Rana muscosa

Mountain Yellow-legged frog–(Sierra Nevada DPS) Candidate

Description:

The Mountain Yellow-legged frog is light to medium brown, with black or brown spots or lichen like markings on its back. Toe tips are usually dusky and the underside of the hind legs and sometimes the entire belly are yellow or orange. The yellow coloring often extends forward becoming level with the forelimbs. They are diurnal.

Habitat:

Mountain Yellow-legged frogs are usually found by sunny streams with sloping gravely bars and in isolated pools not far from running water.

Range:

Mountain yellow-legged frogs are highly aquatic, rarely found more than a few hops from water. They are endemic to two disjunct areas; 1) the Sierra Nevada mountains in California and Nevada, and 2) the San Gabriel, San Bernardino and San Jacinto Mountains in southern California. A few historic populations are known to have existed in the state of Nevada in the vicinity of Mt. Rose, near Lake Tahoe. Currently, mountain yellow-legged frogs are found scattered throughout nearly all of their historic range in Sierra Nevada, but the number of populations is greatly reduced. This is most notable in the northern-most 125 km of the range (north of Lake Tahoe) and the southern-most 50 km, where only a few populations have been found in the last few years.

Breeding:

Breeding begins soon after ice-melt or early in spring usually from May to August. Eggs are deposited underwater in clusters attached to rocks, gravel, and under banks, or to vegetation in streams or lakes. At higher elevations where the growing season can be as short as three months, tadpoles must over-winter at least once and may take 2 or 3 years of growth before they are large enough to transform in late July early August. During the breeding season, males smell strongly of garlic.

Diet:

Mountain Yellow-legged Frog larvae consume organic debris, plant tissue, algae and small organisms. Adults are insectivores.

Conservation Status:

Causes for decline include trout introduction, chemical pollution, UV-B radiation, disease, and long term changes in weather patterns, especially concerning the severity and duration of droughts.

References:

Drost, C. A., and Fellers, G. M. (1996). "Collapse of a regional frog fauna in the Yosemite area of the California Sierra Nevada, USA." Conservation Biology, 10(2), 414-425.

Jennings, M. R., and M. P. Hayes. (1994). "Amphibian and reptile species of special concern in California." "." Final Report #8023 Submitted to the California Department of Fish and Game.

Jennings, W.B. (1996). "Status of amphibians." "." Sierra Nevada Ecosystem Project, Final Report to Congress, 2, 921-944.

Stebbins, R.C. (1951). Amphibians of Western North America. University of California Press, Berkeley.

Stebbins, Robert C. (1985). A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin, Boston.

Wright A. H. and A.A. Wright (1949). Handbook of frogs and toads of the United States and Canada.. Comstock Publishing Associates, Cornell University Press, Ithaca, New York, USA.

Zweifel, R.G. (1955). "Ecology, distribution, and systematics of frogs of the Rana boyleii group." University of California Publications in Zoology., 54, 207-292.