California Red-Legged Frog
Photo Credit: Carley Sweet, USFWS
California Red-Legged Frog
Basic Species Information
Threatened. The species is likely to become endangered in the foreseeable future throughout all or a significant portion of its range, but they are not in danger of extinction right now.
The California red-legged frog is the largest native frog in the western United States. It ranges in size from 4 to 13 cm long (1.5 to 5 inches).
The abdomen and hind legs of adults are mostly red. The back has small black flecks and larger irregular dark blotches. These have indistinct outlines on a brown, gray, olive, or reddish background color. The spots on the frogs' backs usually have light centers. Lateral folds are prominent on the back.
Tadpoles (larvae) are from 14 to 80 mm long (0.6 to 3 inches). They are dark brown and yellow, with darker spots.
The diet of California red-legged frogs is variable. Larvae probably eat algae. Invertebrates, such as insects, are the most common food items of adult frogs. Vertebrates, such as Pacific tree frogs and California mice, are frequently eaten by larger frogs.
Young frogs are active both during the day and at night, whereas adult frogs are largely nocturnal. Feeding likely occurs along the shoreline and on the surface of the water.
The California red-legged frog occupies a fairly distinct habitat, combining both specific water (aquatic) and river bank (riparian) components. Adults need dense, shrubby or riparian vegetation associated with deep (greater than 2⅓ feet) still or slow moving water.
The frogs do best when they live in deep-water pools with dense stands of overhanging willows with a fringe of cattails. Well-vegetated land (terrestrial) areas within the riparian corridor may provide important sheltering habitat during winter.
California red-legged frogs enter a dormant state during summer or dry weather (estivate) in small mammal burrows and moist leaf litter. They have been found up to 100 feet from water in adjacent dense riparian vegetation.
The frogs breed from November through March. Northern red-legged frogs breed in January to March, soon after the ice melts, while frogs in southern localities have earlier breeding records, November through March.
The species is endemic (native and restricted) to California and Baja California, Mexico, at elevations ranging from sea level to approximately 1,500 meters (5,000 feet). Records of the California red-legged frog are known from Riverside County to Mendocino County along the Coast Range; from Calaveras County to Butte County in the Sierra Nevada; and in Baja California, Mexico.
California red-legged frogs are still locally abundant within portions of the San Francisco Bay area (including Marin County) and the central coast.
Within the remaining distribution of the species, only isolated populations have been documented in the Sierra Nevada, northern Coast, and northern Transverse ranges.
The species is believed to be extinct from the southern Transverse and Peninsular ranges, but is still present in Baja California, Mexico.
Bullfrogs are the most prevalent predators.
California red-legged frogs are currently threatened by loss of habitat from the growth of cities and suburbs, mining, overgrazing by cattle, invasion of nonnative plants, impoundments, water diversions, degraded water quality, and introduced predators, such as bullfrogs.
The fragmentation of existing habitat and the continued colonization of existing habitat by nonnative species may represent the most significant current threats to California red-legged frogs.
WHAT YOU CAN DO
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