Scaup n. 1.A bed or stratum of shellfish; scalp. (Scot.)
2.(Zool.) A scaup duck. See below.
Scaup duck (Zool.), any one of several species of northern ducks of the genus Aythya, or Fuligula. The adult males are, in large part, black. The three North American species are: the greater scaup duck (Aythya marila, var. nearctica), called also broadbill, bluebill, blackhead, flock duck, flocking fowl, and raft duck; the lesser scaup duck (Aythya affinis), called also little bluebill, river broadbill, and shuffler; the tufted, or ring-necked, scaup duck (Aythya collaris), called also black jack, ringneck, ringbill, ringbill shuffler, etc. The common European scaup, or mussel, duck (Aythya marila), closely resembles the American variety.