| Patuxent Science Meeting 2006 Poster Abstract |
| | Food selection among Atlantic Coast seaducks in relation to historic |
| | food habits |
| | Perry MC, Osenton PC, Berlin AM, Kidwell DM |
| | Food selection among Atlantic Coast seaducks during 1999-2005 was determined from hunter- |
| | killed ducks and compared to data from historic food habits file (1890-1985) for major |
| | migrational and wintering areas in the Atlantic Flyway. Food selection was determined by |
| | analyses of the gullet (esophagus and proventriculus) and gizzard of 860 ducks and |
| | summarized by aggregate percent for each species. When sample size was adequate, |
| | comparisons were made among age and sex groupings and also among local sites in major |
| | habitat areas. The blue mussel (Mytilus edulis) was the predominant food of common eiders in |
| | the Canadian Maritimes (43%) and Massachusetts (76%). Scoters in the Canadian Maritimes |
| | fed predominantly on the blue mussel (37%), whereas in Massachusetts only the black scoter |
| | fed predominantly on blue mussels. The surf scoter fed mostly on Atlantic jackknife clam |
| | (Ensis directus; 43%) and Atlantic surf clam (Spisula solidissima; 18%) and the white-winged |
| | scoter diet was fairly evenly mixed among Atlantic surf clam (22%), blue mussel (17%), Atlantic |
| | jackknife clam (15%), and threeline mudsnail (Nassarius trivittatus; 13%). In the Chesapeake |
| | Bay the hooked mussel (Ischadium recurvum; 34%) was the most important food organism for |
| | scoters in general, but the dwarf surf clam (Mulinia lateralis; 35%) was selected most by surf |
| | scoters and the amethyst gem clam (Gemma gemma; 39%) was selected most by white- |
| | winged scoters. The amethyst gem clam was also a predominant food (28%) of long-tailed |
| | ducks in Chesapeake Bay, along with dwarf surf clam (30%). Buffleheads in the bay fed mainly |
| | on dwarf surf clam (59%) and common goldeneyes fed on a mixed diet of hooked mussel and |
| | Atlantic Rangia, (Rangia cuneata). No major differences were noticed between the sexes in |
| | regard to food selection in any of the wintering areas for any of the seaduck species. |
| | Comparisons to historic food habits in all areas failed to detect major differences. However, |
| | several invertebrate species recorded in historic samples were not found in current samples and |
| | two invasive species (Atlantic Rangia and the green crab, Carcinas maenas) were recorded in |
| | modern samples, but not in historic samples. Benthic sampling in areas where seaducks were |
| | collected showed a close correlation between consumption and availability. Each sea duck |
| | species appears to fill a unique niche in regard to feeding ecology, although there is much |
| | overlap of prey species selected. Understanding the food habits of sea ducks in coastal |
| | wintering areas will give managers a better understanding of habitat changes in regard to future |
| | Friday, September 22, 2006 |