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Mountain frogs that live in the Central Sierra are at the center of another legal battle, pitting people who call themselves conservationists against the California Cattlemen’s Association and their lawyers.

The Sierra Nevada yellow-legged frog, the northern population of the mountain yellow-legged frog, and the Yosemite toad, and the tadpoles that metamorphose into them are all hibernating now, in chilly ponds that will not freeze to the bottom this winter.

But lawyers and spokespersons for the environmentalists and the cattlemen are wide awake and in the midst of heated debate. That’s because there’s critical frog habitat in 16 Sierra Nevada counties, including Calaveras and Tuolumne, and livestock industry groups are challenging local frog habitat protections.

Earlier this month, people with the Center for Biological Diversity, the Western Watersheds Project, and the Central Sierra Environmental Resource Center in Twain Harte sided with and intervened on behalf of the federal Fish and Wildlife Service in a lawsuit challenging designation of protected critical habitat for the mountain frogs.

The legal action challenging frog habitat protections was filed by the Pacific Legal Foundation for the California Cattlemen’s Association and others in the livestock industry.

People with the Center for Biological Diversity and the Western Watersheds Project described the foundation as “an extreme private-property-rights group.”

Jenny Loda, a biologist and attorney with the Center for Biological Diversity, said her group is joining the fight to stop Pacific Legal Foundation and the Trump administration “from robbing these precious amphibians of protections they desperately need.”

Mountain frogs and the Yosemite toad have disappeared from most of the Sierra lakes and streams where they used to live, Loda said, adding that protecting some of their most important habitat gives them a fighting chance at recovery.

Frogs vs people

Asked for response, Reed Hopper, senior attorney with Pacific Legal Foundation, said that when the federal Fish and Wildlife Service designated critical habitat covering 1.8 million acres in 16 counties, the agency was required to analyze and adopt alternatives to the designation, and thereby avoid impacts on people who run ag-based businesses.

Hopper emphasized the lawsuit was filed on behalf of California ranchers and farmers, whose livelihoods are at risk from proposed restrictions on grazing in habitat areas.

Also reached for response, Kirk Wilbur, a spokesperson for the California Cattlemen’s Association, added similar perspective.

“To be clear, the California Cattlemen’s Association isn’t suing to overturn the designation of all 1.8 million acres of designated critical habitat for the three amphibian species,” Wilbur said.

“We are suing to force the U.S. Fish and Wildlife Service to follow the law by complying with the Regulatory Flexibility Act, which requires them to examine the economic impacts of their critical habitat designation on local governments and small businesses” such as ranchers, Wilbur said, “and to consider regulatory alternatives that will lessen those economic impacts.”

Some frogs rebounding

Neither the conservationists, the cattlemen or the lawyers mentioned a study released in October 2016 that showed endangered Sierra Nevada yellow-legged frogs have increased seven-fold in abundance in Yosemite National Park, according to 20 years of data from more than 7,000 frog population surveys.

Roland Knapp with the University of California Sierra Nevada Aquatic Research Laboratory in Mammoth Lakes was lead author on the study, “Large-scale Recovery of an Endangered Amphibian Despite Ongoing Exposure to Multiple Stressors.”

Scientists say frogs and other amphibians are reliable indicators of environmental health.

Like miners used to use canaries to warn of toxic gases, people can watch amphibians for signs of unsafe environmental conditions and trends that can change entire ecosystems.

Underwater nets have been strung across beds of some lakes in Yosemite, including Budd Lake at 9,975 feet above sea level. Budd Lake, which feeds Budd Creek and Tuolumne Meadows, is one of the highest-altitude alpine lakes in Tuolumne County and the Tuolumne River watershed.

Park biologists check the nets from time to time for non-native trout. The nets in Budd Lake were there in August 2015 and in July 2016.

In their study, Knapp and his colleagues found frog population growth rates relatively uniform and moderate across most of the northern half of the park, primarily the Tuolumne River watershed.

Growth rates in the southern half of the park, dominated by the Merced River watershed, showed different outcomes. In the Merced River watershed, frog population growth rates were much faster in the eastern headwaters than in the western downstream portion, where five study areas showed negative growth.

Knapp and his colleagues looked at changes in frog abundance by using data from more than 7,000 frog population surveys conducted across Yosemite National Park over a 20-year period between 1993 and 2012, according to their study.

Still endangered

Regardless, people with the Center for Biological Diversity and the Western Watersheds Project say Central Sierra mountain frogs and toads are endangered.

They say the vast majority of critical habitat for the amphibians is on federal public lands, including the Stanislaus National Forest.

The conservationists argue that Sierra Nevada and mountain yellow-legged frogs have declined by about 90 percent up and down the mountain range due to factors including destruction and degradation of habitat, disease, being hunted by nonnative trout, introduction of pesticides and climate change.

More than half of Yosemite toad populations are gone, the conservationists say. The primary threats to Yosemite toads are livestock grazing, climate change and pesticides

“Damage from livestock grazing in fragile, high-elevation habitat is a major reason these amphibians are imperiled,” Paul Ruprecht, an attorney at Western Watersheds Project, said in a prepared statement. “It’s critical to defend against the livestock industry’s direct attack on their habitat.”

But Hopper with Pacific Legal Foundation and Wilbur with the California Cattlemen’s Association maintain their legal action has been mischaracterized and misportrayed.

Fortunately, the Endangered Species Act expressly authorizes the federal Fish and Wildlife Service to exclude areas from critical habitat designation where economic burdens outweigh benefit to the species, Hopper said. Ranchers and farmers have identified essential grazing areas that could be excluded without harming the species, but the federal agency refused to consider that alternative. That’s why they sued.

Wilbur said conservationists are wrong when they say damage from livestock grazing in high-elevation habitat is a major reason frogs and toads are endangered.

By claiming that, they’re relying on “the same discredited studies” the federal Fish and Wildlife Service relied on to list the amphibian species as threatened and endangered, Wilbur said. Multiple studies conducted by UC Davis researchers have shown there are no clear direct or indirect impacts from livestock grazing on Yosemite toad populations.

Wilbur said the authors of the UC Davis studies stated in part, “our results do not support previous studies that found a negative impact of grazing on amphibian populations.”

From north to south in the Sierra Nevada, here are the counties that include critical mountain frog habitat getting challenged by livestock industry groups: Lassen, Plumas, Sierra, Nevada, Placer, El Dorado, Alpine, Amador, Calaveras, Tuolumne, Mariposa, Madera, Mono, Fresno, Tulare and Inyo.