The Sierra Nevada mountain range in California and Nevada is home to some of our country’s most spectacular geography, including Yosemite Valley, Mount Whitney, the highest point in the contiguous United States, and Lake Tahoe, the largest alpine lake in North America. The mountains host wilderness areas accessible only by foot or horseback, and three national parks—Yosemite, Sequoia, and King’s Canyon. The ecology of the mountains is complex and defined by distinct ecosystem characteristics at different elevations. The Mountain Yellow-legged frogs—both species —are found in creeks, lakes, and sunny riverbanks at elevations from 1,200 to 7,500 feet.

The closely-related Sierra Nevada Yellow-legged frog and the Southern Mountain Yellow-legged are important for an intricate food web—eating large quantities of insects, which may carry human diseases, as well as serving as a food source for snakes, birds, beetles and dragonflies. These frogs are two and a half inches as adults. Their abdomens and the undersides of their hind legs are yellow-to-orange, and their backs are yellow-to-reddish, with dark brown or black blotches. Males develop small, glandular growths— nuptial pads—on the base of their thumbs to help them hold females during mating season. They have adapted to survive in environments that are too cold for most amphibians. Both species are highly vulnerable to the deadly chytrid fungus which has spread through the Sierra Nevada in the past decade, decimating frog populations.

Water in the Balance

The Yellow-legged frogs are highly aquatic, depending on the clear, cool waters of mountain lakes and streams for their survival. Their habitat is undergoing manmade changes that threaten their survival. Non-native trout have been introduced into the fishless mountain lakes. These trout are voracious predators of tadpoles and can eat frog populations to extinction.

Pesticides from California’s Central Valley also contribute to the species’ decline. The windborne chemicals accumulate in the high mountains and pollute streams and lakes. Frogs have permeable skin that easily absorbs toxic chemicals, which makes them especially vulnerable. Frogs are indicators of environmental stress; their health is indicative of the health of the biosphere as a whole.