This species is found throughout the western Baltic Sea. They forage at sea at depths ranging from 1 to 20 meters. They benefit when large amounts of mussel are available, especially from reefs with blue mussel. They mostly occur in flocks of less than 100 individuals, but also often in larger flocks that spread over a larger area.
The Common eider is a regularly occuring migratory bird species protected under article 4.2 of the Birds Directive (Directive 2009/147/EC).