For the first time in nearly 50 years, a population of a nearly extinct type of frog has been rediscovered in California’s San Bernardino National Forest.
The rare mountain yellow-legged frog was re-found when biologists from the U.S. Geological Survey (USGS) and scientists from the San Diego Natural History Museum retraced a 1908 expedition through the San Jacinto Wilderness near Idyllwild, Calif.
Scientists hope that this rediscovery, along with captive breeding and efforts to restore frog habitat, bodes well for the future of the 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.
USGS and San Diego Natural History Museum biologists found the endangered frog during separate trips in June. The frogs were spotted at two locations about 2.5 miles apart in the Tahquitz and Willow creeks in the San Jacinto Mountains. The number of frogs in the area has not yet been determined.
"If this population is large, it could play an important role in the re-establishment of this species across Southern California," said Adam Backlin, a USGS scientist who led the survey team that spotted the first new Tahquitz Creek frogs on June 10.
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.
The goal of the breeding program, which began after the rare frogs were rescued from a drying creek, is to return the mountain yellow-legged frog to its native habitat.
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