Black Swan

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Image:BlackSwan.JPG

Common Name: Black Swan
Scientific Name: Cygnus atratus

Size: 43-56 inches (110-142 cm); Wingspan: 63-79 inches (160-200 cm)

Habitat: Australia; south western and eastern Australia and adjacent coastal islands. In the southwest the range encompasses an area between North West Cape, Cape Leeuwin and Eucla; while in the east it covers a large region bounded by the Atherton Tableland, the Eyre Peninsula and Tasmania, with the Murray Darling Basin supporting very large populations of Black Swans. It is uncommon in central and northern Australia. It was hunted to extinction in New Zealand, but was reintroduced in 1864 as an ornamental species.

Their habitat extends across fresh, brackish and salt water lakes, swamps and rivers with underwater and emergent vegetation for food and nesting materials. Permanent wetlands are preferred, including ornamental lakes, but Black Swans can also be found in flooded pastures and tidal mudflats, and occasionally on the open sea near islands or the shore.

Status: Least Concern. Global population: Unknown amount of adult individuals. The population trend appears stable. The Black Swan is protected in New South Wales, Australia under the “National Parks and Wildlife Act 1974 (s.5)”.

Diet: Submerged and emergent aquatic vegetation as well as grasses and grains. They often “tip up” to reach submerged aquatic vegetation and “dabble” on the water surface.

Occasionally they will graze on land, but they are clumsy walkers.

Nesting: Sexes are alike with the male being slightly larger than the female. Black Swans are mostly black-feathered birds, with white flight feathers. The bill is bright red, with a pale bar and tip; and legs and feet are greyish-black. Males have a longer and straighter bill than females. Cygnets are a greyish-brown with pale-edged feathers.

The Black Swan is largely monogamous, pairing for life with a 6% divorce rate. Black Swans nest in the wetter winter months (February to September). Black Swans nest in isolated pairs or small colonies in shallow wetlands.

The nest is essentially a large heap or mound of reeds, grasses and weeds built in shallow water or on islands. It measures between 1 and 1.5 meters (3-4½ feet) in diameter and up to 1 meter high. The nest is reused every year, restored or rebuilt as needed. Both parents share the care of the nest. A typical clutch contains 4 to 8 greenish-white eggs that are incubated for about 35–40 days. Incubation begins after the laying of the last egg, in order to synchronize the hatching of the chicks.

Prior to the commencement of incubation the parent will sit over the eggs without actually warming them. Both sexes incubate the eggs, with the female incubating at night. The change over between incubation periods is marked by ritualized displays by both sexes. If eggs accidentally roll out of the nest both sexes will retrieve the egg using the neck (in other swan species only the female performs this feat). After hatching, the cygnets are tended by the parents for about 9 months until fledging.

Cool Facts: While Black Swans were once thought to be sedentary, the species is now known to be highly nomadic. There is no set migratory pattern, but rather opportunistic responses to either rainfall or drought. In high rainfall years, emigration occurs from the southwest and southeast into the interior, with a reverse migration to these heartlands in drier years. When rain does fall in the arid central regions, Black Swans will migrate to these areas to nest and raise their young. However, should dry conditions return before the young have been raised, the adult birds will abandon the nests and their eggs or cygnets and return to wetter areas.

Recent studies have shown that around a third of all broods exhibit extra-pair paternity. An estimated one-quarter of all pairings are homosexual, mostly between males. They steal nests, or form temporary threesomes with females to obtain eggs, driving away the female after she lays the eggs.

The Black Swan was a literary or artistic image, even before the discovery of Cygnus atratus. Cultural reference has been based on symbolic contrast and as a distinctive motif.

The Black Swan's role in Australian heraldry and culture extends to the first founding of the colonies in the eighteenth century. It has often been equated with antipodean identity, the contrast to the white swan of the northern hemisphere indicating 'Australianness'. The Black Swan is featured on the flag, and is both the state and bird emblem, of Western Australia; it also appears in the Coat of Arms and other iconography of the state's institutions.


Found in Songbird Remix Waterfowl Volume 3: Swans of the World

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