Whistling Swan, Cygnus (columbianus) columbianus, is the nominate North American form, and Bewick's Swan Cygnus (columbianus) bewickii is the European subspecies. The latter is named after the engraver Thomas Bewick, who specialised in illustrations of birds and animals.
Bewick's is the smallest of the three British swans, similar in appearance to the Whooper Swan[?], but smaller, shorter-necked and with a more rounded head shape, with variable bill pattern, but always showing more black than yellow (the other way round with Whooper Swans). The bill pattern for every bird is unique, and scientists make detailed drawings of each and give them names to assist with studying this species.
Their breeding habitat is wetland. They pair for life, and their cygnets stay with them all winter; they are sometimes joined by offspring from previous years.
These birds feed mainly by grazing on farmland. They have a high pitched honking call.