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Northern Prairie Wildlife Research Center

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Distribution and Abundance of Predators that Affect
Duck Production: Prairie Pothole Region


The prairie pothole region of North America is vital to the continent's waterfowl. This region of approximately 777,000 km2 of prairie and aspen parkland habitat presently extends from southeastern South Dakota to central Alberta (Fig. 1) and contains millions of fertile wetlands suited for production of many duck species (Mann 1974; Bellrose 1976). Although the prairie pothole region is only 10% of North America's duck breeding grounds, about half of the continent's ducks fledge there (Smith et al. 1964; Bellrose 1976). Hence, factors of duck production in the region are of special interest to individuals and agencies responsible for the welfare of North American waterfowl populations (Crissey 1969; Pospahala et al.1974; Bellrose 1976; Turner et al. 1987).

gif -- prairie pothole region

1 Hay Lakes
2 Holden
3 Penhold
4 Gayfold
5 Denzil
6 Leask
7 Hanley
8 Yorkton
9 Craik
10 Earl Grey
11 Shamrock
12 Inchkeith
13 Ceylon
14 Goodwater
15 Moore Park
16 Cartwright
17 Morgan
18 Plentywood
19 Plaza
20 Sharon
21 Streeter
22 Courtenay
23 Eldridge
24 Litchville
25 Jud
26 Fredonia
27 Kulm
28 Hitterdahl
29 Hawley
30 Lake Park
31 Hosmer
32 Madison
33 Parkston

Figure 1. Prairie pothole region (excludes southwest Minnesota and northcentral Iowa where wetlands are essentially eliminated from extensive drainage [Mann 1974] with aspen parkland and prairie zones and locations of study area.

Predation on hens, young, and eggs severely limits duck production in the prairie pothole region (Johnson et al.1992; Sargeant and Raveling 1992). Most information about predation on duck species in the region is on the mallard (Anas platyrhynchos). Recent studies revealed that mortality rates of mallards during spring and summer averaged 0.19-0.40 for hens, 0.50-0.73 for prefledged young, and 0.88-0.92 for clutches (nests) and that predation was the major cause of mortality (Sergeant and Raveling 1992). Mortality rates of other duck species are also high, and predation is the principal mortality agent (Klett et al. 1988).

Evolutionary adaptations of prairie ducks that minimize the effects of predation include large clutches, renesting, antipredator behaviors, and cryptic coloration of hens. However, the intensity of predation varies with changes in the environment, which can have severe effects on waterfowl populations (Sergeant and Raveling 1992). During the last 120 years, the prairie pothole region has been transformed from largely pristine wilderness to an intensively farmed area (Bird 1961; Kiel et al. 1972; Turner et al. 1987). Coupled with this change have been changes in composition of predator communities and in abundance of nearly all predator species. Presently, most nesting habitat for ducks is fragmented and degraded, and nesting hens and their eggs and ducklings are exposed to different types of predator communities than existed during pristine times (period of recorded history to about 1870; Cowardin et al.1983, 1985; Greenwood et al.1987).

Published accounts of predator populations in the prairie pothole region are fragmented and sketchy. In this report, we summarize in species accounts information about the history and population structure of mammalian and avian predator species that affect duck production in the region. We also provide new data on the distribution and abundance of those predator species and discuss factors of predator abundance and the implications of our findings for duck production.

We restricted our evaluations to wild mammals and birds that prey on adult ducks, duck eggs, or ducklings and were resident in one or more study areas. This included nearly all predator species with potential effect on duck production in the prairie pothole region. Among the reptiles and amphibians in the region, only the snapping turtle (Chelydra serpentina) has potential to influence duck production. Snapping turtles occur in some permanent wetlands in southern portions of the region (Conant 1958), where they probably take some adult ducks and ducklings (Coulter 1957; Kirby and Cowardin 1986). Certain predatory fishes, especially the northern pike (Esox lucius) and largemouth bass (Micropterus salmoides), occur in some freshwater lakes, ponds, and rivers of the region where they probably take some ducklings (Lagler 1956). Domestic cats and dogs are abundant throughout the region, but have not been implicated in significant predation on ducks.

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