| Description   White-winged scoters are large and stocky birds,  measuring about 21 inches in length. They are among the largest of all ducks.  Males are all black, with a white, comma-shaped patch around each eye. Females  may have whitish patches on the face and are a dark brown color. The male's  bill is black at the base with reddish sides and an orange nail. The female's  bill is similar in color but less bright. Both males and females have red legs  and a white stripe on their wings. Range  The  white-winged scoter has a wide range. Its summer breeding grounds extend from  Alaska into Central Canada. During migration, it can be found around the Great Lakes.  It spends its winters along the west and east coast of North America. |  | Habitat  During  the breeding season, white-winged scoters can be found in a variety of  habitats. These include wooded coastlines, small freshwater lakes and rivers in  northern coniferous forests, wooded arctic tundra and alpine zones. In the  winter, white-winged scoters inhabit coastal waters, preferring estuaries and inlets with  large mussel beds. Diet   A diving duck, the white-winged scoter feeds on  the bottom of lakes and oceans. Their diet consists mostly of mollusks, such as  clams and mussels. Scoters will also eat crustaceans, worms, echinoderms,  amphipods, isopods and small fish. In freshwater habitats, white-winged scoters  will also feed on adult and larval insects and plant material. Life CycleBreeding begins in mid-May. Females make a shallow depression on the ground for their nest. They prefer a site with tall grass, among hummocks or under bushes. They line the nest with sticks and down. Nests are close to the water.   White-winged  scoters lay 6-16 creamy buff or light pink eggs per female. Chicks hatch with  downy feathers and their eyes open. They leave their nests as soon as they're  dry and are able to feed themselves immediately.  BehaviorThe  population of white-winged scoters on the Great Lakes is rising due to the  growing population of the invasive zebra mussel.  |