California red-legged frog
California red-legged frogs are endemic to California and extreme northern Baja California, Mexico. This species occurs most commonly along the Northern and Southern Coast Ranges, and in isolated areas in the foothills of the Sierra Nevada Mountains. The frog is a federally listed threatened species of the United States and is protected by law.
The back of Rana draytonii is brown, grey, olive, or reddish color, with black flecks and dark, irregular, light-centered blotches, and is coarsely granular. There is a dark mask with a whitish border above the upper jaw, and black and red or yellow mottling in the groin. The lower abdomen and the underside of its hind legs are normally red. Males can be recognized by their enlarged forelimbs, thumbs, and webbing. Juveniles have more pronounced dorsal spotting, and may have yellow, instead of red, markings on the underside of the hind legs. A characteristic feature of the red-legged frog is its dorsolateral fold, which is visible on both sides of the frog, extending roughly from the eye to the hip. Rana draytonii looks very similar to the Northern Red-legged Frog and was previously considered a subspecies.
Ecology and behavior
This species is estimated to have disappeared from 70% of its range, and is now only found in about 256 streams or drainages in 28 counties of California. However, California red-legged frogs are still common along the coast and the majority of their population declines are in the Sierra Nevadas. Breeding occurs from November to March (breeding has been recorded earlier in the southern limits of its range). The male frogs' advertisement call is a series of a few small grunts, usually given while swimming around underwater. Choruses are weak and easily missed. This species is usually active in daylight and inhabits dense, shrubby or emergent riparian vegetation and still or slow-moving perennial and ephemeral water bodies that also serve as breeding sites. The California red-legged frog hybridizes with the Northern red-legged Frog in Sonoma County and Marin County is an important food source for the endangered San Francisco garter snake.
The tadpoles (larvae) of this species may metamorphose into frogs within several months of hatching from the egg, or may "overwinter", which extends the time it takes a tadpole to metamorphose from seven to 13 months. Recent discoveries, such as overwintering, have management implications for this threatened species, particularly when aquatic habitat undergoes modification.
This frog is listed as threatened and is protected by California law. The main cause of their population decline is habitat loss and destruction, but introduced predatory species such as bullfrogs might also be a big factor. After years of litigation initiated by land developers organizations, specifically the Home Builders Association of Northern California, and scientific back-and-forth, the U.S. Fish and Wildlife Service announced in April 2006 the designation of about 450,000 acres (1800 km²) of critical California habitat for the threatened frog. This protected habitat did not include any land in Calaveras County, the setting of Mark Twain's short story, "The Celebrated Jumping Frog of Calaveras County", which features this species.
On 17 September 2008, the US Fish and Wildlife Service proposed to more than triple the habitat of the California red-legged frog, citing political manipulation by former deputy assistant secretary at the United States Department of the Interior Julie MacDonald. According to the Los Angeles Times, "Development and destruction of wetlands have eliminated the frogs from more than 70% of their historic range. MacDonald would have reduced what was left of the frog's range by 82%." San Mateo County and Monterey County of CA seem to have some of the largest healthy populations of these frogs, especially in coastal wetlands.
In March 2010, the U.S. Fish and Wildlife Service announced 1,600,000 acres (6,500 km2) of protected land for the species throughout California. The largest population of the frog will be given protection on a 48-acre stretch of land in Placer County.
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- USFWS Species Profile
- United States Fish and Wildlife Service. Recover Plan for the California Red-legged Frog. 2002. p. 1
- Fellers, G. M., A. E. Launer, G. Rathbun, S. Bobzien, J. Alvarez, D. Sterner, R. B. Seymour, and M. Westphal. 2001. Overwintering tadpoles in the California red-legged frog (Rana aurora draytonii). Herpetological Review 32:156–157.
- A California frog may be about to get room to stretch its red legs
- "California Red-Legged Frog". Wild Equity Institute. http://wildequity.org/species/22. Retrieved August 29, 2011.
- "California Red-Legged Frog". California Department of Pesticide Regulation. 2002. http://www.cdpr.ca.gov/docs/endspec/espdfs/crlfall.pdf. Retrieved August 29, 2011.
- Endangered California Red-Legged Frog to Receive Large New Protected Habitat Area - Finally
- .PDF Maps of Northern and Southern Protected Ranges via FWS
- Perlman, D. Red-legged frogs get 48-acre preserve in Sierra. San Francisco Chronicle November 24, 2010.
- Hillis, D. M. (2007) Constraints in naming parts of the Tree of Life. Mol. Phylogenet. Evol. 42: 331–338.