The Southern Cassowary is native to Australia and New Guinea. It is one of three species and all have a fibrous skin-covered casque on their head. The casque can extend up to 18 cm (7 in) in height.
As to the main purpose of the casque, there are a number of theories. Included is the idea that it helps the bird in its natural habitat of dense rainforest to barge through thick vegetation while running. It is also thought to protect its head from low branches and falling fruit. Another theory suggests the casque amplifies deep sounds in the forest.
It has been observed as a weapon to assert dominance among its own species. Pushing forest litter aside during foraging is another observation. These are perhaps secondary functions however.
