Occurrence and implications of staging Black Scoters Melanitta americana in a heavily trafficked urban estuary

During a land-based survey of wintering seaducks, I detected approximately 50 000 Black Scoters Melanitta americana on the Lower New York Bay. which borders both New York and New Jersey. During their 14-day stay, the scoters were regularly disturbed by large container vessels and smaller watercraft, but consistent numbers remained throughout the survey. Based on recent population estimates, this congregation of Black Scoters represents 16.6% to 25% of the eastern North American population. Using data from the National Audubon Society Christmas Bird Count, I found that Black Scoters have dramatically increased in abundance during the winter on count circles at sites around the bay; however those increases were not correlated with North Atlantic Oscillation indices averaged over October-December each year from 1990 to 2017. Bivalve mollusks, a major food source for Black Scoters, are abundant throughout the bay. and they have likely played a role in the increased use of the bay by this species. Local efforts to restore Eastern Oyster Crassostrea virginica populations to the bay may promote increased use by Black Scoters and other seaducks, providing an opportunity for targeted conservation efforts. Current plans to build a surge gate at the mouth of the bay as a storm-risk mitigation measure may result in the Lower Bay being avoided by Black Scoters and other seaducks. which in turn may have negative population-level effects for these seaduck species.