A meta‐analysis of American black duck winter habitat use along the Atlantic Coast

American black duck (Anas rubripes) populations declined by more than 50% between the 1950s and 1990s, and the species serves as a flagship for conserving salt marsh habitats along the Atlantic Coast. Black ducks have generally been well studied throughout the annual cycle, but surprisingly, we lack a synthetic, quantitative understanding of their space use during the winter. This limits our ability to prioritize habitat acquisition and restoration efforts. We used >17,000 telemetry locations from 235 black ducks ranging from Connecticut to Virginia to study home range composition and space use during winter in relation to habitat quality, urbanization, and severe weather. Despite substantial environmental variation, home range sizes were similar among regions and years. Smaller home and core ranges contained a greater proportion of salt marsh habitat, and ducks experiencing more 4-day freeze events had larger home and core ranges. Ducks exposed to prolonged periods of cold weather had smaller core ranges when those areas comprised more energy-rich freshwater habitats. When we examined individual telemetry locations, we found that ducks used irregularly inundated high marsh more at night, presumably for foraging, and urban habitats more during the day and evening crepuscular periods. We found that black ducks used regularly inundated low marsh less on days where the temperature never rose above freezing, and instead used subtidal areas and forested wetlands more. Finally, we found ducks were marginally more likely to use freshwater habitats during high tides. Our study confirms that black ducks depend on salt marsh for wintering habitat, and points to an unexpectedly important role for forested wetlands during periods of cold weather. We found no evidence that black ducks avoided urban areas or roads, which supports the inclusion of all available habitats in carrying capacity modeling. We emphasize that new hypothesis-driven, local telemetry studies are needed to further elucidate the relationships between black duck movements and environmental variation, especially cold weather. Further, given that most remaining coastal wetlands are currently protected via state and federal lands, we suggest black duck habitat management should strive to acquire and restore brackish and forested wetlands in close proximity to coastal marshes. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.