A recent survey of mountain yellow-legged frogs released into the wild by San Diego Zoo Global wildlife conservationists indicates that the populations are showing signs of stress related to drought conditions in California. The juvenile frogs, released into the San Jacinto mountains in two protected sites, are representatives of a species brought to the brink of extinction by the threat of wildfire, habitat destruction and chytrid fungus. The young frogs hatched at the San Diego Zoo Institute for Conservation Research and were introduced as tadpoles into the wild in 2013.

"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 for Conservation Research. "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."

Of the 300 tadpoles that were released, researchers believe about 25% continue to survive. The species is believed to number less than 200 individuals in the San Gabriel, San Bernardino and San Jacinto mountains, where they once thrived. Institute for Conservation Research conservationists, working in collaboration with government partners —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 these rare frogs.

Bringing species back from the brink of extinction is the goal of San Diego Zoo Global. As a leader in conservation, the work of San Diego Zoo Global includes onsite wildlife conservation efforts (representing both plants and animals) at the San Diego Zoo, San Diego Zoo Safari Park, and San Diego Zoo Institute for Conservation Research, as well as international field programs on six continents. The important conservation and science work of these entities is made possible by the San Diego Zoo Global Wildlife Conservancy and is supported in part by the Foundation of San Diego Zoo Global.

Explore further Sobering update on Jamaica's largest vertebrate

Provided by Zoological Society of San Diego