Two types of yellow-legged frogs, and a kind of toad found in Yosemite National Park, won extra protection Thursday when federal authorities declared nearly 3,000 square miles in California’s Sierra Nevada mountains as critical habitat for the endangered animals.
The designation by the US Fish and Wildlife Service means closer controls on human activities that could threaten the Sierra Nevada yellow-legged frog, the mountain yellow-legged frog, and the Yosemite toad. The designation mainly affects federal land.
Naturalist surveys of California’s Sierra mountains from a century ago described the yellow-legged frogs as lining almost every foot of mountain lake shores, said Jeff Miller, a conservation advocate for the Center for Biological Diversity environmental group.
Over the past few decades, the frogs and toads have had to contend with a host of threats. They include the stocking of Sierra lakes with voracious trout and other non-native fish, diseases fostered by climate change and pesticides blown in from California’s Central Valley farms.
About 90 percent of the yellow-legged frogs have gone, Miller said.
“These were a very common species once. They pretty much disappeared,” said Miller.
He recently helped crews reintroduce the frogs to one Sierra waterway after workers had netted and removed non-native fish that eat the amphibians, part of a yearslong effort to remove the non-native predators of frogs.
Climate change and pesticides, as well as grazing by livestock, also have eradicated more than half of the original population of the Yosemite toad. The three species were listed as endangered in 2014.
Wildlife officials are working with the Oakland and San Francisco zoos to raise additional numbers of the amphibians for release in the wild, said Jennifer Norris, field supervisor for the agency’s Sacramento office.