California Red-Legged Frog

Description

The California red-legged frog is a rare amphibian species found almost exclusively in the state of California. It’s well-known for being the frog featured in Mark Twain's short story The Celebrated Jumping Frog of Calaveras County and is named for the reddish coloring on the underside of its legs and belly. The frog’s back and head can range from red to brown or gray. Its back and the top of its legs are covered in small black spots and large dark blotches. Typically the frog’s face has a dark mask and a light-colored stripe above the jaw that extends to the shoulder. The frog also has folds running down the side of its back, rough skin, and partially webbed toes. It is the largest native frog in the western United States and is usually two to five inches (5 to 12 centimeters) long.

Range

California red-legged frogs are found almost exclusively in California, with a few sightings outside of the United States in Baja, Mexico. Historically they could be seen throughout most of California’s coastal areas, but their population has dwindled.

These 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, as these frogs cannot tolerate excessive heat. When California red-legged frogs are not breeding, they might be seen in wet meadows or damp grasses. California red-legged frogs are mainly solitary during the year and active at night. Their main predators are birds, raccoons, snakes, and the invasive American bullfrog.

Diet

A California red-legged frog will eat just about anything it can catch and fit in its mouth. Most of the time they eat invertebrates, but on occasion, they will consume smaller amphibians and mammals.

Life History

These frogs begin breeding around November and continue through April. The males arrive early at the breeding grounds and sit in groups calling to females. Females lay large egg masses and the males fertilize the eggs. The eggs hatch and the larvae go through metamorphosis throughout the summer. These frogs can live upward of 10 years in the wild, but it’s suspected that many do not live this long.

Conservation

These frogs are federally listed as threatened. Threats to their population include invasive species, habitat loss, and overexploitation. In the 19th and 20th centuries, they were overharvested for food. Now water resources are overused, depleting frogs of the water habitat they need for homes and breeding. Furthermore, farms, homes, and other buildings have been built on their wetland habitats.

Learn more about our California Regional Center's work to save the California red-legged frog and other frog species.

Fun Fact

Male California red-legged frogs communicate with females using a series of short, soft grunts. They will grunt several times, then end the call with a growl.

Sources

Animal Diversity Web, University of Michigan Museum of Zoology

eNature.com

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

U.S. Fish & Wildlife Service