Northern Prairie Wildlife Research Center
Many current management strategies seek to increase duck nest success by separating the nest from the predator. One way to provide this separation for upland-nesting ducks in the northern prairies is by managing peninsulas. Peninsulas in this paper are defined as projections of land into water, connected to the mainland at the base by an isthmus. Peninsulas provide good management sites because they are naturally attractive to nesting ducks and mammalian predator access is limited to a narrow isthmus. Predation can be greatly reduced at peninsulas by placing barriers on the isthmuses and removing predators that gain access.
Peninsula management has been most widely applied in the Prairie Pothole Region and to a lesser extent in the prairies and plains to the west (Figure 1). Managed peninsulas are usually natural parcels of land located in large wetlands. A variety of peninsula types can be managed including long narrow ones that project nearly across the wetland and broad ones that extend only a short distance into the wetland.
Duck nest success in the northern prairies averaged over 50% on peninsulas managed with predator barriers and predator control. On average, each managed peninsula contained 1.3 nests/acre (3.2 nests/ha). Duck nest success on unmanaged peninsulas was usually less than 15% with about 0.3 nests/acre (0.7 nests/ha).
|Figure 1. Peninsula management has been primarily applied in the Prairie Pothole Region of the United States and Canada and secondarily in the plains region to the west.|
|Mallards, gadwalls, and blue-winged teal are the primary nesting species attracted to managed peninsulas. (photo by USFWS)|
Predator barriers normally applied at peninsulas include electric fences and water-filled moats. Electric fences are the most cost-effective barrier because heavy equipment is not required for construction. In North Dakota, in the 1980s, the mean capital cost of constructing electric fences across peninsulas was $7,600 or about $7/foot. This compares to a mean capital cost of $207,000 for moats or about $100/foot. The cost of each fledged duck, including capital, maintenance, and predator trapping, was estimated at $12 for fenced sites and $62 for moated sites.
|Electric fences are the most cost-effective predator barrier on peninsulas, because heavy equipment is not required for construction. (photo by USFWS)|