The Mute Swan (Cygnus olor) is a species of swan and a member of the waterfowl family Anatidae. It is native to much of Eurasia, and (as a rare winter visitor) the far north of Africa. It is an introduced species in North America, Australasia and southern Africa. The name 'mute' derives from it being less vocal than other swan species. Measuring 49 to 67 inches in length, this large swan is wholly white in plumage with an orange beak bordered with black. It is recognizable by its pronounced knob atop the beak, which is larger in males.
The mute swan was first formally described by the German naturalist Johann Friedrich Gmelin as Anas olor in 1789, and was transferred by Johann Matthäus Bechstein to the new genus Cygnus in 1803. Both cygnus and olor mean "swan" in Latin; cygnus is a variant form of cycnus, a borrowing from Greek κύκνος kyknos, a word of the same meaning.
Mute swans can be very aggressive in defense of their nests and are highly protective of their mate and offspring. Most defensive attacks from a mute swan begin with a loud hiss and, if this is not sufficient to drive off the predator, are followed by a physical attack. Swans attack by smashing at their enemy with bony spurs in the wings, accompanied by biting with their large bill, while smaller waterbirds such as ducks are normally grabbed with the swan's bill and dragged or thrown clear of the swan and its offspring.
The wings of the swan are very powerful, though not strong enough to break an adult man's leg, as said anecdotally. Large waterfowl, such as Canada geese, (more likely out of competition than in response to potential predation) may be aggressively driven off, and mute swans regularly attack people who enter their territory. The cob is responsible for defending the cygnets while on the water, and will sometimes attack small watercraft, such as canoes, that it feels are a threat to its young.
The total native population of mute swans is about 500,000 birds at the end of the breeding season (adults plus young), of which 350,000 are in the former Soviet Union. The largest single breeding concentration is 11,000 pairs in the Volga Delta.
The mute swan has been the national bird of Denmark since 1984. Prior to that, the skylark was considered Denmark's national bird (since 1960). The fairy tale "The Ugly Duckling" by Hans Christian Andersen tells the story of a cygnet ostracized by his fellow barnyard fowl because of his perceived homeliness. To his delight (and to the surprise of others), he matures into a graceful swan, the most beautiful bird of all.