California Red-legged Frog Species Profile

California Red-legged Frog
Rana draytonii

General Information

Official Status: Threatened, the California red-legged frog is federally listed under the Endangered Species Act as a threatened species throughout its range in California.

Date listed: May 23, 1996; Federal Register 61 FR 25813

Critical Habitat: On March 17, 2010, we published a final rule to revise designated critical habitat Federal Register 75 FR 12816 (pdf, 4.6 MB)

Recovery Plan: A recovery plan for the California Red-legged Frog (Rana aurora draytonii) was published on May 28, 2002.

California Red-legged Frog

Photo Credit: Jamie Bettaso, USFWS

Photo Gallery for the California Red-legged Frog

Identifying Characteristics:

The California red-legged frog (Rana draytonii; formerly, Rana aurora draytonii) is the largest native frog in the western United States ranging from 1.75 to 5.25 inches from the tip of the snout to the vent (Stebbins 2003). From above, the California red-legged frog can appear brown, gray, olive, red, or orange, often with a pattern of dark flecks or spots. The back is bordered on either side by an often prominent ridge (dorsolateral fold) running from the eye to the hip. The hind legs are well-developed with large, webbed feet. A cream, white, or orange stripe usually extends along the upper lip from beneath the eye to the rear of the jaw. The undersides of adult California red-legged frogs are white, usually with patches of bright red or orange on the abdomen and hind legs. The groin area sometimes exhibits bold black mottling with a white or yellow background.

Current Geographic Range:

The California red-legged frog has sustained a 70 percent reduction in its geographic range as a result of several factors acting singly or in combination (Jennings et al. 1992). Only a few drainages are currently known to support California red-legged frogs in the Sierra Nevada foothills, compared to more than 60 historical records. In southern California, the California red-legged frog has essentially disappeared from the Los Angeles area south to the Mexican border; the only known population in Los Angeles County is in San Francisquito Canyon on the Angeles National Forest.

Life History:

California red-legged frogs spend most of their lives in and near sheltered backwaters of ponds, marshes, springs, streams, and reservoirs. Deep pools with dense stands of overhanging willows and an intermixed fringe of cattails are considered optimal habitat. Eggs, larvae, transformed juveniles, and adults also have been found in ephemeral creeks and drainages and in ponds that do not have riparian vegetation. Accessibility to sheltering habitat is essential for the survival of California red-legged frogs within a watershed, and can be a factor limiting population numbers and distribution. Some California red-legged frogs have moved long distances over land between water sources during winter rains. Adult California red-legged frogs documented to move more than 2 miles in northern Santa Cruz County “without apparent regard to topography, vegetation type, or riparian corridors” (Bulger et al. 2003). Most of these overland movements occur at night.

California red-legged frogs breed from November through March with earlier breeding records occurring in southern localities. California red-legged frogs are often prolific breeders, typically laying their eggs during or shortly after large rainfall events in late winter and early spring. Embryos hatch 6 to 14 days after fertilization and larvae require 3.5 to 7 months to attain metamorphosis. Larvae probably experience the highest mortality rates of all life stages, with less than 1 percent of eggs laid reaching metamorphosis. Sexual maturity normally is reached at 3 to 4 years of age; California red-legged frogs may live 8 to 10 years. Juveniles have been observed to be active diurnally and nocturnally, whereas adults are mainly nocturnal.
The diet of California red-legged frogs is highly variable. Invertebrates are the most common food items, although vertebrates such as Pacific chorus frogs (Pseudacris regilla) and California mice (Peromyscus californicus) can constitute over half of the prey mass eaten by larger frogs (Hayes and Tennant 1985). Larvae likely eat algae.

General Habitat Characteristics:

The California red-legged frog requires a variety of habitat elements with aquatic breeding areas embedded within a matrix of riparian and upland dispersal habitats. Breeding sites of the California red-legged frog are in aquatic habitats including pools and backwaters within streams and creeks, ponds, marshes, springs, sag ponds, dune ponds and lagoons. Additionally, California red-legged frogs frequently breed in artificial impoundments such as stock ponds. Upland habitats downed woody vegetation, leaf litter, and small mammal burrows; habitats that provide protection from predators and prevent desiccation (drying) of California red-legged frogs.

Population and Habitat Status:

Based on the best available information at the time of listing, the historic range of the California red-legged frog was described as extending along the coast from the vicinity of Point Reyes National Seashore in Marin County, and inland from the vicinity of the City of Redding in Shasta County, southward to northwestern Baja California, Mexico (61 FR 25814). The listing rule described an intergrade zone between the California red-legged frog and the closely related (and non-listed) northern red-legged frog (Rana aurora; formerly, Rana aurora aurora) that extended approximately from the Walker Creek watershed in Marin County north to southern Mendocino County. Recent research on the genetics of red-legged frogs indicates that the intergrade zone between the California red-legged frog and the northern red-legged frog likely occurs within a narrower geographic area than previously known, and that the range of the California red-legged frog extends about 60 miles (100 kilometers) further north. California red-legged frogs are known to occur in the following southern three coastal Hydrographic Units in Mendocino County: Point Arena, Garcia, and Gualala.

Threats:

Factors associated with declining populations of the California red-legged frog include degradation and loss of its habitat through agriculture, urbanization, mining, overgrazing, recreation, timber harvesting, non-native plants, impoundments, water diversions, degraded water quality, use of pesticides, and introduced predators. The reason for decline and degree of threats vary by geographic location. California red-legged frog populations are threatened by more than one factor in most locations.

Conservation Needs:

The California red-legged frog recovery plan provides a strategy for recovery of the species. Recovery objectives in the recovery plan include: 1) protecting existing populations by reducing threats; 2) restoring and creating habitat that will be protected and managed in perpetuity; 3) surveying and monitoring populations and conducting research on the biology of and threats to the species; and 4) re-establishing populations of the species within its historic range.