LIFE HISTOEIES OF NORTH AMEEICAK DIVING BIEDS. 65 



Winter range. — Largely unknown. Has been reported from China 

 and Japan in small numbers and on the northwest coast of Norway 

 from Tromso southward (common). Also taken or otherwise re- 

 corded in winter from the Commander Islands, Great Britain (6 ex- 

 amples). Upper Austria, and Italy. 



SpHng 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 hj 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 ARCTIC A (Linnaeus). 



BLACK-THBOATEB 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 speciinens, 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. 



