Imperiled foothill yellow-legged frogs are found in less than half of their historic habitat in the Sierra Nevada and coastline regions of California
SACRAMENTO — A frog smaller than a credit card has been added to the list of endangered species in California.
On Dec. 11, the California Fish and Game Commission approved California Endangered Species Act protections for five of six populations of the foothill yellow-legged frog, a species that has disappeared from more than 50% of its historic habitat in the state. The decision responds to a 2016 petition by the Center for Biological Diversity.
“This is really good news for these iconic but highly imperiled stream-dwelling frogs,” said Jeff Miller, a senior conservation advocate with the Center. “Protecting them will also help safeguard beautiful coastal and Sierra foothill streams which we all rely on for clean drinking water and recreation.”
The commission unanimously voted to protect Southern Sierra, Central Coast and South Coast populations of the frog as endangered; and the Northern Sierra and Feather River populations as threatened. The California Department of Fish and Wildlife determined that foothill yellow-legged frogs in California’s North Coast do not currently warrant protection.
Foothill yellow-legged frogs were once found in streams and rivers along the lower western slopes of the Sierra Nevada as well as in Pacific Coast drainages from the Oregon border to at least as far south as Los Angeles County. This species has now disappeared from more than half of its former California range.
Foothill yellow-legged frogs are impacted by a wide range of threats, including dams, water diversions, logging, mining, livestock grazing, climate change, pesticides, off-road vehicles, disease, urban and agricultural expansion and marijuana cultivation.
Adult foothill yellow-legged frogs (Rana boylii) are from 1.5 to 3 inches long, with a distinctive lemon-yellow color under their legs. They inhabit partially shaded, rocky perennial streams, and their life cycle is synchronized with the seasonal timing of streamflow conditions. These frogs need perennial water where they can forage through the summer and fall months.
The Northern Sierra population ranges from the Middle Fork American River in El Dorado County, north through the Sierra foothills to the upper Yuba River watershed in Plumas County. The Southern Sierra population ranges from the South Fork American River watershed, south through the Sierra foothills to the Tehachapi Mountains. The genetically unique Feather River population is primarily in Plumas and Butte counties.
At least half the known historical frog populations have been lost in every northern and central Sierra county except Plumas County. Healthy frog populations remain in the northern and central Sierras in the American, Clavey, Cosumnes, Feather, Merced, Mokelumne, Stanislaus, Tuolumne and Yuba rivers.
The Central Coast population lives south of San Francisco Bay in the Coast Ranges to San Benito and Monterey counties. Significant foothill yellow-legged frog populations remain in the Diablo Range. The South Coast population is west of the Salinas Valley in Monterey County and south into the southern Coast Ranges. These frogs have now disappeared from all coastal streams south of San Luis Obispo County.
The Center petitioned in 2012 to protect the foothill yellow-legged frog under the federal Endangered Species Act. Under a lawsuit settlement agreement with the Center, the U.S. Fish and Wildlife Service will decide by 2020 on whether the species warrants federal protection.