Source : Webster's Revised Unabridged Dictionary (1913)

Scaup \Scaup\ (sk[add]p), n. [See {Scalp} a bed of oysters or
   mussels.]
   1. A bed or stratum of shellfish; scalp. [Scot.]

Source : WordNet®

scaup
     n : diving ducks of North America having a bluish-gray bill
         [syn: {scaup duck}, {bluebill}, {broadbill}]