Providing evidence to improve practice

Individual study: Bullfrogs: introduced predators in southwestern wetlands

Published source details

Rosen P.C. & Schwalbe C.R. (1995) Bullfrogs: introduced predators in southwestern wetlands. Pages 452-454 in: E.T. LaRoe, G.S. Farris & C.E. Puckett (eds.) Our living resources: a report to the nation on the distribution, abundance, and health of US plants, animals, and ecosystems. U.S. Department of the Interior, Wasington D.C., USA.


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American bullfrog control: Direct removal of adults Control of Freshwater Invasive Species

One replicated, controlled study from 1986-1989 and 1992-1993, in the San Bernardino National Wildlife Refuge, Cochis County, Arizona, USA (Rosen & Schwalbe 1995) found that bullfrog populations rapidly rebounded following intensive removal of the adults.  At one study pond, 854 large (80+ cm body length) bullfrogs had been removed from about 0.2 ha of habitat. After three to four active-season months, a 50-80% rebound toward pre-removal numbers was observed, together with weak evidence of positive effects on native leopard frogs and garter snakes.   From 1986-1989 and 1992-1993, intensive bullfrog removals were conducted two to three times per year using funnel traps, hand spears, guns, and hand capture. Simultaneous monitoring of native ChiriCahua leopard frogs and Mexican garter snakes was carried out at the sites of bullfrog removal.