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Wednesday, July 10, 2013

Species Fact Profile: Black Swan (Cygnus atratus)

Black Swan

Cygnus atratus (Latham, 1790)

Range:  Australia (Includes Tasmania)
Habitat:  Lakes, Rivers, Wetlands
Diet:  Aquatic Plants, Grasses, Insects
Social Grouping: Pairs, Family Groups, Loose Colonies
Reproduction: Monogamous (often for life), breed February through September; a nest of sticks and leaves is built on a floating mound in water; the 5-6 eggs are incubated for 35-48 days by both parents, chicks fledge 150-170 days, are independent at 9 months, and sexually mature at 18-36 months; juveniles form their own flocks
Lifespan:  40 Years
Conservation Status: IUCN Least Concern

  • Body length 110-140 centimeters, wingspan 160-200 centimeters, weight 3.7-8.7 kilograms (males are slightly larger than females)
  • Black plumage with some white wing feathers, a red bill, and red or pink irises; juveniles are gray-brown with lighter bills than the adults
  • Black swans have the longest neck in relation to their body size of any swan species; the neck is often curved into “S” shape
  • Birds molt after the breeding season and unable to fly for a month or so
  • The least territorial of all swans, they sometimes form colonies
  • Largely sedentary, they will become nomadic in times of food scarcity
  • Adults have few predators, but eggs and fledglings can be taken by ravens, raptors, gulls, predatory marsupials, and rodents
  • They have been introduced to Europe and North America; vagrants have been reported in Indonesia and New Guinea
  • A subspecies (C. a. sumnerensisi) was hunted to extinction present in New Zealand; birds of Australian stock were then introduced to New Zealand and have become established
  • Considered a crop pest in some areas, they hunted legally during a short annual season
  • State bird of Western Australia, appearing on Coat of Arms and flag; important in aboriginal lore (in most versions, swans were originally people; in some versions they were originally white and were given black feathers by crows)
  • Prior to 1697 discovery, “black swan” was European metaphor for something that couldn’t exist

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