San Gorgonio Chapter



mountain yellow-legged frog

Rana muscosa

imamountain yellow-legged frogge

Photo source:

San Bernardino County Museum

There are two species of mountain yellow-legged frogs, Rana muscosa and Rana sierrae. They have existed in the mountains of California and Nevada for millions of years, moving up and down in elevation as glaciers advanced and retreated, over time adapting to alpine lake habitats too cold for other amphibians and devoid of predators - until the mid-19th century when settlers began to stock these naturally-fishless habitats with trout.

The Southern Mountain Yellow-legged Frog, also called the Sierra Madre Yellow-legged Frog, occurs in San Bernardino, San Jacinto and San Gabriel Mountains; and in southern Sierra Nevada.

Ninety percent of Rana muscosa populations have disappeared during the past century. Contributing factors to the decline are believed to be introduction of nonnative fishes, especially trout; disease, and contamination from pesticides. Restoration efforts include removal of trout and reintroduction of yellow-legged frogs.

Mountain Yellow-Legged Frog are an integral part of the ecosystem: the tadpoles feed on algae, but after the metamorphosis into frogs they feed primarily on aquatic insects. The frogs are an important prey for birds, garter snakes, coyotes and bears. In some areas the disappearance of mountain yellow-legged frogs has led to a t decline in garter snake populations.

Status: Critically endangered

Links:  Mountain Yellow-Legged Frog site - AmphibiaWeb - Reintroduction Natureserve - Center for Biological Diversity - CDFG - Wikipedia