Impact of invasive exotic animals on native reptiles and amphibians -- Cane toad / Bullfrog

Some species, such as the cane toad (Bufo marinus) were introduced intentionally as agents of biocontrol. Originally native to Central America, the toad has been introduced to tropical and subtropical areas world wide. For example, cane toads were introduced into Hawaii from Puerto Rico in 1932 to control sugar cane beetles and other insect pests (McKeown, 1978). Similar introductions occurred in Florida, U.S. Virgin Islands, the Territories of Guam, American Samoa, and Australia (McCoid, 1995). Unfortunately, the cane toad is well-protected at all life stages by skin glands that secrete a highly toxic fluid and many native predatory animals are killed when they attempt to eat the toad (McCoid, 1995).

Another amphibian that has caused considerable ecological impacts is the bullfrog (Rana catesbeiana). Originally native to eastern North America, the bullfrog has been widely introduced in the western United States where it has been implicated (Rosen and Schwalbe, 1995) in the decline of native ranid frogs and the Mexican garter snake (Thamnophis eques). Bullfrogs are suspected to be significant predators of hatchling and juvenile western pond turtles.

SOURCES

• McCoid, M. J. 1995. Non-native reptiles and amphibians. Pages 433-437 in Laroe, E. T., G. S. Farris, C. E. Puckett, P. D. Doran, and M. J. Mac, editors. Our living resources: a report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems. U.S. Department of the Interior, National Biological Service, Washington, D.C. 530 p.
• McKeown, S. 1978. Hawaiian reptiles and amphibians. Oriental Publishing Company Honolulu. 80 p.
• Rosen, P. C. and C. R. Schwalbe. 1995. Bullfrogs: introduced predators in southwestern wetlands. Pages 452-454 in Laroe, E. T., G. S. Farris, C. E. Puckett, P. D. Doran, and M. J. Mac, editors. Our living resources: a report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems. U.S. Department of the Interior, National Biological Service, Washington, D.C. 530 p.