Common Merganser

The Common Merganser is a large, streamlined diving duck with a narrow red bill whose serrated edges grip fish. Breeding males have a dark green head, white body and salmon-tinted underparts; females and immature birds have grey bodies, rusty heads and shaggy crests. Adults measure 58–72cm and span 78–97cm, with males averaging slightly larger than females (Wikipedia, general species account).

Common Mergansers breed beside clear rivers and lakes in forested country, nesting in tree holes, rock cavities and suitable artificial boxes. They propel themselves underwater with their feet and eat mainly fish, often hunting cooperatively where prey gathers. Northern birds migrate to ice-free inland or coastal water, while families may join into crèches after hatching. The species winters widely on Japanese waters (Wikipedia, general species account).