Mute swans are large birds, measuring 144 to 158 cm. The wingspan is 2 to 2.5 meters. The two sexes are alike in appearance, except that males are generally larger than females. The plumage is white. They are best distinguished from North American swans by the knob at the base of the upper bill, and the color of the bill itself, which is orange, with the tip and base colored black. The head and neck may sometimes be stained brown from water and mud containing iron.
Mute swans breed in the British Isles, north central Europe and north central Asia. They winter as far south as North Africa, the Near East, and to northwest India and Korea. They have been successfully introduced in North America, where they are a widespread species. They are a common breeding species and permanent resident in various locations throughout Michigan and the eastern United States.
Mute swans are the most common swans in the wild, in parks or on country estates in their native range. In winter, they are more common on marine waters. They live in well-sheltered bays, open marshes, lakes, and ponds.
Mute swans do not mate for life, contrary to the stereotype of the 'pining swan' who has lost its mate. In fact, some have been observed to have as many as four mates, or even 'divorce' one mate in favor of another. However, established pairs are more successful breeders than non-established pairs and mute swans do mate with only one other swan during each breeding season.
Mute swans rarely nest in colonies. Nest sites are selected and breeding begins in March or early April. These swans either build a new nest or use a previously constructed mound, such as a muskrat house. The nest is large, made of aquatic vegetation, and lined with feathers and down. It is built well above the normal water level in swampy places near a pond or lake. It is possible for clutches of 5 to 12 to occur, but 5 to 7 is most common. The eggs are pale gray to pale blue-green. Incubation lasts 36 to 38 days. The chicks are brownish gray (gradually turning white within the next 12 months) and only remain in the nest for one day. The male may often take the first-hatched cygnet (hatchling swan) to the water while the female continues to incubate the remaining eggs. They are able to fly in about 60 days. Chicks can ride on the backs of their parents or under their wings. By the following breeding season the parents drive the young away. The cygnets then join flocks of other non-breeding swans, and during this time molt their feathers, becoming flightless for a short period of time. In the next two years, the cygnets begin to bond with a mate and begin to look for suitable breeding territory. Swans do not begin to breed until about their third year.
The sexes share incubation, though the female spends the majority of time sitting, and the male usually stands guard.
Even in semi-domestication, the nest is strongly defended; swans have been known to attack other waterfowl and even people. Blows from their powerful wings can be especially painful. They can be dangerous to children, and are capable of killing or maiming some of the larger predators.
The greatest age recorded for a banded mute swan was 19 years. In captivity, they have lived 30 to 40 years.
There is no mass migration, though in winter there may be gatherings numbering more than 100 individuals in open salt water. When swimming, a mute swan holds its neck in a graceful curve with the bill pointing downward, as opposed to other swans, which carry their bills level and necks erect. Top flight speed is 50 to 55 mph.
(Granlund, McPeek and Adams, 1994; Reilly, 1968; Terres, 1980; http://www.airtime.co.uk/users/cygnus/muteswan.htm)
Mute swans set up large territories of 4 to 10 acres, which can include an entire small lake or pond.
Mute swans have keen vision and hearing. Mute swans are usually silent, as the name suggests. Adults sometimes snort and make hissing noises or puppy-like barking notes or whistles, though the sounds are not far-reaching due to their straight trachea. Also, the sound of the wings during flight, which has been described as a musical throbbing or humming, is very audible. They also use visual displays as a form of communication, such as postures. For example, in an aggressive posture, males often arch their secondary wing feathers over the back.
Mute swans eat mainly aquatic vegetation, but include small proportions of aquatic insects, fish, and frogs. Mute swans plunge their head and long neck below the water's surface to graze.. Swans feed in deeper waters than ducks and other waterfowl that share their habitat and thus do not compete with them directly for food. Rather, food is made more readily available to other birds by swans because parts of the plants they consume float to the surface while the swans are feeding. However, mute swans compete with other swans for food because they feed in similar ways.
Mute swans are large and aggressive birds. As adults they are not often preyed on unless they are old or ill. Eggs and hatchlings are vulnerable to nest predation by raccoons, mink, and a wide variety of other medium to large-sized predators. But swan parents are typically present to protect their young.
Mute swans impact aquatic vegetation communities through their grazing.
Swans may attack people who approach their nests too closely. There are records of them knocking boaters off of jet skis. An adult swan can seriously injure children.
In addition, mute swans are thought to pose a threat to native wildlife as a result of competition for food, territories, and nesting areas.
Mute swans were domesticated for food in Britain. Markings on their feet indicated ownership. Eventual domestication saved the bird from becoming hunted to extinction there. Feathers were also used as quills for writing, the leathery web used for purses, and the wing bones for making whistles.
The successful introduction and expansion of mute swans into North America may pose significant concerns to native wildlife. Common loons (threatened in Michigan) and recently re-introduced trumpeter swans are two species of primary concern. The North American population of mute swans has been increasing steadily since its introduction. These birds are aggressive, and have been known to drive off such stubborn and similarly sized species as Canada geese and trumpeter swans. Wildlife managers seek to control non-native mute swans in areas where native wildlife is being threatened.
Tanya Dewey (editor), Animal Diversity Web.
Alicia Ivory (author), University of Michigan-Ann Arbor.
Granlund, J., McPeek, G., and Adams, R. The Birds of Michigan. Indiana University Press, Indianapolis, 1994.
Halton, W. http://www.airtime.co.uk/users/cygnus/muteswan.htm
Reilly, E. The Audubon Illustrated Handbook of American Birds. McGraw-Hill Book Company, New York, 1968.
Terres, J. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knoph, New York, 1980.