The white-winged scoter is the largest of the three scoters. Adult males are 53–58 cm (21– 23 in.) long and weigh 1,360–1,780 grams (3–4 lbs); adult females are slightly smaller. They are distinguished from other scoters by the all-white patch (speculum) on the secondary feathers of their wings, which is obvious in flight and sometimes visible at rest. Adult males are entirely blackish with a small white, teardrop-shaped patch around its eye. Its orange bill has a black hump at the base and is somewhat wedge-shaped. Females and juveniles of both sexes are dark brownish with paler bellies; females and juveniles have a dark bill and variable amounts of white on their head that can appear as spots.