Cygnus atratus, commonly known as black swans, are native to Australia (including Tasmania) and have been introduced to New Zealand, Europe, and North America. Black swans are found mainly in the wetlands of southern Australia and tend to avoid the northern tropics. They can also be found in across the rest of southern Australia, and in the southeast of Tasmania. After being introduced to Europe as pets, they can now be found there in the wild.
Biogeographic Regions: nearctic (Introduced ); palearctic (Introduced ); australian (Native ); oceanic islands (Introduced )
Swans are the largest of all waterfowl. Black swans' closest relatives are mute swans (Cygnus olor). Cygnus atratus has the classical swan look with a long arched neck and raised eyebrows. As the name implies they are mostly black. Some of the wing feathers are white. They also have reddish or pinkish irises and richly colored red bills with a white line. The juveniles are greyish brown with light tipped feathers and a lighter colored bill. As with many birds, there is sexual dimorphism where the male (called a "cob") is slightly larger than the female (called a "pen").
When they are fully grown they have a length of 110 to 140 cm and weigh between 3700 to 8750 g. The wingspan ranges between 160 to 200 cm.
Range mass: 3700 to 8700 g.
Range length: 1.1 to 1.4 m.
Range wingspan: 160 to 200 cm.
Sexual Dimorphism: male larger
Other Physical Features: endothermic ; bilateral symmetry
Black swans live in lakes, rivers and swampland, which can be fresh, salt or brackish water. They prefer habitats with aquatic vegetation. While their natural habitat is aquatic they are sometimes found in terrestrial areas such as dry pastures or flooded fields when food is scarce.
Habitat Regions: temperate ; tropical ; terrestrial
Aquatic Biomes: lakes and ponds; rivers and streams; coastal ; brackish water
Other Habitat Features: agricultural ; riparian ; estuarine
Habitat and Ecology
Cygnus atratus eats sub-aquatic foliage that it can reach under water using its long neck. It is herbivorous, eating vegetation and plants either in the water or on land in pastures or on farm land. Some common aquatic plants that they feed on are: Typha, Potamogeton, Myriophyllum, Ruppia and algae. Occasionally they also eat insects.
Animal Foods: insects
Plant Foods: leaves; algae
Primary Diet: herbivore (Folivore )
Black swans are important members of thier eosystem both as a predator and as prey for other species.
Black swans flap their wings which produce loud noises and threaten predators with their necks erect and bills pointed down. Eggs are taken by Australian ravens, common rats and golden-bellied water rats, swamp harriers, white-bellied sea eagles, and other hawks. Fledglings are preyed on by swamp harriers, white-bellied sea eagles, quolls, golden-bellied water rats, and sometimes gulls and terns.
- Australian ravens (Corvus coronoides)
- swamp harriers (Circus approximans)
- common rats (Rattus rattus)
- hawks (Accipitridae)
- white-bellied sea eagles (Haliaeetus leucogaster)
- quolls (Dasyurus)
- gulls and terns (Laridae)
- golden-bellied water rats (Hydromys chrysogaster)
Known prey organisms
This list may not be complete but is based on published studies.
Life History and Behavior
Black swans use calls and visual signals to communicate. They have advertisment calls used in territorial defense and specific calls used in Triumph Ceremonies. They have a high pitched, weak voice. They also use visual displays to communicate such as raising their shoulders or flapping their wings to threaten predators or other swans in their territory.
Communication Channels: visual ; acoustic
Other Communication Modes: duets
Perception Channels: visual ; tactile ; acoustic ; chemical
Black swans have been known to live for forty years in the wild.
Status: wild: 40 (high) years.
Black swans are monogamous and often have the same mate for life. They are territorial and stay in solitary pairs when mating but are known to occasionally mate in colonies. The threatening behavior of black swans is similar to mute swans; they both flap and wave their wings with two or three strokes followed by a call. However, the wings of black swans make a louder sound than mute swans. Also the standing stance is different; black swans hold their necks erect with a downward point of the bill and ruffled feathers.
One particularly interesting thing about the courting behavior of black swans is the "Triumph Ceremony". It is used to strengthen pair-bonds between mates, between parents and cygnets (baby swans), and for threatening territorial displays. The male swan approaches the female swan with wings and chin lifted, calling repeatedly. Then the female returns the same call. They then dip their heads alternating with erect postures. After this the birds call with their necks outstretched and bills pointed upward; then they hold their necks at a forty five degree angle and point their bills downward and at a right angle, they proceed to swim in a circle. These ceremonies are primarily initated by the male and tend to increase in frequency when there are more swans around.
Mating System: monogamous
The breeding season is from February through September. Usually the female (occasionally the male) makes a nest of sticks, dead leaves and debris into a floating mound on top of the water. Each female may lay between 5 to 6 eggs, the eggs are laid one day apart. There is a 35 to 48 day incubation period which begins when all the eggs have been laid. Males are known to help with incubation. Chicks are precocial but are brooded on the nest for 2 to 3 weeks after hatching. They fledge from 150 to 170 days after hatching. They remain in family groups for about 9 months and are able to fly at around 6 months old. The chicks are sexually mature in 18 to 36 months. Young black swans join juvenile flocks for one to two years before they begin breeding.
Breeding interval: Black swans can breed repeatedly throughout the breeding season.
Breeding season: The breeding season is from February through September.
Range eggs per season: 5 to 6.
Range time to hatching: 35 to 48 days.
Range fledging age: 150 to 170 days.
Average time to independence: 12 months.
Range age at sexual or reproductive maturity (female): 18 to 36 months.
Range age at sexual or reproductive maturity (male): 18 to 36 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Both male and female black swans incubate the eggs. Chicks are precocial and can swim and feed soon after hatching. They may ride on their parents' backs when they venture into deep water. The chicks can fly in 2 months, but they remain in the family group until the next breeding season. Juvenile black swans often form flocks until they find a mate.
Parental Investment: no parental involvement; precocial ; pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Protecting: Male, Female); pre-independence (Protecting: Male, Female)
Molecular Biology and Genetics
Barcode data: Cygnus atratus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Cygnus atratus
Public Records: 2
Specimens with Barcodes: 4
Species With Barcodes: 1
Currently, black swans are not suffering from population declines. Populations range from the thousands up to tens of thousands in New South Wales.
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
Relevance to Humans and Ecosystems
Black swans are common crop pests, either destroying vegetation or uprooting it. In order to help control black swan populations, a hunting season has been established in some areas.
Negative Impacts: crop pest
Humans benefit from black swans because they eat their eggs and keep them as pets. They are also popular among birdwatchers.
Positive Impacts: pet trade ; food ; ecotourism
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. They are monogamous breeders that share incubation duties and cygnet rearing between the sexes.
Described scientifically by English naturalist John Latham in 1790, the Black Swan was formerly placed into a monotypic 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.
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. 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 centimetres (43 and 56 in) in length and weighs 3.7–9 kilograms (8.2–19.8 lb). Its wing span is between 1.6 and 2 metres (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.
The black swan is common in the wetlands of south western and eastern Australia and adjacent coastal islands. In the south west the range encompasses an area between North West Cape, Cape Leeuwin and Eucla; while in the east it covers are 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.
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 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.
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 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.
Before the arrival of the Māori in New Zealand, a subspecies of the black swan known as the New Zealand swan had developed in the islands, 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 and Lake Ellesmere, and the Chatham Islands. 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, especially Britain, 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 have recorded a maximum of nine breeding pairs in the UK in 2001, with an estimate of 43 feral birds in 2003/04.
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 (genus Typha) is the most important food of birds in wetlands, followed by submerged algae and aquatic plants like Vallisneria. In Queensland aquatic plants like Potamogeton 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.
Relationship with humans
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.
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