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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: American Bullfrog

Taxonomy: available through www.itis.gov

Size: 9 - 15.2 cm

Native Range: Eastern United States, but historically absent from the Cape Cod archipelago and associated islands.

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Found in lakes, ponds, cattle tanks, bogs, and sluggish portions of streams and rivers.  Breeds in June and July producing 10,000 to 20,000 eggs.  Tadpoles transform as quickly as 4 months in warmer climates and up to 3 years in colder locations.  In colder climates, bullfrogs require year-round persistence of water for tadpoles to mature and over-winter. This species has been shown to be an alternative host to the glochidia of native unionid mussel Utterbackia imbecillis (Watters and O'Dee 1998).

The home range of the L. catesbeianus has been estimated to be around 1.6 km (Copper 2017).

Means of Introduction: The original mode of introduction was probably through accidental introduction with fish stocking; however, other means of introduction have also contributed to the spread of this species in the western states.

Impact of Introduction:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Ecological	Economic	Other

The introduced Lithobates catesbeiana out-competes native amphibians in the modified portions of Trinity River, California (Fuller et al. 2011), indicating that habitat modification might aid in the establishment and spread of this species. Lithobates catesbeiana is expanding its population and outcompeting the native Green Frog (Lithobates clamitans). Larvae can have a significant impact upon benthic algae, and thus perturb aquatic community structure. Where introduced populations have been studied in the wWestern U.S., adults consume birds, rodents, frogs, snakes, turtles, lizards, and bats. They are voracious eaters who will also prey on their own young.

Remarks: Frost et al. (2006) revised the genus Rana and most of the North, Central and South American "true frogs" were separated from this taxon and placed into the new genus Lithobates (Frost et al., 2006; Crother, 2008; Collins and Taggart, 2009).  Scientific and standard English names follow Crother (2008).

Based on a study in western Washington, conservation of ephemeral wetlands will halt range expansions of bullfrogs. Permanently inundated wetlands are more likely to house nonindigenous species.

References: (click for full references)

Collins, J.T. and T.W. Taggart. 2009. Standard common and current scientific names for North American amphibians, turtles, reptiles, and crocodilians. Sixth Edition. Publication of The Center for North American Herpetology, Lawrence. iv + 44p.

Cooper, M. 2017. Movement, habitat, and home range of introduced bullfrogs (Lithobates Catesbeianus) on Mad River gravel ponds (Humboldt Co., Ca, USA), with implications for hydro-modification as a method of management. Humboldt State University.

Crother, B.I. (chair). Committee on Standard and English and Scientific Names. 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and  Reptiles Herpetological Circular. No. 37. iii + 86p.

Frost, D. R., T. Grant, J. Faivovich, R. H. Bain, A. Haas, C. F. B. Haddad, R. O. De Sá, A. Channing, M. Wilkinson, S. C. Donnellan, C. J. Raxworthy, J. A. Campbell, B. L. Blotto, P. Moler, R. C. Drewes, R. A. Nussbaum, J. D. Lynch, D. M. Green, and W. C. Wheeler. 2006. The amphibian tree of life. Bulletin of the American Museum of Natural History 297:1-370 + Fig. 50 foldout.

Fuller, T.E., K.L. Pope, D.T. Ashton, and H.H. Welsh, Jr. 2011. Linking the distribution of an invasive amphibian (Rana catesbeiana) to habitat conditions in a managed river system in northern California. Restoration Ecology 19:204-213.

LeClere, J.  2002.  Bullfrog Rana catesbeiana.  Reptiles and Amphibians of Minnesota [online]. Available at URL: http://herpnet.net/Minnesota-Herpetology/frogs_toads/Bull_frog.html 

Watters, T.G. and S.H. O'Dee. 1998. Metamorphosis of freshwater mussel glochidia (Bivalvia: Unionidae) on amphibians and exotic fishes. Am. Midl. Nat. 139: 49-57.

Other Resources:
Bull frog (USDA) 

Bull frog (University of Michigan Museum)

Rana catesbeiana (bullfrog) (Global Invasive Species Program)

US Fish and Wildlife Service Ecological Risk Screening Summary for Lithobates catesbeianus

Author: Liz McKercher, and Denise R. Gregoire

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.