SAN DIEGO (CNS) - About 25 percent of mountain yellow-legged frogs released into the wild last year by San Diego Zoo Global wildlife conservationists have survived so far, zoo officials announced Monday.
The remaining frogs, hatched at the San Diego Zoo Institute for Conservation Research and introduced as tadpoles to two protected sites in the San Jacinto mountains, are showing signs of drought-related stress, according to the zoo.
"When we released these frogs into the wild, we knew they would be facing natural challenges to their survival, like predation," said Frank Santana, a research coordinator with the institute. "The drought is adding an additional challenge to their survival, but we are still finding a significant number of frogs that are healthy and growing."
Zoo officials said the frogs belong to a species close to extinction because of wildfire, habitat destruction and chytrid fungus -- which attacks amphibians.
Of the 300 tadpoles that were released, researchers believe around 75 have survived. That gives the species less than 200 individuals total in the San Gabriel, San Bernardino and San Jacinto mountains, where they once thrived, according to the institute.
Specialists with the zoo, U.S. Geological Survey, U.S. Forest Service, U.S. Fish and Wildlife Service, California Department of Fish and Game and University of California are working to repopulate Southern California with the rare frogs.
San Diego Zoo Global, the organization that operates the zoo and Safari Park, says its goal is to bring species back from the brink of extinction.