The Black Swan (Cygnus atratus) is a large waterbird, a species of swan, which breeds mainly in the southeast and southwest regions of Australia. The species was hunted to extinction in New Zealand, but later reintroduced. Within Australia they are nomadic. with erratic migration patterns dependent upon climatic conditions. Black swans are large birds with mostly black plumage and red bills and white flight feathers. Cobs (males) are slightly larger than pens (females), with a longer and straighter bill.
Cygnets (immature birds) are a greyish-brown with pale-edged feathers.
A mature black swan measures between 1.6 - 2 metres (45 - 56 in) in length and weighs 3.7 - 9 kg (8.2 - 20 lb). Its wing span is between 1.6-2.0 metres (5.2-6.6 ft). The neck is long (relatively the longest neck among swans) and curved in a "S"-shape.
The black swan utters a musical and far reaching bugle-like sound, called either on the water or in flight, as well as a range of softer crooning notes. It can also whistle, especially when disturbed while breeding and nesting. When swimming, black swans hold their necks arched or erect, and often carry their feathers or wings raised in an aggressive display.
In flight, a wedge of black swans will form a line or a "V". with the individual birds lying strongly with undulating long necks, making whistling sounds with their wings and baying, bugling or trumpeting calls.
Like other swans, the black swan is largely monogamous, pairing for life (about 6% divorce rate). 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.
Generally, black swans nest in the wetter months, occasionally in large colonies. A black swan nest is essentially a large heap or mound of reeds. grasses and weeds between 1-1.5 metres (3-4.5 feet) in diameter and up to 1 metre high, in shallow water or on islands. A nest is re-used 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 synchronise 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 ritualised 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). Like all swans, black swans will aggressively defend their nests with their wings and beaks. After hatching. the cygnets are tended by the parents for about 9 months until fledging. Cygnets may ride on their parent's back for longer trips into deeper water, but black swans undertake this behaviour less frequently than Mute or Black-necked swans.
The black swan is unlike any other Australian bird, although in poor light conditions and at a long range it may be confused with a Magpie Goose in flight. However, the black swan can be distinguished by its much longer neck and slower wing beat.
Black swans on the bank of the Swan River in Perth, Western Australia:
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 Western Australian flag, and is both the state and bird emblem of Western Australia. It also appears in the Coat of Arms and other iconography of that state's institutions.
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 distinctive motif.
You may get the feeling from this post that we, particularly we in the west, are particularly proud of our black swans. I have now decided to bore you further and tell you in a second post about our Swan River and some of its history. I've been so interested to learn more than I previously knew and with a bit of luck you may also find it interesting.