Habitat Use of Surf Scoters Wintering in The Mesohaline Region of the Mainstem Chesapeake Bay, Maryland

Kidwell, David M.
University of Maryland - College Park
Publication Date: 

Thesis submitted to the Faculty of the Graduate School of the University of Maryland, College Park,
Surf scoters (Melanitta perspicillata) are common in coastal waters during winter, but remain one of the least studied waterfowl in North America despite indications of a declining population. Surf scoter foraging was investigated in the mesohaline region of the Chesapeake Bay during 2004-2005. The study compared biological and physical characteristics of benthic habitats among scoter feeding and non-feeding sites. Benthic samples were taken seasonally via a Peterson grab. Surf scoters foraged over oyster bar, packed clay and sand habitats, but avoided mud habitats. Clam densities varied seasonally, increasing over winter regardless of scoter foraging activity. Foraging activity appeared to influence hooked mussel densities on hard bottoms. Lack of foraging over mud habitats, where visibility can be limited, suggests that surf scoters may be visual predators and may have been impacted by habitat sedimentation. The correlation of hooked mussel with oyster bars suggests that oyster restoration efforts may positively impact surf scoters.

With an estimated one-third of the Atlantic surf scoter population spending a portion of the winter within Chesapeake Bay (D. Forsell, pers. comm.), the Bay is clearly a seasonally important habitat for surf scoters.