Use of Natural Basin Wetlands by Breeding Waterfowl in North Dakota

Abstract

Use of basin wetlands by breeding populations of 12 species of waterfowl was investigated in 1965 and during 1967-69 throughout the prairie pothole region of North Dakota. Data were obtained primarily by random sampling techniques. Of the total population occupying natural basin wetlands 55 percent occupied seasonal and 36 percent occupied semipermanent wetlands. Seasonal wetlands contained 60 percent of the population of dabbling ducks, while semipermanent wetlands supported 75 percent of the population of diving ducks. On basins with ponded water, highest concentrations of breeding pairs occurred on temporary, seasonal, and semipermanent wetlands; moderate concentrations were recorded on ephemeral, fen, and undifferentiated tillage wetlands; and low concentrations occurred on permanent and alkali wetlands. The proportion of basins that retained ponded water had a direct bearing on the value of each type of wetland to breeding waterfowl. Relative values of the more intermittent types of wetlands are greatly increased during years of ample precipitation. J. WILDL. MANAGE. 41(2):243-253 Shallow basin wetlands in the prairie pothole region of south-central Canada and north-central United States represent the principal breeding habitats of many waterfowl species in North America. Climatic instability and natural differences in the capacity to retain ponded water cause drastic annual and seasonal variations in the distribution and number of ponds, and in the area of ponded water among various types of basins. Densities of breeding waterfowl as related to wetland habitat were investigated in the prairie pothole region by a number of biologists, including Evans and Black (1956), Jenni (1956), Benson (1964), Jessen et al. (1964), Drewien and Springer (1969), Sauder (1969), Smith (1971), and Stoudt (1971). The results of these studies are not comparable because each investigator used his own wetland classification system or a modified version of the systems of Bach (Bach, R. N. 1950. Some general aspects of North Dakota water areas and their study. North Dakota Game and Fish Dept. 13pp. Mimeo.) or Martin et al. (1953). Moreover, most of these studies were restricted to short transects or small blocks of land. Regardless of length, roadside transects may not provide a representative sample of wetlands because of changes in wetland characteristics and densities caused by road construction. Small blocks of land usually contain too few wetlands to make meaningful comparisons of waterfowl use among wetland types. In this paper, we report the use by breeding waterfowl of wetlands classified according to a system designed specifically for the prairie pothole region (Stewart and Kantrud 1971). About 14 percent of the glaciated prairie pothole region of central North America (Fig. 1) occurs in North Dakota. This particular area contained a yearly average of 1,619,000 pairs of breeding ducks (27.6 pairs/km2) during 1967-69 (Stewart and Kantrud 1974). Two earlier reports (Stewart and Kantrud 1973, 1974) utilized nearly the same data in documenting population estimates of breeding waterfowl and their proportional distribution among various wetland types and biotic sections within the prairie pothole region. We hope the information on J. Wildl. Manage. 41(2):1977 243 244 BREEDING WATERFOWL USE BASIN WETLANDS * Kantrud and Stewart