BERKELEY, California, December 15, 2008 (ENS) – Climate change is affecting the Sierra Nevada’s high elevation lakes and the imperiled yellow-legged frogs that depend on them, according to scientists with the U.S. Forest Service and the University of California, Berkeley.

The Sierra Nevada yellow-legged frog once was common in these high elevation lakes and slow moving streams at altitudes ranging from 4,500 to 12,000 feet. But its range has decreased more than 80 percent in the last 90 years.

In a long-term study funded by the Forest Service, the researchers found that the combination of the shallow lakes drying up in summer and predation by introduced trout in the larger lakes limits the frog’s breeding habitat, and can cause its extinction.

These lakes and streams were not inhabited by fish until the hybrid trout were introduced.

“Environmental factors that increase summer drying of small lakes are likely to bring further population decline because the larger lakes are off limits to breeding,” said study co-author Kathleen Matthews a Forest Service scientist at the Pacific Southwest Research Station.

The researchers studied lakes in Kings Canyon National Park’s Dusy Basin that are mostly fed by snowmelt. Climate change models suggest one of the effects of climate change on Sierra Nevada water balance will be a decreased snow pack, with more than half of the current snow water equivalent gone by 2090.

Sierra Nevada yellow-legged frog (Photo by
Gary Nafis courtesyCalifornia Herps)

Sierra Nevada yellow-legged frogs need two to four years of permanent water to complete their development, so repeated tadpole mortality from lakes drying up in summer leads to population decline. The warmer and drier the climate, the more the frogs would be affected, the scientists concluded.

In addition, they believe it was unlikely the frogs were historically restricted to small lakes in Dusy Basin as they are today. Larger lakes free of introduced fish would have provided refuge for the frogs and tadpoles in dry years.

The U.S. Fish and Wildlife Service has determined that listing of the Sierra Nevada yellow-legged frog as an endangered species is warranted but precluded by the need to complete other listing actions of a higher priority.

Matthews co-authored the 10-year study with Krishna Feldman, another Pacific Southwest Research Station scientist and Igor Lacan, of the Berkeley Department of Environmental Science, Policy and Management.

Their findings appear in the current issue of the journal “Herpetological Conservation and Biology.”

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ALBANY, California, March 8, 2008 (ENS) – Scientists believe a wolverine was photographed with a remote-controlled camera on the Tahoe National Forest, the first evidence of wolverines in California found in at least 90 years.

U.S. Forest Service scientists believe an Oregon State University graduate student working on a cooperative project with the agency’s Pacific Southwest Research station photographed a wolverine.

Katie Moriarty, a wildlife biology student, was conducting research on another carnivore called the American marten when a remote-controlled camera she set photographed the animal on February 28.

Forest Service scientists who are experts at detecting rare carnivores believe the photographed animal is a wolverine.

The photograph taken by a
remote-controlled camera
set by Katie Moriarty (Photo
courtesy U.S. Forest Service,
Oregon State University)

The North American wolverine is the largest member of the weasel family. The wolverine resembles a small bear, with a bushy tail and broad head. Adult males weigh 26 to 40 pounds, while females are 17 to 26 pounds. They eat carrion, small animals, birds, insects and berries.

Most U.S. wolverine populations are found in the Northern Cascades in Washington, and Northern Rockies in Montana and Idaho. The nearest known resident population is about 900 miles north of the Tahoe National Forest in Northern Washington.

Attempts have been made for decades to photograph wolverines in California, according to Bill Zielinski, a Forest Service scientist with the Pacific Southwest Research Station and an expert at detecting wolverines, marten and fisher. He said periodic sightings have occurred, but never scientifically confirmed using detection methods that produce verifiable evidence.

Scientists will now use remote-controlled cameras and barbed wire snares that snag hair in an attempt to confirm the presence of wolverines. They may use dogs trained to find wolverine scat, said Zielinski.

Scientists have found dogs to be three and a half times more successful at detecting rare carnivores than remote-controlled cameras in forested areas like the Sierra Nevada Mountains.

Zielinski said hair and scat samples would contain DNA that can be analyzed to determine where the animal originated.

“We have good genetic templates from populations that have been studied elsewhere that can be used to understand the origin of this animal,” he said. “But, first we need a DNA sample.”

In order to avoid interference with ongoing studies, Forest Service officials are not releasing the exact location where the wolverine was photographed.

The agency’s regional forester for California has listed the wolverine as a sensitive species, and the 2004 Sierra Nevada Forest Plan Amendment directs the Forest Service to conduct an analysis to determine if activities within five miles of where a wolverine was detected will affect the species.

“This is an exciting research discovery, both for its scientific value, and as a demonstration of our success in forest management,” said Tahoe National Forest Supervisor Tom Quinn. “For now, we on the Tahoe National Forest have more questions than answers.”

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