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
More sounds of
Rana aurora
|
 |
 |
 |
Adult, Humboldt County |
 |
 |
 |
Sub-adult, Del Norte County |
Sub-adult, Del Norte County |
 |
 |
 |
| |
Adult Male, Humboldt County |
|
 |
 |
 |
|
|
|
 |
 |
 |
| |
Adult, Pacific County, Washington |
|
 |
|
 |
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. |
Tiny metamorph, fewer than two weeks out of the water. |
 |
 |
 |
|
Egg mass |
Mature tadpole |
 |
|
|
Tadpole eyes are set in from the margin of the head. Compare with P. regilla |
Transforming Tadpole |
|
Go to Page 2 to see more pictures of eggs, tadpoles and metamorphs.
|
 |
|
|
Habitat, Del Norte County |
|
Habitat, Humboldt County |
 |
 |
|
Habitat, temporary pools on coastal plain, Humboldt County |
|
|
More pictures of this frog and its habitat are available on our Northwest Herps page.
|
|
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 |
| Typically a pond frog, found in or near water, but can be highly terrestrial, sometimes found in damp places far from water. Primarily diurnal. Will quickly leap off into the brush when startled. |
| 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 |
| Mating and egg-laying occurs in permanent bodies of water usually in January and February, and lasts for only a week or two. Fertilization is external. Amplexus is pectoral. Males develop enlarged forearms and a dark nuptial pad on each thumb. Females lay 750 - 1,300 eggs 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 four to five months. |
| Range |
Ranges from Mendocino County in northern California through Oregon and Washington into southwest 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, but the state regards it as a species worth monitoring. |
|
|
Taxonomy |
| Family |
Ranidae |
True Frogs |
| Genus |
Rana |
True Frogs |
| Species |
aurora |
Northern Red-legged Frog
|
|
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
|
|
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
|
|
Alternate Names |
Formerly Rana aurora aurora - Northern Red-legged Frog.
|
|
Related or Similar California Frogs |
Rana boylii
Rana catesbeiana
Rana yavapaiensis
Rana draytonii
Rana boylii
Rana pretiosa
Rana pipiens
|
|
More Information and References |
Natureserve Explorer
California Dept. of Fish and Game
AmphibiaWeb
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., & F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
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.
Davidson, Carlos. Booklet to the CD Frog and Toad Calls of the Pacific Coast - Vanishing Voices. Cornell Laboratory of Ornithology, 1995.
|
|
|
The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game.
This frog is referred to as Rana aurora aurora by the California Department of Fish and Game.
|
Organization
|
Status Listing
|
| U.S. Endangered Species Act (ESA) |
|
|
| California Endangered Species Act (CESA) |
|
|
| California Department of Fish and Game |
DFG:SSC |
California Species of Special Concern |
| Bureau of Land Management |
|
|
| USDA Forest Service |
|
|
| Natureserve Global Conservation Status Ranks |
G4 |
Apparently Secure |
World Conservation Union - IUCN Red List
|
IUCN:NT |
Near Threatened |
|
|
