Casuarius unappendiculatus

Geographic Range

Northern cassowaries ( Casuarius unappendiculatus ) are restricted to Papua New Guinea and found occasionally in Yapen.

• Biogeographic Regions
• australian australian
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Northern cassowaries are found only in tropical lowland rainforests. They occupy a range from sea level to 500 m above sea level.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• rainforest rainforest

Physical Description

Northern cassowaries are one of the largest vertebrates in Papua New Guinea. They weigh between 25 and 50 kg and can be almost 2 m tall at their full height. They have glossy feathers with a shaggy texture. Their feathers are brown in young cassowaries and turn black by the time they reach maturity, at about 3 years old. Adult birds have a helmet-like casque, or hard structure, on the tops of their heads, the purpose of which is unknown. The most striking feature of northern cassowaries is the bright blue skin that covers most of its long neck and the bright red wattle under the beak. They have only one wattle, giving them the alternate common name, "single-wattled cassowaries." They have long and powerful legs and three toes with claws. There are negligible differences between males and females, leading many cultures of Papua New Guinea to believe only female cassowaries exist. The only noticeable difference is that females tend to be larger. There are no seasonal changes in the colors of cassowaries. However, when they become agitated, the colors on the neck and wattle deepen and they fluff out their feathers to appear bigger and more threatening.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• ornamentation ornamentation

Reproduction

During the winter and spring (June to November) cassowaries become less aggressive towards each other in order to breed. The male will court the female by dancing around her and swelling his neck while she stays still. This is followed by scratching her rump then rubbing necks together. After successful copulation, the female is chased off and will find another mate, while the male incubates the eggs until hatching, about 47 to 56 days. Male cassowaries prepare a nest and court the polyandrous females. Females mate with up to four males. Females lay, on average, 4 eggs per clutch. In captivity, females lay more eggs if eggs are immediately collected from the nest. This increases the total number of eggs to around 20. After the eggs are in the nest, the male cassowary will become aggressive and chase off the female. He then protects the eggs and raises the chicks. However, if the male approaches a female that is not ovulating she will chase him off.

• Mating System
• polyandrous polyandrous

Females lay an average of 4 eggs per clutch and mate with about 4 males per season. This produces an average of 16 eggs per female per breeding season. The father will incubate the eggs for 47 to 56 days. Chicks remain with their father for 9 to 18 months. Chicks reach sexual maturity at 2 years old in females and 3 years old in males. Sexual reproduction occurs late into life: up to 40 years old in females and 37 years old in males.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Female cassowaries provide no parental investment after they have provisioned and deposited their eggs in the nest of a male. Females are chased off by males after laying a clutch. Males incubate and protect the eggs until hatching. Then he protects the young for months, teaching them how to find food and care for themselves. The male will become aggressive towards any threat. Male care lasts about 9 months, although some reports say that it can last as many as 18. During these months, the chicks follow their father, even consuming his feces. Ticks and other bugs found on the father are another food source for the chicks.

• Parental Investment
• male parental care male parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
• pre-weaning/fledging
  • provisioning
    • male
  • protecting
    • male
• pre-independence
  • provisioning
    • male
  • protecting
    • male
• extended period of juvenile learning

Lifespan/Longevity

Many wild cassowaries are killed when they are young because young cassowaries are easier to kill and hunters tend to target them. If birds survive childhood, it is not uncommon for cassowaries to reach an age of 40 years or more. Information on survivorship is limited. A captive bird was estimated to be 61 at death or possibly older. Another captive bird lived to be at least 48 years old.

Behavior

Northern cassowaries are generally regarded as shy and solitary birds. They live alone except for a 9-month period after hatching when male cassowaries care for the chicks. Males are watchful of their chicks and can become very aggressive when the chicks are threatened. When northern cassowaries are excited, they puff out their feathers and the colors in their wattles, necks, and irises will darken. When they are startled, adult birds jump into the air and flail, often defecating in fear and run away. As they run, they crash through underbrush and jump over obstacles, making them hard to follow. Young cassowaries under 9 months of age will simply fall when startled, making this the preferred time to hunt and capture them. In the absence of a male parent, hatchlings can imprint on humans that care for them, looking to them as parental figures. They will form emotional bonds with human caretakers as well. Those that have imprinted on a human will not mate and will attack other cassowaries.

Female cassowaries are generally more aggressive during mating. In captivity, females attack males that attempt to eat before the female has finished. A male cassowary and his chicks were observed to eat mainly in the cooler parts of the day. Northern cassowaries eat and defecate almost constantly. They will even soil sleeping areas, and many hunters will lay in wait in areas with excess excrement as this indicates favored feeding grounds.

• Key Behaviors
• cursorial
• terricolous
• motile motile
• nomadic nomadic
• solitary solitary

Home Range

Although no estimates have been provided in the literature, the home range of northern cassowaries is thought to be large, and can vary from season to season and year to year. Northern cassowary family units show a preference for a particular nesting site, although they rarely visit the nest. Juvenile cassowaries that have been rehabilitated and re-released into the wild with GPS trackers show an affinity for the site at which they were released.

Communication and Perception

Northern cassowaries communicate with a sound that has been described by several sources as a “boom.” It is a sound low enough to almost be infrasound, or ultra low frequencies. It is believed that cassowaries use such a low frequency because they are solitary birds and need a form of communication that will travel long distances. Lower frequencies travel farther in the dense, windless rainforest than higher noises. Male cassowaries have been observed clacking their beaks and using this boom to rally their young. When they boom they hunch down and ruffle their feathers and the young will run to the male and nestle in his feathers. The boom is actually a series of sounds; although there are no frequencies reported in the literature for northern cassowaries, those for captive dwarf cassowaries ( Casuarius bennetti ) have been measured at frequencies as low as 23 Hz. Researchers noticed that dwarf cassowaries begin and end their vocalizations with a much louder, longer “roar” that they measured at 200 to 100 Hz, with lower, shorter booms in between. These calls lasted about 10 seconds. Young northern cassowaries have been observed making a whistling sound and peeping.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Northern cassowaries are frugivorous, in the wild an adult can eat hundreds of berries and fruits in a day. Although their primary diet is fruit, they also eat small animals such as mice, rats, frogs, snakes, lizards, smaller birds and a variety of small insects and snails. They will eat dead animals when they find them. The young have been observed to eat the feces of the males raising them and clutch mates. Adults will eat their own feces as it often contains undigested fruits. Captive cassowaries are fed a mixture of fruits and their protein source is dog or monkey food. They eat almost 19 liters of fruit and almost a liter of a protein source (such as dog food) a day in captivity.

• Primary Diet
• herbivore herbivore
  • frugivore frugivore

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• carrion carrion
• insects

• Plant Foods
• fruit
• flowers

• Other Foods
• dung

Predation

Northern cassowaries are one of the largest animals in Papua New Guinea, so they have few natural predators. Their size makes them a valuable source of meat for humans . Humans use northern cassowaries for meat, ornamental feathers, bones for tools, and trade. Some reports of cassowaries killing humans attribute the attack to self-defense. The tribes of New Guinea that hunt northern cassowaries believe that only a direct blow to the head or an arrow shot from very close range are the only sure ways to kill them. They are, however, susceptible to death being hit by cars and dog or feral pig attacks. They are sometimes caught in traps laid for feral pigs, as well. While they are not commonly preyed upon, northern cassowaries have powerful kicks and very sharp claws that are more than capable of killing a potential predator. A single human hunter is lucky to kill one every five years, while a tribe of about 300 people averages about one adult bird per year.

Ecosystem Roles

Northern cassowaries eat many whole fruits and seeds, dropping the seeds when they defecate. This disperses seeds throughout their environment and are important in forest regeneration. A domestic cassowary was found to have Toxoplasma gondii , a parasite that can cause anorexia, diarrhea, gastrointestinal distress and dyspnea. Toxoplasmosis can affect the usefulness of cassowaries as a food source. It is detected by the presence of antibodies, which appear only after infection.

• Ecosystem Impact
• disperses seeds
• creates habitat

Economic Importance for Humans: Positive

Northern cassowaries are one of the two largest animals in Papua New Guinea, and therefore provide a valuable food source. The people of Papua New Guinea consume both the meat and eggs of cassowaries. They eat many fruits and spread their seeds through defecation, therefore helping with forest regeneration. The seeds of the rare rainforest plant ryparosa ( Ryparosa kurrangii ) has been shown to be much more successful at sprouting after passing through the digestives system of a cassowary. Only 4% of seeds grow without passing through a cassowary, whereas 92% will grow after digestion. There are a multitude of symbolic practices that use northern cassowaries as well. Some tribes of Papua New Guinea use northern cassowary feathers, excretions, bones, and bodies for various rituals. Northern cassowaries are difficult to catch, thus cassowary paraphernalia is valuable.

• Positive Impacts
• pet trade pet trade
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

Northern cassowaries have been known to physically harm or even kill humans. When cornered these birds become very aggressive and have a powerful kick. However, their reputation as a dangerous bird might be exaggerated. While multiple sources maintain that northern cassowaries are dangerous, another source indicates that the last recorded death of a human caused by a northern cassowary was in 1926.

• Negative Impacts
• injures humans

Conservation Status

Northern cassowaries are listed by the IUCN as "vulnerable." There are estimated to be between 1500 and 2000 birds in the wild, some sources estimate fewer than that. It is difficult to get a true estimate due to their solitary nature. The northern cassowary population has been classified as declining as a result of habitat loss and fragmentation and more sophisticated hunting methods. Shotguns are becoming more prevelent and making it much easier to kill adult cassowaries. Other threats include aspergillosis, avian tuberculosis, and natural disasters, such as cyclones.

Additional Links

Encyclopedia of Life

Contributors

Rose Neikirk (author), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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