Southern Cassowary

WHAT’S IN A NAME?

The genus and species names Casuarius casuarius are the Latinized version of the Malay word for this bird, kesuari. This word probably originated from the Papuan Malay words kasu meaning ‘horned’ and weri meaning ‘head’ in reference to the cassowary’s distinctive casque.

There are actually three species of cassowary:  the dwarf cassowary and the northern cassowary which are found only in New Guinea, and our own southern cassowary. It’s also found in New Guinea and adjacent islands, but is the only species that also occurs as far south as Australia, hence its name.

The southern cassowary is also known as the double-wattled cassowary, Australian cassowary and two-wattled cassowary, but here in Australia it’s usually referred to simply as a cassowary.

Fun Fact: The cassowary is the second largest bird in the world by weight! In spite of its size and bright colouration, it is secretive and difficult to see in dense rainforest.

As a flightless bird (one of the ratite family) it has only vestigial wings, comprising 5-6 bare quills.

The body feathers are unusual in that they have a quill that splits in two and they lack the barbules that normally hold feathers together. They look more like hairs, and because they don’t lie flat against its body they help to give the bird its bulky appearance.  The spine of the feather (the rachis) is more exposed to the light than in other birds, giving the cassowary a glossy appearance overall—it seems to shine in sunlight!

Cassowaries communicate through a range of low-frequency guttural vocalizations: hissing, rumbling, coughing and booming noises.  Their purpose may be to attract and court a mate, to warn off other cassowaries and to communicate with chicks.

The distinctive casque, or helmet, on the head of the cassowary is a unique feature!  It has an external sheath of keratin which is pliable and somewhat leathery. Beneath this is a bony core which surrounds an internal mass of spongy connective tissue (trabeculae) and an air-filled cavity.

The casque starts to form in juveniles at about 6months of age.  It can become warped or misshapen over time from accidents or injuries. This makes each casque unique, and helps to identify individual birds.

The function of the casque is not entirely clear.  It has been suggested that the casque helps to amplify vocalizations in dense rainforest. It may have a role in sexual displays. It may even help with thermoregulation by dissipating excess heat.  More research is needed into this fascinating structure!

WHERE DOES IT LIVE?

In Australia southern cassowaries are found only in the wet tropics of far north Queensland, from the northeast coast of Cape York to the Paluma Range north of Townsville.   Within this range they may venture into adjacent habitats such as eucalyptus, mangrove or tea tree and even onto the beach!

Wherever they live, they need access to clean fresh water for drinking and bathing.

Fun Fact: in spite of their bulk, cassowaries are actually good swimmers!

WHAT DO THEY EAT?

Their main diet is rainforest fruit. They prefer fruit that has fallen to the ground, but will sometimes eat fruit from low-hanging branches, and have even been observed jumping to pluck fruit such as figs from higher branches and tree trunks.

Cassowaries eat the fruit of over 240 rainforest trees, shrubs and vines, including quandongs, Davidson plums and native laurels and palms.

They will also eat fungi, flowers, insects, snails, and small vertebrates—just about anything edible!

Food is swallowed whole, and cassowaries are able to eat many rainforest fruits that are too large for other birds.

Fun Fact: Cassowaries do not have a tongue! To manipulate and swallow food they toss it to the back of their throat.  To drink water they scoop it up with their lower beak.

REPRODUCTION

Adult cassowaries are solitary for most of the year. If two males should meet, they will fluff out their feathers and make rumbling noises till one retreats. If a male and female meet, the female can intimidate the male into retreating.

During the breeding season, from May to November, females become more tolerant, and will seek out males to form courting pairs.  At this time the colours of her neck and wattle become more intense. The pair stays together for a few weeks while the male displays through dance, display and vocalization until she’s ready to mate and lay her eggs.

The nest is just a thin mattress of grass and other soft vegetation scraped together in a protected, elevated position in dense scrub or rainforest. Few nests have actually been sighted.

The female lays on average 3 or 4 large eggs, with average dimensions of  138 mm (5 1/2”)  by 95 mm(3 3/4“). They are pale greenish white, covered with an outer bright green membrane. This fades in time to a dull pea-green colour.

After laying her eggs the female leaves the site and takes no more interest in the eggs. She may even seek out other males to mate with.

Meantime, the male incubates the eggs on his own for up to 2 months, during which time he hardly leaves the nest to eat or drink.

Newly hatched chicks are striped cream and dark brown in appearance. This colour pattern helps camouflage them in the dappled sunlight of the rainforest. The male looks after them and can become quite aggressive in their defence.

At about 6 months the chicks lose the stripes and become a drab brown colour. After about 9 months the male chases them away to find their own territory. During this time they are vulnerable to predators and other threats.

The young will not fully develop the glossy black plumage and brightly coloured neck and wattles till about 3 years of age.  By this time they will be sexually mature.

Fun Fact: Cassowaries can live up to 40 years in the wild, and some captive birds have lived longer than 60 years!

STATUS IN THE WILD

The southern cassowary is listed as endangered at both the Queensland state and Australian government levels.

Recent surveys suggest there may be fewer than 4600 cassowaries left in the wild.

Why are they in decline? There are so many threats to their survival, including:

Loss of habitat as rainforests are cleared for housing and for agriculture.

Fragmentation of habitat. This can disrupt cassowary movement patterns, and can separate parts of individual territories, forcing the birds out into the open.

Car strikes. Car strikes are the leading cause of cassowary death, especially in the Mission Beach area. Between 1992 and January 2014 there were 104 deaths from vehicle strikes.

Attacks by dogs. Attacks by domestic and feral dogs are a major cause of mortality and injury around developed areas

Cyclones. Although a natural feature of the tropics, cyclones destroy large tracts of rainforest every year. When food is scarce, cassowaries are forced out into the open, increasing their exposure to risk. In the wake of Cyclone Larry in 2006, one-third of the local cassowary population died.

A KEYSTONE SPECIES

Cassowaries play a crucial role in the diversity and ecological balance of tropical rainforest ecosystems.

Their main food is the fruit of rainforest trees. Only the soft fleshy portion is digested, so the seeds that are excreted are still viable. As the cassowary travels through the rainforest, it deposits these seeds in their own pile of ‘fertilizer’, often far from where they were originally picked up.

Whilst other animals may disperse seeds in a similar manner, the fruits of as many as 70 species of rainforest trees are so large that the cassowary is the only creature that can swallow them whole. 

Without the cassowary, our tropical rainforests would gradually change and become less diverse.

HOW CAN WE HELP?

There is much that we as individuals can do to protect cassowaries and ensure the continued health of our amazing tropical rainforests:

Support the work of conservation organizations such as Rainforest Rescue.

SLOW DOWN when driving through areas in north Queensland where cassowaries are found, for example in Mission Beach.

Never offer food to a cassowary, either in your backyard or from your car. Once a cassowary associates humans with food, it will wander through suburbs, becoming vulnerable to car strikes and dog attacks.

If you live in areas where cassowaries occur, keep your dog confined in your yard.

CASSOWARIES AT BILLABONG SANCTUARY

Billabong Sanctuary is a proud partner in the Southern Cassowary Captive Management Programme of the Zoo Aquarium Association Australasia (ZAA). The aim is to maintain a healthy breeding population in zoos across Australia.

Captive birds are valuable ambassadors for their species, educating visitors about their importance to rainforest health, as well as  the role that we as individuals can play in helping to protect this species.

Captive birds also provide the opportunity for much-needed research into rainforest conservation. For example, James Cook University (JCU) is currently conducting studies at Billabong Sanctuary into a cassowary-proof design for feral pig baiting stations.

Our female cassowary Hope was hatched at Perth Zoo and joined us here in 2013 when she was 9 months old.  In 2019 she was joined by Troppo, who is here on a breeding loan from Currumbin Wildlife Sanctuary.

Every morning visitors have the amazing opportunity to hand-feed one of these magnificent ‘gardeners of the rainforest’.

An experience not to be missed!

Further Reading

https://www.qld.gov.au/environment/plants-animals/animals/living-with/southern-cassowary

Australian Bird Names. A Complete Guide.  2013 – Ian Fraser and Jeannie Gray. CSIRO Publishing  

Australian Birds their Nests and Eggs. 2003. Gordon Beruldsen.

Reader’s Digest Complete Book of Australian Birds. 1990. Reader’s Digest

https://tetzoo.com/blog/2022/4/9/inside-the-cassowarys-casque-updated

Searching for Pekpek: Cassowaries and Conservation in the New Guinea Rainforest. 2014 Andrew L Mack