Researchers find sign of possible large population of endangered frog in California

Evidence of endangered frog group found in Calif.

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 2½ 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.


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