THE CANADIAN FIELD-NATURALIST 



VOL. XXXIV. 



MARCH, 1920. 



No. 3 



THE SCOTERS AND EIDERS. 



By p. a. Taverner. 



(Published by permission of the Geological Survey of Canada.) 



The scoters and eiders are often regarded by 

 the amateur ornithologist and the general sportsman 

 as confusing groups. Whilst the males are well 

 marked by color and bill characters some females 

 bear close general resemblance to each other. The 

 following diagnosis and plates may therefore be of 

 interest to those who have occasion to identify these 



swellings, protuberances and extended processes. 

 In the females these bill characters are reduced; 

 but, except in the American Scoter, they retain 

 enough peculiarity of shape for ready generic recog- 

 nition. Generally juvenile males are similar to the 

 females but soon show sufficient traces of the com- 

 ing adult plumage to mdicate their sex. 



MALE 

 A/VALE 



SCOTERS -GENU5 Oidemia 



iAMACREUSts-Geore Oiaemia ■ 



la 

 O.americancx 



2b 

 O.deglaodi 



O.per^picillata 



ae Jo**N&oN 



species. Two species of eider, Steller's and the 

 Spectacled, are rather different from the others, but 

 as they only arc to be expected in the extreme north- 

 west, Alaska and the Yukon, they need rarely be 

 considered in connection with eastern material. 



Except these two species, the scoters and ciders 

 are ducks of the largest and sturdiest build. As the 

 accompanying plates show, the males are char- 

 acterized by unusually heavy bills often with strange 



THE SCOTERS. 

 The adult males of all the scoters are practically 

 solidly black birds or with only restricted and sharp- 

 ly defined patches of pure white on head or wing. 

 The females arc without variegation, dark brown 

 gradually lightening below or on breast and face, 

 and show no indication of bars or streaks. The 

 bills of all plumages except that of the female 

 American Scoter arc characteristic. 



