La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Fishing success of gulls at a southeast Alaska smelt run
Auteurs :	M. F. Willson, Auteur ; B. H. Marston, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (73(1) Winter, 2002)
Article en page(s) :	91-96
Langues:	Anglais
Résumé :	We observed foraging behavior and success of gulls (Larus spp.) at spawning runs of eulachon (Thaleichthyes pacificus, Osmeridae) in Berners Bay, Alaska, in spring 1996-1998. Adults foraged more effectively (greater than or equal to56% of dives were successful) than immatures (less than or equal to56%) when diving for fish, but there was little difference in the effectiveness of piracy (less than or equal to 23% success for all gull species and age classes). The hypothesis that larger birds would be better pirates and less likely to lose prey to pirates was not well supported, although smaller species seldom attacked larger ones. Age classes less successful at foraging were more likely to act as pirates, but this relationship did not hold among species or between years. The frequency of piracy attempts was positively correlated with the availability of fish captured by other birds.

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