Predator Responses to Treatment Locations of Wood Duck
Nest Boxes
JACKIE L. HENNE AND EDWARD P. HILL
U.S. Fish and Wildlife Service, Mississippi Cooperative Fish and Wildlife
Research Unit, P.O. Drawer BX, Mississippi State, MS 39762
A 2-year study (1997-98) of wood duck (Aix sponsa) reproduction in eight treatments (n=300 boxes) was conducted at Yazoo National Wildlife Refuge (YNWR). YNWR produced 3,024 ducklings, a hatching rate of only 23%. Predation was a major source of nest and egg loss. During the two nesting seasons, 196 (27%) of 735 nests and 2,720 (21%) of 12,940 eggs were lost to predation, and there were signs that 89 hens were killed. This poster describes predator responses on YNWR to box spacing, densities, site characteristics, and history.
Mammalian predators destroyed 143 nests and 2,114 eggs, and were responsible for 88 hen mortalities. Snakes destroyed 39 nests and 477 eggs. Unidentified predators destroyed 14 nests, 159 eggs, and 1 hen. All hen depredation and the majority of nest and egg losses in boxes occurred on dry sites (land) and were caused by mammals. Most nest and egg losses on aquatic sites were caused by snakes.
There were more eggs and nests lost to predation in boxes over land versus those over water. More eggs and nests per box on dry sites were lost to predation in open areas than in those on wooded sites. However, in boxes on dry sites, there was no significant difference in predation between one per pole and two per pole boxes, or between boxes that were closely or widely spaced. Percentages of eggs and nests lost to predation were significantly greater on sites with a prior history of boxes. The highest percentage of nests lost to predation occurred in one per pole boxes on wooded, old sites, whereas, the lowest percentage occurred in one per pole boxes on wooded new sites.
Inferred management suggestions to reduce mammal and snake predation in wood duck nest boxes include: (1) placement of boxes over water in wooded sites, (2) control of emergent vegetation around boxes over water, (3) erection of nest boxes on new isolated sites rather than adding boxes to old sites and, (4) insure that predator guards fit tightly around the support pole. Predation problems will change with the size of the breeding wood duck populations, site history, and predator numbers and composition. Managers need to recognize those changes and respond accordingly.
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