U.S. Fish and Wildlife Service Finds California Amphibian Species Worthy of Consideration


yellow-legged-frog-1In a review of a recent “megapetition” from the Center for Biological Diversity, in which 53 species were proposed for listing under the federal Endangered Species Act (ESA), the U.S. Fish and Wildlife Service found that four California amphibian species, Cascades frog (Rana cascadae), foothill yellow-legged frog (Rana boylii), relictual slender salamander (Batrachoseps relictus), and Western spadefoot (Spea hammondii), were worthy of review to determine whether listing under the federal ESA is warranted. With that finding begins a 12-month evaluation process for these four species. The listing petition for one California amphibian species (California giant salamander [Dicamptodon ensatus]) was found to be lacking information. The petitions for eight additional amphibian species and five reptiles from California are still under review, with decisions assumed to be forthcoming.

The Cascades frog is a medium-sized montane frog of ponds, streams, and lakes in the Trinity Mountains and Shasta and Lassen areas of northern California. The species’ larger range is from northern Butte County north into Washington State, but Cascades frogs are gone from most formerly known sites in California. As such, it is already recognized as a Species of Special Concern by the California Department of Fish and Wildlife (CDFW). One reason posited for the decline of Cascades frogs is the widespread introduction of trout and non-native American bullfrogs in much of its range, possibly combined with the effects of air-borne pollution and a recently described disease known to cause declines in numerous other species.

yellow-legged-frog-2The foothill yellow-legged frog is a frog of coastal and Sierra Nevada foothill streams, found below 5,000 feet in elevation. It was historically found in the north and south Coast Ranges, into the Cascade Range north into Oregon, and down the west slope of the Sierra Nevada into Kern County. Isolated populations are found in Elizabeth Lake Canyon and the San Gabriel Drainage in southern California, as well as in Baja California. This is a frog adapted for life in the rapidly moving water of swollen streams. Breeding takes place among the gravel and cobble bars deposited during spring snowmelt, and tadpoles have a morphology that allows them to stay close to substrates while in rapidly cascading water. Foothill yellow-legged frogs are diurnal and often found basking on exposed rocks or gravel bars in full sunlight and within one leap of water. This species has declined from much of its range, especially from the western slopes of the Sierra Nevada south of Monterey. Reasons for decline are not well understood, but the effects of introduced species, disease, and damming of rivers and streams through massive water reclamation projects are likely intertwined. This species is also recognized as a Species of Special Concern by CDFW, and has been the focus of many surveys and planning efforts by ECORP on water infrastructure projects, including projects with a Federal Energy Resource Council nexus.

The relictual slender salamander occurs only in a small area in the vicinity of the Kern and Tule Rivers in Tulare County, and has been declining at lower elevations. It is apparently now found only on Breckenridge Mountain in Kern County. Very similar in appearance to some other slender salamanders found throughout the state, the relictual slender salamander may require genetic analysis to differentiate it from other salamanders. In common with other slender salamanders, the relictual slender salamander has a narrow body, long tail, and superficially worm-like appearance. This group of salamanders is part of the “lungless” salamander group (Plethodontidae), which perform all respiration though the skin and tissues lining the mouth. They are completely terrestrial, but restricted to moist environments so that desiccation does not occur.

western-spadefootThe western spadefoot is a toad-like frog found in grasslands, vernal pool landscapes, oak woodlands, chaparral, and alluvial fans in California. It is found from southern Shasta County through the Great Central Valley, into central Kern County, west into coastal central and southern California, and south into Baja California. The keratinized “spades” found on the hind feet are used for digging into loose soil, in which a western spadefoot aestivates during hot, dry weather. Upon the start of the rainy season, the frog becomes active, digs itself out of its burrow, and finds temporary rain pools in which to breed. The resultant eggs and tadpoles are adapted to life in these short-term habitats, and tadpoles can transform to froglets in as few as 30 days. The western spadefoot is considered a Species of Special Concern by CDFW due to extensive losses of habitat to agriculture and residential or commercial development. ECORP routinely performs surveys for this species and contributes mitigation guidelines for projects in which western spadefoot may be a concern.

For more information please contact Eric Stitt (Northern California) at (916) 782-9100 or Todd Chapman (Southern California) at (714) 648-0630.