Rana draytonii

Baird and Girard, 1852

California Red-legged Frog

G2Imperiled (G2G3) Found in 88 roadless areas NatureServe Explorer →
G2ImperiledGlobal Rank
Near threatenedIUCN
HighThreat Impact
California red-legged frog (Rana draytonii). Photo by U.S. Fish & Wildlife Service, Public Domain (U.S. Government Work), via ECOS.
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.105364
Element CodeAAABH01022
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNNear threatened
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAmphibia
OrderAnura
FamilyRanidae
GenusRana
Synonyms
Rana aurora draytoniiBaird and Girard, 1852
Other Common Names
California red-legged frog (EN)
Concept Reference
Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
Taxonomic Comments
Genetic evidence supporting the recognition of Rana aurora and R. draytonii as distinct species is presented by Hayes and Miyamoto (1984), Shaffer et al. (2004), Conlon et al. (2006), and Pauly et al. (2008).
Conservation Status
Review Date2015-06-05
Change Date2015-06-05
Edition Date2009-02-27
Edition AuthorsHammerson, G.
Threat ImpactHigh
Range Extent20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Restricted mostly to California, where populations have declined greatly due to habitat loss and degradation, past overexploitation, and introduced species; species continues to be threatened by habitat degradation and exotic species.
Range Extent Comments
Native historical range extended from southern Mendocino County in northwestern California south (primarily west of the Cascade-Sierra crest) to northwestern Baja California (Shaffer et al. 2004). Historical populations on the floor of the Central Valley may not have persisted due to extensive natural flooding (Fellers, in Lannoo 2005). Range is now much reduced in the Sierra Nevada and in southern California, but the species is still present throughout much of its former range in the central California coast range (Fellers, in Lannoo 2005). This species has been introduced in a few places in Nevada, but the current status of those populations is uncertain (A. Cook, cited by Fellers, in Lannoo 2005). Rana draytonii is still present in Baja California, Mexico (USFWS 2000, Grismer 2002, Shaffer et al. 2004). Elevational range extended from sea level to about 1,500 meters (5,000 feet); usually below 1,200 meters (3,935 feet).
Occurrences Comments
Number of distinct occurrences (subpopulations) is unknown but probably is at least several dozen. According to USFWS (2000), the species occurs in about 238 streams or drainages.

In the mid-1990s, most of the occupied habitat was in Monterey, San Luis Obispo, and Santa Barbara counties; the species occurred in only 5 sites south of the Tehachapi Mountains (80+ historic sites) (USFWS 1996) Aggregations including more than 350 adults were known only from Pescadero Marsh Natural Preserve in coastal San Mateo County, Point Reyes National Seashore in Marin County, and Rancho San Carlos in Monterey County (USFWS 1996). More than 120 breeding sites exist in Marin County (Fellers, in Lannoo 2005).

In California, south of Los Angeles, a single population is known from the Santa Rosa Plateau in Riverside County (Shaffer et al. 2004). Only two populations are known to exist south of Santa Barabra (Fellers, in Lannoo 2005).

In the Sierra Nevada, Rana draytonii is now represented by only about a half dozen populations, only one of which is known to have more than 10 breeding adults (Shaffer et al. 2004).
Threat Impact Comments
Factors contributing to local declines include wetland destruction and degradation/fragmentation, urbanization, residential development, reservoir construction, stream channelization, livestock grazing of riparian vegetation, off-road vehicle activity, drought, overharvesting, and exotic fishes (bass, mosquitofish) and possibly bullfrogs (Kiesecker and Blaustein 1988, 1998; USFWS 1994, 1996, 2000; Adams 1999, 2000; Lawler et al. 1999; Cook and Jennings 2001; Kiesecker, Blaustein and Miller 2001a; Cook 2002). Conversion of habitat to more permanent ponds is an important threat (as this allows breeding waters to be invaded by non-native predators). Habitat characteristics and good leaping ability may render Rana aurora/draytonii less vulnerable to bullfrog predation than is Rana pretiosa (Pearl et al. 2004). McAllister and Leonard (in Jones et al. 2005) noted that in many areas red-legged frogs coexist with bullfrogs.

Declines in the red-legged frog complex (including Rana draytonii) also have been attributed to global warming, UV-B radiation (Belden and Blaustein 2002), airborne contaminants (pesticide drift), and disease (see Davidson et al. 2001). Davidson et al. (2002) found support for the negative impact of wind-borne agrochemicals and weaker evidence for the widespread impact of habitat destruction and UV-B radiation; evidence did not support the hypothesis that declines have been caused by climate change.
Ecology & Habitat

Description

Dorsum brown, gray, olive, or reddish, with irregular dark spotting or blotching; usually has a dark mask above the whitish jaw stripe; adults usually red on lower abdomen and underside of legs; usually coarse blackish, red, and yellow mottling in groin; relatively long legs (heel reaches at least to nostril when extended leg is pulled forward; eyes face outward, well covered by lids when viewed from above; prominent dorsolateral folds; snout-vent length usually 8-12 cm in adult males, 9-14 cm in adult females; young may have yellow instead of red on underside of legs and in groin; adult males have enlarged forelimbs and thumb base, more extensive webbing, and average about 2 cm longer in adult SVL (Stebbins 1985, Hayes and Miyamoto 1984).

Diagnostic Characteristics

Differs from subspecies aurora in having more dorsal spots (usually with light centers), rougher skin, shorter limbs, and smaller eyes (Stebbins 1985); also averages larger (by 35-40 mm) in adult SVL (usually 8-14 cm vs. 5-9 cm) (Hayes and Miyamoto 1984).

Habitat

This species usually occurs in or near quiet permanent water of streams, marshes, ponds, lakes, and other quiet bodies of water. In summer, frogs estivate in small mammal burrows, leaf litter, or other moist sites in or near (within a few hundred feet of) riparian areas (Rathbun et al. 1993, cited by USFWS 1994; USFWS 1996). Individuals may range far from water along riparian corridors and in damp thickets and forests. Breeding occurs in permanent or seasonal water of ponds, marshes, or quiet stream pools, sometimes in lakes (Fellers, in Jones et al. 2005); eggs often are attached to emergent vegetation, float at surface (Hayes and Miyamoto 1984).

Reproduction

Breeds typically during or shortly after large rainfall events in late winter or early spring (Hayes and Miyamoto 1984, USFWS 1996). In southern California breeds January-July (primarily in February). Breeding period lasts about 1-2 weeks. Eggs hatch in 6-14 days. Larval mortality tends to be very high. Larvae metamorphose 3.5-7 months after hatching; sometimes they may overwinter (Fellers et al. 2001). Sexually mature in 3-4 years, may live 8-10 years.
Terrestrial Habitats
Forest/WoodlandShrubland/chaparral
Palustrine Habitats
HERBACEOUS WETLANDRiparian
Other Nations (1)
United StatesN2
ProvinceRankNative
NevadaSNANo
CaliforniaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentHigh (continuing)
1.1 - Housing & urban areasHigh (continuing)
1.2 - Commercial & industrial areasHigh (continuing)
2 - Agriculture & aquacultureHigh (continuing)
2.3 - Livestock farming & ranchingHigh (continuing)
4 - Transportation & service corridorsHigh (continuing)
4.3 - Shipping lanesHigh (continuing)
5 - Biological resource useInsignificant/negligible or past
5.1 - Hunting & collecting terrestrial animalsInsignificant/negligible or past
7 - Natural system modificationsHigh (continuing)
7.2 - Dams & water management/useHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesHigh (continuing)
9 - PollutionHigh (continuing)
9.1 - Domestic & urban waste waterHigh (continuing)
9.2 - Industrial & military effluentsHigh (continuing)
9.3 - Agricultural & forestry effluentsHigh (continuing)
11 - Climate change & severe weatherHigh (continuing)
11.2 - DroughtsHigh (continuing)

Roadless Areas (88)
California (88)
AreaForestAcres
Bald RockPlumas National Forest4,675
Bear MountainLos Padres National Forest913
Bear MountainLos Padres National Forest913
Big RocksLos Padres National Forest11,866
Black ButteLos Padres National Forest5,116
Black ButteLos Padres National Forest5,116
Black MountainLos Padres National Forest16,818
Bucks LakePlumas National Forest680
Butt Mtn.Lassen National Forest8,217
CamuesaLos Padres National Forest8,209
CamuesaLos Padres National Forest8,209
Carson - IcebergStanislaus National Forest56,430
Chalk PeakLos Padres National Forest7,472
Cherry LakeStanislaus National Forest1,106
Chips CreekLassen National Forest29,089
Chips CreekPlumas National Forest12,940
Cub CreekLassen National Forest8,643
De La GuerraLos Padres National Forest5,418
De La GuerraLos Padres National Forest5,418
Devil GulchSierra National Forest30,490
DiableLos Padres National Forest19,597
DiableLos Padres National Forest19,597
Dry LakesLos Padres National Forest17,043
Duncan CanyonTahoe National Forest8,621
East YubaTahoe National Forest17,968
Ferguson RidgeSierra National Forest6,104
Fish CanyonAngeles National Forest29,886
Fox MountainLos Padres National Forest52,072
Fox MountainLos Padres National Forest52,072
Garcia MountainLos Padres National Forest7,850
Garcia MountainLos Padres National Forest7,850
Horseshoe SpringsLos Padres National Forest14,089
Horseshoe SpringsLos Padres National Forest14,089
IshiLassen National Forest21,805
JuncalLos Padres National Forest12,289
JuncalLos Padres National Forest12,289
La BreaLos Padres National Forest14,031
La BreaLos Padres National Forest14,031
La PanzaLos Padres National Forest4,954
Little PineLos Padres National Forest1,315
Little PineLos Padres National Forest1,315
Los Machos HillsLos Padres National Forest11,112
Los Machos HillsLos Padres National Forest11,112
Lpoor CanyonLos Padres National Forest13,762
Lpoor CanyonLos Padres National Forest13,762
Machesna MountainLos Padres National Forest12,271
Magic MountainAngeles National Forest15,542
Malduce BuckhornLos Padres National Forest14,177
ManzanaLos Padres National Forest2,101
MatilijaLos Padres National Forest5,218
MatilijaLos Padres National Forest5,218
Middle ForkPlumas National Forest29,278
Middle YubaTahoe National Forest7,379
Mill CreekLassen National Forest7,587
Mirada PimeLos Padres National Forest13,302
MonoLos Padres National Forest28,141
MonoLos Padres National Forest28,141
Mt. RaymondSierra National Forest6,965
NordhoffLos Padres National Forest12,031
North Fork American RiverTahoe National Forest38,495
North Fork American RiverTahoe National Forest38,495
North Fork Middle Fork American RiverTahoe National Forest11,245
North Fork Middle Fork American RiverTahoe National Forest11,245
North MountainStanislaus National Forest7,856
Polk SpringsLassen National Forest9,466
Red MountainAngeles National Forest8,034
RubiconEldorado National Forest4,872
Salt CreekAngeles National Forest11,022
Salt SpringsEldorado National Forest133
San JoaquinSierra National Forest22,474
Santa CruzLos Padres National Forest21,182
Santa CruzLos Padres National Forest21,182
Sespe - FrazierAngeles National Forest4,254
Sespe - FrazierLos Padres National Forest106,910
Stanley MountainLos Padres National Forest14,674
Stanley MountainLos Padres National Forest14,674
Tepusquet PeakLos Padres National Forest5,821
Tepusquet PeakLos Padres National Forest5,821
TequepisLos Padres National Forest9,080
TequepisLos Padres National Forest9,080
Trumbull PeakStanislaus National Forest6,164
TuleAngeles National Forest9,861
TuleAngeles National Forest9,861
West YubaPlumas National Forest6,071
West YubaTahoe National Forest16,059
White LedgeLos Padres National Forest18,632
White LedgeLos Padres National Forest18,632
Wild Cattle MtnLassen National Forest4,965
References (34)
  1. Altig, R. and Dumas, P.C. 1972. <i>Rana aurora</i>. Catalogue of American Amphibians and Reptiles. 160:1-4.
  2. Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.
  3. Belden, L. K., and A. R. Blaustein. 2002. Exposure of red-legged frog embryos to ambient UV-B radiation in the field negatively affects larval growth and development. Oecologia 130:551-554.
  4. Biosystems Analysis, Inc. 1989. Endangered Species Alert Program Manual: Species Accounts and Procedures. Southern California Edison Environmental Affairs Division.
  5. Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
  6. Conlon, J. M., N. Al-Ghafari, L. Coquet, J. Leprince, T. Jouenne, H. Vaudry, and C. Davidson. 2006. Evidence from peptidomic analysis of skin secretions that the red-legged frogs, <i>Rana aurora draytonii</i> and <i>Rana aurora aurora</i>, are distinct species. Peptides 27:1305-1312.
  7. Cook, D. 2002. <i>Rana aurora draytonii</i>. Predation. Herpetological Review 33:303.
  8. Cook, D., and M. R. Jennings. 2001. <i>Rana aurora draytonii</i>. Predation. Herpetological Review 32:182-183.
  9. Crother, B. I. (editor). 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 8th edition. SSAR Herpetological Circular 43:1-104. [Updates in SSAR North American Species Names Database at: https://ssarherps.org/cndb]
  10. Davidson, C., H. B. Shaffer, and M. R. Jennings. 2001. Declines of the California red-legged frog: climate, UV-B, habitat, and pesticides hypotheses. Ecological Applications 11:464-479.
  11. Davidson, C., H. B. Shaffer, and M. R. Jennings. 2002. Spatial tests of the pesticide drift, habitat destruction, UV-B, and climate-change hypotheses for California amphibian declines. Conservation Biology 16:1588-1601.
  12. 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 (<i>Rana aurora draytonii</i>). Herpetological Review 32:156-157.
  13. Frost, D. R. 2010. Amphibian Species of the World: an Online Reference. Version 5.4 (8 April 2010). Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index.php. American Museum of Natural History, New York, USA.
  14. Frost, D.R. 2020. Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History, New York, USA. Online: http://research.amnh.org/herpetology/amphibia/index.html
  15. Green, D. M. 1985. Biochemical identification of red-legged frogs, <i>Rana aurora draytoni</i>, at Duckwater, Nevada. Southwestern Naturalist 30:614-616.
  16. Grismer, L. L. 2002. Amphibians and reptiles of Baja California including its Pacific islands and islands in the Sea of Cortes. University of California Press, Berkeley. xiii + 399 pp.
  17. Hayes, M. P., and M. M. Miyamoto. 1984. Biochemical, behavioral and body size differences between <i>Rana aurora aurora</i> and <i>R. a. draytoni</i>. Copeia 1984:1018-1022.
  18. Hayes, M. P., and M. R. Jennings. 1988. Habitat correlates of distribution of the California red-legged frog (<i>Rana aurora</i>) and the foothill yellow-legged frog (<i>Rana boylii</i>): implications for management. Pages 144-158 in Szaro, R.C., et al., technical coordinators. Management of amphibians, reptiles, and small mammals in North America. USDA For. Serv., Gen. Tech. Rep. RM-166.
  19. Hayes, M. P., and M. R. Tennant. 1985. Diet and feeding behavior of the California red-legged frog, <i>Rana aurora draytoni</i> (Ranidae). Southwestern Naturalist 30:601-605.
  20. Jones, L.L.C., W. P. Leonard, and D. H. Olson, editors. 2005. Amphibians of the Pacific Northwest. Seattle Audubon Society, Seattle, Washington. xii + 227 pp.
  21. Kiesecker, J. M., and A. R. Blaustein. 1998. Effects of introduced bullfrogs and smallmouth bass on microhabitat use, growth, and survival of native red-legged frogs (<i>Rana aurora</i>). Conservation Biology 12:776-787.
  22. Kiesecker, J. M., A. R. Blaustein, and L. K. Belden. 2001b. Complex causes of amphibian population declines. Nature 410:681-684.
  23. Lannoo, M. (editor). 2005. Amphibian declines: the conservation status of United States species. University of California Press, Berkeley. xxi + 1094 pp.
  24. Lawler, S. P., D. Dritz, T. Strange, and M. Holyoak. 1999. Effects of introduced mosquitofish and bullfrogs on the threatened California red-legged frog. Conservation Biology 13:613-622.
  25. Licht, L.E. 1971. Breeding habits and embryonic thermal requirements of the frogs, <i>Rana aurora aurora</i> and <i>Rana pretiosa pretiosa</i>, in the Pacific Northwest. Ecology 52(1):116-124.
  26. Pauly, G. B., S. R. Ron, and L. Lerum. 2008. Molecular and ecological characterization of extralimital populations of red-legged frogs from western North America. Journal of Herpetology 42:668-679.
  27. Shaffer, H. B., G. M. Fellers, S. R. Voss, J. C. Oliver, and G. B. Pauly. 2004. Species boundaries, phylogeography and conservation genetics of the red-legged frog (<i>Rana aurora/draytonii</i>) complex. Molecular Ecology 13:2667-2777.
  28. Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
  29. Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.
  30. U.S. Fish and Wildlife Service (USFWS). 11 September 2000. Proposed designation of critical habitat for the California red-legged frog (<i>Rana aurora draytonii</i>). Federal Register 65(176):54892-54932.
  31. U.S. Fish and Wildlife Service (USFWS). 13 March 2001. Final determination of critical habitat for the California red-legged frog. Federal Register 66(49):14626-14758.
  32. U.S. Fish and Wildlife Service (USFWS). 1994. Proposed endangered status for the California red-legged frog. Federal Register 59(22):4888-4895. 2 February 1994.
  33. U.S. Fish and Wildlife Service (USFWS). 23 May 1996. Determination of threatened status for the California red-legged frog. Federal Register 61(101):25813-25833.
  34. Zeiner, D.C., W.F. Laudenslayer, Jr., and K.E. Mayer, editors. 1988. Califonia's wildlife. Vol. I. Amphibians and reptiles. California Dept. Fish and Game, Sacramento. ix + 272 pp.