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Figure 1.  Prairie pothole region (stippled) showing counties where searches for nests were conducted. Dashed line separates Great Plains from Central Lowlands.

Conservationists have long recognized the importance of the prairie pothole region to breeding waterfowl (21). But current nest success rates of less than 15 percent for mallards (Anas platyrhynchos) and pintails (A. acuta) and less than 20 percent for other ducks are probably inadequate to maintain their populations in much of the region (14). Many waterfowl biologists believe that low waterfowl recruitment in the region is linked to various human activities. European settlement of the region profoundly changed species composition and abundance of mammalian predators (3). Intensified farming concentrated nesting waterfowl in relatively small, remaining untilled habitats, thus increasing vulnerability of the birds and their nests to predation. Therefore the relatively large amounts of land enrolled in CRP could help disperse these concentrations. The presence of CRP could also influence decisions about intensive management of public lands devoted to waterfowl production.

The only published information on use of CRP land by waterfowl is that of Luttschwager and Higgins (16), who studied the effects of emergency haying of CRP land on duck nest success and density of nests in eastern South Dakota. I examined nest success of dabbling ducks on CRP land and compared it with success on planted nesting cover on U.S. Fish and Wildlife Service waterfowl production areas (WPAs). I conducted the research in Minnesota and North Dakota during the CRP (1989-1991) era and also used data gathered on WPAs by other researchers during the pre-CRP (1979-1988) era. Farmers seeded some CRP fields during the last two years of the 1979-1988 era, but stands were still in weedy, early developmental stages.