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.
USGS scientists found this adult mountain yellow-legged frog on June 10 in Tahquitz Creek, a rediscovered population of the endangered frog in the San Jacinto Wilderness, San Bernardino National Forest, California. Credit: Adam Backlin, U.S. Geological SurveyThe 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.
Evidence of endangered frog group found in California
John Antczak, Associated Press Yahoo News 24 Jul 09;
LOS ANGELES – Scientists have found evidence of a potentially large population of the nearly extinct mountain yellow-legged frog in a Southern California wilderness where it hadn't been seen in a half-century, raising prospects for restoring the species to its once wide range.
Like amphibians whose numbers are in decline worldwide, the frog species was believed to have fewer than 200 adult members spread across the San Gabriel, San Bernardino and San Jacinto mountain ranges.
In June, U.S. Geological Survey biologists and a team from the San Diego Natural History Museum each separately found a mountain yellow-legged frog at locations 2 1/2 miles apart in the Tahquitz and Willow creeks area of the San Jacintos, about 85 miles southeast of Los Angeles.
At the time, the USGS team was only intent on assessing the suitability of the area for re-establishing the species, ecologist Adam Backlin said Friday.
In 10 years of working with the species, up to 300 locations had been surveyed in the three mountain ranges without any new populations being discovered, so there was no expectation of finding any frogs, Backlin said.
The first frog was found June 10 in Tahquitz Creek.
"We were just blown away," he said.
The museum scientists made their discovery as they followed in the footsteps of a 1908 natural history expedition in order to determine biological changes. That frog was found June 21 in Willow Creek, a tributary of the Tahquitz.
Scientists knew that the frogs had lived there about 50 years ago because museums have examples of the species from the area, Backlin said.
The historic record indicates the frogs were abundant in every area that had permanent water above an elevation of 1,200 feet, he said.
"Between 1968, the 1970s, they just disappeared off the map," he said. "We're trying to figure out now what happened. So anything that is still currently out there has probably persisted since that time."
The frogs don't bask like other frogs and are hard to spot, he said.
The frogs also typically don't move from place to place, so the distance between the two newly discovered frogs is a preliminary indication of a big population.
"And if there's a large population, there may be more frogs in that one creek than we know of across the entire range of the species," Backlin said.
The discoveries follow the San Diego Zoo's first-ever success in breeding a mountain yellow-legged frog in captivity. Tadpoles rescued from a drying stream in the San Bernardino National Forest were taken to the zoo, and eggs were discovered in a tank in December. One frog matured.
Backlin said captive breeding is difficult because of the need to replicate conditions that include the chill of winter, when the frogs are used to hibernating.
"The hope is that we'll get a lot of animals from that captive population this spring and use those to start developing new populations," he said.