Avian Use of Beaver-Created Wetlands in Northern Wisconsin

Abstract

Waterfowl use of wetlands before and after beaver dam removal was compared to determine affect of wetland drainage on waterfowl. We observed waterfowl from blinds on 15 randomly selected beaver-created wetlands in northern Wisconsin in 1990 and 1991 for 786 hours. Thirty additional wetlands were selected at random for waterfowl surveys to compare to the waterfowl use on study wetlands. Vegetation was sampled, interspersion of emergent vegetation was determined, and wetland area and age determined to relate waterfowl use and wetland variables. Results indicate waterfowl use decreases in the year following dam removal. Comparison of walking waterfowl surveys to - observations from blinds indicated walking surveys underestimated waterfowl use by a factor of 17.7. Area of open water was the only variable that accounted for a significant portion of the .variable associated with waterfowl use index means. We found 0.51 broods {3.24 ducklings)/ha of beaver-created wetland in northern Wisconsin which fell within a range of results found in other regions. Recommendations are made to manage beaver at higher population levels where economic damage is minimal, and to increase habitat area for breeding waterfowl, broods, and molting flocks of waterfowl. Avian use of beaver-created wetlands We conducted avian censuses on 14 randomly selected beaver-created wetlands in northern Wisconsin to determine species richness and composition to test hypothesis that inherent edge of wetlands would attract a high diversity of avian species including nest parasitizers. We observed 87 species between April and August 1991. No brown-headed cowbirds were observed in 1991, although they occurred on 1 wetland in 1990. Recommendations are made for future study of the net affect on avian species using beaver-created wetlands.