A team of scientists released a group of year-old endangered Mountain yellow-legged frogs into a remote portion of the San Bernardino National Forest on July 8, in the hopes that the mix of male and female frogs will repopulate the area.
A total of 253 endangered frogs were released into the area on July 8, by scientists from the San Diego Zoo Wildlife Alliance, the University of California, Los Angeles, the U.S. Forest Service, the California Department of Fish and Wildlife and the U.S. Fish and Wildlife Service.
To get the frogs to the site, scientists travelled "by vehicle to a trailhead in special cooler backpacks that maintain a suitable temperature for this high-altitude species," then undertook an over-five-mile hike to the release location.
Mountain yellow-legged frogs face a number of environmental threats that have lowered their population in Southern California over time.
Historically, the frogs were "widely distributed across the San Gabriel, San Bernardino, San Jacinto, and Palomar mountains," according a statement from the U.S. Forest Service.
But by the time they were added to the endangered species list in 2002, there were estimated to be less than 100 adult frogs left in the wild, thanks to "non-native predators, recreation impacts, and disease."
Those challenges haven't gone away, according to Debra Shier Ph.D., the Brown endowed Associate Director of Recovery Ecology and Southwest hub co-leader for the San Diego Zoo Wildlife Alliance.
“Climate change and chytrid fungus are creating challenges to Mountain yellow-legged frog survival that the species has never faced before,” Shier said.
Scientists and government agencies have worked together for over 20 years on recovery actions to help protect the frogs and boost their population.
Those efforts include managing lands in the Angeles and San Bernardino National Forests to minimize human changes to the environment, and conservation and research from the San Diego Zoo Alliance, U.S. Geological Survey, Los Angeles Zoo, Omaha’s Henry Doorly Zoo and Aquarium, Santa Ana Zoo, and UCLA.
The California Department of Fish and Wildlife also completed an extensive habitat improvement project to benefit the frogs.
The July 8 release was the second to occur at the chosen spot in the San Jacinto Mountains, and a third release is planned for later in the year to bring the total number of frogs released up to 400.
The conditions at the release site in the San Jacinto Mountains are still favorable for the frogs, in spite of the drought conditions around California, but the frog population across their historic habitat range is still low. Recovery efforts will continue into the future, the U.S. Forest Service said.
“The Department has spent a lot of time evaluating, permitting and rehabbing release waters and we’re optimistic about the location.” said Russell Black, Senior Environmental Scientist Supervisor for the California Department of Fish and Wildlife. “It has a large amount of drought resistant habitat that should provide a stable location for these frogs for many years.”