Casuarius casuarius johnsonii
The Southern Cassowary is a large seed-dispersing bird found in Indonesia, New Guinea and tropical Queensland, Australia.
Known as 'rainforest gardeners', the tropical forests would be a very different place without them. They eat fruits whole and spread seeds great distances.
Many plant species (especially those with big seeds) rely on them for seed dispersal and germination.
The cassowary is Australia’s heaviest bird, weighing up to 76kg! Reaching 1.8m in height they come second only to Emus (which can reach 2m).
Like the Emu and Ostrich, the Southern Cassowary is a ratite – a large flightless bird with unusual feathers, strong legs and other distinguishing features that point to its unique evolutionary history.
Two other cassowary species – the Dwarf Cassowary and Northern Cassowary – can be found in New Guinea and Indonesia.
The Southern Cassowary's dense, jet-black plumage allows it to blend into a dark rainforest environment, keep dry and protected from thorny plants.
The cassowary’s neck is bright blue and purple. Their nape and double wattle – the pouches of skin hanging from their neck – are coloured red. Chicks are striped dark brown and white.
Both sexes have a large casque or ‘helmet’ atop their heads. The outside of this protrusion is a tough keratinous material; inside it’s spongy.
Its use is unclear – it may be used to push through dense rainforest undergrowth, to show age or dominance, or to detect the booming call of other cassowaries.
The cassowary is of great cultural significance to many Traditional Owner groups from north Queensland. The bird appears in traditional stories, ceremonies and dances, and was an important source of food.
Where do Southern Cassowaries live?
While the Southern Cassowary (Casuarius Casuarius) is found in New Guinea, one subspecies – Casuarius casuarius johnsonii – lives in Australia. This southern cassowary subspecies is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999.
Cassowaries were once found across much of northern Queensland. They're now limited to three unconnected populations – one in the Wet Tropics and two in Cape York.
In 2014 scientists estimated the Australian population at 4,000 birds and numbers were declining.1
However, globally, the International Union for Conservation of Nature (IUCN) has lifted the status of Southern Cassowaries (Casuarius casuarius) from Vulnerable to of Least Concern.
Cassowaries live in tropical rainforests, melaleuca (paperbark) swamps, mangrove forests woodlands and can even be found foraging along beaches. They require this diverse range of habitats to ensure availability of fleshy fruits year round.
They're capable swimmers, known to swim across rivers and into the sea to escape dog attacks. They're territorial, with a home range up to 2.35 square kilometres.
Behaviour of Southern Cassowaries
Cassowaries are frugivores (fruit eaters), and are known to eat the fruits from 238 plant species.
Many species rely on cassowaries for seed dispersal and germination. For this reason they're known as a 'keystone' species. They've also been called a rainforest gardener, swallowing fruit whole and spreading the seeds great distances. They also occasionally eat small vertebrates, invertebrates, fungi and carrion (dead animals).
They breed when fruit is most abundant – from June to October. The female lays three to five large green eggs in a simple nest scraped in the ground and lined with leaves. Once she's laid the eggs, the female leaves. The male then incubates the clutch for 50 days, raises and protects the chicks for about a year, and then chases them away. Cassowaries can live to 40 years in the wild.
Cassowaries make deep booming and rumbling noises, and hiss when threatened. For such a large bird, they're quite elusive. Typically shy and solitary, they can become aggressive when threatened.
Each foot has three toes and the middle toe has a long claw up to 12cm in length. Normally used to scratch for food and to fight other birds, there have been very rare instances when cassowaries have inflicted serious injuries to people and pets. The majority of these incidents are due to cassowaries searching for food from people due to a shortage of foraging habitat.
Threats to Southern Cassowaries
Habitat destruction and fragmentation are the main causes of the cassowary's dramatic decline. Land clearing for farming and urban development have greatly reduced their habitat. Cyclones in 2006 and 2011 also depleted their food sources and many birds died from starvation.
After cyclones cassowaries venture closer to human settlements, and this makes them more vulnerable to existing threats, especially dog attacks and collisions with vehicles. Road accidents are a large source of mortality. Finally, predation by feral pigs, and diseases such as tuberculosis, also affect their survival.
What's Bush Heritage doing?
Cassowaries are found on Fan Palm Reserve where we’re protecting their food source by controlling feral pigs.;
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1. IUCN Red List (see also Garnett, S. T.; Szabo, J. K.; Dutson, G. 2011. The Action Plan for Australian Birds 2010. CSIRO Publishing, Collingwood.)