California Reptiles & Amphibians

Rana catesbeiana - American Bullfrog

(=Lithobates catesbeianus)

Click on a picture for a larger view

Introduced Range: Red

Listen to this frog:

A short example

More sounds of
Rana catesbeiana

Introduced: not native to California

Adult female, Stanislaus County

Juvenile, Stanislaus County

Large adult, with eye injury, Imperial County

Adult male, Merced County

Juvenile, Merced County

Large adult male, San Mateo County

Adults and juvenile, Kings County
© Patrick Briggs

Adult, Del Norte County
© Alan Barron

Comparison of adult Bullfrog tympanums (the round eardrum behind the eye). The diameter of an adult male's tympanum (left) is larger than the diameter of the eye. The diameter of an adult female's tympanum (right) is smaller than or equal to the diameter of the eye.

Adult female, Benton Co., Oregon

Juvenile male, Benton Co., Oregon

Sub-adult, Adams County, Washington

Male calling at night from a lake.

Adult Female, Yavapai County, Arizona

Tadpole, Merced County

More pictures of tadpoles, and their development can be viewed here.

Habitat, San Joaquin River, Fresno County

Habitat, pools at the edge of a river, Mendocino County

Desert agricultural irrigation pond habitat, Riverside County

Habitat, Yolo County canal

Habitat, agricultural irrigation canal, Sacramento County

Habitat, foothills creek, 500 ft., Stanislaus County

Habitat, large reservoir,
Contra Costa County

Habitat, pond, Marin County

Habitat, large artificial reservoir, Fresno County

Habitat, Colorado River, Imperial County

Tadpole habitat, Merced County

Short Video

A large male Bullfrog calls at night from a lake.

More pictures of this frog and its natural habitat are available on our Northwest Herps page,
and our Texas Herps page.

Description

Size

The largest true frog inhabiting California.
Adults are 3.5 - 8 in. long from snout to vent (5.7 - 11.4 cm). Males grow up to 7 1/8 in. (18 cm), females up to 8 in. (11.4 cm).

Appearance

A large frog, light green to dark olive green above, with dark spots and blotches. Juveniles have many small dark spots. Sometimes light green only on the upper jaw. Cream to yellow below with grey marbling on larger individuals. No dorsolateral folds. A short fold extends from the eye over and past the eardrum to the forearm. Conspicuous tympanum. Males have tympanums larger than their eyes and a yellow throat.

Tadpoles are greenish yellow with small spots, growing up to 6 in. (15.3 cm).

Voice (Listen)

A loud low-pitched two-part drone or bellow, popularly described as "jug-o'rum." These calls are made during the day and at night. Bullfrogs also produce an alarm call, a fast squeak, which is usually made before the frog jumps into the water to escape from danger. A sharp encounter call is also made.

Behavior

Highly aquatic. Rarely found far from water. Active day and night. When startled, usually emits a chirp or squeak, then jumps into the water.

Diet

Eats anything its can swallow, including mammals, birds, amphibians, fish, and reptiles. 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 water from May to late August. Eggs are laid in a sheet of jelly about 2 feet in diameter. Fertilization is external. The egg mass floats at first, then sinks to underwater vegetation just before hatching. Tadpoles transform at the end of their 2nd or 3rd summer, living in warm shallows and dense aquatic vegetation. Transformed froglets are 2 in. (5 cm.)

Range

Native to the eastern and midwestern United States and southeast Canada. Introduced for food due to their large meaty legs
in the 1920's and now established throughout most of the western United States and soutwestern Canada. (Now also introduced around the world, in Hawaii, Mexico, Europe, Asia, South America, Jamaica, and Cuba.)

Occurs throughout most of California. Absent from dry deserts and hight elevations in the Sierra Nevada Mountains. Occurs naturally throughout most of the eastern and southern USA, north barely into Canada, and south just below the Rio Grande in Texas, and west to New Mexico and Colorado.

Habitat

Inhabits warm, sunny, permanent water - lakes, ponds, sloughs, reservoirs, marshes, slow river backwaters, slow creeks. Found in grassland, farmland, prairies, woodland, chaparral, forests, and desert oases.

Taxonomic Notes

This frog has been renamed Lithobates catesbeianus, but this nomenclature is not yet standard.

Conservation Issues (Conservation Status)

This introduced species is probably responsible for the decline of many native species which cannot compete with or fall prey to this invasive species, including frogs, turtles, and waterfowl. Evolution with a diverse number of predatory fish may give bullfrogs a competive advantage over native amphibians in areas where non-native fish are present. Bullfrogs also do well in areas disturbed by humans. Further introduction to waters where they are not present, should be prohibited and methods of eradication from waters where bullfrogs coexist with native amphibians should be studied and implemented if feasible.

Taxonomy
Family	Ranidae	True Frogs
Genus	Rana	True Frogs
Species	catesbeiana	American Bullfrog
Original Description
Shaw, 1802 - Gen. Zool., Vol. 3, Pt. 1, p. 106, pl. 33 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. catesbeiana - honors Catesby, Mark from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Alternate Names
Bullfrog Lithobates catesbeianus
Related or Similar California Frogs
Rana draytonii Rana aurora Rana boylii Rana cascadae Rana pretiosa Rana sierrae Rana yavapaiensis Rana pipiens
More Information and References
Natureserve Explorer California Dept. of Fish and Game AmphibiaWeb 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. Conant, Roger, & Joseph T. Collins. A Field Guide to Reptiles and Amphibians Eastern and Central North America. Third Edition, Houghton Mifflin Company, 1998. Wright, Anna. Handbook of Frogs and Toads of the United States and Canada. Cornell University Press, 1949. Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005. Davidson, Carlos. Booklet to the CD Frog and Toad Calls of the Pacific Coast - Vanishing Voices. Cornell Laboratory of Ornithology, 1995.

Conservation Status
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 not included on the Special Animals List, meaning there are no significant conservation concerns for it in California according to 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
Bureau of Land Management
USDA Forest Service
Natureserve Global Conservation Status Ranks
World Conservation Union - IUCN Red List

Return to the Top