Common Eider

Overview

The Common Eider is one of the largest and heaviest ducks, well adapted to cold coastal waters with exceptionally dense, insulating body feathers. Breeding males show a bold black-and-white pattern - white back, neck, and breast contrasting with a black belly, flanks, and crown - along with a pale green wash on the nape. Females are entirely cryptic brown with heavy barring, providing effective camouflage while incubating on open, exposed nesting grounds. The species' distinctive sloping forehead-to-bill profile, created partly by feathering that extends far up the bill, is a useful structural identification feature.

Feather Identification

• Body contrast: Breeding males show a crisp white back, neck, and breast against a black belly, flanks, and crown, creating one of the most striking black-and-white patterns among sea ducks.
• Nape wash: A pale green tint on the nape adds subtle color to the otherwise white neck and upper back.
• Feathering extent on the bill: Facial feathers extend unusually far up the sides of the bill, contributing to the species' distinctive sloping head-and-bill profile.
• Female barring: Females show dense, heavy brown barring throughout the body, providing camouflage that differs from the finer vermiculations of other female ducks.
• Down feathers: The species is well known for extremely soft, dense down feathers used to line the nest, among the most insulating of any bird.

Plumage Notes

Breeding males show a white back, neck, and breast, black belly, flanks, and crown, and a pale green nape wash. Females are barred brown throughout the year with relatively little seasonal change. Eclipse males become substantially darker and more mottled, losing much of the crisp black-and-white contrast until they regain full breeding plumage. The species undergoes a complete post-breeding molt with a flightless period. Juveniles resemble females and take a few years to acquire full adult male plumage.

Habitat & Range

Common Eiders breed along rocky and sandy coastlines across the northern reaches of the Atlantic and Pacific, often nesting colonially on islands close to the shoreline. Outside the breeding season, they remain largely coastal, foraging in nearshore and offshore waters. The species is partially migratory, with some populations moving south in winter while others remain resident where coastal waters stay ice-free.

Behavior & Field Notes

Common Eiders dive to forage on invertebrates from the seafloor, often in relatively shallow nearshore waters. They nest colonially on coastal islands, with females lining nests using extremely soft down feathers plucked from their own bodies. The species is well known for this down, historically collected after nesting for its exceptional insulating qualities. Calls include a distinctive, soft crooning note given by males during courtship displays. Flight is direct and often low over the water, typically in loose lines.