The prairie pothole region of the northern Great Plains is one of the most important areas for duck reproduction in North America. The region produces, on average, 50% of the primary species of game ducks on the continent (Smith 1995), yet accounts for only 10% of the waterfowl breeding habitat in North America (Smith et al. 1964). Twelve of the 34 species of North American ducks are common breeders in the region. For seven species—mallard, gadwall, blue-winged teal, northern shoveler, northern pintail, redhead, and canvasback—the prairie pothole region accounts for more than 60% of the breeding population (Smith 1995). The region is also a major migration corridor during fall and spring for other ducks, geese, and other water birds.