Alaska during aerial surveys were Black Scoters. Of these, most (157,000) 

 breed on the Yukon Delta. Another 75,000 breed adjacent to Bristol Bay and 

 some 20,000 breed on the Seward Peninsula (King and Lensink 1971 in Bellrose 

 1976). The 1976 survey of waterfowl nesting in Alaska found a breeding popula- 

 tion of 376,200 scoters (Larned et al. 1980). Information on the size of many 

 Old World breeding populations is lacking but this scoter is apparently consid- 

 erably less abundant in the western Palearctic than in the northwest Pacific. 

 Cramp et al. (1977) cited authors listing breeding populations of 1,000 in Ice- 

 land and Finland and about 60 in Britain. 



Winter The Black Scoter winters on the Asian and North American coast- 

 lines of the Pacific Ocean, in the Great Lakes, and on the Atlantic coast south 

 to about the Carolinas and irregularly to Florida and the Gulf States (Map 25) 

 (A0U 1957, Johnsgard 1975). European birds winter mainly off the coast of West- 

 ern Europe, and on the Black, Mediterranean, and Caspian seas (Johnsgard 1978). 



Because winter surveys of waterfowl by the U.S. Fish and Wildlife Service 

 do not distinguish between species of scoter, the distribution and numbers of 

 birds wintering within the United States is poorly known. Bellrose (1976) was 

 puzzled at the small numbers wintering on the Pacific coast and reported an es- 

 timated 250,000 wintering in the Aleutian Islands. During the January 1976 

 waterfowl survey (Larned et al. 1980), totals of about 97,000 scoters were found 

 in the Pacific Flyway and about 60,000 in the Atlantic Flyway. Bellrose (1976) 

 suggested that about 3% of the birds wintering in the Pacific Flyway were Black 

 Scoters and that this species constituted 20% of the scoters wintering along 

 Atlantic coasts. If these figures are still applicable, approximately 2,900 

 Black Scoters winter off the Pacific coasts of the contiguous United States, 

 with another 15,000 wintering off the Atlantic coasts. 



The number of Common Scoters wintering in the Old World is also uncertain 

 but Cramp et al. (1977) listed an estimate of 400,000 to 500,000 wintering in 

 the western Palearctic. 



Migration Migration of Black Scoters is poorly known and recent handbooks 

 (Bellrose 1976, Palmer 1976b) are frankly speculative in describing possible 

 migratory routes. We would rather not add to these speculations until more and 

 better information is obtained on the distribution and size of wintering and 

 breeding populations. Judging from the information available, Black Scoters 

 usually begin to arrive in southeastern waters in early November and have large- 

 ly departed by late April. 



Much of the information available on habitats, food habits and breeding 

 biology of the Black Scoter is from studies made in the Old World. Consequent- 

 ly, much of what is presented in the following sections is largely a summary of 

 information given by Cramp et al. (1977), supplemented by information in other 

 recent handbooks. Presumably much of the data given by Cramp et al. (1977) is 

 generally applicable to North American populations of the Black Scoter. 



HABITAT 



Nesting Most Black Scoters nest well inland in tundra or dwarf heath. 



357 



