Year-round movements of Northern Common Eiders Somateria mollissima borealis breeding in Arctic Canada and West Greenland followed by satellite telemetry.

We implanted satellite transmitters to track Northern Common Eiders Somateria mollissima borealis from breeding grounds in West Greenland and eastern Arctic Canada, and from their wintering grounds in southwest Greenland. We compared distances moved, timing, duration, and patterns of movement between migration flyways and between spring and autumn migration. Common Eiders used two wintering areas linked by three routes. Eiders tracked from a northwest Greenland breeding colony (n = 10) migrated south along the coast to winter exclusively in west and southwest Greenland. Breeders from Arctic Canada wintered in two distinct areas with a tendency to segregate by sex. Some eastern Canadian Arctic Eiders from a colony near Southampton Island, migrated through Hudson Strait along the Labrador and Newfoundland coasts, to winter in Atlantic Canada. However, 60% (n = 25) originating from this colony crossed the Davis Strait to winter in Southwest Greenland, returning in spring to breed in Canada, linking the two north-south flyways.

Mosbech A., Gilchrist G., Merkel F., Sonne C., Flagstad A. & Nyegaard H., ARDEA 94 (3): 651-665