The long-tailed duck (Clangula hyemalis) is a bird typically found at the ice edge. The Baltic Sea is used as a wintering area by millions of long-tailed ducks, and flocks of up to several thousand ducks also winter in the outer sea areas of Helsinki, as long as the sea doesn’t freeze over.
Long-tailed ducks have only recently started wintering in Helsinki due to the increasingly mild winters. In addition to the temperature, this development seems to also be linked to the numbers of mussels. Long-tailed ducks can dive up to ten metres for mussels.
The long-tailed duck has become the most numerous winter waterfowl found in Helsinki, though the large flocks stay largely hidden out at sea. However, small flocks of long-tailed ducks are known to congregate at the tip of Kallahdenniemi and off the coast of Lauttasaari island. The best way to spot long-tailed ducks in the winter is to hop on a boat and peer out at flocks of waterfowl near Katajaluoto.
Long-tailed ducks nest on the shores of tundra lakes far away in Siberia. They don’t start their migration until May, during the night. In the summer, you can only see individual, idle long-tailed ducks out at sea. The long-tailed duck has been designated a threatened species, as the numbers of ducks wintering in the Baltic Sea have declined to less than half over the last decade.