Techniques for Determining the Availability of Food Items to Seaducks Wintering on the Chesapeake Bay, Maryland

Patuxent Wildlife Research Center
U.S. Geological Survey
Publication Date: 

Introduction: Historically, the Chesapeake Bay has been a major wintering area for seaducks. Based on aerial surveys, three species of seaducks, surf scoters (Melanitta perspicillata), black scoters (Melanitta nigra), and long-tailed ducks (Clangula hyemalis), have shown major declines in recent years. One possible explanation for this decline is a reduction of available food items.Data indicates that surf and black scoters likely feed at depths ranging from 10 to 30 feet in the mesohaline region of the Chesapeake Bay. These deep water areas are usually the first to be affected by low oxygen conditions, which may be a factor influencing the quantity and types of food items available to seaducks. Additionally, telemetry Data indicates that as winter progresses, seaducks are forced to move into deeper water in search of preferred food items (Figure 1.). Research is needed to describe the seasonal depletion and availability of seaduck food items as a possible explanation for seaduck population declines.