Large, long-bodied ducks with thin, pointed wings. Their bills are straight and narrow, unlike the wide, flat bill of a “typical” duck. Females have shaggy crests on the backs of their heads. Common Mergansers spend the breeding season in northern forested habitats near large lakes and rivers. Since they nest in cavities of large trees, breeding Common Mergansers are usually found in mature forests. They spend winters on large lakes, rivers, and reservoirs in the southern and coastal regions of their breeding range, and in additional wintering grounds across the northern and western United States. They tend to prefer freshwater wintering habitat over saltwater, but they may winter in coastal bays, estuaries, and harbors.
(Image from Wikipedia)