Whooper swan

The whooper swan ("Cygnus cygnus"), is a large white bird which lives in Europe and Asia. It is the Eurasian counterpart of the North American trumpeter swan. Francis Willughby and John Ray's "Ornithology" of 1676 called this swan "the Elk, Hooper, or wild Swan".
Description.
An adult whooper swan weighs 9-11 kg. It is 140-160 cm long (including neck and head) and it has a wingspan of 205-235 cm. Young swans are grey-brown. They have a pink and black beak. The young get pale grey in end of their first summer. They get the white adult colour before their second winter. Male and female swans look otherwise similar, but the males are larger.
The whooper swan, Bewick's swan and mute swan look quite similar, but the details are different.
Whooper swan is clearly larger than Bewick's swan. When it lands it water or takes off it slides longer distances. 
Behaviour.
Whooper swans eat mainly plants growing in water: leaves, stems and roots. During the winter they also eat grain and vegetables from the fields. Young birds often eat insects. 
The nest is a large pile of plant matter built on dry ground or on small islands near lakeshore. The same nest mound may be used over many years although it is often repaired and new material is added.
Distribution.
Whooper swans spends their summer in Northern Europe and Asia. For winter they migrate to coasts where sea does not freeze.
In year 2006 it was estimated, that there are more than 180,000 whooper swans in the world. Out of these, 10,000-100,000 pairs breed in Russia. Between one thousand and ten thousand birds also spend their winter there.