The Common Merganser is s large, long-bodied duck with thin, pointed wings. Their bills are striaght and narrow and females have shaggy grests on the backs of their heads. They measure between 54 and 71 centimeters in length, and approximately 86 centimeters in wingspan. Adult males have gleaming white bodies and dark, iridescent-green heads. The back is black and the bill red. Females and immature individuals are gray-bodied with a white chest and rusty-cinnamon heads. In flight, both sexes show large white patches on the upperwings. Common Mergansers dive underwater to catch fish. These ducks live mainly on freshwater rivers and lakes. They nest in tree cavities in northern forests near rivers and lakes. Common Mergansers are of low conservation concern.
- Young Common Mergansers leave their nest hole within a day or so of hatching, and start diving and catching their own fish at about 12 days old.
- The oldest Common Merganser on record was a female, about 13 years, 5 months old.
Source: Common Merganser Overview and Identification Information, All About Birds, Cornell Lab of Ornithology