Mute Swan
Cygnus olor
The mute swan is a large waterbird species and one of the heaviest flying birds, known for its white plumage and elegantly curved S-shaped neck. It inhabits lakes, slow-moving rivers, and coastal waters across Eurasia and has been introduced to other continents. It is easily identified by the black knob at the base of its orange bill, which is more prominent in males during the breeding season.
Details
Identification
Pure white plumage, orange-red bill with black base and knob, S-shaped neck posture, and a rhythmic whistling sound produced by wings during flight.
Social behavior
Highly territorial and aggressive towards intruders during the breeding season; often gregarious in larger flocks at food-rich sites during winter.
Diet
Mainly aquatic plants (macrophytes) reached by up-ending; also grazes on grasses in riparian meadows and consumes small amounts of insects and snails.
Hunting strategy
Up-ending or dabbling in shallow water by submerging the long neck to reach vegetation on the bottom.
Overwintering
Remains in the territory as long as the water is ice-free, otherwise moves to larger lakes or marine coasts.
Ecology
Ecological role
Significant consumer of aquatic plants; influences vegetation density and serves as a host for various parasites.
Natural predators
Red fox (eggs and cygnets), White-tailed eagle (young and weakened adults), Raccoon (clutches).
Competitor species
Other large waterfowl such as Greylag geese or Canada geese when foraging on green spaces.
Ecosystem service
Aesthetic enhancement of urban landscapes; regulation of macrophyte growth in water bodies.
Threats
Habitat loss, lead poisoning from fishing tackle, collisions with power lines, and disturbances during the breeding season.
Scientific profile
Morphology & ID
Breeding plumage
Pure white plumage in both sexes; no discernible seasonal variation between breeding and non-breeding plumage.
Non-breeding plumage
Identical to breeding plumage; pure white.
Juvenile plumage
Mostly grey-brown ("cygnet") with a grey bill; the rarer "immutabilis" morph (Polish swan) is white from birth with pale legs.
Sexual dimorphism
Minimal; males (cobs) are on average larger and possess a significantly more prominent black knob at the base of the bill.
Distinguishing features
S-shaped neck, orange-red bill with black base and knob; wings often arched over the back while swimming (threat/courtship display).
Confusion species
Whooper Swan (Cygnus cygnus - yellow bill base, straight neck), Bewick's Swan (Cygnus columbianus bewickii - smaller, yellow bill base).
Bill
Orange-red with a black tip, black cutting edges, and a prominent black knob at the base.
Vocalization
Song
No true song; however, the rhythmic, singing-whistling sound of the wings during flight is characteristic.
Call
Mostly silent; hissing sounds when threatened, soft snoring or barking "chorr" calls when excited.
Distribution & migration
Breeding range
Originally Palearctic (Europe to Central Asia); now also widespread in North America, Australia, New Zealand, and South Africa due to introduction.
Wintering range
Largely congruent with the breeding range; moves to ice-free inland waters or coastal regions (e.g., Baltic Sea) during winter.
Migration details
Predominantly resident in Central Europe; northeastern populations migrate southwest or to the coasts during freezing conditions.
Habitat
Breeding habitat
Eutrophic standing waters, slow-moving rivers, oxbow lakes, park ponds, and sheltered marine bays with reed beds.
Foraging habitat
Shallow water zones with abundant aquatic vegetation; increasingly also on agricultural land (oilseed rape, winter cereals).
Breeding biology
Nest construction
Massive mound of reeds, cattails, and other aquatic plants; often on a solid base in shallow water or floating within reed beds.
Eggs
Large, dirty white to pale greenish, shell coarse-grained and matte.
Parental care
Both parents lead the precocial young; the female primarily incubates while the male guards the territory.
Diet & behaviour
Diet breeding
Predominantly submerged aquatic plants (charophytes, pondweeds), supplemented by small aquatic fauna (snails, insect larvae).
Diet winter
Aquatic plants, grasses, winter cereals, and oilseed rape; frequently supplemental feeding by humans in urban areas.
Feeding technique
Upending (head and neck underwater, hindquarters vertically up) or simple head-dipping.
Foraging strategy
Herbivorous grazer in aquatic and terrestrial habitats.
Sociality
Strictly territorial and in pairs during the breeding season; gregarious in flocks outside the breeding season, often at molting sites.
Flock behaviour
Formation of large non-breeding communities during molting and in winter at food-rich water bodies.
Protection & threats
Main threats
Lead poisoning from fishing weights, collisions with power lines, habitat loss due to shoreline development, and disturbance from recreational activities.
Population trend
Stable to increasing; the species has benefited from the eutrophication of water bodies and the reduction in hunting pressure.
Conservation measures
Protection of reed beds, marking of power lines to prevent collisions, ban on lead shot and lead fishing weights.