The whooper swan (Cygnus cygnus), also called the common swan, is a large bird found in the northern hemisphere. It is the Eurasian equivalent of the North American trumpeter swan and is the type species for the genus Cygnus.
Whooper swans are similar in appearance to Bewick’s swan, but they are larger. They measure between 140 and 165 centimeters in length and have a wingspan between 205 and 275 centimeters. They usually weigh between 7.4 and 14.0 kilograms, with males averaging 9.8 to 11.4 kilograms and females averaging 8.2 to 9.2 kilograms. The heaviest recorded male weighed 15.5 kilograms. The whooper swan is one of the heaviest flying birds. They have a wing chord measuring 56.2 to 63.5 centimeters, a tarsus of 10.4 to 13.0 centimeters, and a bill measuring 9.2 to 11.6 centimeters. They have an angular head shape and a varied bill pattern that shows more yellow than black, unlike Bewick’s swans, which have more black than yellow. Like their relatives, whooper swans are vocal birds with calls similar to those of trumpeter swans.
Whooper swans need large bodies of water to thrive, especially when they are young, as their legs cannot support their weight for long periods. They spend much of their time swimming and foraging for food, mainly plants growing underwater.
Whooper swans have a deep honking call that sounds like geese. Despite their size, they are strong fliers. These swans migrate hundreds or even thousands of miles to wintering sites in southern Europe and eastern Asia. They breed in subarctic Eurosiberia, which is further south than Bewick’s swans in the taiga zone. In northern Scotland, especially in Orkney, they are rare breeders with no more than five pairs nesting in recent years. A few pairs have also bred in Ireland. Occasionally, they can be spotted in the Indian Subcontinent and western North America. Icelandic breeders migrate to the United Kingdom and Ireland for the winter, especially in nature reserves run by organizations like the Royal Society for the Protection of Birds and the Wildfowl and Wetlands Trust.
Whooper swans form lifelong pairs, and their young, called cygnets, stay with them throughout the winter. Sometimes, they are joined by older offspring. They prefer to breed in wetlands, but semi-domesticated birds might build nests anywhere near water. Both the male and female help build the nest, with the male guarding it while the female incubates around 4 to 7 eggs, though it can be as many as 12. The cygnets hatch after about 36 days and have grey or brown feathers. They can fly after 120 to 150 days.
When preparing to fly as a group, whooper swans use various movements to communicate, including head bobs, head shakes, and wing flaps. These movements help the flock decide whether to take off and which swan will lead. Swans that signaled in large groups managed to convince others to follow them 61% of the time, compared to 35% for those that did not signal. Usually, the swan that makes the most head bobs initiates the flock’s flight. This leading swan can be either male or female, but is often a parent rather than a cygnet. This signaling may also help paired mates stay together during flights. Observations show that a swan whose mate engages with its signals is more likely to follow through with the flight. If a whooper swan starts signaling and its mate is not paying attention, it is less likely to follow through with the flight.
They are quite noisy, with calls that are similar to those of Bewick’s swan but are deeper, resonant, and lower-pitched. Their calls often sound like “kloo-kloo-kloo” in groups of three or four.
