RAZORBILLS (ALCA TORDA) FOLLOW SUBARCTIC PREY INTO THE CANADIAN ARCTIC: COLONIZATION RESULTS FROM CLIMATE CHANGE?

Abstract

We describe the occurrence and behavior of Razorbills (Alca torda) visiting Coats Island, Northern Hudson Bay, an area where sea-ice cover in summer has been much reduced since the mid-1990s. Coats Island is 300 km from the previous most-westerly breeding site for the species and nearly 2,000 km from the nearest large colony, in Newfoundland and Labrador. Razorbills appeared at Coats Island coincidentally with an increase in the delivery of Capelin (Mallotus villosus) and sand lance (Ammodytes spp.) to Thick-billed Murre (Uria lomvia) nestlings at the same site and disappeared when sand lance also disappeared. Razorbill populations are expanding in eastern North America, and this expansion may partly account for their dispersal. The ability of Razorbills to track changes in a preferred prey item well outside the boundary of their normal range suggests that this species is capable of adapting rapidly to climate change.