TROPHIC RELATIONS OF SEABIRDS 



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Table 12. Use of food resources by seabirds in the oceanic and offshore neritic habitats, Bering 

 Sea domain. Information is from Tables 1-10. (Trophic level I = plants, II = secondary 

 carnivore, III = tertiary carnivore, IV = upper level carnivore; Sc = scavenger on carrion, 

 offal, or detritus [II-IV]; x = major food in diet, o = minor food, = incidental food, ? 

 = probable food.) 



Information contained in Tables 11-15 can 

 be summarized to show characteristics of sea- 

 bird trophic relations. One such characteristic 

 is the range of diet breadth or diet complexity 

 (Table 16). Few species (about 6%) feed on 

 only one type of prey and might, therefore, be 

 referred to as "specialists." Included are 

 eared grebe (Podiceps caspicus), Laysan alba- 

 tross, brown pelican, emperor goose (Philacte 

 canagica), black brant (Bernicia bernicla), 

 peregrine falcon, and whiskered auklet 

 (Aethia pygmaea). Consideration of these 

 species as specialists may require revision 



when more data become available. Except for 

 the albatross and auklet, these species are 

 members of the inshore neritic cohort. Food 

 specialization does not seem to be character- 

 istic of oceanic birds in particular or of most 

 seabirds in general. 



Most species (roughly 53% in any commu- 

 nity) include two or three prey categories in 

 their diets usually midwater schooling fish, 

 squid, and crustaceans. These birds include 

 the most numerous in the communities the 

 shearwaters and some alcids which feed 

 largely on three prey types, and also include 



