Rana aurora

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AMPHIBIA	ANURA	RANIDAE

Scientific Name:

Rana aurora

Species Authority:

Baird & Girard, 1852

Common Name/s:

English

–

Northern Red-legged Frog

Assessment Information [top]

Red List Category & Criteria:

Least Concern ver 3.1

Year Assessed:

2008

Assessor/s

Geoffrey Hammerson

Evaluator/s:

Stuart, S.N., Chanson, J.S., Cox, N.A. & Young, B.E. (Global Amphibian Assessment Coordinating Team)

Justification:
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.

History:

2004

–

Near Threatened (IUCN 2004)

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).
Countries:	Native: Canada; United States
Range Map:	(click map to view full version)

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

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

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.

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).

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).

Citation:	Geoffrey Hammerson 2008. Rana aurora. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 04 December 2008.
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