What is "scotch duck"

Scotch \Scotch\, a. [Cf. Scottish.] Of or pertaining to Scotland, its language, or its inhabitants; Scottish.

Scotch broom (Bot.), the Cytisus scoparius. See Broom.

Scotch dipper, or Scotch duck (Zo["o]l.), the bufflehead; -- called also Scotch teal, and Scotchman.

Scotch fiddle, the itch. [Low]
--Sir W. Scott.

Scotch mist, a coarse, dense mist, like fine rain.

Scotch nightingale (Zo["o]l.), the sedge warbler. [Prov. Eng.]

Scotch pebble. See under pebble.

Scotch pine (Bot.) See Riga fir.

Scotch thistle (Bot.), a species of thistle ( Onopordon acanthium); -- so called from its being the national emblem of the Scotch.