Hooded Mergansers (Lophodytes cucullatus) Use Nest Boxes Designed for Wood Ducks (Aix sponsa): A Changing Demographic

Abstract

Increasing populations of Hooded Mergansers (Lophodytes cucullatus) (Heusmann et. al 2000) may be out-competing Wood Ducks (Aix sponsa) for nest boxes on some sites in Massachusetts. Hooded Mergansers' use increased from ≤2% of boxes in 1979 to 25% by 2013, while Wood Ducks' use increased from an average of 22% in 1979 to a peak of 65% by the mid-1990s and has since declined to 57%. We estimate that Hooded Mergansers may be important nest competitors on 13 of 51 study sites.