In the 1990s, flocks of tens of thousands of Razorbills (Alca torda), greatly outnumbering the local breeding population and, so of unknown origin were observed wintering off the island of Grand Manan, Bay of Fundy, Canada. To determine their origin, 39 radio transmitters were deployed on Razorbills at major breeding centers at Corossol Island (n = 10), Québec, the Gannet Islands, Newfoundland and Labrador (n = 15), and a colony near the overwintering area at Machias Seal Island (n = 14) in 2007. From January–March 2008, flights around Grand Manan detected 19 transmitter-fitted birds - twelve from Machias Seal Island, five from Corossol Island and two from the Gannet Islands. The findings confirm that Razorbills making up the wintering flocks off Grand Manan are not only local birds but also birds from major centers of the North American breeding distribution. Therefore, North American Razorbills from all breeding areas are vulnerable to mismanagement of the Bay of Fundy ecosystem, already degraded by over-exploitation and threatened by pollution from a variety of energy developments.