Zoo officials hope chilling frogs will stimulate their reproductive drive

Scientists at the San Diego Zoo are chilling endangered frogs to encourage breeding, the zoo announced Friday.

The scientists at the zoo’s Institute for Conservation Research placed 24 mountain yellow-legged frogs into special refrigerators cooled to 40 degrees on Jan. 1 and will keep them there to hibernate until next month.

The frogs tend to hibernate in cold weather and mate when they wake up. Females in the wild lay up to 200 eggs when the snow begins to melt.

There are only about 200 mountain yellow-legged adult frogs remaining in the San Bernardino, San Gabriel and San Jacinto mountains, according to Adam Backlin, a U.S. Geological Survey ecologist.

The San Diego Zoo has 61 adult frogs.

“We hope that by simulating the cold of the mountains where this critically endangered frog has been found, the San Diego Zoo will be able to increase the mountain yellow-legged frog population,” said Jeff Lemm, a research coordinator at the zoo. “The tadpoles we raise will be reintroduced into remote mountainous areas of Southern California where these frogs were found historically.”

Amphibians are on the decline globally because of habitat loss, non-native predators, climate change and the spread of the deadly chytrid fungus.

There are three types of frogs or toads on the federal endangered species list in Southern California.