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A Guide to the Amphibians
and Reptiles of California


California Red-legged Frog - Rana draytonii

Baird and Girard, 1852
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Red-legged Frogs Range Map
Historical Range in California: Orange & Purple
Northern Red-legged Frog: Red & Purple



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California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
  Adult, San Mateo County  
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult male, interior of the Coast Range, western Fresno County Adult, Marin County Adult, San Mateo County Adult, showing the red coloring underneath the legs, San Mateo County
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
  Sub-adult, Contra Costa County  
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult, Contra Costa County. Adult, Marin County Adult, Contra Costa County Adult, Contra Costa County
© Edgar Ortega
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult, San Mateo County Adult, San Mateo County Adult, Contra Costa County. Adult, Contra Costa County.
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult, San Mateo County Adult, San Joaquin County.
© James Rexroth
Adult, San Mateo County Adult, Marin County
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult, Alameda County Adult, Alameda County Adult, Monterey County
© Anonymous Contributor
Adult, Marin County
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult, San Luis Obispo County
© Patrick Briggs
Adult, San Luis Obispo County
© Patrick Briggs
Adult , Santa Cruz County © Ruby Christine Head
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Adult, Contra Costa County Adult male, interior of the Coast Range, western Fresno County Adult, Santa Barbara County
© Vince Semonsen
Adult, Marin County
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
These frogs, discovered by Sean Barry in Butte County in 1997, are some of the last known California Red-legged Frogs remaining in the Sierra Nevada mountains.
© Sean Barry
Adult, San Mateo County
© 2005 Brad Alexander
Adult, Santa Barbara County
© Jason Butler
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
Juvenile, Contra Costa County Juvenile, Contra Costa County Juvenile, Contra Costa County Sub-adult, Contra Costa County
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog sign
Adult, Santa Cruz County, with a transmitter attached to its waist. After it is released, the frog can be found later by using an antenna with a radio receiver that can track the transmitter. This way the frog's movement and behavior can be studied for part of the year. Mature frogs use fat stored in their thighs to produce gametes as the breeding season nears. When the thighs have been significantly reduced in size, the transmitters will slip off the frogs.

© Neil Keung 
Animal capture and handling authorized under Federal permits and State Parks permits.
Adult, Nippomo, San Luis Obispo County
© Tamara Spaur
A California Red-legged Frog and a Foothill Yellow-legged Frog in the same creek in Santa Clara County.
© Owen Holt
San Mateo County Park Sign

       
Habitat
California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat
This row shows four views of the same breeding pond, Contra Costa County, in full years, and as it dried up during the great drought of 2013 and 2014 +?
Contra Costa County breeding pond in November of a very dry year (2013). The edge of the pond at this time is full of newly metamorphosed juvenile frogs.
© Mark Gary
The same pond seen to the left the following October, almost completely dried up with no pond life remaining.
© Mark Gary
California Red-legged Frog Habitat California Red-legged Frog Habitat tiger salamander habitat California Red-legged Frog Habitat
Habitat, San Mateo County Habitat, cattle pond, Contra Costa County Seasonal pond used for breeding,
Contra Costa County.
Follow this link to see more pictures of this pond as it looked in different months
(of different years) showing how the pond and its surroundings change over the seasons.
Habitat, pond, San Mateo County
San Francisco Gartersnake Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat
Habitat, San Mateo County Habitat, San Mateo County Habitat, breeding pond, Santa Lucia Preserve, Monterey County. Courtesy of David Keegan & Susan Whitford Habitat, breeding pond, Santa Lucia Preserve, Monterey County. Courtesy of David Keegan & Susan Whitford
California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat
Habitat, coastal marsh, Marin County Habitat, Riverside County wetlands Habitat, coastal lagoon, Marin County
California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat
Habitat, small coastal pond, Marin County, during different seasons Breeding pond, Contra Costa County
California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat
Habitat, Alameda County Habitat, small creek, Contra Costa County Habitat, small drainage, San Luis Obispo County © Patrick Briggs
California Red-legged Frog Habitat California Red-legged Frog Habitat California Red-legged Frog Habitat  
Breeding area, Contra Costa County
Habitat, Contra Costa County Habitat, Contra Costa County  
       
Short Videos
California Red-legged Frog California Red-legged Frog California Red-legged Frog California Red-legged Frog
A large adult California Red-legged Frog sits still at the edge of a pond under some vegetation until a grasshopper lands nearby when it explodes into action, grabbing the insect on the underside of its long sticky pink tongue. The same frog to the left eating grasshoppers, but this time shown in slow motion so you can see its big tongue in action. Red-legged frogs around a couple of small ponds in July. Red-legged frogs around a small pond in August.
California Red-legged Frog California Red-legged Frog California Red-legged Frog  
Two male California Red-legged Frogs are seen here in a Contra Costa County pond in March in amplexus with California Toads (possibly females.) Male toads attempt to wrestle the frogs off their prospective mates. When they grab the frogs, the frogs give their low chuckling release call, while the toads make their peeping release call. The video also starts and ends with the frog release calls. A bunch of juvenile California Red-legged Frogs sit around on a sunny summer afternoon in a pond in Contra Costa County. Adult frogs sitting around in ponds in Contra Costa and Marin Counties.  
     
Description
 
Size
Adults are 1.75 - 5.25 inches long from snout to vent ( 4.4 - 13.3 cm.)

Appearance
A medium-sized frog with a slim waist, long legs, smooth skin and webbing on the hind feet.
Ridges on the sides (dorsolateral folds) are prominent.
Legs are relatively long.
The eyes are outward oriented.
Color and Pattern
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 marking 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 hind legs and lower belly 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.
Male/Female Differences
Males develop enlarged forearms and a dark nuptial pad on each thumb during the breeding season.
Young
Often the coloring under the legs and lower belly is yellowish.
Larvae (Tadpoles)
Tadpoles are brown marked with small dark spots with eyes set in from the margin of the head. (Compare with P. regilla.)
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.

Life History and Behavior
Activity
Primarily diurnal.
Typically a pond frog, found in or near water, but can wander overland at times, sometimes found in damp places far from water, including cool and moist bushes and thickets.
Found active all year except in wetlands that dry out in summer, where frogs will estivate in moist refuges until the late fall rains.
Movement
Long rear legs give this frog excellent leaping ability, which it relies on to avoid predators by quickly leaping into vegetation or water.
Defense
Frogs remain immobile to avoid detection, but when a threat gets too close, they will quickly leap off into the brush or water.
Territoriality
Not known, but not considered territorial except when breeding males act aggressively with each other at breeding sites.
Longevity
Unknown.
Voice  (Listen)
The call is a weak series of 5 - 7 notes, sounding like uh-uh-uh-uh-uh, lasting 1 - 3 seconds. After the series there is sometimes a last note which is similar to a growl or groan. The calls are made during the day or at night in the air and underwater and are easily missed. Calling lasts only one to two weeks at a location. Rana draytonii south of San Francisco have paired vocal sacs. Frogs north to Del Norte County, including Rana aurora, have rudimentary vocal sacs.
Diet and Feeding
Diet consists of a wide variety of invertebrates, and occasionally small vertebrates such as fish, mice, frogs and salamander larvae.
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.

Tadpoles probably feed on algae, diatoms, and detritus by grazing the surface of rocks and plants.
Breeding
Reproduction is aquatic. Fertilization is external.
Fertilization is external, with the male grasping the back of the female and releasing sperm as the female lays her eggs.

The reproductive cycle is similar to that of most North American Frogs and Toads. Mature adults come into breeding condition and the males call to advertise their fitness to competing males and to females. Males and females pair up in amplexus in the water where the female lays her eggs as the male fertilizes them externally. The eggs hatch into tadpoles which feed in the water and eventually grow four legs, lose their tails and emerge onto land where they disperse into the surrounding territory.

Males typically become reproductively mature at 2 years, females at 3 years of age.
Males develop enlarged forearms and a dark nuptial pad on each thumb during the breeding season.

Mating and egg-laying occurs in permanent and temporary bodies of water - mostly ponds, but also marshes, lagoons, and slow-moving parts of streams.

Breeding occurs from late November to April, depending on the location, and lasts for only a week or two.
Some adults inhabit the breeding pond all year, but other frogs disperse into other habitats and must travel overland some distance, usually on rainy nights, to get to the breeding pond.
Eggs
Females lay from 300 - 4,000 eggs (average 2,000) in a large gelationous oval cluster which is attached to plants near the water surface.
Eggs hatch after about four weeks.
Tadpoles and Young
Tadpoles metamorphose in four to seven months, but at some sites they overwinter and metamorphose the following summer.

Habitat
Found mainly near ponds in humid forests, woodlands, grasslands, coastal scrub, and streamsides with plant cover.
Most common in lowlands or foothills.
Frequently found in woods adjacent to streams.

Breeding habitat is in permanent or ephemeral water sources; lakes, ponds, reservoirs, slow streams, marshes, bogs, and swamps.

Ephemeral wetland habitats require animal burrows or other moist refuges for estivation when the wetlands are dry.

Geographical Range
Endemic to California and northern Baja California. Historically, this species was found along the coast and Coast Ranges from Mendocino County in northern California south to northern Baja California, and inland east through the northern Sacramento Valley into the foothills of the Sierra Nevada mountains, south to Tulare county, and possibly Kern county. They probably did not occur in the central vallley due to annual floods. Three museum specimens of California Red-legged Frogs were collected from Santa Cruz Island in 1919, but the species is probably no longer present on the island.

A narrow range overlap with Rana aurora (about 5 km) 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.


* In 2013, Sean Barry and Gary Fellers published a report evaluating the status of Rana draytonii in the Sierra Nevada, documenting only 20 historical Sierra Nevada localities and one Cascades Mountains locality. After conducting field surveys they found frogs extant in large numbers at only one of those localities, but they found an additional 7 new populations and 3 single-specimen occurances extending from Butte County southeast to Mariposa County, a distance of about 171 miles (275 km.)

* "Historically, R. draytonii in the Sierra Nevada probably bred in stream pools, which tend to be small with limited forage and thus may have constrained the historical size and number of Sierra Nevada R. draytoinii populations. Since the 1850's, manmade ponds sometimes capable of supporting large R. draytonii populations have supplemented stream pool breeding habitat. Excluding the southernmost and Yosemite historical localities, the current range of Sierra Nevada R. draytonii differs little from the historical range, and further surveys may reveal additional surviving Sierra Nevada R. draytonii populations."
Elevational Range
From sea level to 5,000 ft. (1,525 m.)

Notes on Taxonomy
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.

Before being split 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.

Conservation Issues  (Conservation Status)
Populations in the Sierra Nevada Mountains and in southern California have declined seriously possibly due to introductions of non-native predators such as American Bullfrogs and fish, habitat loss due to development and agriculture, and pesticide pollution. Windborne pollutants from agriculture in the Central Valley have probably contributed considerably to the extirpation of the species in the nearby Sierra Nevada foothills. Much of this frog's prime habitat of foothills grassland has been destroyed by develoment in the Bay Area and in the Sierra Nevada foothills. The role of the Chytrid fungus and of the introduced bullfrog in Rana draytonii declines are not well understood.

* In 2013, Sean Barry and Gary Fellers published a report evaluating the status of Rana draytonii in the Sierra Nevada, documenting only 20 historical Sierra Nevada localities and one Cascades Mountains locality. After conducting field surveys they found frogs extant in large numbers at only one of those localities, but they found an additional 7 new populations and 3 single-specimen occurances extending from Butte County southeast to Mariposa County, a distance of about 171 miles (275 km.) which differs little from the historical range. "R. draytonii are threatened primarily by habitat modification and loss related to human population increase."

In 2009, only six recently-discovered populations were known in the Sierra Nevada, and these were all discovered after 1997. Only two very small extant populations are known from South of Santa Barbara, one on the Santa Rosa Plateau in Riverside County, and one in Ventura County. The species apparently persists in northern Baja California.

In the fall of 2010, the Placer Land Trust partnered with Westervelt Ecological Services to permanently protect the Big Gun Preserve, 52 acres of mixed conifer woodlands, chaparral, and riparian corridors, located in the Middle Fork American River watershed, which contains the largest remaining Sierra Nevada population of California Red-legged Frogs.

** A 2009 study by Antonia D'Amore and others documented male Rana draytonii in amplexus with juvenile American Bullfrogs and has proposed that this causes reproductive interference by the invasive species which could cause a reduction in the population growth rate of Rana draytonii since these males no longer call to attract females which causes fewer females to attempt to breed at the site, and because males engaged in amplexus are at greater risk of predation. And it raises the possibility that male Rana draytonii will find the smaller female Rana draytonii unattractive, leaving them without mates. This preference by the males leads them into an "evolutionary trap."

Official California State Amphibian
Governor Jerry Brown signed legislation that made the California Red-legged Frog California's official state amphibian in June, 2014. (He's the same "Small Is Good" governor Brown who was so far ahead of his time in the 1970's that he was elected governor of the state again 35 years later after everyone caught up with him.) The bill was proposed to the "Save The Frogs!" organization by an afterschool club at Sea View Elementary School in Imperial County and carried by Assemblyman V. Manuel Perez of Coachella.

It seems that you have to be a threatened or extinct species to earn this honor, so maybe it's not so good after all. The California Red-legged Frogs in the foothills of the Sierra Nevada mountains were nearly eaten into extinction by the sudden influx of hundreds of thousands of hungry alien predators, also known as Miners of the California Gold Rush of 1849. They were then finished off by the proliferation of another uncontrollable apex predator, the Land Developer, which has used its bulldozers to eradicate the species in almost all of Southern California and forced it into exile into the few remnant ponds they have not turned into shopping malls and housing developments in the northern part of the state.

I would have voted for the California Tiger Salamander to be the California state amphibian since then Californians would have learned what a salamander is, and that they're valuable even though you can't eat them. They're also plenty endangered and have the name of the state in both the common and scientific names. But to accomplish this kind of hard-hitting legislation, you need the lobbying clout in Sacramento that "Save The Frogs" has, at least when it's teamed up with some dynamic elementary school kids.

Maybe we should have a state amphibian and a state salamander? Maybe some ambitious elementary school will want to pursue it some day.... That's right, I'm talking to you Martin Van Buren Elementary School in Indio!  Are you gonna let some rival Coachella school get the better of you?

Taxonomy
Family Ranidae True Frogs Rafinesque, 1814
Genus Rana True Frogs Linnaeus, 1758
Species draytonii California Red-legged Frog

Baird and Girard, 1852
Original Description
Rana aurora - 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.
draytonii - honors Drayton, Joseph

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Alternate Names
Formerly Rana aurora draytonii - California Red-legged Frog

Related or Similar California Frogs
Rana aurora
Rana boylii

Lithobates catesbeiana
Rana cascadae

More Information and References
California Department of Fish and Wildlife

AmphibiaWeb

Center for Biological Diversity

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., 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.

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.

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, Albert Hazen and Anna Wright. 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.

Jones, Lawrence L. C. , William P. Leonard, Deanna H. Olson, editors. Amphibians of the Pacific Northwest. Seattle Audubon Society, 2005.

* Sean J. Barry and Gary M. Fellers. History and Status of the California Red-legged Frog (Rana draytonii) in the Sierra Nevada, California, USA Herpetological Conservation and Biology 8(2):456-502. Published: 15 September 2013.

** D'Amore, Antonia, Erik Kirby and Valentine Hemingway. Reproductive Interference By An Invasive Species: An Evolutionary Trap? Herpetological Conservation and Biology 4(3):325-330. Submitted: 2 September 2008; Accepted: 9 November 2009.

Conservation Status

The following status listings come from the Special Animals List and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.


This frog is referred to as Rana aurora draytonii on the Special Animals List.

Organization
Status Listing
U.S. Endangered Species Act (ESA) FT - 5/20/96 Threatened
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife DFG:SSC California Species of Special Concern
Bureau of Land Management
USDA Forest Service


















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