THE INFLUENCE OF NEST BOX AND HABITAT CHARACTERISTICS ON WOOD DUCK NEST BOX USE AND SUCCESS IN DELAWARE

Abstract

Wood Ducks (Aix sponsa) choose natural nesting cavities based on surrounding habitat, cavity height, and entrance dimensions. Assuming the criteria influencing the hens’ choice of nest boxes are similar, efforts to optimize nest box placement based on those specifications can have a considerable impact on the efficiency of wood duck management. Volunteers and workers at Delaware Wildlands Betts and Armstrong farms, Augustine Creek Estuarine Marsh Complex, Delaware have collected nest box use of 126 wood duck boxes 2004–2009 and 2011–2015. In April-August 2017, I monitored wood duck use of 128 functioning boxes located on this property. I checked each box for use and potential success at least twice throughout the breeding season. I further collected nest box and habitat characteristics including horizontal diameter of entrance (cm), orientation of entrance (degrees), height of entrance (cm), post placement (on land or water), distance to the nearest box (m), distance to open water (m), and average visual obstruction in the four cardinal directions (cm). All boxes had the same mean dimensions of 31x31x61, same PVC pipe predator guard, and minimal age difference. I tested a series of apriori model using General Linear Modeling and Akaike Information Criteria to assess how nest box and habitat characteristics might affect long term use of the boxes Nest box use was positively influenced by nearness to open water, lower visual obstruction, and further distance to neighboring nest. I further tested a series of apriori models that assessed the impact of nest box and habitat characteristics on use of both boxes on one poll. I determined higher double box use occurred with lower height and lower visual obstruction. Last, I estimated nest success in 2017. In 2017, of the 128 boxes available, 45 nests were initiated and of those, 10 (22%) were identified as dump nests with no nesting materials or incubation attempted. Of the remaining 35 active nests, 7 showed signs of nest parasitism with >15 eggs incubated. Dump nests occurred more frequently over land and further away from water and parasitized nests occurred more frequently further from water. Ultimately only 2 nests were successful thus having a low apparent nest success of 2/35 = 5.7%.