Nonbreeding distribution and movement of adult Razorbills (Alca torda) breeding in Atlantic Canada and Québec

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University of New Brunswick


Winter conditions can have significant carry-over effects on seabird populations, yet specific factors have been difficult to identify simply because the complete patterns of winter distributions are unknown. Using a combination of GLS tags and stable isotope analyses, this study presents the first description of the nonbreeding movements of Razorbills (Alca torda) from seven breeding colonies in Atlantic Canada and Québec. Tagging data described the relative degree of migratory connectivity, revealed five distinct migration strategies for Razorbills breeding on Machias Seal Island, and identified fall and spring moulting areas. Feathers from tagged individuals provided tissue-specific isotope values for known locations, allowing discriminant analysis to predict putative moulting areas of feathers sampled from untagged individuals. These methods circumvented the need for spatially explicit isoscapes and species- and tissue-specific discrimination factors, and allowed nonbreeding movement patterns to be inferred for a greater number of individuals than tagging alone would otherwise permit.