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By Cheryl Jackson
Geographic Range
Cygnus atratus, commonly known as black swans, are native to Australia and Tasmania but have been introduced to New Zealand and Europe. Black swans are found mainly in the wetlands of Southern Australia and tend to avoid the northern tropics. They can also be found in southeast Australia to southwest 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:
palearctic 
(introduced ); australian (native ); oceanic islands (introduced ).
Habitat
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. ()
These animals are found in the following types of habitat:
temperate ; tropical ; terrestrial .
Aquatic Biomes:
lakes and ponds; rivers and streams; coastal ; brackish water .
Wetlands: swamp .
Other:
agricultural ; riparian ; estuarine .
Physical Description
(130.24 to 306.24 oz)
(3.61 to 4.59 ft)
(62.99 to 78.74 in)
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. ()
Some key physical features:
endothermic ; bilateral symmetry .
Sexual dimorphism: male larger.
Reproduction
Black swans can breed repeatedly throughout the breeding season.
The breeding season is from February through September.
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 systems:
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. ()
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).
Lifespan/Longevity
Black swans have been known to live for forty years in the wild. ()
Behavior
Black swans tend to move in flocks; they are the least territorial of all swans and sometimes nest in colonies. They are nomadic when food is scarce but are otherwise sedentary. They feed at dusk and travel at night, calling as they fly. ()
Home Range
We do not have information on home range for this species at this time.
Key behaviors:
flies; natatorial ; nocturnal ; motile ; nomadic ; sedentary ; territorial ; social ; colonial .
Communication and Perception
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. ()
Other communication keywords:
duets .
Food Habits
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.
Predation
- 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)
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, swamp harriers, common rats, hawks, and white-bellied sea eagles. Fledglings are preyed on by swamp harriers, white-bellied sea eagles, quolls, and sometimes gulls and terns. ()
Ecosystem Roles
Black swans are important members of thier eosystem both as a predator and as prey for other species.
Economic Importance for Humans: Negative
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. ()
Ways that these animals might be a problem for humans:
crop pest.
Economic Importance for Humans: Positive
Humans benefit from black swans because they eat their eggs and keep them as pets. They are also popular among birdwatchers. ()
Ways that people benefit from these animals:
pet trade ; food ; ecotourism .
Conservation Status
Currently, black swans are not suffering from population declines. Populations range from the thousands up to tens of thousands in New South Wales. ()
Contributors
Cheryl Jackson (author), University of Michigan-Ann Arbor.
Phil Myers (editor), Museum of Zoology, University of Michigan. Alaine Camfield (editor), Animal Diversity Web.
