One of only three swan species that inhabit the southern hemisphere, the large Black swan is an unmistakable water bird. The body of an adult Black swan is mostly black, except for its broad white wing tips, visible in flight. Its bill is bright red, having a pale tip and bar, and its feet and legs are grayish-black. Its neck is long (the longest neck amongst swans, relative to its size) and it is curved into an "S"-shape. The males are slightly bigger than the females, and have a longer and straighter beak. Juvenile black swans are grayish-brown with lighter-edged feathers.
Black swans are natives of Australia, including Tasmania, and mainly occur in Australias south-eastern and south-western wetlands. In addition, there is an introduced population of black swans in New Zealand and Japan. Black swans inhabit rivers, lakes, and swampland in water that is fresh, salt or brackish. They prefer habitats that have aquatic vegetation, but sometimes live in terrestrial areas like flooded fields or dry pastures when food is scarce.
Black swans may be found on their own but they also often form loose groups consisting of several hundred or sometimes thousands of birds. They usually move in flocks, sometimes nest in colonies and are the least territorial of swan species. When food is scarce they are nomadic but otherwise they are sedentary. They travel at night and feed at dusk, but most of their activity is during the daytime. They are strong fliers, travelling together in a line or V shape, beating their wings slowly, which makes whistling noises. On the water as well as in flight, black swans make a range of high-pitched, musical, bugling, baying or trumpeting calls. They have also been heard to make a variety of softer crooning notes. If disturbed while nesting they tend to make a whistling sound.
Black swans are monogamous and often have the same mate for life. They are territorial and remain in solitary pairs during mating but occasionally mate in colonies. February through September is the breeding season. Usually the female swan makes a nest from sticks, debris and dead leaves into a mound floating on the water. She lays 5 to 6 eggs, one day apart. Incubation starts once all the eggs are laid and lasts 35 to 48 days. Males help with incubation. The cygnets are precocial, though they are brooded in the nest after hatching for a period of 2 to 3 weeks. They fledge between 150 to 170 days old. Black swans can fly at about 6 months old and stay with their family group for about 9 months. They reach sexual maturity within 18 to 36 months.
There are no major threats to Black swans, although brief hunting seasons have been instigated in some parts of their range due to crop damage caused by this bird.
According to Wikipedia, the current global population of the Black swan is estimated to be up to 500,000 birds. The numbers of this species are stable today and it is classified as least concern (LC) on the IUCN Red List.
Black swans are important in their ecosystem, as they affect species populations which they consume, and as a food source for their natural predators.