The Whooper swan is a big migratory bird and is considered the most elegant of the swan family. They 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 mate and built nests 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 the newborn cygnets.
Whooper swans are active in the daytime, foraging 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 to 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.
A Whooper swan feeds in shallow water and eats aquatic plants and roots. 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 with 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 four-five 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 sexually mature after around 4 years.
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, and oil pollution from exploration for oil, exploitation and transportation, and disturbance from tourism.
The Birdlife resource states that the global population of Whooper swans is 180,000 birds, with the population in Russia estimated at 10,000-100,000 mating pairs and about 1, 000-10,000 wintering individuals. The European population is estimated at 25,300-32,800 pairs, which equates to 50,600-65,500 mature individuals. Overall, currently Whooper swans are 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