SAN DIEGO — The San Diego Zoo Wildlife Alliance is taking steps to ensure an endangered species doesn’t go extinct.

The alliance, in collaboration with Omaha’s Henry Doorly Zoo and Aquarium, have reintroduced more than 70 endangered Endangered Mountain Yellow-legged Frogs into a lake in the San Bernardino Mountains. 

The zoo’s wildlife alliance noted this release marks the first time the Southern California distinct population segment of the Endangered 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, part of a conservation breeding and reintroduction program.

“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.” 

Before being reintroduced into the lake, the frogs were placed in a protective habitat at the lake for seven days to adjust to their new surroundings. The team checked the frogs’ health every day and fed them several kinds of insects.

The frogs are microchipped, and the San Diego Zoo Wildlife Alliance stated it will continue its surveys at the lake to keep track of how the animals are faring 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.” 

The species’ survival is threatened by several factors, among them disease, introduced predators, wildfires and drought, the alliance stated.

“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,” according to the alliance.

The San Diego Zoo Wildlife Alliance, the U.S. Fish and Wildlife Service and the U.S. Geological Survey have been working to manage and propagate the species since 2006.