Likely Common Eider (also Eider Duck); exact species uncertain

This is a beautifully barred, insulating body feather typical of a large sea duck. Common Eiders are bulky, long-lived diving ducks; males are striking black-and-white with green nape patches, while females are rich brown and barred.

Warm buff to brown overall, with repeated pale horizontal barring across the vane. The rachis is pale brown; the fluffy base is cream-white. Sex, age, wear, and lighting affect the exact tones.

Upper vane is pennaceous with interlocking barbules; lower portion is strongly plumulaceous and downy, with an unusually conspicuous aftershaft.

Moderately slender, straight rachis with dense, regularly angled barbs above and loose, radiating barbs below; banding crosses both vanes.

Soft, matte, insulating, and partly silky; the upper vane is smooth while the basal aftershaft is airy and down-like.

Likely body/flank or breast, rather than a wing or tail feather, based on its rounded outline, soft texture, and large downy aftershaft.

Rounded contour form, strong horizontal barring, and exceptionally large fluffy aftershaft are the principal clues; it is not shaped like a primary, secondary, or tail feather.

Coastal marine environments, rocky shores, estuaries, tundra islands, and northern lakes; nests on the ground near water.

Common Eiders breed across Arctic and subarctic North America, Greenland, northern Europe, and Siberia, wintering along temperate northern coasts.

Common Eiders are benthic predators that consume mussels, crabs, and other invertebrates, linking coastal food webs. They remain widespread but face threats from climate change, oil pollution, disturbance, and changing marine prey.

Barred feathers of scoters, mergansers, or other ducks may resemble this, but the broad contour shape and massive aftershaft favor eider; exact species identification from one body feather is unreliable.

Eider down is among the finest natural insulating materials and is collected from nests after breeding, rather than requiring birds to be killed.

Eiderdown has a long history in bedding and cold-weather clothing, especially in Iceland and Scandinavia. In many jurisdictions, possession of wild bird feathers is regulated, including under migratory-bird laws.

Look for similar feathers beneath coastal nesting colonies, roosts, and wintering shorelines, especially after molt. Compare several feathers and use location, size, and associated birds rather than relying on one specimen.

Appears naturally shed and moderately worn, with some fraying in the down; no obvious oil staining or parasite damage. Condition: Good.