Large, dark sea duck. Breeding males have a colorful bill and white patches on the nape and forehead. Females and first-year males are dark brown with white patches on the cheek and face. Note large, thick-based bill to help separate from female White-winged Scoter. Breeds on lakes and ponds in northern Canada and Alaska; winters in flocks in harbors, bays, and other coastal waters, where dives for mussels and other aquatic invertebrates. Uncommon to rare inland, especially in migration. Frequently mixes with other sea duck species, especially eiders and scoters.