Lithobates catesbeianus
(Shaw, 1802)
Common Name:
American Bullfrog
Synonyms and Other Names:
Rana catesbeiana, Rana mugiens, Rana scapularis
Identification:
Lithobates catesbeianus is the largest true frog native to Eastern North America (Dorcas and Gibbons 2008). Adults range in size between 9 and 15.2 cm (snout vent length) (Powell et al. 2016). Lithobates catesbeianus can be identified by their green or olive smooth skin, often with dark mottling on their backs, while their stomachs are white to cream mottled with dark pigment (Dorcas and Gibbons 2008). The back of the thighs are flecked with small light spots (Johnson 2007). The hind feet are webbed with the longest toe extending past the webbing (Johnson 2007; Powell et al. 2016). The dorsolateral ridge (ridge around eardrum) that can be found behind the tympanum (eardum) is absent in L. catesbeianus (Dorcas and Gibbons 2008; Powell et al. 2016). Female L. catesbeianus have tympanum approximately the same size as their eye, while males have tympanum twice as large (Dorcas and Gibbons 2008). This is the only species in the southeast U.S. with males larger than females (Dorcas and Gibbon 2008). Tadpoles can be differentiated from other frog species by their large size (approximately 15 cm), olive green color, scattered black dots, and lack of visible intestinal coil (Dorcas and Gibbons 2008). The call of L. catesbeianus is described as a series of deep bass notes (Powell et al. 2016) Lithobates catesbeianus may be confused with other native species, such as the River frog, Lithobates heckscheri, which is darker brown with white spots on the lower lip and dark spots on the upper lip (Dorcas and Gibbons 2008). Pig frogs, Lithobates grylio, are commonly confused with L. catesbeianus, however pig frogs have a more pointed snout and the webbing on their hind feet extends the whole length of the longest toe (Dorcas and Gibbons 2008). Juvenile bullfrogs may be confused with green frogs, Hyla cinerea; however, green frogs have a dorsolateral (on back and sides) ridge extending at least partially down its body (Dorcas and Gibbons 2008).
Size:
9 - 15.2 cm
Native Range:
: Native to the eastern United States, but historically absent from the Cape Cod archipelago and associated islands. Not historically present in the southern portion of Florida or the Okefenokee Swamp (Dorcas and Gibbons 2008).
Great Lakes Nonindigenous Occurrences:
Native to most of the eastern US, with range expansion reports into adjacent watersheds since the 1890s. Populations in the upper Peninsula of Michigan, most of Minnesota, the Lake Erie islands, and Ontario are considered nonindigenous. This species has spread westward to California and Hawaii, northward into Maine and Canada, and southward to Puerto Rico.
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Lithobates catesbeianus are found here.
Full list of USGS occurrences
Table last updated 5/1/2024
† Populations may not be currently present.
Ecology:
Lithobates catesbeianus are habitat generalists and can be found in permanent aquatic habitats such as, ponds, lakes, reservoirs, backwater rivers, ditches, swamps, marsh, bogs, cattle tanks, irrigation canals, and occasionally temporary water bodies (Dorcas and Gibbons 2008; Powell et al. 2016). Juveniles can disperse large distances overland (Dorcas and Gibbons 2008). Adult home ranges have been estimated to be approximately 1.6 km (Cooper 2017).
This species hibernates buried in the mud underwater, while some individuals may overwinter in burrows on land and emerge later in the spring than most true frogs (Powell et al. 2016). The persistence of water bodies is essential for tadpoles to mature and overwinter (Dorcas and Gibbons 2008).
Lithobates catesbeianus are nocturnal generalist predators and have been shown to consume various prey including insects, leeches, centipedes, scorpions, fishes, other frogs, small alligators, turtles, snakes, rodents, bats, birds, and juvenile mink (Kats and Ferrer 2003; Dorcas and Gibbons 2008; Flynn et al. 2017). Bullfrogs have also been known to cannibalize in dense populations (Dorcas and Gibbons 2008; Flynn et al. 2017). Bullfrog tadpoles’ chemical cues affect behavior of native larvae (Kiesecker and Blaustein 1997; Anderson and Lawler 2016). This species also serves as a host to the glochidia of native unionid mussel Utterbackis imbecilis, the paper pondshell (Watters and O’Dee 1998).
Female L. catesbeianus can lay 6,000-20,000 eggs at a time (Urbina et al. 2020). Eggs hatch in 2-5 days and can take four months up to two years to metamorphosize (Urbina et al. 2020). In the bullfrog’s native southern U.S. range, breeding occurs from February – October (Urbina et al. 2020.) However, breeding is limited to the warm summer months in introduced populations in the Pacific northwest (Urbina et al. 2020).
Great Lakes Means of Introduction:
Lithobates catesbeianus has likely expanded its range in the Great Lakes basin through northward dispersal from its native range.
Great Lakes Status:
This species is expanding its range northward within the Great Lakes basin. It is considered native in the southern parts of the basin and non-native in the northern watersheds.
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
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Lithobates catesbeianus has a high environmental impact where introduced to the Great Lakes. Lithobates catesbeianus is host to Lernaea cyprinacea in bullfrogs in Ohio (within native range of bullfrog) (Matson 2019); this non-native parasitic copepod can infect other amphibians and fish and may be spreading with bullfrogs. L. catesbeianus is also a potential carrier for chytrid fungus, Batrachochytrium dendrobatidis and Saprolegnia ferax which infect other frog species (Liu et al. 2016; Deschamps and De Vocht 2016; Adampoulou and Legakis 2016; Madalozzo et at. 2016; Falaschi et al 2020; Johovic et al. 2020; Bissattini et al. 2020).
Lithobates catesbeianus causes acoustic interference with the calls of other frogs (Barbosa et al. 2017) and may interfere with their reproduction. In a laboratory setting, L. catesbeianus tadpoles inhibit the growth of the Northern leopard frog (Rana pipiens) tadpoles and have replaced Northern leopard frog where the species co-occur (Rose 1960; Johnson et al. 2011). L. catesbeianus tadpoles outcompete other tadpoles and cause a reduced body size and survivorship in native amphibian larvae due to reduction of benthic algae (Anderson and Lawler 2016).
Lithobates catesbeianus directly consumes other amphibians (Jameson 1956; Dumas 1966; Zhang et al. 2015; Deschamps and DeVocht 2016; Liu et al. 2016; Oda et al. 2019; Johovic et al. 2020; Bissattini et al. 2020) and juvenile turtles (Nicholson et al. 2020) and likely poses a threat to several at risk native species.
There is little to no evidence that Lithobates catesbeianus has significant socioeconomic impact where introduced to the Great Lakes.
There is little to no evidence that Lithobates catesbeianus has significant benefit where introduced to the Great Lakes.
Lithobates catesbeianus has been shown to preferentially prey on Procambarus clarkii (red swamp crayfish) in areas where both species are introduced (Bissattini and Vignoli 2017). The authors speculate that the presence of the crayfish may reduce the impact of L. catebeianus on native amphibians, but do not demonstrate that L. catebeianus will control P. clarkii populations.
Management:
Regulations (pertaining to the Great Lakes region) Lithobates catesbeianus is named among IUCN’s 100 worst invaders.
Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Physical
Physical removal of adults (trapping, fishing) and/or tadpoles (netting) is often used to reduce population levels. Landscape management (buffer zones, elimination of habitat along managed edges of natural areas) may be an effective management tool (Madalozzo et al. 2016). Pond-filling and/or replacement of permanent ponds with seasonal pools has been used to eliminate L. catesbeianus populations (Cooper 2017).
Chemical
Rotenone will effectively kill tadpoles, but non-target mortality of other fishes and amphibians typically contraindicate use.
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
Remarks:
The genus Rana was revised, and North, Central, and South American “true frogs” were placed into the genus Lithobates (Frost et al. 2006). In 2005 the National Park Service in Yosemite Valley, Yosemite National Park started using eDNA paired with audio recording devices to detect bullfrogs and subsequently remove them. This long-term eradication and monitoring effort is the first successful bullfrog removal at the landscape level and allowed for the reintroduction of the federally endangered Rana draytonii (California red-legged frog) to Yosemite Valley in 2016 (Kamoroff et al. 2020). Another control method for this species that is being investigated is the sterile male release technique, sterile males are released into the population to reduce breeding (Descamps and De Vocht 2022).
References
(click for full reference list)
Author:
Audrey Jordon
Contributing Agencies:
Revision Date:
3/21/2024
Peer Review Date:
3/21/2024
Citation for this information:
Audrey Jordon, 2024, Lithobates catesbeianus (Shaw, 1802): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=71&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 3/21/2024, Peer Review Date: 3/21/2024, Access Date: 5/1/2024
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.