Impact of Fluctuating Water Levels on Feeding Ecology of Breeding Blue-Winged Teal

Foods consumed by breeding blue-winged teal (Anas discors) before and after a hydrological change are compared on a study area located in the glaciated prairie pothole region of south-central North Dakota. Food selection shifted from a diet high in snails consumed on seasonal wetlands to one dominated by midge larvae consumed on semi-permanent lakes entering a drawdown phase. Total invertebrate contribution to the diet was similar for the two periods and varied from 89 percent ( 1967-71) to 97 percent (1973). Animal foods dominated the diet of laying females accounting for 99 percent by volume, of which snails comprised 38 percent, crustacea 14 percent, and insects 44 percent. J. WILDL. MANAGE. 41(3):426-433 The semi-arid climate of the glaciated prairie pothole region of North America is a dominant factor in the ecology of prairie wetlands. The annual moisture deficit in this area results in unstable water levels and in water high in dissolved solids (Langbein 1961, Leitch 1964, Kuznetsov 1970:22, Sloan 1972, Eisenlohr 1972, Stewart and Kantrud 1972, Swanson et al. 1974b). In response to this water regime aquatic biotic communities are continually adjusting to changing water levels. The hydrological and geological interactions on the glaciated prairie have produced a unique and highly attractive aquatic habitat for breeding waterfowl (Smith et al. 1964). The purpose of this paper is to describe the impact of changing wetland conditions on the feeding ecology of breeding blue-winged teal in the prairie pothole region of south-central North Dakota. Appreciation is extended to F. B. Lee, D. S. Gilmer, H. F. Duebbert, J. T. Lokemoen and A. D. Kruse for critical review