The Mute Swan is the biggest representative of the Anseriformes order. It measures between 7 to 15 kg in weight, 150-170 cm in length, and 220-240 cm in wingspan. It is a bird with strong wings and bill. In captivity it lives between 30 to 40 years. There is age dimorphism and slightly marked sexual dimorphism. Both sexes have snow white plumage. The bill is bright, orange-red, and the male has a large knob on it. Young birds are light grey with a brownish tint and become white at their 3rd year, their bill is brownish. The neck of the Mute Swan is thicker compared to other swans and the characteristic feature for it is that it keeps it in the shape of “S”.
The Mute Swan is not mute but its calls are hoarse and muffled. It also makes snorting and hissing sounds.
Distribution and Habitat
The Mute Swan is a pelearctic species that breeds in Europe, Kazakhstan, Asia Minor, Central Asia, Iran, and China. It winters by the North Sea and the Baltic Sea, in Central Europe and Southeast Europe, Central Asia, the Persian Gulf, and the Yellow Sea. It is partly a migratory species which was transferred to North America where it is non-migratory.
The Mute Swan inhabits lake coastal areas, dams and bigger rivers. It can be also found in saline water basins, including seas and oceans. It is semi feral in lots of areas around the world and lives as a park bird. Sometimes even the feral populations settle close to people.
In Bulgaria the Mute Swan is breeding, migratory and wintering species which is found in the wetlands at the Danube river and the Black Sea coast. Individual pairs breed in the interior of the country.
The Mute Swan feeds on aquatic plants, seeds and the small invertebrates it swallows by chance with them. In the winter it feeds on crops.
The Mute Swan is a monogamous bird and pairs usually stay together for life. During the breeding period there are battles in which both males and females take part and might end with serious injuries.
The nests of the Mute Swan are big, built of plants and usually on the border between open water areas and reed beds or other coastal plants, on flowing islets or beaten down old reed. It lays from 5 to 9 eggs measuring 120 x 80 mm in length and 340 g in weight and these are the largest eggs laid by a flying bird. Only the female incubates the eggs for 35 days. The chicks hatch developed enough to move and eat independently and go to the water right away. They start flying when they reach 4-5 months and reach sexual maturity at the age of 3. The chicks stay with their parents until the spring when the next breeding period starts.
According to IUCN its status is Least Concern, but in Bulgaria according to the Red Data Book it is Vulnerable.