La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	The fall migration of Jaegers on Lake Ontario
Auteurs :	D. F. Sherony, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (70(1) WIN 1999)
Article en page(s) :	33-41
Langues:	Anglais
Résumé :	There is a regular annual fall migration of jaegers (Stercorarius spp.) over the Great Lakes. Data from shoreline observation sites show that higher numbers of jaegers have been reported from Lake Ontario. Parasitic Jaegers account for 80% of identified jaegers and 70% of these are juveniles. Peak migration of Parasitic Jaegers (S. parasiticus) occurs between 22 September and 27 October. Peak migration of Pomarine Jaegers (S. pomarinus) was 1-2 wk later. Approximately 70% of the days of high jaeger counts occurred on the day of or day after the passage of a cold front. Two weather conditions, one dominated by a strong low pressure system and the other by a strong high pressure system, are associated with 90% of the high-count days. Weather and occurrence data support the hypothesis that jaegers seen on Lake Ontario originate from James Bay.

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