Threatened frog species released into California forest after successful breeding program

A group of wildlife biologists in Northern California took another step in the conservation effort of the threatened Foothill yellow-legged frogs on June 30, releasing 115 of the frogs into the Feather River in Plumas National Forest.

According to the U.S. Fish and Wildlife Service, the release marks the first release of captive-reared, Foothill yellow-legged frogs into the wild. As part of the conservation effort, biologists bred the species at the Oakland Zoo after collecting tadpoles from the Feather River. In the wild, species egg masses, found in the watersheds they inhabit, have decreased dramatically over recent years as species numbers have fallen throughout the state.

The project required the cooperation of organizations like the U.S. Fish and Wildlife Service, U.S. Forest Service, the Oakland Zoo and Pacific Gas and Electric Co., among others. Wildlife biologists celebrated the release as an indication that the Foothill yellow-legged frog can successfully make the transition from a captive breeding environment into the wild.

“The lessons these tiny frogs have taught us about captive rearing will set the stage for this species’ conservation,” said U.S. Fish and Wildlife Service biologist Kat Powelson in a prepared statement. “They’re part of an experiment showing us how to successfully captive rear, translocate and release their more imperiled brothers and sisters, especially along the Southern California coast.”

The Foothill yellow-legged frog has a historic range throughout California and into southern Oregon. In December 2019, the state categorized the species as endangered along the state’s south and central coast and the southern Sierra Nevada region. It also deemed the species population along the Feather River as threatened. The species population along the northern fork of the Feather River near the Cresta Dam, in Plumas National Forest, has diminished in recent years.

A 2016 conservation study commissioned by the U.S. Department of Agriculture found that “water development and diversions are likely to be the primary cause of population declines” in the species. Forms of human encroachment, such as dams, pollution, logging, mining, and urban and agricultural expansion, decimated the species population, leading conservationists to call for habitat restoration in the rivers and uplands where the species lives.

The collapse of the species population has caused concern among biologists because adults of the species consume mosquitoes and yellowjackets.

Conservation efforts for the species have persisted along the Feather River watershed since 2002.

This story was originally published July 7, 2020 at 1:42 PM with the headline "Threatened frog species released into California forest after successful breeding program."