Northern Prairie Wildlife Research Center
FRANK KARTCH AND RICK WARHURST
Ducks Unlimited Inc., 6115 East Main, Bismarck, ND 58501
DU's major emphasis, while creating secure nesting habitat projects, has been to separate nest predators from upland-nesting waterfowl species and to construct water level control structures capable of eliminating detrimental water level fluctuations for over-water nesting species.
Separating upland-nesting waterfowl from predators is accomplished by the construction of islands, peninsula cutoffs, electric fences, and artifical nesting structures. Construction projects that create secure nesting habitat compose 43% of the projects completed out of the GPRO. In North Dakota, 65% of the 94 completed projects provide secure nesting habitat. In Minnesota, South Dakota, and Montana the figures are 21%, 25%, and 31%, respectively.
DU constructs islands in permanent wetlands in order to provide an effective water barrier during the entire length of the nesting season. Islands have been constructed on 54 project sites. Island sizes vary from 0.1 acre to 2.0 acres depending on the size and water quality of the wetland in which the island is constructed. Freshwater wetlands attract more predators, therefore smaller, more numerous islands are constructed to reduce nest losses. Larger islands are built in alkali wetlands because reduced mammalian predator numbers occur in this habitat which leads to higher waterfowl nest success. Islands are constructed only if wetland complexes that supply breeding pair and brood-rearing habitat are present.
The GPRO staff works closely with wetland managers to ensure the size, shape, location, and construction material of each island will lead to maximum productivity and longevity. DU constructs islands a minimum of 100 yards from the nearest shoreline and no less than 65 yards apart. Islands that will receive intensive predator control may be constructed 60 yards from shore. Establishing and maintaining dense nesting cover on the island, to attract nesting waterfowl and prevent erosion, is a critical responsibility of the management agency. One of the more productive DU island projects has been the Big Meadows Waterfowl Production Area located in northwestern North Dakota. In 1987, 625 duck nests were located on 25 islands resulting in 50 nests per acre and an apparent nest success of 96%.
Peninsula cutoffs also create secure nesting islands through the excavation of a 100-yard wide, 3-foot deep channel across the base of an upland peninsula. Excavated materials are often added to the lee side of the peninsula to increase the final size of the island. DU has constructed 16 peninsula cutoffs ranging in size from a few acres to over 100 acres. The Lake Arena DU - North Dakota Game and Fish Cooperative Project, located northeast of Bismarck, has proven to be an excellent example of the productivity of a peninsula cutoff project. From 1985 to 1988, the number of nests located increased from 6 to 184 on the 100-acre island.
An electric fence is an effective predator barrier. To date DU has constructed 20 electric fence predator barriers. DU constructs electric fences across the base of land peninsulas and encloses dense nesting cover units adjacent to wetland complexes. These 5-foot high barriers are constructed with penta-treated 5-inch diameter posts and 1-inch square mesh galvanized wire. Burrowing predators are discouraged by burying wire mesh 1 foot. The bottom 2 feet of fence, around the exclosure, are constructed with 2-inch mesh to allow ducklings to exit the exclosure. Solar powered battery units supply 7,500-8,000 volts to wires located at the top and base of the fence. The Lake Albert electric fence project stands out for its mallard production. This DU - South Dakota Game, Fish and Parks Cooperative Project produces over 70 waterfowl nests each year (almost all mallards).
The GPRO has also provided nearly 2,000 waterfowl nesting structures for use on federal, state, and private lands.