Black Swan
Overview
The Black Swan is a large waterbird
Anatidae
Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...

, a species of swan
Swan
Swans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...

, which breeds mainly in the southeast and southwest regions of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The species was hunted to extinction in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, 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
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 and red bills
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

. They are monogamous breeders that share incubation duties and cygnet rearing between the sexes.

The Black Swan was described scientifically by English naturalist John Latham
John Latham (ornithologist)
John Latham was an English physician, naturalist and author. He was born at Eltham in Kent, and was the eldest son of John Latham, a surgeon there, and his mother was a descendant of the Sothebys, in Yorkshire....

 in 1790.
Encyclopedia
The Black Swan is a large waterbird
Anatidae
Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...

, a species of swan
Swan
Swans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...

, which breeds mainly in the southeast and southwest regions of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The species was hunted to extinction in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, 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
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 and red bills
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

. They are monogamous breeders that share incubation duties and cygnet rearing between the sexes.

The Black Swan was described scientifically by English naturalist John Latham
John Latham (ornithologist)
John Latham was an English physician, naturalist and author. He was born at Eltham in Kent, and was the eldest son of John Latham, a surgeon there, and his mother was a descendant of the Sothebys, in Yorkshire....

 in 1790. It was formerly placed into a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 genus, Chenopis.
Black Swans can be found singly, or in loose companies numbering into the hundreds or even thousands. Black Swans are popular birds in zoological gardens and bird collections, and escapees are sometimes seen outside their natural range.

Description

Black Swans are primarily black-feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...

ed birds, with white flight feathers. The bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

 is bright red, with a pale bar and tip; and legs and feet are greyish-black. 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 110 and 142 cm (43.3 and 55.9 in) in length and weighs 3.7 –. Its wing span is between 1.6 and 2 m (5.2 and 6.6 ft). The neck is long (relatively the longest neck among the swans) and curved in an "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 as a line or a V, with the individual birds flying strongly with undulating long necks, making whistling sounds with their wings and baying, bugling or trumpeting calls.

The Black Swan is unlike any other Australian bird, although in poor light and at 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.

Distribution

The Black Swan is common in the wetlands of south western and eastern Australia and adjacent coastal islands. In the south west the range ecompasses an area between North West Cape
North West Cape
North West Cape is a large peninsula of land in the north west coast of Western Australia. Cape Range runs down the spine of the peninsula and Ningaloo Reef runs along the western edge...

, Cape Leeuwin
Cape Leeuwin
Cape Leeuwin is the most south-westerly mainland point of the Australian Continent, in the state of Western Australia.A few small islands and rocks, the St Alouarn Islands, extend further to the south. The nearest settlement, north of the cape, is Augusta. South-east of Cape Leeuwin, the coast...

 and Eucla
Eucla, Western Australia
Eucla is the easternmost locality in Western Australia, located in the Goldfields-Esperance region of Western Australia along the Eyre Highway, approximately west of the South Australian border...

; while in the east it covers are large region bounded by the Atherton Tableland
Atherton Tableland
The Atherton Tableland is a fertile plateau which is part of the Great Dividing Range in Queensland, Australia. It is located west to south-south-west inland from Cairns, well into the tropics, but its elevated position provides a climate suitable for dairy farming. It has an area of around...

, the Eyre Peninsula
Eyre Peninsula
Eyre Peninsula is a triangular peninsula in South Australia. It is bounded on the east by Spencer Gulf, the west by the Great Australian Bight, and the north by the Gawler Ranges. It is named after explorer Edward John Eyre who explored some of it in 1839-1841. The coastline was first explored by...

 and Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

, with the Murray Darling Basin supporting very large populations of Black Swans. It is uncommon in central and northern Australia.

The Black Swan's preferred habitat extends across fresh, brackish and salt water lakes, swamps and rivers with underwater and emergent vegetation for food and nesting materials. Permanent wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

s 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.

Black Swans were once thought to be sedentary, but 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 south west and south east 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.

Black Swans, like many other water fowl, lose all their flight feathers at once when they moult
Moult
In biology, moulting or molting , also known as sloughing, shedding, or for some species, ecdysis, is the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life cycle.Moulting can involve the epidermis , pelage...

 after breeding, and they are unable to fly for about a month (This time may vary). During this time they will usually settle on large, open waters for safety.

The species has a large range, with figures between one to ten million km² given as the extent of occurrence. The current global population is estimated to be up to 500,000 individuals. No threat of extinction, or significant decline in population has been identified with this numerous and widespread bird.

Black Swans were first seen by Europeans in 1697, when Willem de Vlamingh
Willem de Vlamingh
Willem Hesselsz de Vlamingh was a Dutch sea-captain who explored the central west coast of Australia in the late 17th century.- Vlamingh and the VOC :...

's expedition explored the Swan River
Swan River (Western Australia)
The Swan River estuary flows through the city of Perth, in the south west of Western Australia. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow....

, Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

.

Introduced populations

Before the arrival of the Māori in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, a subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of the Black Swan known as the New Zealand Swan
New Zealand Swan
The New Zealand Swan is an extinct swan from the Chatham Islands and the South Island of New Zealand. It was originally described as a separate species from the Black Swan based on the slightly larger size of the fossil bones found and the apparent absence of the Black Swan from New Zealand prior...

 had developed in the islands, but was apparently hunted to extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

. 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 Rotorua
Lake Rotorua is the second largest lake in the North Island of New Zealand by surface area, and covers 79.8km2. With a mean depth of only 10 metres it is considerably smaller than nearby Lake Tarawera in terms of volume of water. It is located in the Bay of Plenty region...

, Lake Wairarapa
Lake Wairarapa
Lake Wairarapa is a lake at the southern end of the North Island of New Zealand, 50 kilometers east of Wellington. The lake covers an area of 78 km², and is the third largest in the North Island, fractionally smaller than Lake Rotorua...

 and Lake Ellesmere
Lake Ellesmere
Lake Ellesmere / Te Waihora is located in the Canterbury Region of the South Island of New Zealand. It is actually a broad, shallow lagoon located directly to the west of Banks Peninsula, separated from the Pacific Ocean by a long narrow sandy spit called Kaitorete Spit, or more correctly Kaitorete...

, and the Chatham Islands
Chatham Islands
The Chatham Islands are an archipelago and New Zealand territory in the Pacific Ocean consisting of about ten islands within a radius, the largest of which are Chatham Island and Pitt Island. Their name in the indigenous language, Moriori, means Misty Sun...

. 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.

The Black Swan is also very popular as an ornamental waterbird in western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, especially Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, and escapes 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, but the Wildfowl and Wetlands Trust
Wildfowl and Wetlands Trust
The Wildfowl & Wetlands Trust is a wildfowl and wetland conservation charity in the United Kingdom. Its patron is Queen Elizabeth II.It was founded in 1946 by the ornithologist and artist Sir Peter Scott, initially as the Severn Wildfowl Trust...

 have recorded a maximum of nine breeding pairs in the UK in 2001, with an estimate of 43 feral birds in 2003/04.

A colony of black swans in Dawlish
Dawlish
Dawlish is a town and civil parish in Teignbridge on the south coast of Devon in England, from the county town of Exeter. It has a population of 12,819...

, Devon
Devon
Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

 has become so well associated with the town that the bird has been the town's emblem for forty years.

Behaviour

Diet and feeding

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
Typha
Typha is a genus of about eleven species of monocotyledonous flowering plants in the family Typhaceae. The genus has a largely Northern Hemisphere distribution, but is essentially cosmopolitan, being found in a variety of wetland habitats...

 (genus Typha) is the most important food of birds in wetlands, followed by submerged algae and aquatic plants like Vallisneria
Vallisneria
Vallisneria is a genus of freshwater aquatic plant, commonly called eelgrass, tape grass or vallis. The genus has 6-10 species that are widely distributed, but do not grow in colder regions....

. In Queensland aquatic plants like Potamogeton
Potamogeton
Potamogeton is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed...

and 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. 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 bird up-ends to reach lower. Black Swans are also able to filter feed at the water's surface.

Nesting and reproduction

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 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 (3-4½ feet) in diameter and up to 1 metre high, in shallow water or on islands. A 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 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 and Black-necked Swans.

Conservation

The Black Swan is protected under the Australian National Parks and Wildlife Act, 1979. It is evaluated as Least Concern on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 of Threatened Species.

Australian culture

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
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

; it also appears in the Coat of Arms
Coat of arms
A coat of arms is a unique heraldic design on a shield or escutcheon or on a surcoat or tabard used to cover and protect armour and to identify the wearer. Thus the term is often stated as "coat-armour", because it was anciently displayed on the front of a coat of cloth...

and other iconography of the state's institutions.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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