Common mergansers are the largest of the merganser genus in North America. Males are mostly white with a solid dark head and back. The heads have a green sheen in light and the backs are black. Females have gray bodies and chestnut brownish red heads with short crest that extend down the neck.
In Alaska they can be found from Dillingham to Fairbanks extending west south of the Yukon River but your best chances to view them is along the coast.