How to Spot an Eider
The Eider duck is distinguished by its bulky body and wedged bill. The brown female is known such, while the male eider is particularly set apart by its black-and-white plumage and green nape of the neck. Drakes of the European, eastern North American and Asia/western North American races are characterized by bill color and plumage nuances.
The Common Eider finds sustenance from the sea as it dives for crustaceans and mollusks, mussels being particularly preferred.