Download AMERICAN BULLFROG FACT SHEET Rana catesbeiana

AMERICAN BULLFROG FACT SHEET Rana catesbeiana DISTRIBUTION: American bullfrogs are native to the eastern United States (Bullfrog info sheet, CA State) and range from Nova Scotia south to central Florida and westward across the Great Plains (Govindarajulu, et. al. 2006) in the United States. Bullfrogs have spread to all of the lower 48 states, as well as South America, Asia and Europe. The bullfrog has been introduced into many areas as invasive species, often for food (Govindarajulu, et. al. 2006). FEEDING: Adult bullfrogs are opportunistic feeders, making them a formidable predator for native species. Bullfrogs can eat anything from small mammals, such as mice, to invertebrates such as tarantulas and scorpions, as well as other anurans (Bullfrog info sheet, CA State). Cannibalism of juveniles by adults is common (Bury and Whelan, 1984). Metamorph diet consists of small terrestrial insects, while juvenile diet is composed of larger terrestrial insects (Govindarajulu, et. al. 2006). Tadpoles are mainly herbivorous (U.S. Environmental Protection Agency), eating diatoms, algae, and other plant material (Bullfrog info sheet, CA State). HABITAT CHOICE: Bullfrog tadpoles typically take 1‐2 years to metamorphose (Bullfrog info sheet, CA State; Treanor and Nicola 1972; Govindarajulu, et. al. 2006; Bury and Whelan 1984). Therefore, permanent water sources are needed for reproduction, such as ponds, ditches, cattle tanks, rivers, streams, lakes and wetlands. Bullfrogs have invaded a variety of habitats, including deserts and brackish ponds. Non flowing water has also been associated with bullfrog site occupancy (Santos‐Barrera, G. et. al. 2009). There is a potential for invasion by bullfrogs as long as there are perennial water sources. Govindarajulu, et. al. (2006) listed the preferred optimum environmental temperature of bullfrogs to be 15‐32° C, with an average body temperature of 30° C. Lillywhite (1970) listed the critical thermal maximum was 38.2° C. Bullfrogs emerge from hibernation in late April and early May in habitats where winter hibernation is necessary, and breeding choruses develop when air temperature exceeded 20° C (Govindarajulu, et. al. 2006; Wright, 1914) and water temperature ranges between 13 and 17° C (Govindarajulu, et. al. 2006). Metamorphic tadpoles have been shown to select higher temperature waters to increase the rate of development (Crawshaw et al., 1992). Moore (1942) stated that embryonic bullfrogs have a high minimal temperature of 15° C for development which is the same at the northern and southern extremes of its range in the United States. Bullfrogs have been observed in ponds with a pH ranging from 4.55 to 6.37, with lower bullfrog densities observed in ponds with lower pH levels, even though pH levels were not low enough to cause toxicity to eggs or larvae (Clark, 1986). Browne et. al. (2009) stated biotic interactions within the amphibian community and alkalinity as major factors correlated with bullfrog abundance and that bullfrog abundance was negatively correlated with silica, alkalinity, the presence of agriculture within 200m and newt abundance. Hecnar and M'Closkey (1996) found that general water chemistry appears to play a small role in amphibian species richness (including bullfrogs) in south‐western Ontario, Canada. Wright and Wright (1949) listed shoreline cover as an important habitat for adults and shallow water as important habitat for tadpoles. Dickerson (1931) suggested that bullfrogs prefer deep water with shallow margins and a cover of submerged and emergent vegetation. Males may use emergent vegetation and floating debris as "croaking posts” (Bullfrog info sheet, CA State). Bullfrog eggs are deposited among aquatic plants or brush growing on the bottom (Stebbins 1954). Shallow pond margins may also be important for tadpoles and juveniles, as tadpoles use shallow waters near shore for at least six months while completing development (Bullfrog info sheet, CA State). MOVEMENT AND BEHAVIOR: Adults often travel considerable distances from standing water on rainy nights. Dispersal of juveniles, however, may occur without rain (Bullfrog info sheet, CA State; Gahl et. al. 2009). Dispersal of male bullfrogs may be less because males are territorial, and protect their territory by wrestling other males. Maximum dispersal and migratory distances documented in peer reviewed literature ranged from .64 km to 1.6 km (Raney 1940, Ingram and Raney 1943, Smith and Green 2005). In areas with mild winters, bullfrogs are active all year, but they undergo periods of inactivity or hibernate in cold climates. Terrestrial individuals may be active at all times of the day (Bullfrog info sheet, CA State) and are nocturnal predators. Males call at all times of day. Few fish have been shown to eat bullfrog larvae (Kruse et. al. 1977), possibly because bullfrog larvae and eggs are chemically defended or due to their relatively “unpalatable nature”. Bullfrogs frequently co‐
occur with fish, other amphibians, and crayfish. Invertebrate predators, such as dragonfly larvae, are known to be largely unaffected by chemical deterrents and consume bullfrog tadpoles (P. Eklöv and E. Werner, 2000). REPRODUCTION: Bullfrogs emerge from hibernation in the spring depending on temperature, as evidenced by early emergence in warm periods and northward progression of emergence (Dickerson, 1931). Date of chorusing also has a northward progression (Willis et. al. 1956). Breeding and egg‐laying can occur from March‐July (Stebbins 1985, Bury and Whelan 1984), with a longer duration in the southern U.S. Females deposit 10,000 to 20,000 eggs in disk‐shaped masses about 1 egg thick and 1 to 5 ft in diameter (Stebbins 1972) with mean egg mass size of 13,014 +/‐ 7,296 eggs (Govindarajulu, et. al. 2006). In some localities bullfrogs may produce more than one clutch per season (Emlen 1977). Tadpoles hatch 3 to 5 days after eggs were laid (Govindarajulu, et. al. 2006).Tadpoles may reach 14 cm (5.5 in) in length (Bullfrog info sheet, CA State) and require anywhere from 4 months to 3 years to transform (George, 1940; Wright, 1920), with age at transformation greater in the north (Willis et. al, 1956). Bullfrogs have discrete overlapping generations (Doubledee et al. 2003). REFERENCES Browne, C. L., Paszkowski, C.A., Foote, A.L., Moenting, A. and Boss, S.M. 2009. "The Relationship of Amphibian Abundance to Habitat Features Across Spatial Scales in the Boreal Plains".Ecoscience. 16 (2): 209‐223. Bury, R.B. and Whelan, A.J. 1984. Ecology and management of the bullfrog. U.S. Fish and Wildlife Service Resource Publication 155. Clark, K. L. 1986. "Distributions of anuran populations in central Ontario relative to habitat acidity". Water, Air, and Soil Pollution. 30: 727‐734. Crawshaw, L.I., Rausch, R.N., Wollmuth,L.P. and Bauer, E.J. 1992. "Seasonal Rhythms of Development and Temperature Selection in Larval Bullfrogs, Rana catesbeiana” Shaw. Physiological Zoology. 65: 346‐359. Dickerson, M. C. 1931. The frog book. Doubleday, New York. 253pp. Doubledee, R. A., Muller, E. B., & Nisbet, R. M. 2003. Bullfrogs, Disturbance Regimes, and the Persistence of California Red‐Legged Frogs. The Journal of Wildlife Management, 67:424‐438. Emlen, S. T. 1977. "Double clutching" and its possible significance in the bullfrog. Copeia 1977:749‐751. Gahl, M. K., Calhoun, A. J. K., & Graves, R. 2009. Facultative Use of Seasonal Pools by American Bullfrogs ( Rana catesbeiana ). Wetlands, 29:697‐703. George, I. D. 1940. A study of life history of the bullfrog, Rana catesbeiana Shaw, at Baton Rouge, Louisiana. Unpublished Doctoral Dissertation, Univ. Michigan, Ann Arbor: 96 pp. Govindarajulu, P., Price, W. S., & Anholt, B. R. 2006. Introduced Bullfrogs (Rana catesbeiana) in Western Canada: Has Their Ecology Diverged?. Journal of Herpetology 40:249‐260. Hecnar, S. J., and M'Closkey, R.T. 1996. "Amphibian species richness and distribution in relation to pond water chemistry in south‐western Ontario, Canada". Freshwater Biology. 36 (1). Ingram, W. M. and E. C. Raney. 1943. Additional studies on the movement of tagged bullfrogs. American Midland Naturalist 29:239–41. Kruse, K.C., and M.G. Francis. 1977. "A Predation Deterrent in Larvae of the Bullfrog, Rana catesbeiana". Transactions of the American Fisheries Society. 106: 248‐252. Lillywhite, H. B. 1970. "Behavioral Temperature Regulation in the Bullfrog, Rana catesbeiana". Copeia.1970: 158‐168. McKercher, L. and Gregoire, L. 2012. Lithobates [=Rana] catesbeianus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=71 RevisionDate: 9/14/2011 Moore, J. A. 1942. Embryonic temperature tolerance and rate of development in Rana catesbeiana Biol. Bull., 83: 375‐88. Morey, S. Bullfrog Info Sheet CA State. Originally published in Zeiner, D.C., W.F.Laudenslayer, Jr., K.E. Mayer, and M. White, eds. 1988‐1990. California's Wildlife. Vol. I‐III. California Depart. of Fish and Game, Sacramento, California. Raney, E. C. 1940. Summer movements of the bullfrog, Rana catesbeiana Shaw, as determined by the jaw‐
tag method. American Midland Naturalist 23:733–45. Santos‐Barrera, G. et. al. 2009. Lithobates catesbeianus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 23 April 2012. Smith, M. A. and D. M. Green. 2005. Dispersal and the metapopulation paradigm in amphibian ecology and conservation: are all amphibian populations metapopulations? Ecography 28:110–28. Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw‐Hill, New York. 536pp. Stebbins, R. C. 1972. California amphibians and reptiles. Univ. California Press, Berkeley. 152 pp. Stebbins, R.C. 1985. A field guide to western reptiles and amphibians. Second edition, revised. Houghton Mifflin Company, Boston, Massachusetts, USA. Treanor, R. R., and S. J. Nicola. 1972. A preliminary study of the commercial and sporting utilization of the bullfrog, Rana catesbeiana Shaw, in California. Calif. Dept. Fish and Game, Inland Fisheries Adm. Rep. 72‐
4, Sacramento. 23pp. U.S. Environmental Protection Agency, Region 10: The Pacific Northwest, Bullfrogs (Rana catesbeiana). April 20th, 2012. URL: http://yosemite.epa.gov/r10/ECOCOMM.NSF/Invasive+Species/Bullfrog. Werner, E. E., and Eklov, P. 2000. "Multiple predator effects on size‐dependent behavior and mortality of two species of anuran larvae". Oikos. 88 Willis, Y.L., Moyle, D.L., and Baskett, T.S. 1956. "Emergence, Breeding, Hibernation, Movements and Transformation of the Bullfrog, Rana catesbeiana, in Missouri". Copeia. 1956: 30‐41. Wright, A. H. 1914. Life histories of the Anura of Ithaca, New York. Carnegie Inst. Washington, Pub., 197:98 pp. Wright, A. H. 1920. Frogs, their natural history and utilization. U. S. Bur. Fish. Doc., 888: 44 pp. Wright, A. H., and A. A. Wright. 1949. Handbook of frogs and toads of the United States and Canada. Cornell Univ. Press, New York. 640pp.