What is "whistling hawk"

Whistling \Whis"tling\, a. & n. from Whistle, v. Whistling buoy. (Naut.) See under Buoy. Whistling coot (Zo["o]l.), the American black scoter. Whistling Dick. (Zo["o]l.)

1. An Australian shrike thrush ( Colluricincla Selbii).

2. The song thrush. [Prov. Eng.] Whistling duck. (Zo["o]l.)

   1. The golden-eye.

   2. A tree duck. Whistling eagle (Zo["o]l.), a small Australian eagle ( Haliastur sphenurus); -- called also whistling hawk, and little swamp eagle. Whistling plover. (Zo["o]l.)

      1. The golden plover.

      2. The black-bellied, or gray, plover. Whistling snipe (Zo["o]l.), the American woodcock. Whistling swan. (Zo["o]l.)

         1. The European whooper swan; -- called also wild swan, and elk.

         2. An American swan ( Olor columbianus). See under Swan. Whistling teal (Zo["o]l.), a tree duck, as Dendrocygna awsuree of India. Whistling thrush. (Zo["o]l.)

            1. Any one of several species of singing birds of the genus Myiophonus, native of Asia, Australia, and the East Indies. They are generally black, glossed with blue, and have a patch of bright blue on each shoulder. Their note is a loud and clear whistle.

            2. The song thrush. [Prov. Eng.]