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NEWS RELEASE

More Than 70 Endangered Mountain Yellow-legged Frogs Reintroduced into Southern California Lake in Cross-country Effort to Conserve the Species 

Lake Release is a First for the Southern California Population of Frogs 

SAN DIEGO (Nov. 14, 2023) – San Diego Zoo Wildlife Alliance, in collaboration with Omaha’s Henry Doorly Zoo and Aquarium, reintroduced more than 70 endangered mountain yellow-legged frogs into a lake located in the San Bernardino Mountains. This release marks the first time the Southern California distinct population segment of the mountain yellow-legged frog has been reintroduced into a lake instead of a mountain stream. The frogs were bred at San Diego Zoo Wildlife Alliance’s Beckman Center for Conservation Research between 2020 and 2022, and then reared at Omaha’s Henry Doorly Zoo and Aquarium. The cross-country effort to save this California frog is part of a robust conservation breeding and reintroduction research program aimed at restoring populations of this declining species throughout its historic range.  

“We have the unique ability to act as a remote head-start facility for the conservation recovery team and are committed to helping conserve these frogs,” said Derek Benson, amphibian conservation researcher and lead keeper, Omaha’s Henry Doorly Zoo & Aquarium. “We are thrilled to be part of the return of these animals to a historic site as the population rebounds.” 

The frogs were released in two cohorts. The first group arrived from Omaha on the day of their release and were placed in a protective habitat at the lake for seven days, so they could adjust to their new surroundings. The team performed daily health checks on the frogs and fed them a variety of insects, including those collected from their environment. The second cohort arrived the following week and were released into the lake alongside the initial group. Researchers are evaluating the release techniques, along with several other factors, to better understand which combination of reintroduction strategies will prove most beneficial for the mountain yellow-legged frogs’ survival. The frogs are microchipped for identification, and San Diego Zoo Wildlife Alliance continues to conduct post-reintroduction surveys at the lake to monitor their success in the habitat.  

“Lakes have the advantage of more permanent water that is less likely to dry up in a drought,” said Debra Shier, Ph.D., Brown Endowed Associate Director of Recovery Ecology, San Diego Zoo Wildlife Alliance. “When water habitats like streams do begin to lose water, adult frogs may be able to move, but tadpoles can’t. It’s important that we’re identifying and preserving suitable habitats in the mountain yellow-legged frogs’ native range that can hopefully prove hospitable for this species for years to come—despite the increasing pressures brought on by climate change.” 

Classified as Endangered on the International Union for Conservation of Nature Red List of Threatened Species, severe population fragmentation has led to estimates of fewer than 200 adult mountain yellow-legged frogs remaining in their native habitats. The mountain yellow-legged frog is facing many threats to its survival, including disease, introduced predators, wildfires and drought driven by climate change. Breeding programs for species facing an uncertain future in their native habitats are critical for recovery. San Diego Zoo Wildlife Alliance and its partners, including U.S. Fish and Wildlife Service and U.S. Geological Survey, are working to manage and propagate this species as part of a full-scale conservation breeding and reintroduction research program. The program began in 2006 as a salvage effort, but has evolved to include genetic diversity management, disease management, assistive reproductive technologies, behavioral studies, field surveys and statistical analyses. Teams take a rigorous, scientific approach to enhance breeding and reintroduction efforts for this species. To date, San Diego Zoo Wildlife Alliance has bred and reintroduced thousands of individuals back into high-elevation mountain habitats and monitored their success. 

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About San Diego Zoo Wildlife Alliance 
San Diego Zoo Wildlife Alliance, a nonprofit conservation leader, inspires passion for nature and collaboration for a healthier world. The Alliance supports innovative conservation science through global partnerships. Through wildlife care, science expertise and collaboration, more than 44 endangered species have been reintroduced to native habitats. Annually, the Alliance reaches over 1 billion people, in person at the San Diego Zoo and San Diego Zoo Safari Park, and virtually in 150 countries through media channels, including San Diego Zoo Wildlife Explorers television programming in children’s hospitals in 13 countries. Wildlife Allies—members, donors and guests—make success possible.