Black swan

In flight

Before the arrival of the Māori in New Zealand, a related species of swan known as the New Zealand swan had developed there, but was apparently hunted to extinction. In 1864, the Australian black swan was introduced to New Zealand as an ornamental waterfowl and populations are now common on larger coastal or inland lakes, especially Rotorua Lakes, Lake Wairarapa, Lake Ellesmere, and the Chatham Islands.[5] Black swans have also naturally flown to New Zealand, leading scientists to consider them a native rather than exotic species, although the present population appears to be largely descended from deliberate introductions.[11]

The black swan is also very popular as an ornamental waterbird in western Europe, especially Britain, and escapees are commonly reported. As yet, the population in Britain is not considered to be self-sustaining and so the species is not afforded admission to the official British List,[12] but the Wildfowl and Wetlands Trust have recorded a maximum of nine breeding pairs in the UK in 2001, with an estimate of 43 feral birds in 2003–2004. A small population of black swans exists on the River Thames at Marlow, on the brook running through the small town of Dawlish in Devon, near the River Itchen, Hampshire, and the River Tees near Stockton on Tees.[13] The Dawlish population is so well associated with the town that the bird has been the town's emblem for forty years.[14]

There are also wild populations in Japan, having originally been imported during 1950–1960.[15][16][17]

One of several black swans at Lake Eola Park in Orlando, Florida, USA

Black swans have been reported in Florida, but there is no evidence that they are breeding; persistent sightings may be due to continual releases or escapes. Orange County, California reported black swans in Lake Forest, Irvine and Newport Beach on October 5, 2020, and Santa Ana in December 2021 in the “Versailles on the Lake” apartment community. The "Lake Forest Keys” community bought the original swans about eight to ten years ago and since then there have been many births and gaggles from the original couple" according to a report in the Orange County Register.[18][19] Black swans formerly resided in the vicinity of Lake Junaluska, a large lake in Waynesville, North Carolina.[20]

Black swans can also be found in Mainland China.[21] In 2018 one group of swans was introduced to the Shenzhen University campus on an artificial lake in Guangdong Province.

The black swan is almost exclusively herbivorous, and while there is some regional and seasonal variation, the diet is generally dominated by aquatic and marshland plants. In New South Wales the leaf of reedmace (genus Typha) is the most important food of birds in wetlands, followed by submerged algae and aquatic plants such as Vallisneria. In Queensland, aquatic plants such as Potamogeton, stoneworts, and algae are the dominant foods. The exact composition varies with water level; in flood situations where normal foods are out of reach black swans will feed on pasture plants on shore.[22] The black swan feeds in a similar manner to other swans. When feeding in shallow water it will dip its head and neck under the water and it is able to keep its head flat against the bottom while keeping its body horizontal. In deeper water the swan up-ends to reach lower. Black swans are also able to filter feed at the water's surface.[23]

Like other swans, the black swan is largely monogamous, pairing for life (about 6% divorce rate).[24] Recent studies have shown that around a third of all broods exhibit extra-pair paternity.[25] An estimated one-quarter of all pairings are homosexual, mostly between males.[26] They steal nests, or form temporary threesomes with females to obtain eggs, driving away the female after she lays the eggs.[27][28][29]

Generally, black swans in the Southern hemisphere nest in the wetter winter months (February to September), occasionally in large colonies. A black swan nest is essentially a large heap or mound of reeds, grasses and weeds between 1 and 1.5 metres (3–4+1⁄2 feet) in diameter and up to 1 metre high, in shallow water or on islands.[2][10] A nest is reused every year, restored or rebuilt as needed. Both parents share the care of the nest. A typical clutch contains four to eight greenish-white eggs that are incubated for about 35–40 days.[30] Incubation begins after the laying of the last egg, 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.[31] 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).[32] Like all swans, black swans will aggressively defend their nests with their wings and beaks.[33] After hatching, the cygnets are tended by the parents for about nine months until fledging.[2][5] Cygnets may ride on their parent's back for longer trips into deeper water, but black swans undertake this behaviour less frequently than mute and black-necked swans.[34]

• 
  Up-ending in deeper water to reach food
• 
  Cygnus atratus, spring rain
• 
  Parent with cygnets in Australia
• 
  A Black swan and its nest at Booragoon Lake
• 
  Cygnus atratus – MHNT

The black swan is protected in New South Wales, Australia under the National Parks and Wildlife Act 1974 (s.5). The Black Swan is fully protected in all states and territories of Australia and must not be shot. [35] It is evaluated as Least Concern on the IUCN Red List of Threatened Species.[1]

The state flag of Western Australia was officially adopted in 1870 and modified slightly in 1953.

The black swan was a literary or artistic image among Europeans even before their arrival in Australia. 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 bird and state emblem of Western Australia; it also appears in the Coat of Arms and other iconography of the state's institutions. The Black Swan was the sole postage stamp design of Western Australia from 1854 to 1902.[36]

The Noongar People of the South-West of Australia call the black swan Kooldjak along the West and South-West coast, Gooldjak in the South East and it is sometimes referred to as maali in language schools.[37]

• Scott, Peter (1972). The Swans. London: Michael Joseph. ISBN 978-0-7181-0707-9.