Use of Tree Cavities and Nest Boxes by Wood Ducks at Missisquoi National Wildlife Refuge

We measured use rates, nest success, and inter- and intra- specific nest parasitism by ducks using tree cavities and nest boxes in an old-growth forested floodplain at Missisquoi National Wildlife Refuge in Swanton, VT. Our study represents a previously under-explored opportunity to evaluate various breeding-season characteristics for ducks using both natural and artificial nest cavities in the same forested stand in the northeastern US. Overall use (72.5% vs. 14.5%) and nest-success rates (48.3% vs. 0.0%) were greater in artificial nest boxes but so was nest parasitism (62.1% vs. 0.0%). In addition, Aix sponsa (Wood Duck) were the only species using artificial nest boxes consistently even though this region represents a rare location in North America where they coexist with Lophodytes cucullatus (Hooded Merganser) and Bucephala clangula (Common Goldeneye), which are also cavity-nesting obligates. We found many (n = 35) unused available tree cavities over 2 years, and thus it is unlikely nest site availability is a limiting factor for population growth of cavity nesting ducks at Missisquoi NWR. Future research efforts should try to determine the factors affecting nest-cavity selection.