Abstract
We evaluated the use of predator fences within 2 Waterfowl Production Areas (WPA) within the Devils Lake WMD, North Dakota, April 25 thru July 30, 2012. Each WPA had contained a managed predator fence embedded in grass of approximately 80 acres in size, and also contained an adjacent grassland block of similar size which was not fenced. We used a chain drag to locate duck nests and made weekly nest checks for the purposes of reporting nest success and nest densities both within and outside of the fences. Predator fences were constructed in 1997 and 1998 and their efficacy has not been evaluated in over 10 years. Habitat metrics were monitored for each of the 4 fields including plant species composition, visual obstruction readings (VOR), and litter depth. A total of 377 waterfowl nests were located during the study and nest success varied for each field, but nest success in both the Edwards WPA and Wengeler WPA predator fenced units equaled 73% and 56% Mayfield, respectively. Nest densities within either fenced field averaged 2.26 and 1.18 nests/acre respectively. Unfenced area results showed mixed results; the Edwards WPA unfenced block had nest success at 72% Mayfield and nest density near 1.25 nests per acre; the Wengeler WPA unfenced patch had nest success rates at 21% Mayfield and nest densities at .36 nest/ acre. Habitat conditions were similar (p >.05) for three fields (Edwards fenced, Edwards unfenced, Wengeler fenced) with respect to visual obstruction and litter depth, but habitat conditions were significantly poorest (low VOR, low litter depth) at the Wengeler unfenced patch suggesting a causal relationship for low nest densities and nest success. Wetland densities and condition (adequately wet) were similar at all sites under investigation. Management implications suggest that predator fences can be a valuable tool within a heavily fragment landscape such as the locations we investigated, but poor habitat conditions as found at the Wengeler unfenced patch suggests that habitat restoration is warranted to potentially improve nest success and nest densities at this location. It is likely that no amount of upland habitat management can improve habitat conditions at this location, and these poor habitat structure metrics within a site with high waterfowl pair densities are a trigger to re-plant and restore this upland area to more robust, diverse mixture of grasses and forbs.
