diversity today petitioned the California Fish and Game Commission to list all populations of the highly imperiled mountain yellow-legged frog as endangered under the California Endangered Species Act. Mountain yellow-legged frogs inhabit high-elevation lakes, ponds, and streams in the Sierra Nevada Mountains and Transverse Ranges of California and are on a rapid trend to extinction. Their rapid decline is due to predation by introduced trout, spread of diseases that may be exacerbated by exposure to pesticides, and habitat alterations caused by climate change, drought, and livestock grazing.

“Once the most abundant frog in the high Sierra, the mountain yellow-legged frog now barely clings to survival,” said Jeff Miller, a conservation advocate with the Center for Biological Diversity. “The mountain yellow-legged frog needs the protections of the California Endangered Species Act to have any chance at recovery.”

Although mountain yellow-legged frogs throughout California should be protected under the federal Endangered Species Act, the U.S. Fish and Wildlife Service has only listed the Southern California population as endangered. In response to a 2000 petition filed by the Center for Biological Diversity, the Service determined that Sierra Nevada mountain yellow-legged frogs also warrant federal listing as endangered, but that such listing is precluded by actions to list other species. As a fallback the agency placed the Sierra population on the candidate list, which does not confer federal protection. The average time on the waiting list for candidate species is 17 years, and many animals and plants have gone extinct while languishing on this list.

“Continued delay of federal protection for all mountain yellow-legged frog populations is placing this unique California amphibian at risk of extinction,” said Miller. “Without federal action, this frog needs protection under the California Endangered Species Act.”

Only a few decades ago, it was difficult to walk around many of the Sierra’s alpine lakes without tripping over diminutive mountain yellow-legged frogs, known as “mountain gnomes.” These hardy survivors of freezing Sierra winters are vulnerable to a host of modern threats that have driven the species to the brink of extinction. Surveys since 1995 at 225 historic frog localities show extinction of 93 percent of the northern and central Sierra populations and 95 percent of southern populations.

This month the California Department of Fish and Game released a final environmental impact report on the impacts of stocking of hatchery fish on mountain yellow-legged frogs and other imperiled species, which unfortunately failed to adopt sufficient mitigation to protect the species from the impacts of past and ongoing fish stocking.

The Center for Biological Diversity is a national nonprofit conservation organization with more than 255,000 members and online activists dedicated to the protection of endangered species and wild places.


Mountain yellow-legged frogs are adapted to high-elevation habitats without aquatic predators. Widespread stocking of nonnative trout in high-elevation Sierra lakes by the California Department of Fish and Game has been the primary cause of decline for the species. Introduced trout prey on tadpoles and juvenile frogs and change the food web of the aquatic ecosystems frogs depend upon. Since 2000, the National Park Service and U.S. Forest Service have begun removing nonnative trout from some high Sierra lakes on federal lands in an attempt to restore yellow-legged frog populations.

In 2006 the Center for Biological Diversity filed suit against Fish and Game for failing to complete an environmental review of the impacts of fish stocking on sensitive aquatic species; in 2007 a court ordered the state agency to conduct a public review of the stocking program’s impacts. In 2008 Fish and Game agreed to interim restrictions prohibiting stocking trout in water bodies with species sensitive to nonnative fish. Although the state has taken steps to reduce trout stocking in areas with yellow-legged frogs, stocked trout continue to harm frog populations and limit recovery. Permanent protection and management decisions to stop stocking and remove trout in key frog habitats are necessary to reduce trout predation of mountain yellow-legged frogs.

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.

Mismanagement of national forest lands has degraded frog habitat where livestock grazing, logging, off-road vehicles, and recreational activity are allowed in frog habitat. Rapid 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.

The mountain yellow-legged frog was recently re-described by scientists as two distinct species: the southern mountain-yellow-legged frog (Rana muscosa), which occurs in the southern Sierra and Transverse Ranges of Southern California; and the Sierra Nevada mountain yellow-legged frog (Rana sierrae), in the central and northern Sierra.

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