About Cygnus cygnus (Linnaeus, 1758)
The whooper swan (Cygnus cygnus (Linnaeus, 1758)) is similar in appearance to Bewick's swan, but is larger. It measures 140–165 centimetres (55–65 inches) in length, with a wingspan of 205–275 cm (81–108 in). Its typical weight range is 7.4–14.0 kilograms (16+1⁄4–30+3⁄4 pounds), with an average of 9.8–11.4 kg (21+1⁄2–25+1⁄4 lb) for males and 8.2–9.2 kg (18–20+1⁄4 lb) for females. The highest verified recorded mass is 15.5 kg (34+1⁄4 lb), from a wintering male in Denmark. The whooper swan is considered to be among the heaviest flying birds. Its standard measurements are as follows: wing chord 56.2–63.5 cm (22+1⁄8–25 in), tarsus 10.4–13.0 cm (4+3⁄32–5+1⁄8 in), and bill 9.2–11.6 cm (3.6–4.6 in). It has a more angular head shape and a more variable bill pattern that always has more yellow than black; in contrast, Bewick's swans have more black than yellow. Like their close relatives, whooper swans are vocal, with a call similar to that of the trumpeter swan. Whooper swans need large areas of water to live in, especially while they are still growing, because their legs cannot support their body weight for extended periods. The whooper swan spends much of its time swimming, straining water to find food, or eating plants that grow on the bottom. Whooper swans have a deep honking call that resembles geese, and despite their large size, they are powerful fliers. They can migrate hundreds or even thousands of miles to wintering sites in southern Europe and eastern Asia. They breed in subarctic Eurosiberia, further south than Bewick's swans, in the taiga zone. They are rare breeders in northern Scotland, particularly in Orkney, with no more than five pairs breeding there in recent years; a handful of pairs have also bred in Ireland in recent years. This bird is an occasional vagrant to the Indian subcontinent and western North America. Icelandic breeding whooper swans overwinter in the United Kingdom and Ireland, especially in wildfowl nature reserves managed by the Royal Society for the Protection of Birds and the Wildfowl and Wetlands Trust. Whooper swans pair for life, and their cygnets stay with them throughout the winter; they are sometimes joined by offspring from previous years. Their preferred breeding habitat is wetland, but semi-domesticated birds will build a nest anywhere close to water. Both the male and female help build the nest. The male stands guard over the nest while the female incubates the eggs. The female usually lays 4–7 eggs, with an exceptional clutch size of 12. Cygnets hatch after about 36 days and have grey or brown plumage. They can fly when they are 120 to 150 days old. When a flock of whooper swans prepares to take flight, they use a variety of signaling movements to communicate with each other. These movements include head bobs, head shakes, and wing flaps, and they influence whether the flock will take flight, and if so, which individual will lead. In large groups, whooper swans that used these signaling movements were able to convince their flock to follow them 61% of the time. In comparison, swans that did not signal were only able to get a following 35% of the time. In most cases, the whooper swan in the flock that makes the most movements (head bobs) is also the swan that initiates the flock's flight. This flight initiator can be either male or female, but is more likely to be a parent than a cygnet. Additionally, this signaling method may help paired mates stay together during flight. Observational evidence shows that a swan whose mate pays attention to and participates in its partner's signals is more likely to follow through with the flight. Thus, if a whooper swan starts initiating flight signals, it is less likely to actually carry through with the flight if its mate is not paying attention and therefore less likely to join. Whooper swans are very noisy; their calls are strident, similar to those of Bewick's swan but on average more resonant and lower-pitched, and are described as kloo-kloo-kloo when produced in groups of three or four.
