We estimated nest success of mallard (Anas platyrhynchos), gadwall (A. strepera), blue-winged teal (A. discors), northern shoveler (A. clypeata), and northern pintail (A. acuta) for 5 regions in North Dakota, South Dakota, and Minnesota, for 1-3 periods between 1966 and 1984, and for 8 habitat classes. We obtained composite estimates of nest success for regions and periods by weighting each habitat proportional to the number of nest initiations. The distribution of nest initiations was derived from estimates of breeding populations, preferences of species for nesting habitats, and availability of habitats. Nest success rates ranged from \u3c5 to 36% among regions, periods, and species. Rates were lowest in western Minnesota (MNW) and eastern North Dakota (NDE), intermediate in central North Dakota (NDC) and eastern South Dakota (SDE), and highest in central South Dakota (SDC). In regions with comparable data, no consistent trend in nest success was apparent from early to late periods. Gadwalls and blue-winged teal nested more successfully than mallards and pintails; the relative success of shovelers varied regionally. Ducks nesting in idle grassland were the most successful and those nesting in cropland were least successful. Mammalian predation was the major cause of nesting failure (54-85%) in all habitats, but farming operations resulted in 37 and 27% of the nesting failures in cropland and hayland, respectively. Most of the populations studied were not self-sustaining.
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