Rana aurora


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Rana aurora
Species Authority: Baird & Girard, 1852
Common Name(s):
English Northern Red-legged Frog
Taxonomic Notes: Shaffer et al. (2004) presented genetic evidence supporting the recognition of Rana aurora and R. draytonii as distinct species.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-01-01
Assessor(s): Geoffrey Hammerson
Reviewer(s): Global Amphibian Assessment Coordinating Team (Simon Stuart, Janice Chanson, Neil Cox and Bruce Young)
Listed as Least Concern in view of the wide distribution, numerous subpopulations, ability to use altered habitats, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.
2004 Near Threatened

Geographic Range [top]

Range Description: Range extends from southwestern British Columbia, including Vancouver Island in Canada, south along the coast of the United States (primarily west of Cascade-Sierran crest), to northwestern California (Shaffer et al. 2004). The species has been introduced and is well established and widely distributed on Graham Island, Queen Charlotte Islands (Haida Gwaii), British Columbia; it is unclear whether the species is native there or introduced many years ago (Ovaska et al. 2002). Rana aurora also is introduced and established on Chichagof Island, Alaska; the source of the frogs was Oregon (Hodge 2004).
Canada; United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is represented by a large number of occurrences. Total adult population size is unknown but presumably exceeds 10,000. This species is relatively widespread and common over most of its range (McAllister and Leonard, in Jones et al. 2005; Pearl in Lannoo 2005).

Over the long term, extent of occurrence, area of occurrence, number/condition of subpoppulations, and population size have declined, but the amount of decline is uncertain. Currently, area of occupancy, number of subpopulations, and population size probably are declining, though the magnitude of the decline is uncertain.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Habitat includes the vicinity of quiet permanent waters of streams, marshes, or (less often) ponds and other quiet bodies of water. The frogs are sometimes found in damp woods and meadows some distance from water, especially during wet weather. This species occurs in sites with dense vegetation (e.g., willows) close to water and some shading. Red-legged frogs may occupy ephemeral pools if the water remains until late spring or early summer (Biosystems Analysis 1989). Estivation sites include small mammal burrows and moist leaf litter in dense riparian vegetation up to 26 meters from water (Rathbun et al. 1993, cited by USFWS 1994). Desiccation cracks in dry pond bottoms may be used as refuges (Alvarez, 2004, Herpetol. Rev. 35:162-163). Breeding sites most often are in permanent water; eggs are attached to stiff submerged stems at the surface of the water.
Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): 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 1998; USFWS 1994, 1996, 2000; Adams 1999, 2000; Lawler et al. 1999; Cook and Jennings 2001; Kiesecker, Blaustein and Miller 2001a; Cook 2002). An important threat is the loss of wetlands in the Willamette Valley (Oregon) and Puget Lowlands (Washington), but populations remain in some urbanized areas (see Pearl, in Lannoo 2005). 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 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.

Conservation Actions [top]

Conservation Actions: Rana aurora occurs in many protected areas, including several small wildlife refuges in Oregon and Washington managed by the U.S. Fish and Wildlife Service and in some state refuges. Most of its range is within actively managed agricultural and forestry matrix (under the control of private owners, the Bureau of Land Management, or the U.S. Forest Service).

Bibliography [top]

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Adams, M.J. 2000. Pond permanence and the effects of exotic vertebrates on anurans. Ecological Applications: 559-568.

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Briggs Sr, J.L. 1987. Breeding biology of the Cascade frog, Rana cascadae, with comparisons to R. aurora and R. pretiosa. Copeia: 241-245.

Brown, H.A. 1975. Reproduction and development of the red-legged frog, Rana aurora, in northwestern Washington. North-west Science: 241-252.

Bulger, J.B., Scott, N.J. and Seymour, R.B. 2003. Terrestrial activity and conservation of adult California redlegged frogs Rana aurora draytonii in coastal forests and grasslands. Biological Conservation: 85-95.

Cook, D. and Jennings, M.R. 2001. Rana aurora draytoni. Predation. Herpetological Review: 182-183.

Corkran, C.C. and Thoms, C. 1996. Amphibians of Oregon, Washington and British Columbia. Lone Pine Publishing, Edmonton, Alberta.

Davidson, C., Shaffer, H.B. and Jennings, M.R. 2001. Declines of the California Red-legged Frog: climate, UV-b, habitat, and pesticides hypotheses. Ecological Applications: 464–479.

Davidson, C., Shaffer, H.B. and Jennings, M.R. 2002. Spatial tests of the pesticide drift, habitat destruction, UB-B, and climate-change hypotheses for California amphibian declines. Conservation Biology: 1588-1601.

Doubledee, R.A., Muller, E.B. and Nisbet, R.M. 2003. Bullfrogs, disturbance regimes, and the persistence of California red-legged frogs. Journal of Wildlife Management: 424-438.

Fellers, G.M., Launer, A.E., Rathbun, G., Bobzien, S., Alvarez, J., Sterner, D., Seymour, R.B. and Westphal, M. 2001. Overwintering tadpoles in the California red-legged frog (Rana aurora draytonii). Herpetological Review: 156-157.

Green, D.M. 1985. Biochemical identification of red-legged frogs, Rana aurora draytoni, at Duckwater, Nevada. Southwestern Naturalist: 614-616.

Green, D.M. 1986. Systematics and evolution of western North American frogs allied to Rana aurora and Rana boylii: electrophoretic evidence. Systematic Zoology: 283-296.

Green, D.M. 1986. Systematics and evolution of western North American frogs allied to Rana aurora and Rana boylii: karyological evidence. Systematic Zoology: 273-282.

Hayes, M.P. and Miyamoto, M.M. 1984. Biochemical, behavioral and body size differences between Rana aurora aurora and R.a. draytoni. Copeia: 1018-1022.

Hayes, M.P., Pearl, C.A. and Rombough, C.J. 2001. Rana aurora aurora (Northern redlegged frog). Movement. Herpetological Review: 35-36.

IUCN. 2008. 2008 IUCN Red List of Threatened Species. Available at: (Accessed: 5 October 2008).

Jennings, M.R. and Hayes, M.P. 1994. Amphibian and reptile species of special concern in California. Final Report submitted to the California Department of Fish and Game, Inland Fisheries Division. Contract No. 8023.

Jones, L.L.C., W. P. Leonard, and D. H. Olson, editors. 2005. Amphibians of the Pacific Northwest. Seattle Audubon Society, Seattle, Washington.

Kiesecker, J.M. and Blaustein, A.R. 1998. Effects of introduced bullfrogs and smallmouth bass on microhabitat use, growth, and survival of native red-legged frogs (Rana aurora). Conservation Biology: 776-787.

Kiesecker, J.M., Blaustein, A.R. and Miller, C.L. 2001. Potential mechanisms underlying the displacement of native red-legged frogs by introduced bullfrogs. Ecology: 1964-1970.

Lannoo, M. (editor). 2005. Amphibian declines: the conservation status of United States species. University of California Press, Berkeley, California.

Lawler, S.P., Dritz, D., Strange, T. and Holyoak, M. 1999. Effects of introduced mosquitofish and bullfrogs on the threatened California red-legged frog. Conservation Biology: 613-622.

Leonard, W.P., Brown, H.A., Jones, L.L.C., McAllister, K.R. and Storm, R.M. 1993. Amphibians of Washington and Oregon. Seattle Audubon Society, Seattle, Washington.

Licht, L.E. 1971. Breeding habits and embryonic thermal requirements of the frogs, Rana aurora aurora and Rana pretiosa pretiosa, in the Pacific Northwest. Ecology: 116-124.

Nussbaum, R.A., Brodie, Jr., E.D. and Storm, R.M. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho, Moscow, ID, USA.

Pearl, C.A. 2005. Rana aurora, Northern red-legged frog. In: Lannoo, M.J. (ed.), Status and Conservation of U.S. Amphibians. Volume 2: Species Accounts, University of California Press, Berkeley, California.

Reaser, J.K. 2003. Occurrence of the California red-legged frog (Rana aurora draytonii) in Nevada, USA. Southwestern Naturalist: 400-401.

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 (Rana aurora/draytonii) complex. Molecular Ecology 13: 2667-2777.

Stebbins, R.C. 1985. A Field Guide to Western Reptiles and Amphibians. Second Edition. Houghton Mifflin Company, Boston, Massachusetts.

Stebbins, R.C. 2003. A Field Guide to Western Reptiles and Amphibians, Third Edition. Houghton Mifflin Company, Boston, Massachusetts.

U.S. Fish and Wildlife Service. 1994. Proposed endangered status for the California red-legged frog. Federal Register (2 February 1994): 4888-4895.

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Citation: Geoffrey Hammerson 2008. Rana aurora. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 01 September 2015.
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