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Volume XVII November-December, 1915 Number (3 
THE YELLOW-BILLED LOON: A PROBLEM IN MIGRATION 
By WELLS W. COOKE 
T HE MIGRATION route of the Yellow-billed Loon (Gavia adamsi ) is prob- 
ably the most incomprehensible problem of migration on the North Amer- 
ican continent. The species breeds on the Arctic coast from Franklin Bay, 
just east of the mouth of the Mackenzie River, along the whole of the Arctic 
coast of Alaska, and on the Siberian side west certainly to the Chukchi Penin- 
sula and probably to the mouth of the Kolyma River. 
The only place where the species has been found in numbers during the 
winter season is on the coast of Norway. Here, on the northwest coast in the 
neighborhood of Tromso, it was common the winters of 1892-3 and 1893-4, and 
many specimens were taken from September to January. It also ranged along 
the whole west coast even to the southern end. In addition it is known in winter 
in Japan and China and as a rare spring and fall migrant around the Sea of 
Okhotsk. It is unknown in winter anywhere in the Western Hemisphere and 
there are no records of its occurrence in this half of the world between November 
and May. It is known to breed in the Mackenzie Valley along the seacoast, and 
during the summer visits Great Slave Lake, arriving at the western end in May 
and being present at the eastern end until late October. It is common here in 
August and early September, and is still more common on Clinton-Colden and 
Aylmer lakes. The problem is as to whence come the early May birds and 
whither go the late fall birds. 
Since the species is unknown anywhere in the Western Hemisphere in 
winter, it follows that the breeding birds of the Mackenzie coast winter some- 
where in the Eastern Hemisphere, presumably in Japan and China, though the 
numbers reported from anywhere in eastern Asia in the winter are very small 
compared with the multitudes recorded throughout the great extent of the 
summer home. Apparently the real winter home of the great bulk of the species 
has not yet been discovered. 
But assuming that the winter home is somewhere in eastern Asia, then the 
birds in spring must go on the Asiatic side to the Arctic Ocean and then eastward 
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