These ducks are usually quiet except on breeding territory. The male duck has a shrill whistle "tyu-tyu-vit…tyu-vit…tyu-tyu-vit" (Dementiev and Gladkov 1952) and a quiet whistle ending with a wavering "uit-trr" (Flint et al. 1984). The female duck has a hoarse, quack, short two-syllable inciting call, and a high pitched, two to four syllable Decrescendo call (Lorenz and Von de Wall 1960). The "Anas falcata" are known to have very striking and beautiful sickle feathers. This is in comparison with many other birds like swans and geese.