Black Swan Cygnus atratus Adult Black Swan in breeding plumage. Photo: John Spiers Black Swans are an iconic Australian bird, the symbol of Western Australia, but common throughout the southern half of the continent. Black Swan in breeding colours. Photo: John Spiers Black Swans are almost entirely vegetarian, feeding on the leaves and shoots of various aquatic plants (Typha, Potamogeton, Myriophyllum, Ruppia), algae and pondweeds, and pasture grasses. Small animals may be taken accidentally. Food is taken by reaching underwater with its long neck, dabbling on the surface and upending. They may also be seen grazing on the banks of wetlands. Photo by john Spiers.Adult Black Swan feeding submerged vegetation to young. Photo: John Spiers Breeding occurs when water levels are high. In South Australia, this is usually between August and October. Pairs are monogamous but with as much as 38% of cygnets resulting from extra-pair copulations. Nests are a large mound of floating plant material. The clutch consists of 4-6 large pale blue-green eggs. Incubation is by both sexes. Multiple clutches may be raised each season. Description A large swan with most of the feathers being black except for the white alula, primaries and outer secondaries. These are not visible when the bird is at rest, but make a striking contrast when it takes flight. The cere is orange-red and covers most of the bill except for the nail which is grey. In the breeding season, the cere becomes bright scarlet, a horizontal white band crosses the bill proximally to the nail, and the eye changes from white to red. The feet are dark grey. Males and females are alike except that the female is smaller and bill and eye colour are lighter. Newly hatched young are a downy, light-grey. As they mature light brown feathers appear and the immatures become grey-brown, lighter versions of the adults. Black feathers appear and the birds darken into the black adult Where to find it Black Swans may be seen throughout the state in suitable habitats. They favour large lakes, lagoons, reservoirs and rivers, whether the water be fresh, brackish or saline, and where aquatic plants and soft terrestrial vegetation is available. They tend to be sedentary if conditions are suitable but in droughts will move to permanent waterbodies. They also gather on large lakes when becoming flightless during the annual moult (September to February).