The Mute Swan (Cygnus olor) is a species of swan, and thus a member of the duck, goose and swan family Anatidae. It is native to much of Europe and Asia, and (as a rare winter visitor) the far north of Africa. It is also an introduced species in North America, Australasia and southern Africa.
Measuring 125 to 170 centimetres in length, this large swan is wholly white in plumage with an orange bill bordered with black. It is recognisable by its pronounced knob atop the bill.
Despite its Eurasian origin, its closest relatives are the Black Swan of Australia and the Black-necked Swan of South America, not the other Northern Hemisphere swans. The species is monotypic with no living subspecies.
Adults of this large swan range from 125 to 170 centimetres (49 to 67 in) long with a 200 to 240 centimetres (79 to 94 in) wingspan. They may stand over 120 centimetres (47 in) tall on land. Males are larger than females and have a larger knob on their bill.
The Mute Swan is one of the heaviest flying birds, with males (known as cobs) averaging about 12 kilograms (26 lb) and the slightly smaller females (known as pens) weighing about 9 kilograms (20 lb).
The Mute Swan is less vocal than the noisy Whooper and Bewick's Swans; the most familiar sound associated with Mute Swan is the vibrant throbbing of the wings in flight. This sound is unique to the species, and can be heard from a range of 1 to 2 kilometres (0.6 to 1 mi), indicating its value as a contact sound between birds in flight. They do however make a variety of grunting, hoarse whistling, and snorting noises, especially in communicating with their cygnets, and usually hiss at predators trying to enter their territory.
The cob is also 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 cob will also try and chase the predator out of his family territory, and will keep animals such as foxes and birds at bay.
The population in the United Kingdom is about 22,000 birds.
Populations in western Europe were largely exterminated by hunting pressure in the 13th-19th centuries, with the exception of semi-domesticated birds maintained as poultry by large landowners. Better protection in the late 19th and early 20th centuries allowed birds to return to most or all of their former range. More recently in the period from about 1960 up to the early 1980s, numbers declined significantly again in many areas, primarily due to lead poisoning from birds swallowing discarded fishing sinkers made from lead. After lead weights were replaced by other less toxic alternatives, Mute Swan numbers increased again rapidly.
The phrase swan song refers to this swan and to the legend that it is utterly silent until the last moment of its life, and then sings one achingly beautiful song just before dying.
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 ostracised 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.
Today, the Crown (the British monarch) retains the right to ownership of all unmarked mute swans in open water.
The Mute Swans in the moat at the Bishops Palace have for centuries been trained to ring bells via strings attached to them to beg for food.