\Shel"drake`\, n. [Sheld + drake.]
1. (Zo["o]l.) Any one of several species of large Old World
   ducks of the genus {Tadorna} and allied genera, especially
   the European and Asiatic species. ({T. cornuta, or
   tadorna}), which somewhat resembles a goose in form and
   habit, but breeds in burrows.
Note: It has the head and neck greenish black, the breast,
      sides, and forward part of the back brown, the
      shoulders and middle of belly black, the speculum
      green, and the bill and frontal bright red. Called also
      {shelduck}, {shellduck}, {sheldfowl}, {skeelduck},
      {bergander}, {burrow duck}, and {links goose}.
Note: The Australian sheldrake ({Tadorna radja}) has the
      head, neck, breast, flanks, and wing coverts white, the
      upper part of the back and a band on the breast deep
      chestnut, and the back and tail black. The chestnut
      sheldrake of Australia ({Casarca tadornoides}) is
      varied with black and chestnut, and has a dark green
      head and neck. The ruddy sheldrake, or Braminy duck
      ({C. rutila}), and the white-winged sheldrake ({C.
      leucoptera}), are related Asiatic species.
2. Any one of the American mergansers.
Note: The name is also loosely applied to other ducks, as the
      canvasback, and the shoveler.