Problems and opportunities managing invasive Bullfrogs: is there any hope?

The American Bullfrog (Rana catesbeiana Shaw) is a widely introduced and invasive anuran that is frequently blamed for population declines of indigenous species (Bury and Whelan 1984). Once established, Bullfrog populations are often either difficult or impossible to eradicate depending on habitat and landscape features (Schwalbe and Rosen 1988, Doubledee et al. 2003, Govindarajulu et al. 2005). Bullfrogs are representative of a large but neglected suite of non-indigenous species (NIS) that are characterized by: (1) a broad invasion that is well established in some areas; (2) a lack of obvious economic impacts compared to some other invasive species; and (3) a lack of reasonably feasible control methods. Despite demonstrated conservation concerns, invasive species like the Bullfrog do not tend to attract the resources necessary to attempt large scale management because of their lack of economic impact and the difficulty of control methods. This leaves biologists responsible for managing habitats invaded by such species with little hope and few options for promoting the persistence of sensitive indigenous species. With these issues in mind, we consider the case of the Bullfrog, review management options, and suggest directions for future research with this and similar species.