scaup 
(skôp)
(skôp)n. pl. scaup or scaups
1. Either of two diving ducks (Aythya marila or A. affinis) of the Northern Hemisphere, the male of which has gray, black, and white plumage. Also called bluebill.
2. A small diving duck (Aythya novaeseelandiae) of New Zealand, having dark plumage.
[Short for scaup-duck, perhaps from Scots scalp, scaup, bed of mussels (from its feeding on shellfish).]