LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 65 
Winter range.—Largely unknown. Has been reported from China 
and Japan in small numbers and on the northwest coast of Norway 
from Tromsé southward (common). Also taken or otherwise re- 
corded in winter from the Commander Islands, Great Britain (6 ex- 
amples), Upper Austria, and Italy. 
Spring migration —Birds leave the coast of Norway early in spring, 
although single individuals have been taken from May to the end of 
July. ‘They reached Point Barrow May 15, 1882, and May 25, 1883; 
Colville River, June 6, 1909; and Point Humphrey, Alaska, June 3, 
1914. At this time they are also common in the Mackenzie region 
(Mackenzie River above Fort Simpson, May 20, 1905; Hay River, 
Great Slave Lake, May), but it is unknown by what route they reach 
this section. Specimens have been taken in spring and summer in 
southeastern Alaska (Admiralty Island, May 25,1911) and seen about 
June 1, 1911, at Admiralty Island; June 5, 1911, south end of Lynn 
Canal, and June 17, 1911, east shore of Lynn Canal. The record from 
Loveland, Colorado, May 25, 1885, is erroneous. 
Fall migration—Route unknown. They have been noted in the 
Mackenzie region: Fort Enterprise, September 26; Mackenzie River 
near mouth of Nahanni River, October 15; Franklin Bay, migrating 
west, September 6. Arctic Sound, between Cherre Islands and Kater 
Point, Northwest Territory; last seen, September 16. Alaska: Point 
Barrow, September 29; St. Michael, October 14; St. Paul Island, 
Bering Sea, one taken in August; near Nushagak, September 21. 
Gulf of Anadyr, Siberia, September 1. In southeastern Alaska one 
was taken August 17, 1911, at Dixon Harbor and one seen in Novem- 
ber, 1910, at Gastineau Channel. One was taken at Kodiak, Novem- 
ber 1, 1868. The species usually arrives on the coast of Norway in 
October (earliest September 22). 
Egg dates—Alaska: 4 records, June 6, 7, 10, and 17. Mackenzie: 
2 records, June 20 and 21. 
GAVIA ARCTICA (Linnaeus). 
BLACK-THROATED LOON. 
HABITS, 
The status of the European form of the black-throated loon, as an 
American bird, can not be clearly demonstrated without some study 
of the systematic status of this group of loons. From the study of a 
large number of~-specimens, from various portions of the circum- 
polar range of the black-throated loon, it becomes apparent that there 
is probably but one species, which may be divided into four sub- 
species, all of which intergrade in all of the characters which 
separate them and all of which show so much individual variation 
that averages alone will identify them. Size is the most satisfactory 
character, but even in this there is some overlapping. 
a 
