Canadian Wildlife Service Occasional Papers Occasional Papers report the peer-reviewed results of original research carried out by members of the Canadian Wildlife Service or supported by the Canadian Wildlife Service. Editorial Board The Canadian Wildlife Service C.D. Ankney The Canadian Wildlife Service of Envi- University of Western Ontario ronment Canada handles wildlife matters that are the responsibility of the Canadian government. David Cairns These include protection and management of Fisheries and Oceans Canada migratory birds as well as nationally significant Fred Cooke wildlife habitat. Other responsibilities are endan- Simon Fraser University gered species, control of international trade in endangered species, and research on wildlife A.W. Diamond issues of national importance. The service coop- University of New Brunswick erates with the provinces, territories, Parks Canada, and other federal agencies in wildlife Charles J. Henny research and management. U.S. Geological Survey For more information about the Canadian Raymond McNeill Wildlife Service or its other publications, please Université de Montréal contact: Ross J. Norstrom Canadian Wildlife Service Publications Canadian Wildlife Service David Peakall Environment Canada King’s College London Ottawa, Ontario K1A 0H3 University of London (819) 997-1095 (819) 997-2756 (fax) Austin Reed
[email protected] Canadian Wildlife Service http://www.cws-scf.ec.gc.ca Harold Welch Northwater Consultants Managing Editors Hugh Boyd Canadian Wildlife Service Erica H. Dunn Canadian Wildlife Service Patricia Logan Canadian Wildlife Service R.I.G. Morrison1 Estimates of shorebird R.E. Gill, Jr.2 B.A. Harrington3 populations in North America S. Skagen4 G.W. Page5 C.L. Gratto-Trevor6 S.M.