The Common Merganser, (Goosander in Europe), Mergus merganser, is a large sized duck, which is distributed over Europe, North Asia and North America. It is most common on lakes and rivers. Its nests can be found in treeholes.
There are three subspecies
Males and females are easily distinguished, since the male merganser has a dark green head, while the head of the female is reddish-brown. The Common Merganser is 70 cm long with a 78-94 cm wingspan.
These large fish-eaters have serrated edges to their bills to help them grip their prey. Along with the Smew and the other Mergansers, they are therefore often known as "sawbills". They also eat mussels and shrimps; young birds mainly eat aquatic insects.