The southern cassowary
Threatened species and communities
The southern cassowary is one of Australia's most imposing birds – large, colourful, and flightless. It is found only in the dense tropical rainforests of north-east Queensland. Continuing clearing and fragmentation of rainforest, and increased mortality from cars and dogs have reduced cassowary numbers to perhaps as few as around 2000, threatening the species with extinction.
The southern cassowary Casuarius casuarius belongs to an ancient group of flightless birds that includes Australia's emu, Africa's ostrich and New Zealand's kiwi and now-extinct moa. As tall as an adult human (up to 170 centimetres), the female southern cassowary is Australia's heaviest bird. The cassowary has draping, shiny black plumage and a colourful naked neck and head – brilliant blue and purple with long, drooping red wattles and an amber eye – topped with a helmet-like structure known as a casque. The colour of the skin changes with mood, brightening when the bird is aroused.
The cassowary has no tail, and its wing stubs carry a small number of long, modified quills, like rounded fingernails, which curve around the body. Each heavy, well-muscled leg has three toes, with the inside toe bearing a large dagger-shaped claw that can be used in defence. When the bird is cornered or protecting chicks, it kicks out with both feet at once, and can injure, or even kill, dogs or humans. More usually, it dashes off when alarmed, head lowered, casque first, through the heavy undergrowth. It reaches 40 kilometres per hour in short sprints and can even swim.
Illustration by Barbara Cameron Smith
While the southern cassowary Casuarius Casuarius is found in New Guinea and surrounding islands, one subspecies – Casuarius casuarius johnsonii – lives in Australia, mostly in dense, tropical rainforests that provide a supply of fruit all year round.
This southern cassowary subspecies is listed as endangered under the Environment Protection and Biodiversity Conservation Act 1999, the main Commonwealth legislation for protecting the environment and conserving biodiversity.
At the time of European settlement, the cassowary lived in tropical rainforests from Paluma Range (north of Townsville) to the tip of Cape York. Today, the species is listed as nationally endangered, and it is estimated that there are less than 2200 individuals in populations near Mission Beach and Cooktown and on Cape York.
More often heard than seen, the cassowary is most active at dawn and dusk, and rests in a sunny, sheltered spot in the middle of the day. Individuals have large home ranges, of up to seven square kilometres.
The cassowary uses its feet and its hard, helmet-like casque to sift through leaf litter, mostly for a wide variety of fallen fruit, but also for dead animals, snails, fungi and other rich organic matter, and it occasionally plucks fruit from low branches. The bird swallows fruit whole and the seeds can end up in large piles of multicoloured dung – a ready-made fertiliser. The cassowary is critical to the survival of many rainforest plants, spreading the seeds of about 150 species. Rats and small marsupials sometimes feast on seeds in the droppings.
Cassowaries have distinctive mateship rituals. The female has an impressive display when proclaiming her territory. Her feathers bristle and, with her neck arched down, she puffs out her throat to make a thunderous booming sound, the effort shaking her whole body. Females are the bigger, more colourful sex, weighing up to 85 kilograms, compared to the male's 40 kilograms.
Between June and August, the male builds a flat dish of leaves, grass and sticks on the forest floor or among grass at the forest edge, using the same nesting site over many years. Into this nest, the female lays from three to five large, glossy, pale pea-green eggs, each weighing about 600 grams. The male sits on them for about 50 days, rarely eating or drinking. Hours after hatching, the brown and buff striped chicks can walk and feed themselves, but the male protects them for nine months or more. The chicks that survive mature at two to three years and can live as long as 40 years.
Male adult cassowary on nest with chicks
Illustration by Sharyn Wragg
Only 20-25% of former cassowary habitat remains, and much of it is still under pressure.
Threats to the southern cassowary include:
- vehicle traffic – road kills are a major cause of adult cassowary deaths
- dogs, which attack and kill chicks and juveniles
- feral pigs, which damage cassowary habitat.
To survive, cassowaries need large areas of rainforest. There is a need for protection of existing habitat and greater control of dogs and pigs. As well as creating protected areas such as national parks, some local residents are establishing nurseries of cassowary food plants to restore rainforest on cleared land and create corridors to link remaining patches of vegetation.
- Marchant S and Higgins PJ (1990). Handbook of Australian New Zealand and Antarctic Birds, Volume 1. Ratites to Ducks. Oxford University Press, Melbourne.
- Olsen P, Crome F and Olsen J (1993). The Birds of Prey and Ground Birds of Australia. Angus and Robertson and the National Photographic Index of Australian Wildlife, Sydney.
Threatened Species Ecosystems Unit
Queensland Parks and Wildlife Service
PO Box 155
Brisbane Albert Street
Phone 07 3225 1295