Southern Cassowary (Casuarius casuarius): Facts and Habitat

What does a southern cassowary look like?

An adult southern cassowary is covered in coarse, glossy black feathers that look more like hair than plumage. Each feather has two long, loose shafts, and the plumage hangs down over the body like a shaggy coat. This helps shed rain and protects the bird as it pushes through dense undergrowth.

The bare skin of the head and neck is vivid blue, with red on the back of the neck and two red wattles, up to about 18 cm (7 in) long, hanging from the throat. The name “double-wattled cassowary” comes from these wattles, which separate the southern species from its two relatives, the northern cassowary and the dwarf cassowary of New Guinea.

On top of the head sits a tall, brownish casque, a helmet-like crest usually about 13–18 cm (5–7 in) high. It is covered by a hard sheath of keratin, the same material as fingernails, and grows larger with age. Its purpose is still debated, as explained in what a cassowary’s casque is for.

The wings are tiny and almost hidden. Each carries a few stiff, bare quills that look like thick black spines. The legs, by contrast, are massive. Each foot has three toes, and the inner toe bears a straight, sharp claw up to about 12 cm (4.7 in) long.

Males and females look alike, but females are larger, with a taller casque and brighter skin. Chicks are pale brown with dark lengthwise stripes, which they lose after a few months. Young birds then turn plain brown before gaining black adult plumage and a full casque over their first 3–5 years.

How big is a southern cassowary?

The southern cassowary is one of the largest birds in the world. Only the two ostrich species are heavier on average, and it is the heaviest bird outside Africa. It usually stands 1.5–1.8 m (4 ft 11 in–5 ft 11 in) tall, and the largest reliably measured birds reach about 2 m (6 ft 7 in).

Females are clearly the larger and dominant sex, a pattern called reverse sexual size dimorphism. The heaviest modern wild birds are thought to reach around 85 kg (187 lb). Nineteenth-century hunters in Queensland reported much heavier birds, but those weights are old and unverified. To see how it compares with other giants, see the largest birds in the world.

Where do southern cassowaries live?

Southern cassowaries live in the lowland tropical rainforests of southern New Guinea, shared by Papua New Guinea and Indonesia, and on some nearby islands such as the Aru Islands. A population on the Indonesian island of Seram may have been introduced by people long ago, since cassowaries have been traded across the region for centuries.

In Australia the species survives only in northeastern Queensland, mainly in the Wet Tropics between Townsville and Cooktown and in patches of Cape York Peninsula. Here it lives mostly below about 1,100 m (3,600 ft), while in New Guinea it is usually found below about 500 m (1,600 ft).

Rainforest is its core habitat, but cassowaries also use swamp forest, mangroves, nearby eucalypt woodland and fruit-bearing gardens on forest edges. Each bird needs a large home range to find enough fruit through the year.

What do southern cassowaries eat?

Southern cassowaries are mainly fruit eaters. They walk the forest floor picking up fallen fruit and swallow much of it whole, including fruits as big as a tennis ball. Studies of their droppings in Queensland have found the remains of well over 200 plant species, including laurels, palms, quandongs, figs and lilly pillies of the myrtle family.

Fruit makes up most of the diet, but cassowaries are opportunists. They also eat fungi, snails, insects and other invertebrates, and occasionally fish, frogs, small birds, eggs, small mammals and carrion. They can eat some fruits that are poisonous to many other animals.

Because fruit passes through the gut quickly, often within a day, seeds are dropped in a pile of dung far from the parent tree. For many large-seeded rainforest plants the cassowary is one of the few animals able to swallow and spread their seeds, which is why ecologists call it a keystone species of the Wet Tropics.

Behavior and communication

Cassowaries are shy, solitary birds that usually avoid people. Adults live alone within large home ranges that overlap with those of other birds, and they meet mainly to breed. They are most active in the early morning and late afternoon and often rest during the heat of the day.

Despite their bulk, they are fast and agile. A cassowary can run at up to about 50 km/h (31 mph) along forest paths, leap high when startled and swim strongly across rivers and streams.

Cassowaries communicate with hisses, rumbles and very deep booming calls. Some of these calls are so low that they sit near the lower limit of human hearing, and low sounds travel well through dense forest. Chicks keep in contact with their father using high whistles and chirps.

When threatened or cornered, a cassowary can defend itself with forward kicks of its powerful legs and sharp inner claws. Most attacks on people involve birds that have learned to expect food, as described in is the cassowary the most dangerous bird?.

How do southern cassowaries breed?

The breeding season in Australia mostly runs from about June to October, during the cooler, drier months, but it varies. Males and females pair briefly. The male builds a simple nest on the ground, a mat of leaves and plant litter about 5–10 cm (2–4 in) thick and up to about 1 m (3.3 ft) across.

The female lays a clutch of usually 3–5 large eggs that are glossy pea-green when fresh and fade with age. Each egg is about 12–16 cm (4.6–6.2 in) long and weighs roughly 570–630 g (1.3–1.4 lb). Once she has laid, the female leaves. She may then mate with another male and lay a second clutch in his territory, a breeding system in which one female has several male partners.

The male incubates the eggs alone for about 50 days, eating little in that time. After hatching, the striped chicks can walk within hours and follow their father, who guards them and leads them to food for around 9 months or more. Young birds become independent at about 9–12 months and usually start breeding at about 3–5 years old, when the casque and adult plumage are fully developed.

How long do cassowaries live?

The lifespan of wild southern cassowaries is poorly known, because individual birds are hard to follow in dense rainforest over many years. Adults have few natural predators and are thought to live for several decades.

In zoos, cassowaries have lived 40 years or more. Survival is lowest for chicks and young birds, which are taken by predators such as feral pigs and dogs, and many birds of all ages die on roads.

Predators and threats

Adult cassowaries have few natural enemies. In New Guinea, people have long hunted them for meat and feathers. In Australia, the main threats are human ones:

• Habitat loss: clearing of lowland rainforest for farming, towns and roads has removed much of the cassowary’s best habitat, especially in Queensland.
• Road deaths: vehicle strikes are one of the leading known causes of death in Australia, particularly where roads run through or beside rainforest.
• Dog attacks: domestic and feral dogs kill chicks and young birds and can injure adults.
• Feral pigs: introduced pigs eat eggs, compete for fallen fruit and damage the forest floor.
• Cyclones: severe tropical cyclones, such as Cyclone Larry in 2006 and Cyclone Yasi in 2011, strip fruit from trees and leave birds short of food.
• Feeding by people: birds that are fed lose their fear of people, move toward roads and gardens and become more likely to be hit by cars or to approach people.

Conservation status

The IUCN lists the southern cassowary as Least Concern across its whole range, because it still occupies a large area of New Guinea where much forest remains. The population is, however, thought to be decreasing, and the total number of wild birds is uncertain. One older estimate put it at roughly 10,000–20,000.

The Australian population is much smaller and is listed as Endangered under Australian federal law. Estimates have varied widely over the years, from a few thousand to around 5,000 birds. Protection of large areas of the Wet Tropics World Heritage Area, wildlife corridors, lower speed limits and warning signs on roads, and education campaigns against feeding are all used to help the birds.

Myths and facts about cassowaries

Myth: The cassowary is the most dangerous bird in the world. It can certainly injure people, but in more than a century only two human deaths caused by southern cassowaries are well documented, and one of those involved a captive bird. Most attacks are linked to birds being fed.

Myth: The casque is a bony battering ram. Cassowaries do not ram through the forest head first. The casque has a light, spongy core inside its keratin covering and is more likely used for display, sound or shedding heat.

Fact: Cassowaries look like dinosaurs for a reason. Their scaly legs, three-toed feet and large claws recall their theropod ancestors. All birds are living dinosaurs, as explained in are birds dinosaurs?.

Cassowaries and people

Cassowaries have been important to the peoples of New Guinea and northern Australia for thousands of years. In New Guinea, they have been hunted, kept and traded alive, and their feathers, bones and claws have been used for ornaments and tools. Some scientists have suggested that people in New Guinea may even have collected cassowary eggs and raised the chicks as long as 18,000 years ago.

In Australia today, the cassowary is a flagship animal of the Wet Tropics. Towns such as Mission Beach celebrate the bird, and visitors may see one crossing a road or walking through a rainforest park. The best way to see a wild cassowary is from a distance, quietly, without ever offering food. It is the closest living relative of the emu, and like the emu its father is the only parent that raises the young.