White-winged Scoter
White-winged Scoters are diving ducks that feed extensively on shellfish. They swallow mussels, clams, and other mollusks whole. They can take shells as long as two inches, grinding them up in the powerful gizzard.

White-winged Scoters are among the latest waterfowl to migrate to their breeding range in spring and to begin nesting in the interior of northwestern North America. Pairs form during migration or soon after arrival. The female typically builds the nest in the shelter of a thorny rose or currant, often on an island of a freshwater lake. She may return to the same nest site, or even the same nest, each year. White-winged scoters do not establish territories, except for the small area that a male defends around his mate. On average, the female lays nine eggs. After she begins incubation, the male abandons her, leaves the area, and undergoes molt. Nonbreeders and any females whose nests have failed apparently join the males. The location of White-winged Scoter molting grounds is not known.
White-winged Scoter Range Map

Once the young have hatched, the female broods them for 12 to 24 hours, before leading them to water. Within 36 hours of hatching, the chicks are able to feed themselves, diving after small shrimp-like creatures known as amphipods. The chicks dive under water to avoid gull attacks, but infant mortality is high in the first few weeks. At two weeks, the females abandon their chicks. Different broods may join up in flocks of 30 to 50 chicks, sometimes attended by one or more hens, or led by the eldest chick. Most White-winged Scoters remain on saltwater for their first summer, migrating north and south along the coast with the seasons.

White-winged Scoters migrate to the Pacific or Atlantic coasts for the winter. On the West Coast they inhabit sheltered bays and estuaries from western Alaska to northern Baja California. About 70 percent of the Atlantic population winters between the Chesapeake Bay and Long Island Sound, but smaller numbers may be found from the Gulf of Saint Lawrence to northern Florida. The small number of White-winged Scoters that winter on the eastern Great Lakes may be increasing because of the proliferation of zebra mussels.

Like Black and Surf scoters, White-winged Scoters dive for shellfish in relatively shallow waters. Of the three species, White-winged Scoters tend to take the larger prey and to dive in slightly deeper waters.

Description: White-winged Scoters are heavy-bodied diving ducks with relatively short necks. They must run across the water to take flight. They are the largest of the three scoter species, and are easily distinguished in flight by the wing patches formed by the secondary feathers that contrast strongly with the dark body. The wing patches may be partially visible when the birds are at rest as well.

Males are black and have a small white comma-shaped area behind and below the eye. The bill is orange with a black knob at the base and top of the upper mandible. Females are dark brown with two white patches on each side of the head. When the white wing patches are not visible she may resemble a female Surf Scoter, which also has two white facial patches. The Surf Scoter, however, has a more vertical patch at the front of the head, while the White-winged Scoter's patch is oval shaped.


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