merganser

Any of several diving ducks with long, slender, serrated bills for catching fish, widely distributed in the northern hemisphere. Most have crested heads. (Genus Mergus, family Anatidae.)

The male common merganser or goosander (M. merganser) has a greenish-black head, black back, and a pinkish-white breast and underparts; the male red-breasted merganser (M. serrator) drake has a crested glossy green head, white neck, red breast and black upper surface with white margins. The females of both are very similar, with crested chestnut heads, white underparts, and grey backs. M. australis is a rare species found only in the Auckland Islands.