248 BAY, SEA OR DIVING DUCKS 



these parts. Of this food Bent (1923) says: "The growth of this excellent 

 duck food, on which the numerous duck clubs largely depend for their 

 good shooting, is being much injured by carp and by the increasing 

 abundance of swans; both of these species root up or trample down 

 this grass so extensively that the feeding grounds for ducks are much 

 injured." Migration in the autumn is usually well started by October, 

 but Canvas-backs often linger on the way until forced south by severe 

 cold weather. Of their migration in the autumn from Delta Duck Sta- 

 tion, Manitoba, II. A. Hochbaum, in notes sent to the author, says: 

 "The early flight of Canvas-backs from the north is apparently in- 

 fluenced by weather, as strong north winds and storms in September 

 always bring down an early flight to the Delta Marsh. Weather, how- 

 ever, apparently plays no part in the mass movement of Canvas-backs 

 southward from Delta, and, come what may north winds, ice and snow, 

 or mild Indian summer the Canvas-back always leaves Delta Marsh 

 about the middle of October." In the spring these hardy birds are 

 among the earliest migrants and follow the break-up of the ice, start- 

 ing their northward voyage in late February and early March. 



Greater Scaup Duck 



Nyroca marila 



(Nyroca marila nearctica, of Peters) 

 (mi-ro-ka, ma-ri-la; he-ark- ti-ka) 



Colour Plates Nos. 19 and 17. Downy Young No. 34. 



SCIENTIFIC NAME 



Nyroca, Latinized form of the Russian word Nirok or Nyrok, meaning a 

 diving duck; marila, Greek, morile, meaning charcoal, from the pitch-black fore- 

 parts; nearctica, from Greek, neo, meaning new, and arcto, meaning the north, 

 referring to the New World Arctic (in contradistinction to palearctic, meaning 

 the Old World Arctic). 



COLLOQUIAL NAMES 



IN GENERAL USE: Big bluebill; bluebill. IN LOCAL USE: American widgeon; 

 bay blackhead; bay broadbill; bay shuffler; big bay bluebill; big blackhead; big 

 broadbill; big fall-duck; black duck; blackhead; black-headed broadbill; black- 

 headed duck; black-headed raft duck; blackjack; blackneck; blue-billed widgeon; 

 broadbill; broadbill bluebill; bullhead; bullneck; butterball; canvasback blue- 

 bill; deep-water broadbill; dosgris (greyback, sometimes corrupted to dogs); 

 dos gris de mer (sea greyback); fall duck; flock duck; greenhead; greyback; lake 

 bluebill; laker; mussel-duck; raft duck; salt-water broadbill; sea dos gris (sea 

 greyback); sea duck; shuffler; troop duck; troop fowl; widgeon; winter broadbill. 



DESCRIPTION 



ADULT MALE. WINTER PLUMAGE: Head and neck, same as those of Lesser 

 Scaup Duck, except that the gloss on the head is strongly green with slight indica- 

 tions of violet in certain lights, instead of glossed with purplish as in that species; 

 bill, same colour as that of Lesser Scaup but more rugged in character, wider near 



