Mute swans are among the heaviest flying birds in the world, yet on water they look as light as a cloud. They have snowy-white feathers, an orange beak with a black bump on top, and a long, curving neck that often makes the shape of a question mark.
They are called 'mute' because they are quieter than other swans, but they are not silent. They hiss and snort, and their wings make a humming, throbbing sound as they fly. Swan families stay close, and the fluffy grey babies, called cygnets, sometimes ride on a parent's back.
In 1843 the Danish writer Hans Christian Andersen wrote 'The Ugly Duckling', about a grey little bird that everyone teases, until it grows up into a glorious swan. Denmark loved the story so much that in 1984 the mute swan was chosen as the national bird.