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California Red Legged Frog

Rana draytonii Baird & Girard 1852

Description

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Rana draytonii ranges in size from 1.5 to 5 inches in length, making it the largest native frog in the Western United States (Wright and Wright 1949). Adult females are significantly longer than males, with an average snout- urostyle length of 138 mm versus 116 mm for adult males (Hayes and Miyamoto 1984).

Dorsolateral folds are prominent. Tadpoles range in length from 14 to 80 mm, and are a dark brown or olive, marked with darker spots (Storer 1925).

The hind legs and lower abdomen of adult frogs are often characterized by a reddish or salmon pink color, and the back is brown, gray, olive, or reddish brown, marked with small black flecks and larger irregular dark blotches (Recovery Plan for the California Red-legged Frog 2002; Stebbins 1985).

Dorsal spots often have light centers, and in some individuals form a network of black lines (Stebbins 1985). Rana draytonii differs from its close relative R. aurora , the Northern red-legged frog, in several ways. Adult R. draytonii are 35 to 40 millimeters longer than adult R. aurora (Hayes and Miyamoto 1984). The dorsal spots of R. draytonii are more numerous, and usually have light centers (Stebbins 1985). R. draytonii also has rougher skin, shorter limbs and smaller eyes than R. aurora (Stebbins 1985). R. draytonii has paired vocal sacs and typically calls from the air, while R. aurora lacks vocal sacs and may call underwater (Hayes and Krempels 1986; Licht 1969).

Egg masses in R. draytonii are deposited such that the mass floats at the surface (Hayes and Miyamoto 1984), whereas R. aurora submerge the mass in deeper water (Licht 1969; Storm 1960).

R. draytonii breed from November to April (Storer 1925), while R. aurora breeds from January to March (Nussbaum et al 1983).

Rana draytonii is widely believed to have inspired Mark Twain's fabled story, "The Celebrated Jumping Frog of Calaveras County."

The California Red-legged frog was Federally listed on June 24, 1996.

This species was featured as News of the Week:

May 13, 2019: The California Red-legged Frog, Rana draytonii, has not been seen in Yosemite National Park for at least 50 years. Yet, thanks to the cooperative efforts of the National Park Service, Yosemite Conservancy, San Francisco Zoo & Gardens, U. S. Fish & Wildlife Service, California Department of Fish & Wildlife, and NatureBridge, once again Red-legged frogs are back in Yosemite. In a program that began in 2016, an estimated 4,000 frog eggs and 500 adult frogs have been reintroduced from a captive breeding program at the zoo. But with another 200 adult frogs released in April and another 275 to be released in June, the reintroduction program is now fully operational. The captive population was founded with frogs collected in El Dorado County, in the foothills of the Sierra Nevada north of Yosemite. The frogs were released in Cook’s Meadow, in view of Yosemite Falls in Yosemite Valley. Transponders attached to 75 frogs will enable researchers to follow the frogs in the future. This trial reestablishment might set the stage for future attempts in other parts of the Sierra Nevada where the frogs once thrived. (David B. Wake)

Leer mas in espagñol. Cuenta por Fauna del Noroeste.

References

  • Jennings, M. (). Electronic database of California red-legged frog occurrences.
  • Natural Diversity Data Base (). California Department of Fish and Game, Natural Heritage Division, Sacramento, California.

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Distribution and Habitat

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Before the settlement of Europeans on the west coast, R. draytonii was probably common throughout the Coast Range from Point Arena (Mendocino County) south to Baja California, in the Sierra Nevada foothills, and around the northern part of the Central Valley. Records of this frog on the floor of the Central Valley probably represented short-term populations that did not survive the seasonal flooding of the valley floor (Zeiner et al. 1988; Jennings and Hayes 1985; Hayes and Krempels 1986).

Today the species is still common in the San Francisco Bay area (primarily Marin, Contra Costa, and Alameda Counties). Moderately large populations are also found in some parts of the Coast Range from San Mateo County south to San Luis Obispo ). Isolated populations exist in the Sierra Nevada foothills, northern Transverse Ranges, and Baja California (Natural Diversity Data Base 2001; Jennings in litt. 1998; Fellers unpubl.). R. draytonii live in areas subject to temporal and spatial changes, and therefore make use of a variety of habits, consisting of both aquatic, upland and riparian (Recovery Plan for the California Red-legged Frog 2002).

Adults breed in ponds or deep pools in slow-moving creeks. Where ponds are seasonal in nature, thickets and log jams along riparian corridors provide important non-breeding habitat. Populations are most likely to persist in areas with multiple breeding sites surrounded by suitable non-breeding habitat(N. Scott and G. Rathbun in litt. 1998).

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Life History, Abundance, Activity, and Special Behaviors

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R. draytonii breeds during a 1-2 week period between November and April, depending on locality (Stebbins 1985; Storer 1925). Egg masses consist of between 300 and 5,000 eggs (Recovery Plan for the California Red-legged Frog 2002; Storer 1925; Fellers unpubl.).

Egg masses are nearly always attached to emergent vegetation. Eggs hatch after 6 to 14 days depending on water temperature ( Jennings 1988).

Larvae typically metamorphose in 3.5 to 7 months, usually between July and September ( Storer 1925; Wright and Wright 1949), but some overwinter and transform after more than 12 months in the larval stage (Fellers et al. in press). Males may attain sexual maturity at 2 years, females at 3 (Jennings and Hayes 1985), and adult frogs may live 8 to 10 years. (Jennings et al in lit 1992). Larvae are thought to be algal grazers ( Jennings et al in lit 1992), and the adult diet consists mostly of invertebrates. Pacific Tree Fogs (Hyla regilla) and California mice (Peromyscus californicus are occasionally consumed by adult frogs ( Hayes and Tennant 1985). Juvenile frogs may be active both nocturnally and diurnally, whereas adult frogs are primarily active nocturnally ( Hayes and Tennant 1985). The primary predators on R. draytonii include garter snakes (Thamnophis spp.), raccoons (Procyon lotor), and great blue herons (Ardea herodias). Less frequently, red-legged frogs are eaten by American bitterns (Botaurus lentiginosus), black-crowned night herons(Nycticorax nycticorax), and rarely by red-shouldered hawks (Buteo lineatus)(Jennings and Hayes 1990; Rathbun and Murphy 1996). Other introduced species such as the bullfrog (Rana catesbeiana) and non-native fish also prey on the frog.

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Life History, Abundance, Activity, and Special Behaviors

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Many factors are contributing to the decline of R. draytonii populations, the main being habitat destruction and degradation. Introduced predators and perhaps disease have also contributed to the decline of this species.

This species has been extirpated from 99% of its Sierra Nevada range and is believed to be extinct in the Central Valley. Breeding populations remain along the coast, from San Mateo County to San Luis Obispo County. In 1996, it was declared a threatened species and over 4 million acres of habitat were designated as critical. However, in 2006 developers sued and 90% of that habitat designation was lost.

Now that has been partially remedied, thanks to legal action by the Center for Biological Diversity. As of March 16, 2010, the U. S. Fish and Wildlife Service has designated 1.6 million acres of habitat as critical, and the agency has acknowledged that the earlier reduction was flawed because of political interference from the Bush Administration.

The US Fish and Wildlife Service has published A Recovery Plan (2002, pdf) for the California Red-legged Frog, which remains a guideline for conservation of this iconic species. Delisting of the species may be possible by 2025 if recovery goals are met according to this report.

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Relation to Humans

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The primary impact from humans has been from direct habitat loss, especially the construction of houses, shopping centers, and roads. Much of the range of Rana draytonii has been historically grazed, both by dairy and by beef cattle. Cattle grazing in riparian zones causes serious damage to the vegetation, stream channel, and water quality. Rana draytonii may have benefited from beef cattle grazing due to the increased number of stock ponds that are maintained for the cattle.

Rana draytonii are also threatened by a number of introduced (non-native) species, some of which are regularly introduced by humans. These include sunfish, bass, trout, mosquitofish, and bullfrogs.

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California red-legged frog

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The California red-legged frog (Rana draytonii) is a species of frog found in California (USA) and northern Baja California (Mexico). It was formerly considered a subspecies of the northern red-legged frog (Rana aurora).[2] The frog is an IUCN vulnerable species, and a federally listed threatened species of the United States, and is protected by law.[1][3]

Distribution

The California red-legged frog is found in California and extreme northern Baja California, northwestern Mexico.[1] This species now occurs most commonly along the northern and southern Coast Ranges, and in isolated areas in the foothills of the Sierra Nevada mountains.[1] The current southernmost California populations are on the Santa Rosa Plateau in Riverside County, and within the Upper Las Virgenes Canyon Open Space Preserve in the Simi Hills in eastern Ventura County, near the community of West Hills.[1][4] In 2015, egg masses from the nearby Simi Hills were introduced to two streams in the Santa Monica Mountains. Juvenile frogs were found living at the locations a year later.[5][6]

Description

R. draytonii is a moderate to large (4.4–14 cm (1.7–5.5 in)) frog. The back is a brown, grey, olive, or reddish color, with black flecks and dark, irregular, light-centered blotches, and is coarsely granular. A dark mask with a whitish border occurs above the upper jaw, and black and red or yellow mottling is in the groin. The lower abdomen and the undersides of its hind legs are normally red. The male can be recognized by its large fore limbs, thumbs, and webbing. The juvenile frog has more pronounced dorsal spotting, and may have yellow, instead of red, markings on the undersides of the hind legs. A characteristic feature of the red-legged frog is its dorsolateral fold, visible on both sides of the frog, extending roughly from the eye to the hip. R. draytonii looks very similar to the northern red-legged frog.

Ecology and behavior

This species has disappeared from an estimated 70% of its range, and is now only found in about 256 streams or drainages in 28 counties of California.[7] However, the species is still common along the coast, and most of their population declines are in the Sierra Nevada and Southern California. The California red-legged frog is an important food source for the endangered San Francisco garter snake in San Mateo County.

Breeding occurs from November to March, or sometimes earlier toward the southern limits of its range. The male frog's advertisement call is a series of a few small grunts, usually given while swimming around under water. 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 tadpoles (larvae) of this species may metamorphose into frogs within about 7 months of hatching from the egg, or may overwinter, taking up to 13 months.[8] This is a recent discovery, which may have management implications for the species, particularly when aquatic habitat undergoes modification.

Conservation

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California red-legged frog in habitat
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Egg mass

This frog is listed as threatened and is protected by federal and California law. The main cause of the population decline is habitat loss and destruction, but introduced predatory species, such as American bullfrogs, might also be a factor.

2006

After years of litigation initiated by land developers' organizations, specifically the Home Builders Association of Northern California, and scientific back-and-forth, the US 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.

2008

On September 17, 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 Julie MacDonald at the United States Department of the Interior. 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%."[9] San Mateo County and Monterey County seem to have some of the largest healthy populations of these frogs, especially in coastal wetlands.[10][11]

2010

In March 2010, the US Fish and Wildlife Service announced 1,600,000 acres (6,500 km2) of protected land for the species throughout California, which has implications regarding development and use of such land.[1][12][13] The largest population of the frog will be given protection on a 48-acre stretch of land in Placer County.[14]

2015

A new law designates the California red-legged frog the “state amphibian” Presently, it is subject to protection under both federal and state laws passed in 1996. Although the designation as official state amphibian does not provide legal protection to the frog as a threatened species, it does highlight the importance that California places on the frog's preservation.[15]

See also

References

  1. ^ a b c d e f Hammerson, Geoffrey (2008). "Rana draytonii". IUCN Red List of Threatened Species. IUCN. 2008: e.T136113A4240307. doi:10.2305/IUCN.UK.2008.RLTS.T136113A4240307.en.
  2. ^ Frost, Darrel R. (2018). "Rana draytonii Baird and Girard, 1852". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 31 December 2018.
  3. ^ "California red-legged frog (Rana draytonii)". ECOS Environmental Conservation Online System. U.S. Fish and Wildlife Service. Archived from the original on 2 July 2017. Retrieved 31 December 2018.
  4. ^ Federal Register: "Endangered and Threatened Wildlife and Plants: Revised Designation of Critical Habitat for California Red-Legged Frog; Final Rule" . pg. 3 of pdf . accessed 6.16.2013
  5. ^ Carlson, Cheri (June 15, 2015). "Gone for decades, red-legged frogs surviving in Santa Monica Mountains". Ventura County Star. Retrieved 5 March 2016.
  6. ^ DWORETZKY, JOE (2019-07-25). "The threatened frogs of the Santa Monica Mountains always had it hard. The Woolsey fire made things much worse". Los Angeles Times. Retrieved 2019-07-25.
  7. ^ Recovery Plan for the California Red-legged Frog (Rana aurora draytonii) (PDF) (Report). Portland, Oregon: U.S. Fish and Wildlife Service. 2002. Retrieved 2013-04-03.
  8. ^ Fellers, G. M., et al. 2001. Overwintering tadpoles in the California red-legged frog (Rana aurora draytonii). Herpetological Review 32:156–157.
  9. ^ Cart, J. Room to stretch a frog's red legs. Los Angeles Times September 17, 2008.
  10. ^ "California Red-Legged Frog". Wild Equity Institute. Retrieved August 29, 2011.
  11. ^ "California Red-Legged Frog" (PDF). California Department of Pesticide Regulation. 2002. Archived from the original (PDF) on May 25, 2017. Retrieved August 29, 2011.
  12. ^ 6:19 pm (2010-03-16). "Endangered California Red-Legged Frog to Receive Large New Protected Habitat Area - Finally". Latimesblogs.latimes.com. Retrieved 2014-01-26.
  13. ^ .PDF Maps of Northern and Southern Protected Ranges via FWS Archived May 13, 2008, at the Wayback Machine
  14. ^ Perlman, D. Red-legged frogs get 48-acre preserve in Sierra.San Francisco Chronicle November 24, 2010.
  15. ^ Assembly Bill 2364 codified as Government Code §422.7. Effective January 1, 2015.
    "California red-legged frog named state amphibian". KPCC. Associated Press. 7 July 2014. Retrieved 1 January 2015.
    "New California laws for 2015: Frogs, drones, Confederate flags". Los Angeles Times. 1 January 2015. Retrieved 1 January 2015.
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California red-legged frog: Brief Summary

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The California red-legged frog (Rana draytonii) is a species of frog found in California (USA) and northern Baja California (Mexico). It was formerly considered a subspecies of the northern red-legged frog (Rana aurora). The frog is an IUCN vulnerable species, and a federally listed threatened species of the United States, and is protected by law.

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