California Red-Legged Frog

Genus: Rana
Species: aurora draytonii (also known as Rana draytonii)

The California red-legged frog is a rare species of frog found almost exclusively in the state of California. It became famous for being the frog featured in Mark Twain's short story The Celebrated Jumping Frog of Calaveras County. Today, the California red-legged frog is on the Endangered Species list, because it is threatened by invasive species and habitat loss. 


California Red-legged Frog

Description: This frog species is named appropriately!  It has a reddish coloring on the underside of the legs and belly.

A California red-legged frog's back and head can range from red to brown and/or gray. The back and top of the legs are covered in small black spots and large dark blotches.

Typically, the face has a dark mask and a tan or light colored stripe above the jaw that extends to the shoulder. The California red-legged frog has folds running down the side of its back, rough skin and partially webbed toes.


Size: The California red-legged frog is 2-5 inches long. It is the largest native frog in the western United States.


Diet: California red-legged frogs will eat just about anything they can catch and fit in their mouths. Most of the time, they eat invertebrates, but on occasion, they will consume smaller amphibians and mammals.


Typical Lifespan: They can live upwards of 10 years in the wild; however, it is suspected that many do not live that long. 


Habitat:  California red-legged frogs like slow-moving or standing deep ponds, pools and streams. Tall vegetation, like grasses, cattails and shrubs, provide protection from predators and the sun. They cannot tolerate excessive heat. When California red-legged frogs are not breeding, you might see them in wet meadows or damp grasses.


Range:  California red-legged frogs are found almost exclusively in California with a few sightings in Baja, Mexico. Historically, they could be seen throughout most of the California coastal areas; however, their population has dwindled. According to the U.S. Fish and Wildlife Service, California red-legged frogs are only found in 238 streams in 31 California counties.  


Communication: California red-legged frog males communicate to females by a series of short, soft grunts--"unh-unh-uh-uh -grr." They will grunt several times then end the call with a growl.


Life History and Reproduction:  California red-legged frogs begin breeding around November and continue through April. The males arrive at the breeding grounds early and sit in groups calling to females.  The females lay large egg masses and the males fertilize the eggs. The eggs hatch and the larvae go through metamorphosis throughout the summer.

California red-legged frogs are mainly solitary during the year and active at night. They do not like very hot temperatures and will seek shade within tall grasses and reeds. The main predators of California red-legged frogs are birds, raccoons, snakes and the invasive exotic American bullfrog.


Threats to California Red-legged Frogs:

  • Invasive Species : Non-native bullfrogs in California are eating many California red-legged frogs.
  • Habitat Loss Homes, farms and buildings were built on their wetland habitats.
  • Overexploitation : In the 19th and 20th Centuries, they were over harvested for food. 
  • Overexploitation : Water resources are overused, depleting frogs of the water habitat they need for homes and breeding.

California red-legged frogs are listed as Threatened under the Endangered Species Act.

 

National Wildlife Magazine Articles:

The Case of the Missing Amphibians

 

Sources:

University of Michigan's Animal Diversity Web

eNature.com

Environmental Defense Fund - Backfromthebrink.org

Environmental Defense Fund

U.S. Fish and Wildlife Service

Peterson Field Guides: Western Reptiles and Amphibians. Stebbins, Robert C. 2nd edition. New York: Houghton Mifflin Company, 1985.

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