Migration Timing of Canada Warblers Near the Northern Edge of Their Breeding Range

摘要

Canada Warblers (Wilsonia cana-densis) are one of the last warblers to arrive in breeding areas in northern Alberta and one of the first to depart in autumn resulting in a condensed breeding chronology relative to other locally breeding wood warblers. Males arrived before females during spring migration, while in autumn, adult females departed prior to males. Second-year males arrived later (P = 0.029) than after-second year males. Adult males departed later (P = 0.015) than adult females. Hatch-year birds departed after adult females but prior to adult males. Female Canada Warblers remained in breeding areas for 62 days while males remained 72 days. These data provide the shortest documented breeding site occupancy estimate for any bird that shows a post-nuptial molt. The short time spent in breeding areas may impose energetic constraints that influence breeding, molt, and survival, particularly for females.