Rana catesbeiana (Shaw, 1802) - Bullfrog


Information Last Reviewed Spring 2007


Native to the eastern United States, bullfrogs have been introduced to much of the rest of the continental United States and Hawaii. In some introduced areas, absence of natural predators has resulted in high bullfrog population densities, overwhelming native fauna. Significant adverse impacts, primarily through predation, have been documented on populations of native amphibians, reptiles, and fish.



General Biology


Life Cycle

Habitat Characteristics






Web Sites






Phylum Chordata

Class Amphibia

Order Anura

Family Ranidae




General Biology:











Bullfrogs are true frogs (order Anura), exhibiting smooth skin, long hind legs with extensively webbed hind feet, and teeth in the upper jaw. Their large size, distinct tympanic membranes (eardrums), absence of dorsolateral ridges, and breeding call distinguish this species from most other North American frogs. Adult bullfrogs are greenish, brownish, or sometimes blackish, and may exhibit dark spots or mottling dorsally. Ventral coloration ranges from whitish to yellowish, with or without dark mottling. Male bullfrogs exhibit a yellow throat, and the tympanic membrane is approximately twice the size of the eye (female tympanic membranes are roughly equal to the size of the eye). Tadpoles are greenish to yellowish with black spots dorsally and are usually whitish ventrally.  Tadpoles may metamorphose during their first year or overwinter and metamorphose during their second year.




Distinguishing Characteristics






Life Cycle:


Bullfrog life cycles include an aquatic larval stage and a semi-aquatic adult stage. Bullfrog populations may reach high densities in areas devoid of natural predators (fish, snakes, turtles, etc.)










Habitat Characteristics:


Preferred Environment








Native Range


North American Distribution


Probable Means of Introduction






Bullfrogs are predators that eat practically anything that they can catch and swallow, including terrestrial and aquatic invertebrates (particularly crayfish), fish, other frogs, turtles, snakes, birds, mammals, etc.






Introduced bullfrogs have been blamed for native species declines in much of western North America.










Control Measures


Prevention Techniques






Bury, R. B., and J. A. Whelan. 1984. Ecology and management of the bullfrog. U.S. Fish and Wildlife Service Resour. Publ. 155. 23 pp.


Conant, R., and J. T. Collins. 1991. Reptiles and Amphibians. Eastern/Central North America. Houghton Mifflin Company. Boston. 450 pp.


Hayes, M. P. and M. R. Jennings. 1986. Decline of ranid frog species in western North America: are bullfrogs (Rana catesbeiana) responsible? Journal of Herpetology 20:490-509.


Leonard, W. P., H. A. Brown, L. L. C. Jones, K. R. McAllister, and R.M. Storm. 1993. Amphibians of Washington and Oregon. Seattle Audubon Society, Seattle, WA. 168 pp.


Schwalbe, C. R., and P. C. Rosen. 1988. Preliminary report on effects of bullfrogs on wetland herpetofauna in southeastern Arizona. Pages 166-173 in R. C. Szaro, K. E. Severson, and D.R. Patton eds. Management of amphibians, reptiles, and small mammals in North America. U.S. Forest Service Gen. Tech. Rep. RM-166, Fort Collins, CO.


Vial, J. L., and L. Saylor. 1993. The status of amphibian populations: a compilation and analysis. International Union for the Conservation of Nature and Natural Resources, Species Survival Commission, Declining Amphibian Populations Task Force Working Document 1. 98 pp.




Web Sites:



Bullfrogs: Introduced Predators in Southwestern Wetlands



Introduced species of Hawaii



Impact of invasive exotic animals on native reptiles and amphibians