The southern cassowary (Casuarius casuarius), also known as double-wattled cassowary, Australian cassowary, or two-wattled cassowary, is a large, flightless, mostly black bird, found in Indonesia, Papua New Guinea, and northeastern Australia. It is one of the three living species of cassowary, alongside the dwarf cassowary and the northern cassowary. It is a ratite and therefore related to the emu, ostrich, rhea and kiwi. Southern cassowaries are among the largest birds in the world, only weighing less than ostriches. The Australian population is listed as Endangered under federal and Queensland state legislation.
Taxonomy Presently, most authorities consider the southern cassowary monotypic, but several subspecies have been described. It has proven very difficult to confirm the validity of these due to individual variations, age-related variations, the relatively few available specimens (and the bright skin of the head and neck – the basis upon which several subspecies have been described – fades in specimens), and that locals are known to have traded live cassowaries for hundreds, if not thousands of years, some of which are likely to have escaped/been deliberately introduced to regions away from their origin. Cassowaries are the sister lineage of emus, both being in the family casuariidae. The binomial name Casuarius casuarius is derived from its Malay name kesuari. The southern cassowary was first described by Carl Linnaeus, in his 18th-century work Systema Naturae, as Struthio casuarius, from a specimen from Seram, in 1758. It is now the type species of the genus Casuarius. Common names for the species include southern cassowary, double-wattled cassowary, Australian cassowary, and two-wattled cassowary. The southern cassowary has been described under a large number of scientific names, all of which are now considered taxonomic synonyms for the species.
Description
The adult southern cassowary has stiff, bristly black plumage, a blue face and a long neck, red on the cape and two red wattles measuring up to 18 cm (7.1 in) in length hanging down around its throat. A horn-like brown casque, measuring 13 to 20 cm (5.1 to 7.9 in) high, sits atop the head. The bill can range from 9.8 to 19 cm (3.9 to 7.5 in). The plumage is sexually monomorphic, but the female is dominant and larger with a longer casque, larger bill and brighter-coloured bare parts. Plumage of the southern cassowary develops as it grows, juveniles with soft, fuzzy and striped plumage for the first few months. Immature birds are covered in hair-like brown plumage, and as they grow, the feathers darken. The three-toed feet are thick and powerful, equipped with a lethal dagger-like claw up to 12 cm (4.7 in) on the inner toe. Southern cassowaries are among the largest living birds, only being lighter on average than ostriches, the largest contemporary individuals have been recorded around 85 kg (187 lb) and 2 m (6 ft 6+1⁄2 in) tall. Typically, the bird stands 1.5–1.8 m (4.9–5.9 ft) in height. Male southern cassowaries are lighter than the females, weighing between 29.2–55 kg (64–121 lb). Adult female birds can weigh from 46.7 kg (103 lb) to 76 kg (168 lb). From 1870 to 1894, Archibald Meston, Robert Johnstone, and others had shot, weighed, and documented southern cassowaries in Queensland that far exceeded typical mass. These specimens ranged in mass from 168–263 lb (76–119 kg). In 1889, Meston claimed the specimen shot by John Nairne was weighed at 263 lb (119 kg) although he later cited the figure as 280 lb (130 kg) and 250 lb (110 kg). Meston had written, "there is no reason to suppose that was the largest living specimen" in reference to this specimen. With powerful legs, the southern cassowary can run at speeds of up to 50 km/h (31 mph) and jump nearly 2 m (6.6 ft) vertically. They are strong swimmers capable of moving across rivers and streams.
Research In 2026, scientists discovered that southern cassowary casques glow under ultraviolet light, and in different patterns than northern cassowary casques.
Range and habitat The southern cassowary is distributed in Indonesia, Papua New Guinea, and northeastern Australia. It mainly inhabits tropical rainforests but may make use of nearby savannah forests or mangroves stands. The species prefers elevations below 1,100 m (3,600 ft) in Australia, and 500 m (1,600 ft) in New Guinea. As of 2018, according to Birdlife International, the breeding populations were as follows:
Diet
Southern cassowaries forage on the forest floor for fallen fruit and seeds and are capable of safely digesting some fruits and seeds toxic to other animals. They also eat fungi, and some insects, other invertebrates (such as snails), small vertebrates (such as fish, frogs, small birds and their eggs and nestlings, and small mammals), and carrion. When food is scarce, both wild and captive cassowaries have been seen to ingest earth, perhaps seeking supplementary minerals. Inspection of the faeces reveals that commonly ingested fruits are Davidsonia pruriens, Syzygium divaricatum, and members of the palm (Arecaceae), quandong (Elaeocarpaceae), laurel (Lauraceae), and myrtle (Myrtaceae) families.
Behavior Southern cassowaries make a thunderous call during mating season, and hissing and rumblings otherwise. Chicks will make frequent high-pitched contact whistles and chirps to call the male.
Breeding
The southern cassowary is a solitary bird, which pairs only in breeding season, in late winter or spring (but highly variable). The male builds a nest on the ground, a mattress of herbaceous plant material 5 to 10 centimetres (2–4 in) thick and up to 100 centimetres (39 in) wide. This is thick enough to let moisture drain away from the eggs. The male also incubates the eggs and raises the chicks alone. A clutch of three to five eggs are laid measuring 11.8–15.8 cm (4.6–6.2 in) in length and 8.2–10.2 cm (3.2–4.0 in) in width, with a mass of around 567–634 g (1.250–1.398 lb). They have a granulated surface and are initially bright pea-green in colour although they fade with age. The incubation period takes around 50 days. Chicks hatch precocial, fully feathered, and able to move and explore within hours of hatching. Parental care is done solely by the male, who the chicks depend on for survival. Young birds typically become independent at 9–12 months of age. It will take around 4–5 years for the casque and adult plumage to fully develop, this is also the time in which successful breeding usually starts.
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