Winter Habitat Selection by a Declining American Black Duck Population

An understanding of habitat selection and patterns of use by American black ducks (Anas rubripes; hereafter black ducks) during winter is important ecologically and for conservation of this declining species in the mid-continent population of its North American range. During winters 2010-2011 and 2011-2012, we obtained 3,816 locations of 111 radiomarked female black ducks captured at Tennessee National Wildlife Refuge (TNWR), a waterfowl sanctuary closed to hunting and a wintering area for a significant portion of Mississippi Flyway black ducks. We determined the influence of diel period, hunting season, refuge, and distance to nearest road on habitat selection in both winters by fitting generalized linear mixed effects models and examining probabilities of selection. Top-ranked models and habitat selection by black ducks differed somewhat each winter; however, through both winters black ducks used a complex of land cover types, including open water, cropland, and forested, emergent herbaceous, and scrub-shrub wetlands. Black ducks also had greater probability of selecting: 1) emergent or scrub-shrub wetlands, especially at night, than other land cover types; 2) areas on TNWR than off the refuge; and 3) areas closer to roads and levees. Our results emphasize the importance of a complex of land cover types and sanctuary with minimal human disturbance at TNWR for black ducks wintering in Tennessee, USA. Managed emergent herbaceous wetlands and croplands and also scrub-shrub wetlands may be particularly important components of complexes because they provide foraging, roosting, and pairing habitats for wintering black ducks. (c) 2021 The Wildlife Society.