Overwater Nest Structures for Ducks and Geese
HAROLD A. DOTY AND ANTHONY J. RONDEAU
U.S. Fish and Wildlife Service, Minnesota Wetlands Management District,
Route 1, Box 76, Fergus Falls, MN 56537
The glaciated prairie region of North America historically provided expansive native prairie plant communities with countless numbers of natural wetlands critical for the production of upland-nesting ducks. Drastic changes in these habitat conditions are now prevalent over much of the area following a century of converting the grasslands to cultivated croplands and through wetland drainage. The reduction of this habitat base has forced upland nesting ducks into abnormally close proximity to terrestrial predators during the nesting season. A result of these changes has been a dramatic decrease in waterfowl production throughout the region.
In order to protect both ducks and geese as well as their eggs from predators, manmade overwater nest sites were evaluated throughout the region for a number of years. Europeans have utilized structures for hundreds of years and have employed them to increase the overall production of wild ducks for specific areas. Locally, nesting success by mallards and Canada geese in overwater structures has generally been much higher than in a nearby upland nesting cover. While overall success in upland sites has ranged from 10 to 20%, the success rate of mallard nests in nearby nesting structures has often ranged from 75 to 90%. While a variety of different structure styles have proven effective, it is apparent that overwater positioning, installation, and maintenance are especially critical to the success of any overwater nesting structure project.
The effectiveness of overwater nesting structures to increase the rate of waterfowl nest success, by reducing nests lost to predators, is demonstrated throughout these trials. Overwater nesting structures provide an additional tool for waterfowl managers to use in their efforts to increase local waterfowl production.
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