As the name implies, these birds have white undersides to their wings that are easily identified when in flight. They are the largest of all the scoters, growing to over two feet in length, and the males sport jet-black bodies with patches of the white undersides showing through, orange bills with a squarish knob at the base and blue eyes with a small white stripe dashing from the back. (Females are brown with more white spots than the males.) These birds can be found in the ponds and lakes of the Canadian and Alaskan forests and tundra before wintering on the coasts.