Common swan
The Whooper swan (Cygnus cygnus) is a large northern hemisphere swan. It is the Eurasian counterpart of the North American trumpeter swan. It is considered the most elegant of the swan family.
Whooper swans have pure white feathers. Their webbed feet and their legs are black. Half the beak at the base is orangey-yellow and the tip is black. The markings on the beak differ between individuals and they can be recognized by means of the pattern. Juveniles are usually white but some are gray.
Whooper swans have an extensive range and are found in the boreal zone within Eurasia and on many nearby islands. They migrate hundreds or thousands of miles to wintering sites in eastern Asia and southern Europe. There are occasional vagrants in western North America and the Indian subcontinent. Whooper swans breed on the banks of freshwater pools, lakes, shallow rivers, marshes, swamps, and bogs. They favor habitats with emergent vegetation, and this may offer additional protection for their nests and newborn cygnets.
Whooper swans are active in the daytime and spend much of their time swimming, straining the water for food, or eating plants that grow on the bottom. They are very noisy and have a deep honking call. They forage on water by head-dipping or upending, and they graze on the ground as well. They are territorial during summer but social in the winter. These swans live in flocks near wetlands. Bigger flocks of over 40 birds are more usual from October to November, with smaller flocks with fewer than 30 being more common between January and early spring. A social hierarchy exists, with the larger families up at the top, the pairs in the middle, while unpaired individuals are at the bottom. Dominant swans can feed for longer, and individuals will seek to join a flock for added protection. Aggressive male swans may cause one family to become more dominant over another one of equal size. Whooper swans are very noisy and have a deep honking call.
Whooper swans are herbivores (folivores, graminivores). They feed on aquatic plants and roots, leaves, stems, sedges and grasses. The young eat small insects and a variety of invertebrates to satisfy their high protein needs for growth and development.
Whooper swans are monogamous birds and form pairs for life. Mates have courtship displays where the pair face each other, with their quivering wings half-opened in a raised position. Each swan alternatively bends to extend its neck. Such displays are accompanied by loud trumpeting calls. A whooper swan strongly defends its territory throughout the nesting period. The mating season runs from late April to early May. Whooper swans are solitary nesters. The nest is located on a large mound made from plant material, usually moss and lichens. Nests are built near water, on islands, or on lake shores. Females lay 4-5 eggs and incubation lasts around 35 days, carried out by the mother, while the father guards the site. The cygnets fledge at three months, being able to fly when they are 4 to 5 months old. Cygnets seldom initiate flight but participate in pre-flight signals to communicate with their mother and father. They become independent after one year and reproductively mature after around 4 years of age.
Human activities threaten Whooper swans, such as hunting, nest destruction, egg poaching, habitat loss, and degradation, including the reclamation of inland and coastal wetlands, especially in Asia. Threats to the swan's habitat include agricultural expansion, overgrazing by livestock (e.g. sheep), wetland drainage for irrigation, vegetation cutting for livestock feed for winter, roading developments, oil pollution from exploration for oil, exploitation, and transportation, and disturbance from tourism.
According to the IUCN Red List, the total population size of the Whooper swan is above 180,000 individuals. The population in Russia consists of around 10,000-100,000 breeding pairs and around 1,000-10,000 wintering individuals. The European population consists of 25,300-32,800 pairs, which equates to 50,600-65,500 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
Whooper swans play a vital role in affecting plant community structures, due to the large quantities of biomass being lost when they feed on the submerged macrophyte they prefer, fennel pondweed, which stimulates the pondweed to grow at intermediate depths
