Scientific name: Cygnus olor (J. F. Gmelin, 1789)
Bird group: Swans
Field characters. 145-160 cm. Differs from Tundra Swan and Whooper Swan in orange-red bill with prominent black knob at base, and in carrying neck in a more graceful S-shaped curve. Legs black. Juveniles unevenly dingy brown above and whitish below, with greyish bills and legs.
Voice. Generally silent; hissing sound when nest or young are threatened. Wing-beats produce a loud, humming sound resembling "vaou-vaou-vaou".
Distribution. Originally a bird from steppe lakes, but introduced and semi-domesticated in many countries. Wholly migratory in some parts, moving short distances to form winter flocks in other parts, mainly sedentary in other regions.
Habitat. Semi-domesticated birds frequent almost any kind of open, stagnant or slow-flowing waters with ample vegetation at depths which they can reach.
Food. Chiefly aquatic plants obtained at depths up to 1 m by immersing head and neck or by up-ending.
Eggs. Unmarked, ground colour pale grey-green, covered with chalky layer when fresh, becoming stained brown or yellow during incubation. Texture not glossy, becoming scratched during incubation. Shape subelliptical/elliptical. Size 113 x 74 mm (100-22 x 70-80), weight 345 g (294-385).