In July, you can see plenty of eider (Somateria mollissima) broods swimming in Helsinki’s archipelago. Often several females will bring their broods together to form large nursery flocks.
The eider, which feeds mainly on mussels, is the most common waterfowl in the Baltic Sea. At its height, the Finnish breeding population consisted of nearly 200,000 pairs. Currently there are over 1,000 pairs nesting in Helsinki’s sea areas. Although eider populations in other parts of the Gulf of Finland have declined, decreasing by nearly half in the last two decades, the eider population of Helsinki has increased.
On some islets off the coast of Helsinki, eiders nest in clusters of several dozen pairs. In the Gulf of Finland, and nowadays in Helsinki as well, the eider population is regulated by the white-tailed eagle, which likes to hunt in the outermost islets. In response, eiders have been found to be moving towards the inner archipelago, where they are better protected from eagles.
A few years ago, a female eider was found to be incubating its eggs in a safe spot by the door of a restaurant on the Pihlajasaari islands. Eiders do not usually nest on the mainland or on the shores of large, forested islands due to the presence of four-legged predators.