SNFPA Draft Supplemental Environmental Impact Statement

June 2003

Chapter 3: Affected Environment

3.2. Species of the Sierra Nevada

3.2.1. Endangered, Threatened, and Proposed Species

3.2.1.1. California Red-Legged Frog (Rana aurora)

The information below was extracted and summarized from the following reference: USDI Fish and Wildlife Service. 2002. Recovery Plan for the California Red-Legged Frog (Rana aurora draytonii). U.S. Fish and Wildlife Service, Portland, OR. 173 pages. Detailed references can be found in that document. This section updates and supplements the information found in FEIS Volume 3, Chapter 4, Part 4.3, pp. 27-28.

Habitat Requirements: Adult California red-legged Frogs require dense, shrubby, or emergent riparian vegetation close to deep (greater than 2.3 feet), still or slow-moving waters. Cool water temperatures are also required. Historically, these frogs were found in the Central Valley of California where intermittent streams that included some area with water at least 2.3 feet deep, had largely intact emergent or shoreline vegetation, lacked introduced bullfrogs, and tended to have native rather than introduced fish. Dense vegetation close to the water and shading of moderately deep water appeared to be the most important habitat characteristics

During dry periods, the California red-legged frog rarely is encountered far from water. During periods of wet weather, starting with the first rains of fall, some individuals may make overland excursions through upland habitats. Most of these overland movements occur at night. Evidence from marked and radio-tagged frogs on the San Luis Obispo County coast suggest that frog movement, via upland habitats, of about 1.6 kilometers (1 mile) are possible over the course of a wet season. Frogs have been observed to make long-distance movements that are straight-line, point to point migrations rather than using corridors for moving in between habitats. The manner in which California red-legged use upland habitats is not well understood; the amount of time California red-legged frogs spend in upland habitats, patterns of use, and whether there is differential use of uplands by juveniles, subadults, and adults is being studied.

Current Range and Distribution

Presently, this species is known to occur in about 238 streams or drainages in 23 counties of central and southern California. In the Sierra Nevada, it is thought to occur from Shasta to Mariposa counties at elevations from sea level to 5,000 feet elevation. Recent surveys indicate that the California red-legged frog is extremely rare or virtually extirpated in the Sierra Nevada foothills.

Based on limited survey data, national forests within this species' range have estimated the current population to be between 50-200 individuals. Population trend information for the past ten year period is virtually unknown due to the lack of detections and species specific surveys.

The California red-legged frog potentially occurs on the following national forests within the planning area: Lassen, Plumas, Eldorado, and Tahoe. Staff on all of these national forests have been surveying for California red-legged frog with only the Plumas National Forest, Feather River District having positive identifications totalling two new populations. Other national forests within the Sierra Nevada surveying for this species include the Sequoia and Sierra National Forests.

Status

The California red-legged frog was proposed for listing as endangered on February 2, 1994, with no critical habitat proposed. The final listing of the species as threatened was on May 23, 1996. It has been extirpated from 75 percent of its former range. A revised Draft Recovery Plan for the California red-legged frog is presently in review stage. Central Valley populations of the red-legged frog are currently extinct, and only 3 areas in the remainder of the State currently support over 350 adults. Critical habitat was proposed on September 11, 2000 (65 FR 54892) with the Final Rule made on March 13, 2001 (66 FR 14625-14674). The Homeowners Association of Northern California and Others file suit in the 9th Court regarding the Final Rule. A settlement agreement was reached and modification in the designated critical habitat was made.

USDA Forest Service · Pacific Southwest Region