U.S. Geological Survey Home Page USGS Patuxent Wildlife Research Center Science Meetings; dedicated to Chandler S. Robbins USGS Patuxent Wildlife Research Center; Science Meetings dedicated to Chandler S. Robbins Dedicated to Chan Robbins USGS Patuxent Wildlife Research Center; Science Meetings dedicated to Chandler S. Robbins Poster Abstracts from USGS Patuxent Wildlife Research Science Meetings, October, 2006
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



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