Cassowary Facts

Females stand up to about 5.6 feet and can weigh up to 167 pounds; in a reversal of the usual pattern, males are smaller (around 110 pounds) and duller. The body is covered in coarse, hair-like black feathers that give no lift and little warmth but shield the skin from thorns and vines in thick undergrowth; the wings are vestigial stubs ending in bare keratin quills. The bare neck is vivid blue, purple, and red, hung with two red throat wattles, and the skull carries the casque — a tall, blade-like keratin helmet over spongy bone whose function is still debated (crash helmet, sound resonator, or heat radiator). The signature feature is the foot: a straight inner claw of 4 to 5 inches, driven by powerful legs into a forward kick that can inflict deep wounds. It is a ratite, kin to the ostrich, emu, rhea, and kiwi; the family Casuariidae holds three cassowary species.

The southern cassowary is restricted to dense tropical rainforest in New Guinea, the Aru Islands, and a small, fragmented strip of the Wet Tropics coast in Far North Queensland, Australia. It is an obligate rainforest dweller, needing large tracts of continuous, multi-canopied forest — with mangrove and eucalyptus edges — to find fruit year-round. It moves along the forest floor and swims well, handling strong currents and even crossing to offshore islands.

Despite their fearsome reputation, cassowaries are mainly frugivores: more than 90% of the diet is fallen fruit, topped up with fungi, snails, insects, and the occasional small vertebrate or carrion. Their gut handles toxic, fibrous rainforest fruits like the cassowary plum, passing food through quickly so little toxin is absorbed, and stripping the flesh while passing large seeds intact — deposited whole, in dung, well away from the parent tree. This makes the cassowary a keystone of the Australian rainforest: over 100 tree species rely on it to move their large seeds, because no other native animal has a wide enough gape to swallow them.

Cassowaries are solitary and territorial, each defending a home range that can span several square miles; when two meet, the smaller bird — usually the male — retreats, and confrontations involve raised feathers, hissing, and striking the ground. Because dense forest soaks up higher-pitched sound, they communicate over distance with infrasound, a deep resonating "boom" of about 23 to 32 Hertz near the bottom of human hearing, that carries through the vegetation to signal territory and readiness to breed without any visual contact.

Cassowary breeding reverses the usual bird roles. In the dry season, when fruit peaks, a female enters a male's territory, mates, and lays three to five large lime-green eggs in a leaf-lined scrape — then leaves to find and mate with other males. The male does all the work: he incubates for about 50 days, barely eating and losing weight, then raises the striped, camouflaged chicks alone, guiding their foraging and guarding them from wild dogs and feral pigs for up to 16 months before driving them off as they grow their adult casque. Wild cassowaries can live up to 20 years.

The southern cassowary is Vulnerable. Interior New Guinea populations are fairly stable, but the Australian population has declined sharply to around 4,000 birds. The main driver is habitat loss: clearing in the Wet Tropics for housing, sugarcane, and infrastructure has fragmented the forest, forcing birds across busy highways — vehicle strikes are now the leading cause of adult death in Australia. Residential spread also brings dogs that kill chicks and sub-adults, and feral pigs that compete for fruit and wreck nests. Conservation centers on halting rainforest clearing, building corridors and road crossings, and regulating dogs in cassowary country — because losing the bird would ripple through every tree that depends on it.

• Rainforest Rescue - Save the Cassowary
• San Diego Zoo Wildlife Alliance - Cassowary
• Australian Government Department of Climate Change, Energy, the Environment and Water - Southern Cassowary
• IUCN Red List - Casuarius casuarius