Canvasback
Aythya valisineria
It ranges from 48–56 cm (19–22 in) in length and weighs 862–1,588 g (1.900–3.501 lb), with a wingspan of 79–89 cm (31–35 in). It is the largest species in the genus Aythya, and the largest diving duck in North America. Canvasbacks are similar in size to a mallard but with a heavier and more compact build. 191 males wintering in western New York averaged 1,252 g (2.760 lb) and 54 females there averaged 1,154 g (2.544 lb). The canvasback has a distinctive wedge-shaped head and long graceful neck.
ID text from Wikipedia, CC BY-SA 4.0
Greater Scaup
Aythya marila
The adult greater scaup is 39–56 cm (15–22 in) long with a 71–84 cm (28–33 in) wingspan and a weight of 726–1,360 g (1.601–2.998 lb). It has a light blue bill with a small black nail on the tip, yellow eyes, and is 20% heavier and 10% longer than the closely related lesser scaup. The male has a dark head with a green to purple sheen, a black breast, a light back, a black tail, and a white underside. The drake or male is larger and has a more rounded head than the female. The drake's belly and flanks are a bright white.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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