American bullfrog

{{Short description|Species of amphibian}} {{About|the bullfrog in North America|the Asian bullfrog|Banded bullfrog}} {{Good article}} {{Cleanup|reason=Redundant/repetitive information|date=March 2026}} {{Speciesbox | fossil_range = | image = North-American-bullfrog1.jpg | image_caption = Adult male | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn">{{cite iucn |author=IUCN SSC Amphibian Specialist Group. |year=2022 |title=''Aquarana catesbeianus'' |volume=2022 |article-number=e.T58565A193396825 |doi=10.2305/IUCN.UK.2022-1.RLTS.T58565A193396825.en |access-date=8 February 2025}}</ref> | status2 = G5 | status2_system = TNC | status2_ref = <ref name=NatureServe>{{cite web |title=''Lithobates catesbeianus'' |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.105926/Lithobates_catesbeianus |website=NatureServe Explorer An online encyclopedia of life |version=7.1 |publisher=NatureServe|access-date=20 September 2023}}</ref> | taxon = Lithobates catesbeianus | authority = (Shaw, 1802) | range_map = Lithobates catesbeianus distribution.png | range_map_caption = Natural range – blue; Introduced range – red | synonyms = {{collapsible list | {{plainlist | style = margin-left: 1em; text-indent: -1em; | *''Rana catesbeiana'' Shaw, 1802 *''Rana pipiens'' – Daudin, 1802 *''Rana taurina'' Cuvier, 1817 *''Rana mugiens'' Merrem, 1820 *''Rana scapularis'' Harlan, 1826 *''Rana conspersa'' LeConte, 1855 *''Rana catesbyana'' Cope, 1889 *''Rana catesbyana'' Werner, 1909 *''Rana (Rana) catesbeiana'' – Boulenger, 1920 *''Rana nantaiwuensis'' Hsü, 1930 *''Rana mugicus'' Angel, 1947 *''Rana catesbyana'' Smith, 1978 *''Rana (Rana) catesbeiana'' Dubois, 1987 *''Rana (Aquarana) catesbeiana'' Dubois, 1992 *''Rana (Novirana, Aquarana) catesbeiana'' Hillis & Wilcox, 2005 *''Lithobates (Aquarana) catesbeianus'' Dubois, 2006 *''Rana (Lithobates) catesbeiana'' Fouquette and Dubois, 2014 }} }} | synonyms_ref = }}

The '''American bullfrog''' ('''''Lithobates catesbeianus'''''), often simply known as the '''bullfrog''' in Canada and the United States, is a large true frog native to eastern North America. It typically inhabits large permanent water bodies such as swamps, ponds, and lakes. Bullfrogs can also be found in manmade habitats such as pools, koi ponds, canals, ditches, reservoirs and culverts.<ref>{{Cite journal |last=Snow |first=Nathan P. |last2=Witmer |first2=Gary |date=2010 |title=American Bullfrogs as Invasive Species: A Review of the Introduction, Subsequent Problems, Management Options, and Future Directions |url=https://escholarship.org/uc/item/5j46t7f2 |journal=Proceedings of the Vertebrate Pest Conference |language=en |volume=24 |issue=24 |doi=10.5070/V424110490 |issn=0507-6773}}</ref> The bullfrog gets its name from the sound the male makes during the breeding season, which sounds similar to a bull bellowing. They are generalist carnivores, consuming a wide variety of prey. In turn, they are eaten by predators such as alligators, snakes, and birds.

The bullfrog is large and is commonly eaten throughout its range, especially in the southern United States where they are plentiful. Their use as a food source has led to bullfrogs being introduced outside of their native range. Bullfrogs have been introduced to more than 40 countries and many continents including Western United States, the Caribbean, South America, Western Europe, Belgium, Italy, Spain, Greece, China, Japan, South Korea, Malaysia, Southeast Asia, and more.<ref>{{Cite journal |last=Lado |first=Ignacio |last2=Laufer |first2=Gabriel |last3=Segura |first3=Angel M. |date=2026-02-01 |title=Global distribution and environmental preferences of the non-native American bullfrog Aquarana catesbeiana |url=https://doi.org/10.1007/s10750-025-05992-1 |journal=Hydrobiologia |language=en |volume=853 |issue=4 |pages=981–999 |doi=10.1007/s10750-025-05992-1 |issn=1573-5117}}</ref> In these places they are considered an invasive species due to their voracious appetite and the large number of eggs they produce, which has a negative effect on native amphibians, certain insects and other fauna. Bullfrogs are very skittish which can make their capture difficult and thus they often become established.

Other than for food, bullfrogs are also used for dissection in science classes. Albino bullfrogs are sometimes kept as pets, and bullfrog tadpoles are often sold at ponds or fish stores.

==Taxonomy== The specific name, ''catesbeiana'' (feminine) or ''catesbeianus'' (masculine), is in honor of English naturalist Mark Catesby.<ref>Feduccia, Alan (editor) (1985). ''Catesby's Birds of Colonial America''. Chapel Hill, North Carolina: University of North Carolina Press. 208 pp. {{ISBN|978-0807848166}}. (''Rana catesbeiana'', Preface, p. xiii).</ref> Some authorities use the scientific name, ''Lithobates catesbeianus'',<ref>{{cite web |url=http://research.amnh.org/vz/herpetology/amphibia/ |title= American Museum of Natural History: Amphibian Species of the World 5.5, an Online Reference |author=Frost, Darrel |author-link=Darrel R. Frost |year=2011 |work=Herpetology |publisher=The American Museum of Natural History |access-date=2013-02-17}}</ref> although others prefer ''Rana catesbeiana''.<ref name="Hillis2007"/><ref name="HillisandWilcox2005"/><ref name="Yuan16">{{Cite journal|last=Yuan|first=Z.-Y.|display-authors=etal|date=2016|title=Spatiotemporal diversification of the true frogs (genus Rana): A historical framework for a widely studied group of model organisms|journal=Systematic Biology|volume=65|issue=5 |doi=10.1093/sysbio/syw055|pmid=27288482|pages=824–42|doi-access=free|hdl=2292/43460|hdl-access=free}}</ref><ref>{{cite web | url = https://amphibiaweb.org/cgi/amphib_query?rel-scientific_name=contains&where-scientific_name=Rana+catesbeiana | title = ''Rana catesbeiana'' | publisher = Amphibiaweb.org}}</ref>

Cladogram of the position of the American bullfrog within ''Lithobates,'' after Martínez‐Gil et al. 2025:<ref>{{Cite journal |last=Martínez‐Gil |first=Helena |last2=Kaliontzopoulou |first2=Antigoni |last3=Enriquez‐Urzelai |first3=Urtzi |date=2025-08-16 |title=Different Macroevolutionary Trajectories Lead to Contrasting Ecogeographical Patterns in Two Widespread Frog Radiations |url=https://onlinelibrary.wiley.com/doi/10.1111/geb.70109 |journal=Global Ecology and Biogeography |language=en |volume=34 |issue=8 |doi=10.1111/geb.70109 |issn=1466-822X|doi-access=free }}</ref>{{clade| {{clade |label1=''Lithobates'' |1={{clade |1=''L. sylvaticus'' (wood frog) |2={{clade |1={{clade |1=''L. septentrionalis'' (mink frog) |2={{clade |1=''L. grylio'' (pig frog) |2={{clade |1={{clade |1=''L. clamitans'' (green frog) |2=''L. okaloosae'' (Florida bog frog) }} |2={{clade |1=''L. hecksheri'' (river frog) |2='''''Lithobates catesbeianus''''' ('''American bullfrog''') }} }} }} }} |2={{clade hidden|mode=left|expand-text=''Lithobates spp.'' (incl. type species ''L. palmipes'') |1={{clade |1={{clade |1=''L. maculatus'' (highland frog) |2={{clade |1=''L. warszewitschii'' (Warszewitsch's frog) |2=''L. vibicaria'' (green-eyed/Rancho Redondo frog) }} }} |2={{clade |1={{clade |1=''L. vaillanti'' (Vaillant's frog) |2=''L. juliani'' (Maya Mountains frog) }} |2={{clade |1=''L. bwana'' (Rio Chipillico frog) |2=''L. palmipes'' (Amazon River frog) }} }} }} |2={{clade |1={{clade |1=''L. sierramadrensis'' (Sierra Madre frog) |2=''L. tarahumarae'' (Tarahumara frog) }} |2={{clade |1={{clade |1=''L. pipiens'' (northern leopard frog) |2={{clade |1=''L. chiricahuensis'' (Chiricahua leopard frog) |2={{clade |1=''L. montezumae'' (Montezuma leopard frog) |2=''L. dunni'' (Patzcuaro frog) }} }} }} |2={{clade |1={{clade |1=''L. palustris'' (pickerel frog) |2={{clade |1=''L. areolatus'' (crawfish frog) |2={{clade |1=''L. sevosus'' (Mississippi gopher frog) |2=''L. capito'' (gopher frog) }} }} }} |2={{clade |1={{clade |1=''L. sphenocephalus'' (southern leopard frog) |2={{clade |1=''L. blairi'' (plains leopard frog) |2=''L. berlandieri'' (Rio Grande leopard frog) }} }} |2={{clade |1=''L. macroglossa'' (Guatemala plateau frog) |2={{clade |1={{clade |1=''L. forreri'' (Forrer's grass frog) |2=''L. omiltemanus'' (Guerreran leopard frog) }} |2={{clade |1=''L. magnaocularis'' (Northwest Mexico leopard frog) |2={{clade |1=''L. onca'' (relict leopard frog) |2=''L. yavapaiensis'' (lowland leopard frog) }} }} }} }} }} }} }} }} }} }} }} |style=font-size:85%; line-height:85%;}} |2=''Rana'' }}

==Description== The dorsal (upper) surface of the bullfrog has an olive-green background color, either plain or with mottling and banding of grayish brown. The ventral (under) surface is off-white blotched with yellow or gray. Often, a marked contrast in color is seen between the green upper lip and the pale lower lip.<ref name="Georgia" /> The teeth are tiny and are useful only in grasping.<ref name="Cardini 1974" /> The eyes are prominent with brown irises and horizontal, almond-shaped pupils. The tympana (eardrums) are easily seen just behind the eyes and the dorsolateral folds of skin enclose them. The limbs are blotched or banded with gray. The fore legs are short and sturdy and the hind legs are long. The front toes are not webbed, but the back toes have webbing between the digits with the exception of the fourth toe, which is unwebbed.<ref name="Georgia">{{cite web |url=http://wwknapp.home.mindspring.com/docs/bullfrog.html |title=Bullfrog – ''Rana catesbeiana'' |author=Knapp, W. W. |date=2008-05-28 |work=The Frogs and Toads of Georgia |access-date=2013-01-20 |archive-url=https://web.archive.org/web/20181025125545/http://wwknapp.home.mindspring.com/docs/bullfrog.html |archive-date=2018-10-25 }}</ref>

{{Multiple image | image1 = American bullfrog (51239614029).jpg | image2 = American bullfrog (51239041743).jpg | align = center | total_width = 550 | caption1 = Male | caption2 = Female }}

Bullfrogs are sexually dimorphic, with males being smaller than females and having yellow throats.<ref>{{cite journal |last1=Tessa |first1=G. |title=Age and body size in four introduced populations of the American bullfrog, Lithobates catesbeianus (Ranidae) |journal=Italian Journal of Zoology |date=2016 |volume=83 |issue=4 |pages=497–502|doi=10.1080/11250003.2016.1259360 }}</ref> Males have tympana larger than their eyes, whereas the tympana in females are about the same size as the eyes.<ref name="Georgia" /> Bullfrogs measure about {{cvt|3.6|to|6|in|cm|0|}} in snout–to–vent length. They grow fast in the first eight months of life, typically increasing in weight from {{cvt|5|to|175|g|oz}},<ref name="Lutz" /> and large, mature individuals can weigh up to {{cvt|500|g|lb}}.<ref name="r1" /> In some cases bullfrogs have been recorded as attaining {{cvt|800|g|lb}} and measuring up to {{cvt|8|in|cm}} from snout to vent. The American bullfrog is the largest species of true frog in North America.<ref name="Lutz" /><ref name="r2" />

=== Tongue biomechanics === The speed of a bullfrog's tongue strike is much faster than it should be if muscles were the only force behind it. Similar to the tension on a slingshot pulled all the way back, when the frog's mouth is closed, tension is put into the elastic tissues of the tongue, and also into the elastic tendons of the lower jaw. When the frog attacks prey, the act of opening its mouth is akin to the release of a slingshot; the elastic force stored up in both the tongue and the jaw are combined to shoot the tip of the tongue toward the prey much faster than the prey's ability to see the strike and evade capture, completing the strike and retrieval in approximately 0.07 seconds. Another benefit of this elastic-force based attack is that it is not dependent on background temperature: a frog with a cold body temperature has muscles that move more slowly, but it can still attack prey with the same speed as a warm bullfrog.{{Citation needed|date=March 2026|reason=I'm assuming it's the citation for the next paragraph as well}}

Ballistic tongue projection of the related leopard frog is possible due to the presence of elastic structures that allow storage and subsequent release of elastic recoil energy. This accounts for the tongue projecting with higher power output than would develop by muscular action alone.<ref>{{Cite journal|last1=Sandusky|first1=Paula E.|last2=Deban|first2=Stephen M.|date=2012-12-01|title=Temperature Effects on the Biomechanics of Prey Capture in the Frog Rana pipiens|journal=Journal of Experimental Zoology Part A: Ecological Genetics and Physiology|volume=317|issue=10|pages=595–607|doi=10.1002/jez.1751|pmid=22952141|doi-access=free|bibcode=2012JEZA..317..595S }}</ref> Also, such mechanism relieves the tongue's musculature from physiological constraints such as limited peak power output - mechanical efficiency and thermal dependence by uncoupling the activation of the depressor mandibulae's contractile units from actual muscular movement. In other words, the kinematic parameters developed by contribution of the elastic structures differ from those developed by muscular projection, accounting for the difference in velocity, power output, and thermal dependence.<ref>{{Cite journal|last1=Deban|first1=Stephen M.|last2=Lappin|first2=A. Kristopher|date=2011-04-15|title=Thermal effects on the dynamics and motor control of ballistic prey capture in toads: maintaining high performance at low temperature|journal=Journal of Experimental Biology|volume=214|issue=8|pages=1333–1346|doi=10.1242/jeb.048405|pmid=21430211|doi-access=}}</ref>{{Technical inline|date=March 2026}}

==Distribution== thumb|In typical aquatic habitat The bullfrog is originally native to eastern North America, where it is commonly found in every U.S. state east of the Mississippi River. Its natural range extends from the eastern Canadian Maritime Provinces to as far west as Idaho and Texas, and as far north as Michigan (including the Upper Peninsula), Minnesota and Montana; it is largely absent in North Dakota.<ref name="NAGS71">{{cite web |url=https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=71 |title=''Lithobates catesbeianus'' (Shaw, 1802) |date=2011-09-14 |author1=McKercher, Liz |author2=Gregoire, Denise R. |work=Nonindigenous Aquatic Species |publisher=U.S. Geological Survey |access-date=2013-01-20}}</ref>

Within North America, the bullfrog has been introduced to Nantucket island, as well as portions of the western U.S., including Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. In these states, it is considered to be an invasive species, as concerns exist that it may outcompete or prey upon native species of reptiles and amphibians, disrupting the delicate ecological balance of certain areas.<ref name="NAGS71" /> It is very common on the West Coast, especially in California, where it is believed to pose a threat to the California red-legged frog, and is considered to be a factor in the decline of that vulnerable species.<ref>{{cite iucn |author=Geoffrey Hammerson |date=2008 |title=''Rana draytonii'' |volume=2008 |article-number=e.T136113A4240307 |doi=10.2305/IUCN.UK.2008.RLTS.T136113A4240307.en |access-date=12 November 2021}}</ref> Bullfrogs have been found to feed on the young of several snakes, including the California endemic giant garter snake, a threatened species.<ref>{{Cite journal |last1=Carpenter |first1=Niel M. |last2=Casazza |first2=Michael L. |last3=Wylie |first3=Glenn D. |date=2005 |title=Rana catesbeiana (Bullfrog). Diet |journal=Herpetological Review |volume=33 |page=130}}</ref> In early 2023, the Utah Department of Natural Resources began tweeting tips on how to catch and cook bullfrogs in an effort to encourage residents to help control the growing population by catching the invasive frogs for food.<ref>{{cite web |title=Why Utah's Wildlife Services is suggesting bullfrogs for your dinner table |date=1 Mar 2023 |author=Derick Fox |website=ABC4 |url=https://www.abc4.com/news/wasatch-front/why-utahs-wildlife-services-is-suggesting-bullfrogs-for-your-dinner-table/}}</ref>thumb|left|Female American bullfrog

The bullfrog has also been introduced to Hawaii, South America, Asia, the Caribbean, and Europe for various purposes including [https://mdc.mo.gov/improve-your-property/habitat-management/pond-and-stream-management/ponds-fish-frog-management/frog frog farming] and population control of other species.<ref>Both, Camila, et al. "Widespread occurrence of the American bullfrog, Lithobates catesbeianus (Shaw, 1802)(Anura: Ranidae), in Brazil." ''South American Journal of Herpetology'' 6.2 (2011): 127-134.</ref> Specifically, the bullfrog has been introduced to the extreme south of British Columbia, Canada, nearly every state in Mexico, as well as Belgium, Cuba, the Dominican Republic, Haiti, Italy, Jamaica, the Netherlands, and Puerto Rico.<ref name=ISSG>{{cite web |url=http://www.issg.org/database/species/ecology.asp?si=80&fr=1&sts= |title=''Lithobates catesbeianus'' (=''Rana catesbeiana'') (amphibian) |author=Crayon, John J. |date=2009-12-03 |work=Global Invasive Species Database |publisher=Invasive Species Specialist Group |access-date=2013-01-20}}</ref> It is also found in Argentina, Brazil, China, Colombia, Japan, South Korea, Uruguay and Venezuela.<ref>{{Cite web |url=http://www.savethefrogs.com/threats/invasive-species/ |title=SAVE THE FROGS! - Invasive Species |access-date=2017-01-29 |archive-url=https://web.archive.org/web/20171010004639/https://www.savethefrogs.com/threats/invasive-species/ |archive-date=2017-10-10 }}</ref><ref name=AmphibiaWeb>{{cite web |url=http://www.amphibiaweb.org/cgi-bin/amphib_query?rel-common_name=like&where-scientific_name=rana+catesbeiana&account=amphibiaweb |title=''Rana catesbeiana'' |author1=Lu, Christine |author2=Sopory, Ambika |date=2010-08-23 |publisher=AmphibiaWeb |access-date=2013-01-20 |archive-url=https://web.archive.org/web/20160510205406/http://www.amphibiaweb.org/cgi-bin/amphib_query?rel-common_name=like&where-scientific_name=rana+catesbeiana&account=amphibiaweb |archive-date=2016-05-10 }}</ref> The reasons for introducing the bullfrog to these areas have largely been intentional, either to provide humans with a source of food<ref>{{Cite web |title=The Japanese Bullfrog {{!}} Perspectives on History {{!}} AHA |url=https://www.historians.org/publications-and-directories/perspectives-on-history/september-2020/the-japanese-bullfrog |access-date=2022-06-25 |website=www.historians.org}}</ref> or as biological control agents. In addition, the unintended escape of frogs from breeding establishments or scientific research facilities, captive escapees or released pets are also a possibility.<ref name=ISSG/> Conservationists are concerned that the bullfrog is relatively immune to the fungal infection ''chytridiomycosis'' (also called 'chytrid' fungus) which has been ravaging numerous frog species: as it invades new territories, it may assist in the spread of this lethal fungus as an asymptomatic carrier, spreading the fungus to more susceptible, native species of frog it encounters.<ref>{{cite journal|last1=Borzée|first1=Amaël|last2=Kosch|first2=A. Tiffany|last3=Kim|first3=Miyeon|last4=Jang|first4=Yikweon|title=Introduced bullfrogs are associated with increased Batrachochytrium dendrobatidis prevalence and reduced occurrence of Korean treefrogs|journal=PLOS ONE|date=May 31, 2017|volume=12|issue=5|article-number=e0177860|doi=10.1371/journal.pone.0177860|pmid=28562628|pmc=5451047|bibcode=2017PLoSO..1277860B|doi-access=free}}</ref><ref name=AmphibiaWeb/>

==Biology== === Ecology === Bullfrogs are voracious, opportunistic, ambush predators that prey on any small animal they can overpower and consume. Bullfrog stomachs have been found to contain rodents, small lizards and snakes, other frogs and toads, other amphibians, crayfish, other crustaceans,<ref name="animaldiversity.org">{{cite web | url=https://animaldiversity.org/accounts/Lithobates_catesbeianus/ | title=Lithobates catesbeianus (American Bullfrog) | website=Animal Diversity Web }}</ref> small birds, scorpions, tarantulas and bats,<ref>{{cite journal | author = Mikula P | year = 2015 | title = Fish and amphibians as bat predators | journal = European Journal of Ecology | volume = 1 | issue = 1| pages = 71–80 | doi = 10.1515/eje-2015-0010 | doi-access = free }}</ref><ref name="eattheinvaders">{{cite web |url=http://eattheinvaders.org/bullfrog/ |title=Bullfrog |author=Moyle, Peter |date=2012-07-04 |work=Eat the Invaders |access-date=2013-02-18}}</ref> as well as the many types of invertebrates, such as snails, worms and insects, which are the usual food of ranid frogs.<ref>{{Cite web|url=https://animaldiversity.org/accounts/Lithobates_catesbeianus/|title = Lithobates catesbeianus (American Bullfrog)|website=Animaldiversity.org}}</ref> These studies revealed the bullfrog's diet to be unique among North American ranids in the inclusion of a large percentage of aquatic animals, such as fish, tadpoles, ram's horn snails, and dytiscid beetles, as well as the aquatic eggs of fish, frogs, insects, or salamanders.<ref name="animaldiversity.org"/> Cannibalism has been observed in bullfrog populations in resource-limited environments.<ref>Leivas, P. T., Leivas, F. W., & Moura, M. O. (2012). Diet and trophic niche of Lithobates catesbeianus (Amphibia: Anura). ''Zoologia (Curitiba)'', ''29'', 405-412.</ref> Bullfrogs are able to capture large, strong prey because of the powerful grip of their jaws after the initial ranid tongue strike. However, there is a correlation found with size of prey relative to body size of the bullfrog. Juveniles and adults typically go after prey that is relative to their own body size.<ref>Ortíz-Serrato, Liliana, et al. "Diet of the Exotic American Bullfrog, Lithobates Catesbeianus, in a Stream of Northwestern Baja California, Mexico." Western North American Naturalist, vol. 74, no. 1, 2014, pp. 116–22, https://doi.org/10.3398/064.074.0112.</ref> The bullfrog is able to make allowance for light refraction at the water-air interface by striking at a position posterior to the target's perceived location. The comparative ability of bullfrogs to capture submerged prey, compared to that of the green frog, leopard frog, and wood frog (''L. clamitans, L. pipiens'', and ''L. sylvaticus'', respectively) was also demonstrated in laboratory experiments.<ref name="Cardini 1974" />

Prey motion elicits feeding behavior. First, if necessary, the frog performs a single, orienting bodily rotation ending with the frog aimed towards the prey, followed by approaching leaps, if necessary. Once within striking distance, the bullfrog begins its feeding strike, which consists of a ballistic lunge (eyes closed as during all leaps) that ends with the mouth opening. At this stage, the fleshy, mucus-coated tongue is extended towards the prey, often engulfing it, while the jaws continue their forward travel to close (bite) just as the tongue is retracted. Large prey that do not fit entirely into the mouth are stuffed in with the hands. In laboratory observations, bullfrogs taking mice usually swam underwater with prey in mouth, apparently with the advantageous result of altering the mouse's defense from counter-attack to struggling for air. Asphyxiation is the most likely cause of death of warm-blooded prey.<ref name="Cardini 1974" /> [[File:Gator with bullfrog at Lake Woodruff - Flickr - Andrea Westmoreland.jpg|thumb|An American alligator (''Alligator mississippiensis'') feeding on a bullfrog]] Bullfrogs are an important item of prey to many birds (especially large herons), North American river otters (''Lontra canadensis''), predatory fish, and occasionally other amphibians. Predators of American bullfrogs once in their adult stages can range from {{cvt|150|g|oz}} belted kingfishers (''Megaceryle alcyon'') to {{cvt|1100|lb|kg}} American alligators (''Alligator mississippiensis'').<ref>{{cite journal|author1=Murray, B. G. |author2=Jehl, J. R. |year= 1964|title=Weight of autumn migrants from coastal New Jersey|journal= Bird-Banding |volume=35|issue=4|url=https://sora.unm.edu/node/49837|pages=253–63|jstor=4511101 |doi=10.2307/4511101|url-access=subscription}}</ref><ref>{{cite web |url=http://genomics.senescence.info/species/entry.php?species=Alligator_mississippiensis |title=American Alligator (''Alligator mississippiensis'') longevity, ageing, and life history |publisher=The Animal Ageing and Longevity Database |access-date=2014-02-06}}</ref> The eggs and larvae are unpalatable to many salamanders and fish, but the high levels of activity of the tadpoles may make them more noticeable to a predator not deterred by their unpleasant taste. Humans hunt bullfrogs as game and consume their legs. Adult frogs try to escape by splashing and leaping into deep water. A trapped individual may squawk or emit a piercing scream, which may surprise the attacker sufficiently for the frog to escape. An attack on one bullfrog is likely to alert others in the vicinity to danger and they will all retreat into the safety of deeper water. Bullfrogs may be at least partially resistant to the venom of copperhead (''Agkistrodon contortrix'') and cottonmouth (''Agkistrodon piscivorus'') snakes, though these species are known natural predators of bullfrogs as are northern water snakes (''Nerodia sipedon'').<ref name=AmphibiaWeb/><ref>Conant, Roger. (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition''. Houghton Mifflin Company, Boston.</ref><ref>{{cite journal|author=Ryan, M. J. |year=1980|title=The reproductive behavior of the bullfrog (''Rana catesbeiana'')|journal=Copeia |volume=1980|number=1|pages= 108–114|url=http://www.sbs.utexas.edu/ryan/Publications/1980-82/1980Copeia108.pdf|doi=10.2307/1444139|jstor=1444139}}</ref> ==== As an invasive species ==== Multiple traits of ''L. catesbeianus'' contribute to its competitive ability, especially as an invasive. The generalist diet of the American bullfrog allows for it to consume food in different environments. They directly predate indigenous frog species, leading to numerous frog declines.<ref>{{Cite journal |last=Snow |first=Nathan P. |last2=Witmer |first2=Gary |date=2010 |title=American Bullfrogs as Invasive Species: A Review of the Introduction, Subsequent Problems, Management Options, and Future Directions |url=https://escholarship.org/uc/item/5j46t7f2 |journal=Proceedings of the Vertebrate Pest Conference |language=en |volume=24 |issue=24 |doi=10.5070/V424110490 |issn=0507-6773}}</ref> When observing the contents of American bullfrog stomachs, it was discovered that adult bullfrogs regularly consume predators of bullfrog young, including dragonfly nymphs, garter snakes, and giant water bugs. Thus, the ecological check on American bullfrog juveniles in invaded areas become less effective. ''L. catesbeianus'' seems to exhibit traits of immunity or resistance against the antipredator defenses of other organisms, with analysis of stomach contents from New Mexican bullfrogs showing the regular consumption of wasps, with no conditioned avoidance due to the wasps' stingers. Along the Colorado river, ''L. catesbeianus'' stomach contents indicate the ability to withstand the discomforting spines of the stickleback fish. Reports of American bullfrogs eating scorpions and rattlesnakes also exist.<ref>{{cite journal|author1=Jancowski K|author2=Orchard S|date=2013|title=Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada|journal=NeoBiota|volume=16|pages=17–37|doi=10.3897/neobiota.16.3806 |doi-access=free}}</ref>

Analysis of the American bullfrog's realized niche at various sites in Mexico, and comparisons with the niches of endemic frogs show that it is possible that the American bullfrog capable of niche shift, and pose a threat to many endemic Mexican frog species, even those that are not currently in competition with the American bullfrog.<ref>López, Jorge Luis Becerra et al. "Evidence of niche shift and invasion potential of Lithobates catesbeianus in the habitat of Mexican endemic frogs." PloS one vol. 12,9 e0185086. 27 Sep. 2017, doi:10.1371/journal.pone.0185086</ref>

Self-sustaining populations of American bullfrogs became established in the United Kingdom around 1999, where their introduction was likely due to accidental escapes and deliberate releases from captivity. These populations appear to be quite small, and are undergoing control by Natural England as the species poses a threat to native amphibians.<ref>{{Cite web |title=American Bull Frog |url=https://www.froglife.org/info-advice/amphibians-and-reptiles/american-bull-frog/ |access-date=2025-01-07 |website=www.froglife.org}}</ref>

The American bullfrog has been known to spread the amphibian pathogen ''Batrachochytrium dendrobatidis'' among populations that it has been introduced to.<ref>{{Cite journal |last1=Garner |first1=Trenton W.J |last2=Perkins |first2=Matthew W |last3=Govindarajulu |first3=Purnima |last4=Seglie |first4=Daniele |last5=Walker |first5=Susan |last6=Cunningham |first6=Andrew A |last7=Fisher |first7=Matthew C |date=2006-05-24 |title=The emerging amphibian pathogen ''Batrachochytrium dendrobatidis'' globally infects introduced populations of the North American bullfrog, ''Rana catesbeiana'' |journal=Biology Letters |volume=2 |issue=3 |pages=455–459 |doi=10.1098/rsbl.2006.0494 |pmid=17148429 |pmc=1686185 |issn=1744-9561}}</ref>

===Breeding season=== The bullfrog breeding season typically lasts two to three months.<ref name=lekorganization/><ref name=notesrana/> A study of bullfrogs in Michigan showed the males arriving at the breeding site in late May or early June, and remaining in the area into July. The territorial males that occupy sites are usually spaced some {{cvt|3|to|6|m}} apart and call loudly.<ref name=territoriality /><ref name=vocalizationaggression /> At least three different types of calls have been noted in male bullfrogs under different circumstances. These distinctive calls include territorial calls made as threats to other males, advertisement calls made to attract females, and encounter calls which precede combat.<ref name=territorygreenfrog/><ref name=reproductivebehavior/>

The males continuously engage in sexual activity throughout the long breeding season.<ref name=lekorganization /> Though The reproductive cycle of American bullfrogs in Oregon is mainly restricted to the summer season when individuals congregate in lentic freshwater systems. Males are present at the breeding pond for longer periods than females during the entire season, increasing their chances of multiple matings.<ref name=territoriality /><ref name=vocalizationaggression /> The sex ratio is typically skewed toward males.<ref name=reproductivebehavior /> Which might lead to some interspecific amplexus events with other North American frogs <ref>Pearl, Christopher A., Marc P. Hayes, Russ Haycock, Joseph D. Engler, and Jay Bowerman. "Observations of Interspecific Amplexus between Western North American Ranid Frogs and the Introduced American Bullfrog (Rana Catesbeiana) and an Hypothesis Concerning Breeding Interference." The American Midland Naturalist 154, no. 1 (2005): 126–34. http://www.jstor.org/stable/3566621.</ref> Conversely, females have brief periods of sexual receptivity during the season. In one study, female sexual activity typically lasted for a single night and mating did not occur unless the females initiated the physical contact.<ref name=lekorganization /><ref name=reproductivebehavior /> Males only clasp females after they have indicated their willingness to mate.<ref name=lekorganization /> This finding refutes previous claims that a male frog will clasp any proximate female with no regard to whether the female has consented.<ref name=territorygreenfrog /><ref name=callstructure/><ref name=soundinfluence/><ref name=acousticinteraction/> Once a male finds a receptive female he will clasp onto her and undergo inguinal amplexus — a reproductive position — using his forelimbs. The enlargement of forelimb muscles is a sexually dimorphic trait seen in the male bullfrog. One study investigating male and female bullfrog forelimbs muscles found males had significantly stronger muscles that could undergo longer durations of activity before the onset of fatigue.<ref>{{Cite journal |last1=Peters |first1=S.E. |last2=Aulner |first2=D.A. |date=2000-12-01 |title=Sexual dimorphism in forelimb muscles of the bullfrog, Rana catesbeiana: a functional analysis of isometric contractile properties |journal=Journal of Experimental Biology |volume=203 |issue=23 |pages=3639–3654 |doi=10.1242/jeb.203.23.3639 |pmid=11060225 |issn=0022-0949}}</ref> The significance of forelimb sexual dimorphism allow males to remain in amplexus with the female for longer durations increasing their chance at reproductive success in the highly competitive mating environment. Females can deposit 1,000 - 40,000 eggs which hatch in 3 - 5 days.<ref>{{Cite journal |last=Snow |first=Nathan P. |last2=Witmer |first2=Gary |date=2010 |title=American Bullfrogs as Invasive Species: A Review of the Introduction, Subsequent Problems, Management Options, and Future Directions |url=https://escholarship.org/uc/item/5j46t7f2 |journal=Proceedings of the Vertebrate Pest Conference |language=en |volume=24 |issue=24 |doi=10.5070/V424110490 |issn=0507-6773}}</ref>

These male and female behaviors cause male-male competition to be high within the bullfrog population and sexual selection for the females to be an intense process.<ref name=lekorganization /> Kentwood Wells postulated leks, territorial polygyny, and harems are the most likely classifications for the bullfrog mating system. Leks would be a valid description because males congregate to attract females, and the females arrive to the site for the purpose of copulation.<ref name=lekorganization /><ref name=territorygreenfrog /> In a 1980 study on bullfrogs in New Jersey, the mating system was classified as resource-defense polygyny. The males defended territories within the group and demonstrated typical physical forms of defense.<ref name=reproductivebehavior />

====Choruses==== Male bullfrogs aggregate into groups called choruses. The male chorus behavior is analogous to the lek formation of birds, mammals, and other vertebrates. Choruses are dynamic, forming and remaining associated for a few days, breaking down temporarily, and then forming again in a new area with a different group of males.<ref name=territorygreenfrog /> Male movement has experimentally been noted to be dynamic.<ref name=reproductivebehavior /> In the Michigan study, the choruses were described as "centers of attraction" in which their larger numbers enhanced the males' overall acoustical displays. This is more attractive to females and also attractive to other sexually active males. Choruses in this study were dynamic, constantly forming and breaking up. New choruses were formed in other areas of the site. Males moved around and were highly mobile within the choruses.<ref name=lekorganization />

A review of multiple studies on bullfrogs and other anurans noted male behavior within the groups changes according to the population density of the leks. At higher population densities, leks are favored due to the difficulty in defending individual territories among a large population of males. This variance causes differences in how females choose their mates. When the male population density is low and males maintain clearer, more distinct territories, female choice is mostly determined by territory quality.<ref name=territorygreenfrog /> When male population density is higher, females depend on other cues to select their mates. These cues include the males' positions within the chorus and differences in male display behaviors among other determinants.<ref name=territoriality /><ref name=territorygreenfrog /> Social dominance within the choruses is established through challenges, threats, and other physical displays. Older males tend to acquire more central locations while younger males were restricted to the periphery.<ref name=lekorganization />

Chorus tenure is the number of nights that a male participates in the breeding chorus.<ref name=chorustenure/> One study distinguishes between chorus tenure and dominant tenure. Dominant tenure is more strictly defined as the amount of time a male maintains a dominant status.<ref name=chorusparticipation/> Chorus tenure is restricted due to increased risk of predation,<ref name=costbenefitchorus/> lost foraging opportunities,<ref name=foragingsuccess/> and higher energy consumption.<ref name=energycommunication/> Calling is postulated to be energetically costly to anurans in general.<ref name=envphysiology/> Energy is also expended through locomotion and aggressive interactions of male bullfrogs within the chorus.<ref name=chorusparticipation />

====Aggressive behavior==== To establish social dominance within choruses, bullfrogs demonstrate various forms of aggression, especially through visual displays. Posture is a key factor in establishing social position and threatening challengers.<ref name=territorygreenfrog /> Territorial males have inflated postures while non-territorial males remain in the water with only their heads showing. For dominant (territorial) males, their elevated posture reveals their yellow-colored throats.<ref name=territoriality /><ref name=territorygreenfrog /> When two dominant males encounter each other, they engage in a wrestling bout. The males have their venters clasped, each individual in an erect position rising to well above water level.<ref name=territorygreenfrog /> The New Jersey study noted the males would approach each other to within a few centimeters and then tilt back their heads, displaying their brilliantly colored gular sacs. The gular is dichromatic in bullfrogs, with dominant and fitter males displaying yellow gulars. The New Jersey study also reported low posture with only the head exposed above the water surface was typical of subordinate, or non-territorial males, and females. High posture was demonstrated by territorial males, which floated on the surface of the water with their lungs inflated, displaying their yellow gulars.<ref name=reproductivebehavior /> Males optimize their reproductive fitness in a number of ways. Early arrival at the breeding site, prolonged breeding with continuous sexual activity throughout the season, ownership of a centrally located territory within the chorus, and successful movement between the dynamically changing choruses are all common ways for males to maintain dominant, or territorial, status within the chorus. Older males have greater success in all of these areas than younger males.<ref name=lekorganization /> Some of the males display a more inferior role, termed by many researchers as the silent male status. These silent males adopt a submissive posture, sit near resident males and make no attempt to displace them. The silent males do not attempt to intercept females but are waiting for the territories to become vacant.<ref name=territoriality /><ref name=territorygreenfrog /> This has also been called the alternate or satellite male strategy.<ref name=territorygreenfrog />

===Life cycle=== After selecting a male, the female deposits eggs in his territory.<ref name=reproductivebehavior /> During amplexus, the male rides on top of the female, grasping her just behind her fore limbs. The female chooses a site in shallow water among vegetation, and lays a batch of up to 20,000 eggs, and the male simultaneously releases sperm, resulting in external fertilization.<ref name="Casper, G. S 2005" /> The eggs form a thin, floating sheet which may cover an area of {{cvt|0.5|to|1.0|m2}}. The embryos develop best at water temperatures between {{convert|24|and|30|°C|°F}} and hatch in three to five days. <gallery mode="packed" heights="140"> File:American Bullfrog, tadpole stage (Rana catesbeiana) (6220036343).png|Tadpole File:Rana catesbeiana IMG 2680.JPG|Froglet with tail File:Juvenile bullfrog.JPG|Juvenile with a small, grey, oval-shaped area on top of the head, the parietal eye </gallery> If the water temperature rises above {{convert|32|°C}}, developmental abnormalities occur, and if it falls below {{convert|15|°C}}, normal development ceases.<ref name="NAGS71" /> Newly hatched tadpoles show a preference for living in shallow water on fine gravel bottoms. American bullfrog tadpoles have also "showed a preference for habitats containing structure."<ref>Smith, Geoffrey, and Brittany Doupnik. "Habitat use and activity level of large American bullfrog tadpoles: choices and repeatability." Amphibia-Reptilia 26.4 (2005): 549-552.</ref> This may reflect a lesser number of predators in these locations. As they grow, they tend to move into deeper water. The tadpoles initially have three pairs of external gills and several rows of labial teeth. They pump water through their gills by movements of the floor of their mouths, trapping bacteria, single-celled algae, protozoans, pollen grains, and other small particles on mucus in a filtration organ in their pharynges. As they grow, they begin to ingest larger particles and use their teeth for rasping. They have downward-facing mouths, deep bodies, and tails with broad dorsal and ventral fins.<ref>{{cite book |title=A Natural History of Amphibians |author=Stebbins, Robert C. |author-link=Robert C. Stebbins |last2=Cohen |first2=Nathan W. |year=1995 |publisher=Princeton University Press |isbn=978-0-691-03281-8 |pages=181–184 }}</ref>

Time to metamorphosis ranges from a few months in the southern part of the range to 3 years in the north, where the colder water slows development.<ref name="Casper, G. S 2005" /> Maximum lifespan in the wild is estimated to be 8 to 10 years, but one frog lived for almost 16 years in captivity.<ref name="Casper, G. S 2005" />

==Relation to humans== [[File:Supermarktfrosch.jpg|thumb|left|Bullfrogs in an Asian supermarket]] The American bullfrog provides a food source, especially in the Southern and some areas of the Midwestern United States. The traditional way of hunting them is to paddle or pole silently by canoe or flatboat in ponds or swamps at night; when the frog's call is heard, a light is shone at the frog which temporarily inhibits its movement. The frog will not jump into deeper water as long as it is approached slowly and steadily. When close enough, the frog is gigged with a multiple-tined spear and brought into the boat.<ref>{{cite web|url=https://seagrant.oregonstate.edu/sites/seagrant.oregonstate.edu/files/bf-species-guide.pdf|title=American Bullfrog|website=Seagrant.oregonstate.edu|access-date=2022-03-10}}</ref> Bullfrogs can also be stalked on land, by again taking great care not to startle them.<ref>{{cite web |url=http://www.wikihow.com/Catch-a-Bullfrog |title=How to Catch a Bullfrog |work=WikiHow to do anything |access-date=2013-02-17}}</ref> In some states, breaking the skin while catching them is illegal, and either grasping gigs or hand captures are used. Like most frogs, the hind legs of the bullfrog are the only parts generally eaten. When cooked, they resemble small chicken drumsticks, have a similar flavor and texture and can be prepared in similar ways.<ref name=eattheinvaders/>

Commercial bullfrog culture in near-natural enclosed ponds has been attempted, but is fraught with difficulties. Although pelleted feed is available, frogs usually will not willingly consume artificial diets, and providing sufficient live prey is challenging. Disease among frogs also tends to be a problem even when great care is taken to provide sanitary conditions. Other challenges to be overcome may be predation, cannibalism, and low water quality.<ref name=culture/> The frogs are large, have powerful leaps, and inevitably escape after which they may wreak havoc among the native frog population.<ref name=eattheinvaders/> Countries that export bullfrog legs include the Netherlands, Belgium, Mexico, Bangladesh, Japan, China, Taiwan, and Indonesia. Most of these frogs are caught in the wild, but some are raised in captivity. The United States is a net importer of frog legs.<ref name="culture">{{cite web |author1=Lutz, C. Greg |author2=Avery, Jimmy L. |year=1999 |title=Bullfrog Culture |url=https://srac.msstate.edu/pdfs/Fact%20Sheets/436%20Bullfrog%20Culture.pdf |url-status=live |archive-url=https://archive.today/20240303232037/https://srac.msstate.edu/pdfs/Fact%20Sheets/436%20Bullfrog%20Culture.pdf |archive-date=2024-03-03 |access-date=2024-03-03 |publisher=Southern Regional Aquaculture Center}}</ref>

During the Great Depression, businessman Dr. Albert Broel promoted bullfrog farming as a way for people experiencing difficult economic times to earn extra money by raising and selling bullfrogs. He published several instructional manuals, including "Frog Raising for Pleasure and Profit," as well as in-person training services. Broel offered to purchase all the adult frogs independent breeders could successfully raise to adult weight. The scheme was, ultimately, unsuccessful for many of the reasons described above. However, the business model of outsourcing livestock raising to independent farmers continues today, especially in the poultry industry.<ref>{{cite book |last1=Voiovich |first1=Jason |title=Bullfrogs, Bingo, and the Little House on the Prairie: How Innovators of the Great Depression Made the Best of the Worst of Times |date=May 13, 2025 |publisher=Jaywalker Publishing |isbn=978-1-7370013-7-9 |pages=36-51}}</ref>

The American bullfrog is used as a specimen for dissection in many biology and anatomy classes in schools across the world.<ref>{{cite news |last1=Torres-Gutierrez |first1=Melissa |title=Dissecting A Frog: A Middle School Rite Of Passage |url=https://www.npr.org/sections/ed/2015/02/25/384348150/dissecting-a-frog-a-middle-school-rite-of-passage |work=NPR |date=February 25, 2015 }}</ref> It is the state amphibian of Missouri, Ohio, and Oklahoma.<ref>{{cite web |url=http://www.netstate.com/states/tables/state_amphibians.htm |title=Official state amphibians |date=2012-07-11 |publisher=NetState.com |access-date=2013-01-23 |archive-url=https://web.archive.org/web/20110514160832/http://www.netstate.com/states/tables/state_amphibians.htm |archive-date=2011-05-14 }}</ref>

In areas where the American bullfrog is introduced, the population can be controlled by various means. One project (3n-Bullfrog project) uses sterile triploïd (3n) bullfrogs.<ref>{{Cite web|url=https://www.natuurenbos.be/bullfrog|title=LIFE 3n-Bullfrog|date=22 October 2019|website=Natuurenbos.be|access-date=11 March 2022}}</ref> In Europe, the American bullfrog is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list).<ref>{{Cite web|title=List of Invasive Alien Species of Union concern - Environment - European Commission|url=https://ec.europa.eu/environment/nature/invasivealien/list/index_en.htm|access-date=2021-07-27|website=Ec.europa.eu}}</ref> This means that this species cannot under any circumstances be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.<ref>{{Cite web|title=REGULATION (EU) No 1143/2014 of the European parliament and of the council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species|url=https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32014R1143&from=EN|url-status=live|archive-url=https://web.archive.org/web/20170303185733/http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32014R1143&from=EN |archive-date=2017-03-03 }}</ref>

==References== {{Reflist|35em|refs= <ref name=acousticinteraction>{{cite journal|author=Littlejohn, M. J.|author2=Martin, A. A. |title=Acoustic interaction between two species of leptodactylid frogs|journal= Animal Behaviour |volume=17|issue=4 |year=1969|pages= 785–791|doi=10.1016/S0003-3472(69)80027-8}}</ref>

<ref name=callstructure>{{cite journal|author=Blair, W. Frank|title=Call structure and species groups in US treefrogs (Hyla)|journal= The Southwestern Naturalist |year=1958|pages= 77–89|doi=10.2307/3669039|volume=3|issue=1/4|jstor=3669039|author-link=:fr:William Franklin Blair}}</ref>

<ref name="Cardini 1974">Cardini, F. (1974). Specializations of the Feeding Response of the Bullfrog, ''Rana catesbeiana'', for the Capture of Prey Submerged in Water. M.S. Thesis, U. of Massachusetts, Amherst, MA</ref>

<ref name="Casper, G. S 2005">Casper, G. S. and Hendricks, R. (2005). ''Amphibian Declines: The Conservation Status of United States Species'', M. Lannoo (ed.) University of California Press {{ISBN|0520235924}}.</ref>

<ref name=chorusparticipation>{{cite journal |author1=Judge, Kevin A. |author2=Brooks, Ronald J. |title=Chorus participation by male bullfrogs,'' Rana catesbeiana'': a test of the energetic constraint hypothesis |journal=Animal Behaviour |volume=62 |issue=5 |year=2001 |pages=849–861 |doi=10.1006/anbe.2001.1801 |hdl=10214/22189 |s2cid=53001833 |url=http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0030/MQ47335.pdf |archive-date=2019-09-12 |access-date=2018-08-02 |archive-url=https://web.archive.org/web/20190912042822/http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0030/MQ47335.pdf }}</ref>

<ref name=chorustenure>{{cite journal|author=Murphy, Christopher G.|s2cid=53184986|title=Chorus tenure of male barking treefrogs, ''Hyla gratiosa''|doi=10.1006/anbe.1994.1301|year=1994|journal=Animal Behaviour|volume=48|issue=4|pages=763–777|doi-access=free}}</ref>

<ref name=costbenefitchorus>{{cite journal |last1=Ryan |first1=Michael J. |last2=Tuttle |first2=Merlin D. |last3=Taft |first3=Lucinda K. |title=The costs and benefits of frog chorusing behavior |journal=Behavioral Ecology and Sociobiology |date=July 1981 |volume=8 |issue=4 |pages=273–278 |doi=10.1007/BF00299526 |s2cid=39431995 }}</ref>

<ref name=energycommunication>{{cite journal |last1=Prestwich |first1=Kenneth N. |last2=Brugger |first2=Kristin E. |last3=Topping |first3=Mary |title=Energy and Communication in Three Species of Hylid Frogs: Power Input, Power Output and Efficiency |journal=Journal of Experimental Biology |date=1 July 1989 |volume=144 |issue=1 |pages=53–80 |doi=10.1242/jeb.144.1.53 |url=http://jeb.biologists.org/content/144/1/53 |citeseerx=10.1.1.500.5149 }}</ref>

<ref name=envphysiology>Pough, F. H., et al. (1992). "Behavioral energetics", pp. 395–436 in ''Environmental physiology of the amphibians'', University of Chicago Press, {{ISBN|0226239446}}.</ref>

<ref name=foragingsuccess>{{cite journal|author1=Woolbright, Lawrence L.|author2= Stewart, Margaret M. |title=Foraging success of the tropical frog, ''Eleutherodactylus coqui'': the cost of calling|journal= Copeia |year=1987|pages= 69–75|doi=10.2307/1446039|jstor=1446039|volume=1987|issue= 1 }}</ref>

<ref name="HillisandWilcox2005">{{cite journal |last1=Hillis |first1=David M. |last2=Wilcox |first2=Thomas P. |title=Phylogeny of the New World true frogs (''Rana'') |journal=Molecular Phylogenetics and Evolution |date=February 2005 |volume=34 |issue=2 |pages=299–314 |doi=10.1016/j.ympev.2004.10.007 |pmid=15619443 }}</ref>

<ref name="Hillis2007">{{cite journal |last1=Hillis |first1=David M. |title=Constraints in naming parts of the Tree of Life |journal=Molecular Phylogenetics and Evolution |date=February 2007 |volume=42 |issue=2 |pages=331–338 |doi=10.1016/j.ympev.2006.08.001 |pmid=16997582 }}</ref>

<ref name=lekorganization>{{cite journal|author=Emlen, Stephen T|title=Lek organization and mating strategies in the bullfrog|jstor=4599103|journal= Behavioral Ecology and Sociobiology |volume=1|issue=3 |year=1976|pages= 283–313|doi=10.1007/BF00300069|s2cid=10792384}}</ref>

<ref name="Lutz">{{cite web |url=https://srac.tamu.edu/index.cfm/event/getFactSheet/whichfactsheet/96/ |title=Bullfrog Culture |author1=Lutz, G. |author2=Avery, J. |publisher=Southern Regional Aquaculture Center |access-date=2013-01-09 }}{{Dead link|date=May 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

<ref name=notesrana>{{cite journal|author=Blair, Albert P|title=Notes on anuran behavior, especially ''Rana catesbeiana''|journal= Herpetologica|volume= 19|issue=2 |year=1963|page= 151}}</ref>

<ref name=r1>{{cite web |url=http://www.seaworld.org/animal-info/animal-bytes/animalia/eumetazoa/coelomates/deuterostomes/chordata/craniata/amphibia/anura/north-american-bullfrog.htm |title=ANIMAL BYTES- North American Bullfrog |publisher=Sea World |access-date=2013-01-09 |archive-url=https://web.archive.org/web/20130730061210/http://www.seaworld.org/animal-info/animal-bytes/animalia/eumetazoa/coelomates/deuterostomes/chordata/craniata/amphibia/anura/north-american-bullfrog.htm |archive-date=2013-07-30 }}</ref>

<ref name=r2>{{cite web |url=http://www.fao.org/fishery/culturedspecies/Rana_catesbeiana/en |title=''Rana catesbeiana'' |publisher=Fisheries and Aquaculture Department |access-date=2013-01-09}}</ref>

<ref name=reproductivebehavior>{{cite journal|author=Ryan, Michael J. |year=1980|title= The Reproductive Behavior of the Bullfrog (''Rana catesbiana'')|url=http://www.sbs.utexas.edu/ryan/Publications/1980-82/1980Copeia108.pdf|journal=Copeia|pages=108–114|doi=10.2307/1444139|volume=1980|issue=1|jstor=1444139}}</ref>

<ref name=soundinfluence>Bogert, Charles Mitchill (1960). ''The influence of sound on the behavior of amphibians and reptiles'', American Institute of Biological Sciences.</ref>

<ref name=territoriality>{{cite journal|author=Emlen, Stephen T|title=Territoriality in the bullfrog, ''Rana catesbeiana''|jstor=1441748|journal= Copeia |year=1968|pages= 240–243|doi=10.2307/1441748|volume=1968|issue=2}}</ref>

<ref name=territorygreenfrog>{{cite journal|author=Wells, Kentwood D|title=Territoriality and male mating success in the green frog (''Rana clamitans'')|journal= Ecology |year=1977|pages= 750–762|doi=10.2307/1936211|volume=58|issue=4|jstor=1936211|bibcode=1977Ecol...58..750W }}</ref>

<ref name=vocalizationaggression>{{cite journal|author=Wiewandt, Thomas A|title=Vocalization, aggressive behavior, and territoriality in the bullfrog, ''Rana catesbeiana''|jstor=1442074|journal= Copeia |year=1969|pages= 276–285|doi=10.2307/1442074|volume=1969|issue=2}}</ref>

}}

==External links== * {{Commons-inline}} * {{Wikispecies-inline|Lithobates catesbeiana}} * [http://a100.gov.bc.ca/pub/eirs/finishDownloadDocument.do?subdocumentId=667 British Columbia Frog Watch Program: Bull Frog Fact Sheet] * [http://www.iucngisd.org/gisd/species.php?sc=80 Bullfrog at the Global Invasive Species Database] * [https://www.invasivespeciesinfo.gov/aquatic/fish-and-other-vertebrates/bullfrog Species Profile - Bullfrog (''Lithobates catesbeianus'')], National Invasive Species Information Center, United States National Agricultural Library.

Category:Amphibians of the United States Category:Amphibians of Canada Category:Amphibians described in 1802 Category:Fauna of the Eastern United States Category:Amphibians of the Dominican Republic Category:Lithobates Category:Extant Miocene first appearances Category:Taxa named by George Shaw Category:Symbols of Missouri Category:Symbols of Ohio Category:Symbols of Oklahoma