Merganser /(?)/

Mer·gan·ser

Merganser

n.
  1. Any bird of the genus Mergus (Merganser), and allied genera of the subfamily Merginae. They are allied to the ducks, but have a sharply serrated bill, eat fish, and dive for food. Also called fish duck. (Zool.)

Phrases & Compounds
White merganser
the smew or white nun.