White-winged Scoter

The White-winged Scoter (Melanitta deglandi) is a large, heavy-bodied sea duck native to North America. As the largest of the three North American scoter species, it presents a bulky profile with a sloping forehead and a thick, wedge-shaped bill. During the breeding season, these ducks inhabit freshwater lakes deep within the western boreal forests and high-latitude tundra. In autumn, they migrate to coastal marine environments, where they are often observed in large, sprawling rafts bobbing on the ocean waves. Both sexes possess a bright white patch on their secondary wing feathers, which is highly visible in flight but can sometimes be hidden when the bird is floating on the water at rest.

Identifying the White-winged Scoter relies primarily on its distinctive plumage highlights and head structure:

• Adult Male: Velvet-black overall with a conspicuous white, comma-shaped patch surrounding and extending behind the pale grayish-white eye. The bill is heavily swollen at the base with a black knob, while the rest of the bill is bright orange-yellow with a pinkish tip.
• Adult Female: Uniformly dark sooty brown with two indistinct, pale spots on the side of the head (one at the base of the bill, the other behind the eye). The eye is dark, and the bill is dark gray without a pronounced basal knob.
• In Flight: Both sexes reveal a broad, bright white patch on the secondaries of the wing (the speculum). This is the single most reliable mark to separate this species from both Surf and Black Scoters at a distance.

Similar Species:

• Surf Scoter: Males lack the white eye patch (having instead large white patches on the forehead and nape) and lack white wing patches. Females have two clean white facial spots but no white wing patch.
• Black Scoter: Males are entirely black with a bright yellow-orange knob on the bill. Females have a clean two-toned head (dark cap, pale cheeks) and lack white wing patches.
• Velvet Scoter (Melanitta fusca): The Eurasian counterpart (rare vagrant to western North America). Males have less orange on the bill sides and a different bill knob shape.

The White-winged Scoter utilizes two vastly different habitats depending on the season:

• Breeding Season: They nest in the interior northwestern regions of North America, stretching from Alaska through western Canada to the northern Great Plains. Their preferred nesting environments are freshwater to brackish boreal lakes, muskegs, and slow-moving rivers, usually surrounded by dense scrub, spruces, or deciduous brush.
• Non-breeding/Winter Season: During winter, they migrate to marine coastal waters. They are widely distributed along both the Pacific and Atlantic coasts of North America, from the Aleutian Islands down to Baja California, and from Newfoundland down to the Carolinas. They also winter regularly in deep, large inland water bodies, most notably the Great Lakes.

Migration:

Migration occurs in late fall and early spring. Birds fly in massive, tightly packed flocks, often traveling along coastlines or directly over land corridors to reach their interior breeding grounds.

Feeding:

White-winged Scoters are expert diving ducks, routinely plunging to depths of 5 to 20 meters. They dive with their wings partially open, using them along with their webbed feet for underwater propulsion. Their diet consists primarily of benthic invertebrates, especially bivalves like mussels, clams, and oysters, as well as crabs, sea urchins, and aquatic insects on breeding lakes. Prey is swallowed whole and crushed in their muscular, grit-filled gizzards.

Social Behavior:

Highly gregarious outside the breeding season, they form large wintering flocks called rafts, which can number in the thousands. These rafts are often mixed with Surf Scoters and Long-tailed Ducks. They fly low over the water in long, single-file lines.

Nesting:

Unlike many ducks, White-winged Scoters nest on the ground, often far from the water's edge. The female selects a well-concealed spot under dense thorny brush or low conifer branches, scraping a shallow depression lined with down feathers. A single clutch typically contains 8 to 10 cream-colored eggs.

Vocalization:

Generally silent when wintering on the coast. During the spring courtship, males make a thin, wheezy whistle or low croaking notes. Females produce a harsh, low-pitched growling rattle when disturbed or protecting her brood.