The Whooper Swan is a large Northern Hemisphere swan. It is the Eurasian counterpart of the North American Trumpeter Swan.
The Whooper Swan is similar in appearance to the Bewick's Swan. However, it is larger, at a length of 140–165 cm (55–65 in) and a wingspan of 205–275 cm (81–108 in). Weight typically is in the range of 7.4–14 kg (16–31 lb).
It has a more angular head shape and a more variable bill pattern that always shows more yellow than black (Bewick's Swans have more black than yellow).
Whooper Swans require large areas of water to live in, especially when they are still growing, because their body weight cannot be supported by their legs for extended periods of time. They spend much of their time swimming, straining the water for food, or eating plants that grow on the bottom.
Whooper Swans have a deep honking call and, despite their size, are powerful fliers. They can migrate hundreds or even thousands of miles to their wintering sites in southern Europe and eastern Asia. They breed in subarctic Eurasia, further south than Bewicks in the taiga zone. [Reference: Wikipedia]
There is a big migration of Whooper Swans each year from Iceland to Ireland in November and back to Iceland in March/April.
It was nice to see them in their breeding grounds.