Southern cassowaries communicate with each other by issuing very loud deep roars which travel well through the forest. These roars are up to 40 decibels louder than the surrounding forest noise, and are at frequencies which are at the very bottom end of what humans can perceive, about 23 Hertz. Cassowaries are one of the only birds to have been recorded making vocalizations this low. There is some speculation about whether the casques on their heads are somehow related to these impressive sounds. It is speculated that the casque could play a role in receiving or producing these sounds. These calls are territorial, warning other cassowaries of their presence.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The biggest threat to southern cassowaries is the destruction of their habitat. These birds are also sometimes killed by cars and their populations are disrupted by feral pigs and dogs. There has been a 30% decline in their numbers in the last 30 years. Fortunately, in Australia, the destruction of habitat has almost completely stopped and in New Guinea there are large areas where the bird is not hunted which helps their numbers. Southern cassowaries will be safe as long as there are large areas of undisturbed forests.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: vulnerable
Although they are usually shy, southern cassowaries can be aggressive towards people, especially when kept in captivity. Southern cassowaries will charge people, jumping at them while slashing with their 12 cm claws. They can cause serious injury and sometimes death. In 2004 southern cassowaries were voted by the Guinness Book of World Records as the worlds most dangerous bird for these reasons.
Negative Impacts: injures humans
Southern cassowaries are important in the mythology of the indigenous peoples of New Guinea and Australia. These birds are captured as chicks and raised in villages so that their feathers can plucked and used in headdresses and the quills can be used as nose ornaments. Eventually, when the birds reach a certain size they are killed for food. There has been a trade of cassowaries in Southeast Asia for over 500 years. It is possible that populations of southern cassowaries on Australia and some of the islands surrounding New Guinea are the result of human introductions through trade.
Positive Impacts: food ; body parts are source of valuable material
Cassowaries live primarily on fruit from a large number of species of trees. When cassowaries eat the fruit the seeds pass through their system and are dispersed far from where they originally fell. The seeds are often still viable after passing through the digestive system of cassowaries. In a typical pile of cassowary dung there can be as much as one kilogram of seeds. In a study of the effects of seed dispersal by cassowaries, the seeds from 78 species of plants were found and 70 of these species' seeds were able to germinate after being passed through the cassowaries. Some of the species found in cassowaries dung include Davidsonia pruriens, Acemena divaricata, Polyalthia michaelii, Acronychia acronychioides and a large number from the Lauraceae family.
Ecosystem Impact: disperses seeds
Mutualist Species:
Southern cassowaries are frugivorous, feeding mostly on fruits from canopy species in the forests where they live. Because these birds cannot fly they must rely on finding fruit that has fallen to the ground. They also eat insects, small vertebrates, and fungi. Inspection of the feces reveals that commonly ingested fruits are Davidsonia pruriens, Acemena divaricata and members of the laurel family (Lauraceae).
Animal Foods: mammals; amphibians; reptiles; insects; terrestrial non-insect arthropods
Plant Foods: fruit
Other Foods: fungus
Primary Diet: herbivore (Frugivore )
Southern cassowaries are found in New Guinea, Cape York, Ceram and Aru Islands.
Biogeographic Regions: australian (Introduced , Native ); oceanic islands (Introduced , Native )
Other Geographic Terms: island endemic
Southern cassowaries live primarily in lowland rainforests, typically less than 1,100 meters elevation, and occasionally are found in eucalyptus forests, savannas, palm scrub, and in forested swamps.
Range elevation: 0 to 1,100 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest
There is little known about the lifespan of southern cassowaries in the wild, but in captivity southern cassowaries have lived 20 to 40 years.
Range lifespan
Status: captivity: 20 to 40 years.
Southern cassowaries are large, robust birds with long powerful legs for running and defense; the claws on the toes are up to 12 cm long. Their bodies are covered with dark brown or black feathers which look more like thick, coarse hair. The neck and head have no feathers and are boldly colored blue and red. On their heads there is a large bony casque which is made of trabecular bone and cartilage. The wings are extremely small and there are vestiges of primary feathers in the form of five or six long white spines. Cassowary chicks are brown with black stripes running the length of their bodies for their first three to six months. Juveniles are brown instead of black and have smaller casques. They do not get the vividly colored necks until they are about one year old. Females are 127 to 170 cm long and up to 59 kg, are larger than the males which are 29 to 34 kg. Southern cassowaries are the largest of the three species of cassowary and the only species to have have two bright red flaps of skin, called wattles, hanging from their neck.
Range mass: 29 to 59 kg.
Range length: 102 to 170 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
It is unknown whether cassowaries have any natural predators, but humans could be considered a predator because cassowaries are sometimes eaten by humans.
Known Predators:
Females are polyandrous; a female will usually breed with two to three males throughout the mating season, starting a new nest every time, which the male will incubate. Courtship consists of the males making a “boo-boo-boo” call while inflating his throat.
Mating System: polyandrous
The breeding season is in winter, when fruit is most abundant. The nest is a pad of vegetation on the ground and there are typically about 4 bright green eggs in a clutch. Incubation, which is exclusively done by the males, lasts for 47 to 61 days. Once the chicks hatch they stay with their father until they become independent at about nine months. At about three years of age, southern cassowaries are able to reproduce.
Breeding interval: Females will mate with 2 to 3 males during the mating season.
Breeding season: Breeding occurs during the austral winter, from June to July.
Range eggs per season: 4 to 8.
Range time to hatching: 47 to 61 days.
Average time to independence: 9 months.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
After the eggs are laid all care of the eggs and offspring are done by males. Males construct a mat of vegetation which will become the nest where they incubate the eggs for 47 to 61 days. The chicks are precocial at hatching, but dependent on their male parents for protection from predators and for teaching them how to find food for themselves. This period will last for about 9 months, when the males will abandon the juvenile cassowaries.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Protecting: Male); pre-weaning/fledging (Provisioning: Male, Protecting: Male); pre-independence (Provisioning: Male, Protecting: Male)
