Cygnus atratusblack swan

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Geographic Range

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. (del Hoyo, et al., 1992; Delacour, 1954)

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. (del Hoyo, et al., 1992; Delacour, 1954; Forshaw, 1998)

Physical Description

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"). (del Hoyo, et al., 1992; Delacour, 1954; Johnsgard, 1965)

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. (del Hoyo, et al., 1992)

  • Sexual Dimorphism
  • male larger
  • Range mass
    3700 to 8700 g
    130.40 to 306.61 oz
  • Range length
    1.1 to 1.4 m
    3.61 to 4.59 ft
  • Range wingspan
    160 to 200 cm
    62.99 to 78.74 in

Reproduction

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. (Delacour, 1954; Forshaw, 1998; Johnsgard, 1965)

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. (Johnsgard, 1965; Kraaijeveld and Mulder, 2002)

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. (del Hoyo, et al., 1992; Forshaw, 1998; "Black Swan", Date Unknown; Wilmore, 1974)

  • 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

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. (del Hoyo, et al., 1992; Kraaijeveld and Mulder, 2002; "Black Swan", Date Unknown)

  • 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. ("Black Swan", Date Unknown)

  • Range lifespan
    Status: wild
    40 (high) years

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, but most activity is during the day. (del Hoyo, et al., 1992; Delacour, 1954; "Black Swan (Cygnus atratus)", 2003; "Black Swan", Date Unknown)

Home Range

We do not have information on home range for this species at this time.

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. (Delacour, 1954; Johnsgard, 1965; Kraaijeveld and Mulder, 2002)

  • Other Communication Modes
  • 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. (del Hoyo, et al., 1992)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • algae

Predation

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. (Johnsgard, 1965; Wilmore, 1974)

Ecosystem Roles

Black swans are important members of thier eosystem both as a predator and as prey for other species.

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. (del Hoyo, et al., 1992; Delacour, 1954; Johnsgard, 1965)

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. (del Hoyo, et al., 1992)

  • Negative Impacts
  • crop pest

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. (del Hoyo, et al., 1992)

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Cheryl Jackson (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

herbivore

An animal that eats mainly plants or parts of plants.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Sedgwick County Zoo. 2003. "Black Swan (Cygnus atratus)" (On-line). Accessed April 06, 2004 at http://www.scz.org/animals/s/bswan.html.

The Chaffee Zoo. Date Unknown. "Black Swan" (On-line). Accessed April 06, 2004 at http://www.chaffeezoo.org/animals/blackSwan.html.

Delacour, J. 1954. Waterfowl of the World. London: Country Life Limited.

Forshaw, J. 1998. Aniseriformes. Pp. 84 in Encyclopedia of Birds, Vol. 1, 2nd Edition. McMahons Point, N.S.W.: Weldon Owen.

Johnsgard, P. 1965. Handbook of Waterfowl Behavior. Ithaca, New York: Comstock Publishing Associates.

Kraaijeveld, K., R. Mulder. 2002. The Functions of the Triumph Ceremonies in the Black Swan. Behavior, 139(1): 45-54.

Wilmore, S. 1974. Swans of the World. New York, New York: Taplinger Publishing Co..

del Hoyo, J., A. Elliott, J. Sargatal. 1992. Black Swan. Pp. 578 in Handbook of the Birds of the World, Vol. 1, 1st Edition. Barcelona: Lynx Edicions.