Hundreds of tiny creatures feared locally extinct return to California mountains

Hundreds of red-legged frog tadpoles, once thought locally extinct and then threatened by storms, have returned to the Santa Monica Mountains, experts reported.

The Aquarium of the Pacific, working with the National Park Service, released almost 600 tadpoles in streams in the mountains near Los Angeles, the aquarium said in a July 15 news release.

The frogs had not been seen in the mountains since the 1970s when the aquarium began a project to reintroduce them in 2014, experts said.

In March 2025, severe late-winter storms endangered fragile red-legged eggs laid in streams and ponds throughout the mountains, the aquarium said.

National Park Service biologists collected the eggs and brought them to the aquarium, where they were hatched and nurtured into tadpoles, experts said.

Biologists will monitor the tadpoles this summer as they grow.

“This project has had its share of ups and downs over the years,” Katy Delaney, ecologist with Santa Monica Mountains National Recreation Area, said in the release. “But with committed partners like the aquarium, we’re writing another hopeful chapter in the comeback story of the California red-legged frog.”

California red-legged frogs, which were once plentiful, are now a federally threatened species under the Endangered Species Act.

The Santa Monica Mountains are about a 50-mile drive west from downtown Los Angeles.

In a related effort, the Los Angeles Zoo, U.S. Geological Survey and the aquarium also released 450 southern mountain yellow-legged frogs in the San Gabriel Mountains, a July 10 news release from the zoo said.

The zoo has been breeding the endangered species since 2007.

This story was originally published July 16, 2025 at 3:24 PM with the headline "Hundreds of tiny creatures feared locally extinct return to California mountains."