Frequency of nest box maintenance: Effects on wood duck nesting in South Carolina

We varied the frequency that wood duck (Aix sponsa) nest boxes were cleaned of nesting materials (i.e., down feathers, egg membranes and shells, and unhatched eggs) in the breeding season to test effects of different maintenance schedules on frequency of nest box use and production of eggs and ducklings. We also tested whether varying the frequency of nest checks influenced accuracy of nesting data. There were fewer nests, eggs, and ducklings produced in nest boxes that were not cleaned of nesting materials than in nest boxes cleaned of nesting materials one or more times during the breeding season. Nest success did not differ among maintenance schedules, but hatching success was greater in nest boxes cleaned out at least once. For nest boxes first checked in April, an independent biologist's estimates of nest box use, nests per box, and successful nests per box did not differ from data gathered during weekly nest box inspections. Total numbers of eggs and ducklings produced per box, however, were underestimated by the independent biologist. These boxes were checked once more by the biologist after the breeding season in August, and production of eggs and ducklings (Apr-Aug) again were underestimated. Nest boxes never cleaned out in the breeding season were checked by the independent biologist in August; all measures of nesting frequency and productivity were greatly underestimated. We recommend assessing nesting activity in boxes and removing old nest materials once after the peak of nesting and again immediately after the breeding season to maximize nest box use and duckling production and to provide accurate estimates of nest box use, nests per box, and successful nests per box. More frequent monitoring of nest boxes will be needed, if accurate estimates of egg and duckling production are required.