What is "whistle duck"

Whistle \Whis"tle\, n. [AS. hwistle a pipe, flute, whistle. See Whistle, v. i.]

1. A sharp, shrill, more or less musical sound, made by forcing the breath through a small orifice of the lips, or through or instrument which gives a similar sound; the sound used by a sportsman in calling his dogs; the shrill note of a bird; as, the sharp whistle of a boy, or of a boatswain's pipe; the blackbird's mellow whistle.

   Might we but hear The folded flocks, penned in their wattled cotes, . . . Or whistle from the lodge.
   --Milton.

   The countryman could not forbear smiling, . . . and by that means lost his whistle.
   --Spectator.

   They fear his whistle, and forsake the seas.
   --Dryden.

2. The shrill sound made by wind passing among trees or through crevices, or that made by bullet, or the like, passing rapidly through the air; the shrill noise (much used as a signal, etc.) made by steam or gas escaping through a small orifice, or impinging against the edge of a metallic bell or cup.

3. An instrument in which gas or steam forced into a cavity, or against a thin edge, produces a sound more or less like that made by one who whistles through the compressed lips; as, a child's whistle; a boatswain's whistle; a steam whistle (see Steam whistle, under Steam).

   The bells she jingled, and the whistle blew.
   --Pope.

4. The mouth and throat; -- so called as being the organs of whistling. [Colloq.]

   So was her jolly whistle well ywet.
   --Chaucer.

   Let's drink the other cup to wet our whistles.
   --Walton.

   Whistle duck (Zo["o]l.), the American golden-eye.