The common eider is a large sea duck found in the northern regions of the world, particularly in the Arctic and sub-Arctic areas. It is known for its distinctive plumage, with males displaying a striking black and white pattern, while females are mottled brown for camouflage. These ducks primarily feed on mollusks and crustaceans, diving underwater to forage. Common eiders are social birds, often seen in groups, especially during the breeding season. They build their nests on the ground, usually near coastal areas, and the females are responsible for incubating the eggs. Their down feathers are highly valued and are often collected for use in insulation products.