More than 350 mountain yellow-legged frogs have been reintroduced into the wild in Southern California’s San Bernardino Mountains, marking one of the largest releases to date and a significant step in efforts to save this endangered species. The release also represents a milestone for Birch Aquarium at Scripps Institution of Oceanography at UC San Diego — the aquarium’s first-ever species reintroduction and a historic moment in its growing conservation work.

Birch Aquarium, in collaboration with San Diego Zoo Wildlife Alliance (SDZWA), UCLA, Big Bear Alpine Zoo and additional partners, released the mountain yellow-legged frogs into a wildlife preserve managed by The Wildlands Conservancy. This effort is part of a long-running recovery program with partners at the U.S. Fish and Wildlife Service, the U.S. Geological Survey, the California Department of Fish and Wildlife and the U.S. Forest Service.

“It was an incredibly exciting and emotional day for our team, as releasing these frogs into the wild marks a historic first for Birch Aquarium,” said Sean Bruce, Assistant Curator of Fishes and Invertebrates. “We have been raising these frogs for more than a year, and to finally reach this milestone is truly remarkable!”

Of the released mountain yellow-legged frogs, 220 were raised behind the scenes at Birch Aquarium, while the rest were raised at SDZWA and UCLA.

“This release was made possible by the extraordinary dedication of our Husbandry Team and the invaluable collaboration of our partner organizations in this recovery project. Our shared passion and expertise made this success possible, and we hope these frogs thrive here for many years to come,” said Bruce.

The Mountain Yellow-Legged Frog's Journey From the Aquarium to the Wild

Each organization carefully transported its mountain yellow-legged frogs in coolers to the mountains. Upon arrival, the team hiked the frogs to three sites along a lake within a protected reserve. At the lake, the frogs were divided into two groups: one for hard release and the other for soft release.

The hard-release frogs were immediately introduced into the lake. The soft-release frogs were temporarily released into a specially designated habitat, where they were closely monitored over the next several days as they gradually acclimated to their new surroundings. This included daily health checks and feeding the frogs a variety of insects. They were then released into the same lake alongside the first group.

Read the full article about the conservation of mountain yellow-legged frogs at UC San Diego Today.