Range in California: Red
California Red-legged Frog: Green
To designate protection for the
California Red-legged Frog, authorities recognize two subspecies of Rana aurora, instead of two full species: Rana aurora and Rana draytonii. Click here to see a range map for these subspecies
Listen to this frog:
One short call
iPhone App
Electronic Field Guide to the
Reptiles and Amphibians of
Southern California
Available Now at the
iTunes App Store. |
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Adult Male, Humboldt County |
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Adult, Humboldt County |
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Sub-adult, Del Norte County |
Sub-adult, Del Norte County |
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Adult, Pacific County, Washington |
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| Sub-adult, Multnomah County, Oregon |
Sub-adult, Multnomah County, Oregon |
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| Sub-adult, Multnomah County, Oregon |
Sub-adult, Multnomah County, Oregon |
Adult, Multnomah County, Oregon |
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Juvenile, 900 ft., Lewis County, Washington. |
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| Comparison with Foothill Yellow-legged Frog |
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Adult Rana aurora on left.
Adult Rana boylii on right.
(Foothill Yellow-legged Frog)
Linn County, Oregon |
Adult Rana aurora on left.
Adult Rana boylii on right.
(Foothill Yellow-legged Frog)
Linn County, Oregon |
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| Breeding, Eggs, and Young |
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Breeding adult male, Humboldt County. Left: throat with very reduced vocal sacs. Right: the same frog calling underwater while resting on the bottom of an artificial pond about 12 inches below the surface. |
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Egg mass |
Tadpole eyes are set in from the margin of the head. Compare with P. regilla |
Mature Tadpole |
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Transforming tadpole |
Tiny metamorph, fewer than two weeks out of the water. |
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You can see more pictures of Northern Red-legged Frog eggs, tadpoles and juveniles Here.
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Habitat |
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Habitat, Del Norte County |
Habitat, Humboldt County |
Habitat, Humboldt County |
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Habitat, temporary pools on coastal plain, Humboldt County |
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You can see more pictures of this frog and its habitat on our Northwest Herps page.
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| Short Videos |
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| A Northern Red-legged Frog on a late summer day. |
Northern Red-legged Frog breeding habitat with eggs in Washington. |
More Northern Red-legged Frog breeding habitat with eggs in Washington. |
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Description |
Size |
| Adults are 1 3/4 - 3 inches long from snout to vent ( 4.4 - 7.6 cm). |
| Appearance |
Coloring is reddish -brown or brown, gray, or olive, with small black flecks and spots on the back and sides and dark banding on the legs. Dark blotches on the back, typically have no light coloring in the center. There is a dark mask on the head and a stripe extending from the shoulder to the front of the upper jaw. The eyes are outward oriented. The hind legs are red underneath, giving this frog its name. On older frogs the red coloring extends onto the belly and sides. The chest and throat are creamy and marbled with dark gray. Yellowish-green and black coloring mottles the groin. Toes are not completely webbed. Legs are relatively long. Dorsolateral folds are prominent.
Tadpoles are brown marked with small dark spots with eyes set in from the margin of the head. Creamy white coloring flecked with small spots covers the lower body. Rows of dorsolateral light spots may be evident running back from behind the eyes. |
| Voice (Listen) |
| The call is a weak series of 5 - 7 notes, sounding like uh-uh-uh-uh-uh, lasting 1 - 3 seconds. Calls during the day or night, typically for only one or two weeks at a location (sometimes longer). Calls are typically made underwater and are easily missed because they are either not audible or very low in volume when heard in the air. Frogs may also call in the air where they are sometimes audible from a small distance. Listen here. According to Stebbins (2003) Rana aurora north of the Smith River in Del Norte County do not have vocal sacs, while frogs from Del Norte County south have rudimentary vocal sacs. |
| Behavior |
Primarily diurnal. Typically a pond frog, found in or near water, but Northern Red-legged Frogs can be wide-ranging and highly terrestrial, sometimes inhabiting damp places far from water. Long rear legs give this frog excellent leaping ability, which it relies on to avoid predators by quickly leaping into vegetation or water.
In captivity, this species is known to live to more than ten years. |
| Diet |
| Eats a wide variety of invertebrates. Typical of most frogs, the prey is located by vision, then a large sticky tongue is used to catch the prey and bring it into the mouth to eat. |
| Reproduction and Young |
Reproduction is aquatic. Fertilization is external. Males develop enlarged forearms and a dark nuptial pad on each thumb during the breeding season. Males typically become reproductively mature at 2 years, females at 3. Breeding and egg-laying occurs in vegetated shallows with little water flow in permanent wetlands and temporary pools which last long enough for tadpoles to transform. Some sources state that breeding takes place in January and February, others as early as October with large numbers of frogs arriving in November and December in Oregon and Northern California. (I have witnessed breeding in Humboldt County as late as early March.) Breeding lasts for only a week or two at a location. Afterwards, adults move back into nearby moist forests and riparian areas, sometimes travelling more than a thousand feet.
Females lay an average of 530 - 830 eggs (ranging from 100 - 1,100) in a large gelationous cluster which is attached to vegetation beneath the water. The egg mass will eventually float to the surface. Eggs hatch after about four weeks.
Tadpoles metamorphose in three to five months. Recently-transformed juveniles often stay at the edge of their birth pond for a few days or weeks before dispersing into nearby moist dense vegetation. |
| Range |
Ranges from Mendocino County in Northern California north along the west coast through Oregon and Washington, west of the Cascades Mountains, on Vancouver Island, and along the southwestern coast of British Columbia.
A narrow range overlap with Rana draytonii occurs in Mendocino County: Shaffer et. al. in research for their 2004 paper found only Rana aurora north of Big River, Mendocino County, both Rana aurora and Rana draytonii between Big River and Mills Creek, Mendocino County, and only Rana draytonii south of Mills Creek. |
| Habitat |
Found in humid forests, woodlands, grasslands, and streamsides with plant cover. Most common in lowlands or foothills. Frequently found in woods adjacent to streams. Breeding habitat is in permanent water sources; lakes, ponds, reservoirs, slow streams, marshes, bogs, and swamps.
From sea level to 4,680 ft. (1427 m.) |
| Taxonomic Notes |
Before being separated into two species, two subspecies of Rana aurora were recognized: R. a. aurora, and R. a. draytonii. Frogs in the very large area between Del Norte County and the Walker Creek drainage in Marin County were considered to be intergrades.
Schaeffer et al. in a 2004 genetics study determined that R. aurora actually consists of two species, R. aurora, and R. draytonii, whose ranges overlap only in a narrow zone in Mendocino County. R. aurora is found to be closely related to R. cascadae. Other studies, including an analysis of vocal sacs, have supported separate species status, concluding that R. aurora and R. draytonii are biologically quite different. |
| Conservation Issues (Conservation Status) |
| No serious threats to this species have been documented, but the state regards it as a species worth monitoring. Introduced predators including American Bullfrogs, and water quality degradation could be negatively affecting the species. |
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Taxonomy |
| Family |
Ranidae |
True Frogs |
| Genus |
Rana |
True Frogs |
| Species |
aurora |
Northern Red-legged Frog
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Original Description |
Baird and Girard, 1852 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 174
from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
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Meaning of the Scientific Name |
Rana - Frog - "Rana" probably mimics how the Romans heard their call.
aurora - Latin - dawn, red - referring to the red color of the underside of the hind legs.
from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
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Alternate Names |
Formerly Rana aurora aurora - Northern Red-legged Frog.
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Related or Similar California Frogs |
Rana boylii
Lithobates catesbeiana
Lithobates yavapaiensis
Rana draytonii
Rana pretiosa
Lithobates pipiens
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More Information and References |
Natureserve Explorer
California Dept. of Fish and Game
AmphibiaWeb
Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.
Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.
Shaffer, H. Bradley, G. M. Fellers, S. Randal Voss, J. C. Olive and Gregory B. Pauly (2004 Species boundaries, phylogeography and conservation genetics of the red-legged frog (Rana aurora/draytonii) complex. Molecular Ecology 13(9): 2667-2677)
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.
Corkran, Charlotte & Chris Thoms. Amphibians of Oregon, Washington, and British Columbia. Lone Pine Publishing, 1996.
Jones, Lawrence L. C. , William P. Leonard, Deanna H. Olson, editors. Amphibians of the Pacific Northwest. Seattle Audubon Society, 2005.
Leonard et. al. Amphibians of Washington and Oregon. Seattle Audubon Society, 1993.
Nussbaum, R. A., E. D. Brodie Jr., and R. M. Storm. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University Press of Idaho, 1983.
Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.
Elliott, Lang, Carl Gerhardt, and Carlos Davidson. Frogs and Toads of North America, a Comprehensive Guide to their Identification, Behavior, and Calls. Houghton Mifflin Harcourt, 2009.
Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005.
Wright, Anna. Handbook of Frogs and Toads of the United States and Canada. Cornell University Press, 1949.
Davidson, Carlos. Booklet to the CD Frog and Toad Calls of the Pacific Coast - Vanishing Voices. Cornell Laboratory of Ornithology, 1995. |
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The following status listings come from the Special Animals List which is published by the California Department of Fish and Wildlife.
This frog is referred to as Rana aurora aurora by the California Department of Fish and Game.
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Organization
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Status Listing
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| U.S. Endangered Species Act (ESA) |
None |
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| California Endangered Species Act (CESA) |
None |
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| California Department of Fish and Wildlife |
DFG:SSC |
California Species of Special Concern |
| Bureau of Land Management |
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| USDA Forest Service |
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Sensitive |
| Natureserve Global Conservation Status Ranks |
G4T4 S2? |
Apparently Secure |
World Conservation Union - IUCN Red List
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