Nevada Fish & Wildlife Office
Pacific Southwest Region

Mountain yellow-legged frog
(Rana muscosa)

Class: Amphibia
Order: Anura
Family: Ranidae
Genus: Rana
Species: muscosa
Length: 1.5 - 3.5 in.
Weight: Males: g; Females: g
Lifespan: Up to 12 years
Feed: Adults: aquatic and terrestrial invertebrates and anuran larvae
Larvae: algae, organic debris, plant tissue, and minute organisms in water.
Breeding: March-June at lower elevations; May-August at higher elevations
Eggs: laid in shallow water and is left unattached in still waters, but may be attached to vegetation in streams

Official Status:

Proposed Endangered


Life History:

A mountain frog. Chiefly diurnal. Emerges shortly after snow melts. Usually found in or close to water. Rarely occurs where predatory fishes have been introduced.

Reproduction is aquatic. Fertilization is external. Mating and egg-laying occurs after high creek waters have subsided, from March - May in the southern California populations. In the southern Sierra Nevada populations, breeding may occur later after the snows melt from May to July.

A cluster of eggs is laid in shallow water and is left unattached in still waters, but may be attached to vegetation in streams.

Tadpoles in the Sierras may overwinter, possibly taking as many as 3 or 4 summers before they transform. There is no information on the larval stage of Southern California populations, but it's possible they could transform their first year.

Distribution and Habitat:

  Occurs in the southern Sierra Nevada and mountains of southern California; numerous population declines and local extirpations have occurred and are ongoing, some in apparently pristine habitats.

Individuals may move hundreds of meters between summer and winter habitats.

The habitat includes sunny riverbanks, meadow streams, isolated pools, and lake borders in the Sierra Nevada, rocky stream courses in southern California. The species seems to prefer sloping banks with rocks or vegetation to the water's edge. Frogs in southern California are typically found in steep gradient streams in the chaparral belt and may range into small meadow streams at higher elevations. In contrast, Sierran frogs are most abundant in high elevation lakes and slow-moving portions of streams. This frog seldom is found away from water, but it may cross upland areas in moving between summer and winter habitats. Wintering sites include areas nearshore under ledges and in deep underwater crevices.



non-native fish introductions, contaminant introductions, livestock grazing, acidification from atmospheric deposition, nitrate deposition, ultraviolet radiation, drought, disease, and other factors


Actions / Current Information:

For Actions and Current Information visit the USFWS ECOS's Species Profile page for the Mountain Yellow-Legged frog.


Last updated: April 16, 2014