Forty-two native species of waterfowl occur commonly in North America, representing 7 taxonomic tribes. Waterfowl present complex management challenges because of their diversity, widespread distribution, and seasonal migration. Among waterfowl species there is wide variation in reproductive potential and mortality rates, as well as predation rates (see Johnson et al. 1992, Sargeant and Raveling 1992). Swans, geese, and sea ducks tend to have lesser reproductive potential (e.g., deferred sexual maturity, smaller clutch size, lesser renesting capacity, variable annual rates of breeding) than other waterfowl groups, but they also have lesser annual mortality rates for eggs and juveniles (Bellrose 1980). In contrast, dabbling ducks and bay (diving) ducks have greater reproductive potential but also greater rates of mortality.

An obvious approach to enhancing populations is to identify key biological factors that affect population size and recruitment and to influence those factors in the most efficient and effective manner (Caughley 1994). For waterfowl, reducing mortality is key to enhancing recruitment rates and populations (Johnson et al. 1992). Generally, we know little about mortality rates of individual species of waterfowl, although we have insight into causes of mortality (see Sargeant and Raveling 1992). For this discussion, we examine problems associated with mortality due to predation. We use the term "problem" but recognize that waterfowl populations are not in peril because of predation. Rather, predation is a problem because it reduces annual production of waterfowl and reduces benefits of habitat conservation activities.

The underlying causes of most predation problems are changes in habitats essential to waterfowl and changes in predator populations. These changes influence rates of predation on waterfowl. Nesting waterfowl suffer from chronic deterioration and loss of critical habitats over much of their breeding range because of encroachment by agricultural, industrial, and residential developments (Sugden and Beyersbergen 1984, Petersen and Hogan 1996). Changes likewise have occurred among predator communities and populations in many waterfowl breeding areas, which have adversely affected survival of waterfowl species (Johnson and Sargeant 1977, Sargeant et al. 1993, Sovada et al. 1995). Decline in abundance or low densities of waterfowl may eventuate a population that is less able to withstand the normal range of predation rates (Raveling 1989). Generally, more than one factor is involved when predation negatively impacts waterfowl populations.

Our purpose is to review the impacts of predation on recruitment and population size of waterfowl in 2 major North American breeding areas, the arctic tundra and coastal region (Arctic Region) and the prairie pothole region (Prairie Region). Although waterfowl breed in numerous other regions of North America, these 2 are especially important (Bellrose 1980). We emphasize species groups in major breeding areas rather than individual species. We focus on predation during the breeding period, because the role predation plays in recruitment and size of populations among waterfowl species is most evident on the breeding grounds (Johnson et al. 1992, Sargeant and Raveling 1992). Finally, we review the status of waterfowl populations, adaptations of waterfowl that minimize impacts of predation, and the underlying factors specific to the breeding areas that influence predation risk for waterfowl. We discuss effectiveness, applicability, and acceptability of predation management options. We discuss management approaches, recommendations, and tradeoffs for obtaining solutions to predation problems where they occur.