OLD CROW 177 



female usually dove on the splashing approach of the male, who fol- 

 lowed her under water. Each female remained in one part of the lake 

 and we did not observe them to go on shore, but the males occasionally 

 left the area. Among the three male specimens, the late increase in 

 size of testes was consistent with the late manifestation of breeding 

 activities. 



The Indians, who call this duck Nya^ say that male white-winged 

 scoters thrash about noisily in furious combat on the brushy shores, at 

 which time they are heedless of the approach of a man or canoe. In 

 this state the males seem to be more preoccupied by combativeness than 

 male oldsquaws. Although male teal are regarded as redoubtable 

 fighters during the mating period they and most ducks only reduce 

 but do not abandon their alertness for other dangers. 



Wliite- winged scoters are conspicuous because of their size and be- 

 cause they remain in the open waters until their late nesting date. 

 There may be little difference in the numbers of white-winged scoters, 

 widgeon, and scaup nesting along the Porcupine, but the scoters are 

 more easily seen, and during their prolonged migratory passage the 

 steady succession of flights must account for the passage of an enor- 

 mous number toward the east and northeast. It would be difficult to 

 speculate upon whether these flights past Old Crow importantly con- 

 tribute to the summer populations of Mackenzie, but they appear to 

 be at least sufficient to occupy the Porcupine Valley as far east as 

 Richardson Mountains. 



Swarth (1936) remarked upon the sudden arrival from the coast 

 of large numbers of white-winged scoters at Carcross May 24-26. 

 If that date is typical of their first arrival, those reaching Old Crow 

 before that date did not migrate through Carcross. I have seen 

 scoters during migration through the upper part of the Copper River 

 Valley, which is still south of the Alaska Range, but have found no 

 reports confirming the overland course from the Gulf of Alaska which 

 would bring them into the upper Yukon Valley. The regularity of 

 their flights up Porcupine River indicates that scoters reach arctic 

 Yukon from the population which winters along the Alaskan coast. 



White-winged scoters seem to be the only species of migratory ducks 

 distinguished into eastern and western races (A. O. U. Check-list, 

 1957). Brooks (1915) named the western race dixom because he 

 found them to have shorter and broader bills. During the breeding 

 season the bills of scoters become more highly colored and the softer 

 parts, in the males, at least, seem to swell. When dry the bills of 

 scoters warp, and it is then difficult to compare their shape. We 



