Biologists rediscover endangered mountain yellow-legged frog population.
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The first mountain yellow-legged frog born in captivity. It was born at the San Diego Zoo's Institute for Conservation Research.
Photo courtesy Ken Bohn, San Diego Zoo.
Biologists from the U.S. Geological Survey (USGS) and scientists from the San Diego Natural History Museum both rediscovered the rare mountain yellow-legged frog in the San Jacinto Wilderness near Idyllwild, Calif.
This rediscovery — along with the San Diego Zoo's first successful breeding of the frog in captivity, and successful efforts by California Department of Fish and Game to restore frog habitat — renews hope of survival for this Southern California amphibian.
Globally, amphibians are on the decline because of habitat loss, effects of climate change and the spread of a deadly pathogen called the chytrid fungus. The mountain yellow-legged frog is one of three frogs or toads on the federal Endangered Species List in Southern California. Prior to this recent discovery, USGS researchers had estimated there were about 122 adult mountain yellow-legged frogs in the wild.
Mountain yellow-legged frogs are not known to migrate far, possibly indicating a significant population. The size of the site represents much more habitat than occupied by the eight other mountain yellow-legged frog populations in the San Jacinto, San Bernardino, and San Gabriel mountain ranges. In those areas, the frog occupies less than a half-mile of stream.
The San Diego Zoo's Institute for Conservation Research was the first to breed a mountain yellow-legged frog in captivity. That amphibian has recently morphed from a tadpole into a froglet, or juvenile frog.
"Historically, scientists have had great difficulty breeding frogs in captivity," said Jeff Lemm, an animal research coordinator for the San Diego Zoo. "We are excited by this success and cautiously optimistic we will have more eggs soon."
In December 2008, researchers at the Institute for Conservation Research discovered a clutch of about 200 mountain yellow-legged frogs eggs in one of its tanks. Researchers were surprised because the frogs were younger than is typical for breeding. Because of the frogs' young age, only a handful of the eggs were fertile. The one frog to mature is thriving (picture above). The next breeding season is expected to be December 2009 to March 2010.
The goal of the breeding program is to return the mountain yellow-legged frog to its native habitat.
Habitat protection and restoration, combined with efforts to reintroduce these frogs to areas where they have been decimated, offers the best hope of returning mountain yellow-legged frogs in Southern California to a healthy, self-sustaining population.