Nature Of Migration In The Species
Breeding and nonbreeding adults migrate between breeding range in arctic tundra regions and wintering areas usually farther south in nearshore marine waters. Migration routes not fully known; some enigmas noted by Cooke (1915), Dixon (1916), and Lincoln (1950) still not adequately explained.
Timing And Routes Of Migration
Generally considered coastal , but Palmer (1962), Godfrey (1966), and North (1993) recognized probability of overland migration. In Alaska, regular coastal migrant in spring and fall at St. Lawrence I., Cape Prince of Wales, Chukchi Sea coast (e.g., Icy Cape), Barrow, and Beaufort Sea coast (e.g., Oliktok Point). Also, regular spring migrant south of breeding range at Anaktuvuk Pass in the Brooks Range, where it may follow Colville River northward. Few spring and fall records of migrants along Yukon-Kuskokwim Delta, Bristol Bay, Pribilofs, Aleutians, or Alaska Peninsula. In Canada, migrates along coasts in Beaufort Sea (e.g., Yukon Territory coast, Mackenzie River Delta), Amundsen Gulf, Bathurst Inlet, Coronation Gulf, and Queen Maud Gulf. Stages apparently regularly in large numbers on Great Slave Lake, southwest of breeding grounds about Thelon Game Sanctuary. Several other spring and fall inland migration records between Great Slave Lake and Pacific coast.
Arrival dates along Alaska coast from St. Lawrence I. to Colville River Delta (and Anaktuvuk Pass) generally 15 May to 1 June; at Colville River Delta, usually 31 May-3 June; east of Colville River and in Canada, generally 1-15 June (North 1993). Peak migration at Seward Peninsula 27 May-7 June; Wales 30 May-3 June; Icy Cape 16-29 June; Wainwright 2-19 June, along Colville River mid-June; Simpson Lagoon (Oliktok Point) 3-9 June; Yukon Territory coast 5-13 June and 28 May-15 June.
Few data on magnitude of migration: 60 staging at Shishmaref Inlet 12 June 1966; 400 passed in loose groups of 10-12 each 16 km offshore from Wainwright 0300-0400 h on 27 May 1958; Lehnhausen and Quinlin (1981) counted 44 in June 1980 at Icy Cape; Johnson and Richardson (1980) estimated 348 migrated east past Oliktok Point in spring 1977; Barry (1976) estimated 4,500 migrated past Cape Dalhousie, Northwest Territories, in May and June 1972, but provided no data upon which estimate was based; and Salter et al. (1980) observed 47 in spring 1975 along the Yukon coast.
Post-breeding birds leave territories and move to coast late August to mid-September. Fall migration late August and September in Canada and Beaufort and Chukchi Seas; August-October in Bering Sea. Latest date in Canada 15 October. Peak migration at Icy Cape, Alaska (n = 203) 14-20 September. Only 13 observed in fall 1975 migrating past Barrow, Alaska. Latest date in arctic Alaska, 29 September in Barrow, but Sage (1971) mentioned birds lingering on Sagavanirktok River into late October. Staging documented at De Salis Bay, Banks Island, in late August and early September; Great Slave Lake in mid-September; and Wainwright Inlet in late September.
Usually migrates at altitudes of less than 100 m. Migrates singly, in pairs or loose flocks; occasionally stages in larger groups in fall (flocks of 30 at Wainwright, 300 on Yellowknife Bay. Flies low over water, staying several hundred meters offshore. Most observations of migrants are made by observers on shore, which may give a false image of migratory behavior. Aerial surveys showed most spring migration in Canadian Beaufort Sea is apparently far offshore. In Chukchi and Beaufort seas in spring, Yellow-billed Loons follow leads in ice pack but sit or feed in leads mostly when delayed by bad weather. Prefers small open-water leads (more than 80% ice cover) and shows little preference for extensive areas of open water in Canadian Beaufort Sea in spring. Migrants in arctic Canada rely on regularly occurring leads about Herschel Island, Cape Dalhousie, and Banks Island; when leads did not form in 1964, many loons died. Wary, gives boats a wide berth. Juveniles disperse with adults in late August and September.
Control And Physiology
Migration periods prolonged. Timing of spring migration controlled somewhat by ice conditions. Peak fall departure closely associated with fledging of offspring. Some adults remain on breeding lakes until these freeze over, and then on rivers until they freeze over. Whether breeding status may affect timing of spring migration, or breeding success may affect timing of fall migration, needs study.
Thanks to North, Michael R. 1994. Yellow-billed Loon (Gavia adamsii), The Birds of North America Online (A. Poole, Ed.). species no. 121
EUROPE & ASIA
Migratory. Like Great Northern Diver G. immer, breeds on high latitude fresh waters but winters on salt water. Freshwater arrivals and departures linked to thawing and freezing; at sea mainly October-May; when late thaw breeding lakes not re-occupied until late June. No ringing recoveries for Eurasia, but principal wintering areas thought to be Bering Sea and adjacent parts of north Pacific, and, in west Palearctic, off north Norway. Thus main migrations east and west along Arctic coasts of Eurasia. Smaller numbers winter off west Norway, and stragglers reach North Sea where identified almost annually in recent years. Infrequent Baltic, though observations in 1960s indicate that may pass regularly in small numbers along Gulfs of Finland and Bothnia. Exceptional inalnd in western Europe. Presumably west Palearctic winterers originate European Russia, but some may come from farther east.
Only vagrant to west Atlantic. In spring, remains offshore until ice breaks on rivers and later on tundra lakes and poolsMigrates singly or in small parties, possibly family groups in autumn.
Thanks to BWP on CD-ROM