The Collaborative International Dictionary of English v.0.48:

Goosander \Goos"an`der\, n. [OE. gossander, a tautological word
   formed fr. goose + gander. Cf. Merganser.] (Zool.)
   A species of merganser (M. merganser) of Northern Europe
   and America; -- called also merganser, dundiver,
   sawbill, sawneb, shelduck, and sheldrake. See
   Merganser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

goosander
    n 1: common merganser of Europe and North America [syn:
         goosander, Mergus merganser]