Mute Swan

Identification

Adults are entirely white with a long neck usually held in a graceful S-curve, an orange bill topped by a black knob that is larger and more swollen in males, and black skin reaching forward to the eye. The tail is long and wedge-shaped and often held slightly raised. Juveniles are dingy grey-brown and are easily confused with other swans until they moult into white over their first winter.

Where water stays open these swans barely migrate. They feed mainly by upending in shallow water to reach submerged plants and algae, and they graze on bankside grass as well. The name is misleading: wings hum rhythmically in flight, and birds hiss, grunt and snort, especially around the nest. Breeding pairs hold large territories, and the male may chase intruders across the water in a dramatic busking display with the wings arched over his back.

They are resident on park lakes, slow rivers, canals and sheltered estuaries and are often the most conspicuous bird on the water. Winter is the best time to find gatherings of young non-breeders on estuaries and gravel pits. Keep a respectful distance in spring — nesting males are famously aggressive and will follow intruders right to the bank.

Family life on the water

Pairs form on the wintering grounds or on the territory itself and often stay together for years, holding the same stretch of water through the breeding season and defending it against other swans, geese and even boats. The nest is a large mound of vegetation at the water's edge, rebuilt and added to each year.

Incubation is shared unequally: the female does most of it while the male patrols. The cygnets are grey-brown when they hatch and are soon riding on a parent's back, which gives them warmth and protection from pike and herons. They stay with the family group for many months, and broods are often led in a line with the adults at front and rear.

Feeding and the moult

Mute Swans feed mostly by upending in shallow water to reach submerged plants and algae, and they also graze on bankside grass, which is why they are so often found on lawns beside a lake. They do not dive, and their reach is limited by the length of the neck, so they concentrate on the shallows.

In late summer, adults moult all their flight feathers at once and are flightless for several weeks. At that period family parties gather on larger, safer water bodies, and young non-breeders collect in herds on estuaries and gravel pits where food is plentiful and disturbance is low.

Confusion risks

Adults are unmistakable: all white, an orange bill with a black knob at the base, and black skin extending forward to the eye. The knob is larger and more swollen on males, though the difference is only reliable in adult birds seen in profile.

The confusion risk is with cygnets and immatures, which are dingy grey-brown and can be taken for another swan species. Young Mute Swans have a relatively short, straight neck and a wedge-shaped tail held slightly raised, while young Whooper and Bewick's Swans show more yellow on the bill and a different head shape. Check the bill pattern carefully.

Where and when to look

Park lakes, slow rivers, canals and sheltered estuaries are the everyday places, and the birds are often the most conspicuous object on the water. Winter is the best time to find gatherings of young non-breeders on estuaries and flooded gravel pits, sometimes in groups of dozens.

Spring and early summer are the season for watching families: look for a pair with cygnets and observe the way the adults shepherd the brood, hiss at dogs and ducks, and turn the nest mound over. Keep a respectful distance, and never let a dog swim at a nesting pair - the birds will attack, and a swan's wing strike can break a bone.

Fieldcraft and conservation notes

Do not feed swans bread. It has little nutritional value and there is a widely held view that a diet of bread and other high-energy food is linked to poor condition and to developmental problems in growing cygnets. Grain, oats, chopped greens or specially formulated waterfowl pellets in small quantities are the usual alternative, and bait should be thrown on the water rather than onto the bank.

Angling litter is a serious hazard for swans, which can swallow hooks or become tangled in line; reporting discarded tackle is a small but genuinely useful act. In North America the species is introduced and in some areas is managed because of its grazing pressure on submerged vegetation, a policy that is actively debated - worth knowing if you record birds there.