scaup \scaup\ skaddp, n. see scalp a bed of oysters or
   mussels.
   1. a bed or stratum of shellfish; scalp. scot.
      1913 webster

   2. zool. a scaup duck. see below.
      1913 webster

   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. see illust. of
      ring-necked duck, under ring-necked. the common
      european scaup, or mussel, duck aythya marila, closely
      resembles the american variety.
      1913 webster
see also:
scalp scaup duck aythya fuligula aythya marila broadbill 
bluebill blackhead flock duck flocking fowl raft duck 
aythya affinis little bluebill river broadbill shuffler aythya collaris 
black jack ringneck ringbill ringbill shuffler ring-necked duck 
ring-necked