The mute swan, (cynus olor), is a very large white waterbird. It has a long S-shaped neck and an orange bill with a black base and a black knob. It flies with its neck extended with a wingspan:208-238 cm, weighing approximately 10-12 kg it is one of the heaviest flying birds.

The population in the UK has increased recently, perhaps due to better protection of this species. Protected in the UK under the Wildlife and Countryside Act, 1981 The problem of lead poisoning on lowland rivers has also largely been solved by a ban on the sale of lead fishing weights. Some birds stay in their territories all year, while others move short distances and form winter flocks. In cold weather, some birds arrive from Europe into eastern England. The mute swan feeds on water plants, insects and snails.

Mute swans can be very aggressive in defence of their nests and are highly protective of their mate and offspring. Most defensive acts from a mute swan begin with a loud hiss and, if this is not sufficient to drive off the predator or intruder, are followed by a physical attack.

The mute swan has been the national bird of Denmark since 1984. Today, the British Monarch retains the right to ownership of all unmarked mute swans in open water, but King Charles III exercises his ownership only on certain stretches of the Thames and its surrounding tributaries. This ownership is shared with the Vintners’ and Dyers’ Companies, who were granted rights of ownership by the Crown in the 15th century.