Cassowaries (Indonesian: kasuari; Biak: man suar 'bird strong';[3][4] Tok Pisin: muruk; Papuan:[clarification needed] kasu weri 'horned head'[5]) are flightless birds of the genus Casuarius, in the order Casuariiformes.

The cassowary has often been labelled "the world's most dangerous bird",[7][8] although in terms of recorded statistics, it pales in comparison to the common ostrich, which kills two to three humans per year in South Africa.

[15] Cassowaries (from Malay: kasuari[16] cognate of several related languages spoken around the Moluccas and New Guinea[17]) are part of the ratite group, which also includes the emu, rheas, ostriches, and kiwi, as well as the extinct moas and elephant birds.

Most authorities consider the taxonomic classification above to be monotypic, but several subspecies of each have been described,[21] and some of them have even been suggested as separate species, e.g., C. (b) papuanus.

[23] A fossil species was reported from Australia, but for reasons of biogeography, this assignment is not certain, and it might belong to the prehistoric Emuarius, which was a genus of cassowary-like primitive emus.

[26] These, along with their wedge-shaped body, are thought to be adaptations to ward off vines, thorns, and saw-edged leaves, allowing them to run quickly through the rainforest.

[28] Their beaks are pointed, sharp and robust but not serrated, which allows them to pick up fruit more easily than the short bills of an emu or an ostrich.

Other suggested functions include batting through the underbrush, as a weapon in dominance disputes, or pushing aside leaf litter during foraging.

Females lay three to eight large, bright green or pale green-blue eggs in each clutch into a heap of leaf litter prepared by the male.

The male incubates those eggs for 50–52 days, removing or adding litter to regulate the temperature, then protects the chicks, which stay in the nest for about 9 months.

The bird avoids the poisons of these fruits due to the presence of their incredibly short gastrointestinal tract, the shortest of all ratites in relation to their size.

[38] This short gut length also allows the birds to eat a wider variety of protein source, which is unsurprising given their omnivorous diet.

Cassowaries are a keystone species of rain forests because they eat fallen fruit whole and distribute seeds across the jungle floor via excrement.

[39][40] In more urbanised areas, especially in Queensland, Australia, 'urbanised' cassowaries have adopted to also feed on picnic blankets, tables and baskets or backyard bird feeders and compost heaps, thereby consuming a wide range of non-natural and non-native foods as well.

[40] Cassowaries feed on the fruit of several hundred rainforest species and usually pass viable seeds in large, dense scats.

Germination rates for seeds of the rare Australian rainforest tree Ryparosa were found to be much higher after passing through a cassowary's gut (92% versus 4%).

[46][47] It was believed that these dogs follow adult birds to catch small prey attracted to the dropped fruits on the rainforest floor.

To protect this species, various conservation efforts have been carried out, including preserving natural habitat and enforcing regulations against illegal hunting.

[58][59] In February 2011, Cyclone Yasi destroyed a large area of cassowary habitat, endangering 200 of the birds – about 10% of the total Australian population.

[60] The Mission Beach community in far north Queensland holds an annual Cassowary Festival in September, where funds are raised to map the bird's habitat.

[62] According to the Department of Primary Industries, Parks, Water and Environment from Hobart, risk assessments on the cassowary as a potential invasive pest states that whilst the birds may have trouble establishing a stable population on the island, they would nonetheless, be considered a destructive element to Tasmania's ecological diversity and recommends strict imports on these birds.

[62] However, since Tasmania lack the same levels of fruit diversity as Queensland and New Guinea, assessments believe that the birds would adapt by also eating invertebrates and small vertebrates.

Unlike the emu, which will live with other sympatric species, such as kangaroos, in "mixed Australian fauna" displays, the cassowary does not cohabit well among its own kind.

The double-wattled cassowary (C. casuarius) is the most popular species in captivity, and it is fairly common in European and American zoos, where it is known for its unmistakable appearance.

Some New Guinea Highlands societies capture cassowary chicks and raise them as semi-tame poultry, for use in ceremonial gift exchanges and as food.

[67] Studies on Pleistocene/early Holocene cassowary remains in Papua suggest that indigenous people at the time preferred to harvest eggs rather than adults.

[41] Due to their omnivorous nature, cassowaries are able to eat all types of human food, including processed ones if interested, although fruit still remains their favourite choosings.

[41][71] A 2013 study from post-mortem investigations found that a combination of fruit scarcity and abundancy in human waste saw the diet of the cassowary intaking vast quantities of non-fruit items, this include fungus, carrion, meat, cheese, bones, pasta, chilli and tomato.

[70] The study give evidence that these birds showed a surprising amount of flexible foraging strategy that has enabled them to persist in rainforest-fragmented landscapes.

In his 1958 book Living Birds of the World, ornithologist Ernest Thomas Gilliard wrote: The inner or second of the three toes is fitted with a long, straight, murderous nail which can sever an arm or eviscerate an abdomen with ease.