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Cassowaries (Casuariidae)

Cassowaries

(Casuariidae)

Class Aves

Order Struthioniformes

Suborder Casuarii

Family Casuariidae


Thumbnail description
Large flightless birds with tiny wings terminating in long spines, shiny black plumage, three toes, a casque on the head (also called a helmet or a crown), and colorful bare skin on the neck

Size
40–67 in (102–170 cm); 30–130 lb (14–59 kg)

Number of genera, species
1 genus; 3 (possibly 4) species

Habitat
Rainforest and adjacent dense vegetation

Conservation status
Potentially endangered by logging and forest clearing and by competition from feral pigs and dogs

Distribution
Cape York (Australia), New Guinea, and some surrounding islands

Evolution and systematics

Cassowaries belong to the group of large flightless birds known as the ratites that have in common a distinctive palate and the lack of a keel to the sternum. The origin of these birds has recently been clarified by the discovery of numerous good fossils in North America and Europe. Whereas it was previously thought that ratites had a southern origin, new fossil evidence has shown flying ratites inhabited the Northern Hemisphere in the Paleocene and Eocene, between 40 million and 70 million years ago. The present Southern Hemisphere distribution of the ratites probably results from the spread of flying ancestors of the group from the north. The cassowaries differ from the rheas and ostriches in their structure and way of life. All cassowary feathers consist of a shaft and loose barbules; there are no rectrices (tail feathers) nor a preen gland and only five to six large wing feathers. On the strongly retrogressed wing, the lower arm and hand are only half as long as the upper arm. The furcula (wishbone) and coracoid (shoulder blade) are degenerate. There is a special palatal structure, and the palatal bones and sphenoids touch one another. Cassowaries are known from fossils of the Pliocene (about three million to seven million years ago) in New Guinea. Although not formally described until the nineteenth century, the first living cassowary to reach Europe was transported to Amsterdam in 1597.

Physical characteristics

Cassowaries are large, long-legged, cursorial (running) birds, with distinctive head casques of trabecular (fibrous and cordlike) bone or calcified cartilage up to 7 in (18 cm) high. The colorful skin of the neck is bare, and long neck wattles adorn two species. The birds weigh 37–130 lb (17–59 kg). Cassowary wings are small, but the shafts of five or six primary feathers remain as long curved spines. Of the three toes, the inner one is armed with a long sharp claw, an effective weapon that is capable of disemboweling an adversary—even a human. Like the emu, the aftershaft of the cassowaries' coarse, black feathers is as long as the main shaft, so that each feather appears double—almost like extremely thick hair.

Distribution

The eastern side of Cape York in northern Australia, throughout New Guinea, New Britain, Seram, and Aru, Japen, Salawati, and Batanta islands. Humans have introduced the birds to some of these islands, and their natural distribution is uncertain.

Habitat

Cassowaries are birds of the rainforest but often stray into adjoining eucalypt forest, palm scrub, tall grassland, savanna, secondary growth, and swamp forest.

Behavior

Except during courtship and egg-laying, cassowaries are solitary birds, seldom seen in groups, and then usually at some source of abundant food such as a fruiting tree. Each bird occupies a home range, moving around within it to find food. Each species has a characteristic territorial boom call, a threatening roar, given with the head bent down under the body. The birds are able to move quietly through the rain-forest until disturbed. The noise of their hasty departure as they crash through the undergrowth is often the first indication of their presence. They swim well and have been recorded reaching an island a mile and a half (2.4 km) from the coast.

Feeding ecology and diet

Cassowaries feed on the fruits of rainforest trees and shrubs. The birds collect most of these from the ground, using their bill and sometimes their casque to unearth the fallen fruit from the litter of the forest floor. As the cassowaries travel, they disperse the seeds of these fruits throughout the rainforest, thus ensuring the continuance of more than 150 species of rainforest plants. In a study of the southern cassowary in north Queensland, Australia, the fruits of laurels, myrtles, and palms were most important. Opportunistically, the birds will take fungi, insects, and small vertebrates, but the basic diet consists of fruit. Disturbance of the forest can have serious consequences for cassowaries. Selective logging can remove almost all of one species of tree, so that the crop of fruit from that species is missing from the forest. If the fruit of this tree forms a significant part of the cassowary's diet, it will be left without food for weeks or months and suffer accordingly. Selective logging damages the bird's habitat more subtly than clear cutting, but equally seriously.

Reproductive biology

Cassowaries nest on a pad of vegetation on the ground. The clutch contains three to eight bright green or greenish blue eggs. Incubation lasts for 50–52 days, and is performed by the male alone. Chicks remain with the male for some months before gaining independence.

Conservation status

Disturbance of the forest is the main factor causing a decline in cassowary numbers. In Australia the cassowary population is estimated at 1,300 to 2,000 adults. Information on the status of New Guinea species is scant. The birds are so secretive—and the political situation so uncertain in West Irian—that any assessment is mere guesswork. It can only be said that the birds, or signs of them, can still be found whenever they are sought.

Significance to humans

Although they do not breed well in zoos, many cassowaries are kept in New Guinea villages. They are caught as chicks and raised to be killed and eaten when mature. Some of these captive birds have caused serious injury, even death, to village people tending them. They attack unexpectedly, slashing with powerful forward kicks, tearing the bodies of opponents with the long sharp claws of the inner toes with such accuracy that they are much feared.

Species accounts

List of Species

Southern cassowary
Bennett's cassowary
One-wattled cassowary

Southern cassowary

Casuarius casuarius

taxonomy

Casuarius casuarius Linnaeus, 1758, Seram.

other common names

English: Double-wattled cassowary, two-wattled cassowary, Australian cassowary, kudari; French: Casoar à casque; German: Helmkasuar; Spanish: Casuario Común.

physical characteristics

50–67 in (127–170 cm); female 128 lb (58 kg), male 64–75 lb (29–34 kg). Distinguished from the other cassowaries by having two wattles hanging from the neck. The bare skin of the head and neck is vividly colored in blue and red, and the legs are gray-green to gray-brown. The species has an especially long inner toenail or spike up to 5 in (12 cm) in length. Chicks are longitudinally striped with black, brown, and cream, and they have a chestnut head and neck for their first three to six months. Immatures have dark brown plumage and small casques, acquiring their colorful necks toward the end of their first year, and glossy adult plumage in about three years.

distribution

The Australian populations are all north of Townsville, Queensland, on the eastern side of Cape York. It is widespread in southern, eastern, and northwestern New Guinea, the Aru

Islands, and Seram. The population on Seram has probably been introduced.

habitat

The southern cassowary lives mainly in lowland rainforest, below 3,600 ft (about 1,100 m).

behavior

Although usually shy, some birds will become tame enough near settlements to approach places where food is regularly put out for them. Adults are territorial, no more than two associating together, except that the chicks stay with their father for about nine months.

feeding ecology and diet

The southern cassowary feeds on the fallen fruits of rainforest trees, fungi, and a few insects and small vertebrates.

reproductive biology

In Australia the southern cassowary breeds in the winter—June and July—coinciding with the abundance of forest fruit, especially laurels (of the family Lauraceae). The nest, on the ground, is often close to the roots of a large tree, and the clutch consists of up to four lime green eggs. Males and females hold separate territories except for a few weeks at laying time. Incubation, by the male alone, 47–61 days, with variation thought to be a response to ambient temperature. Polyandrous females may take on another male or two before mating season ends, providing a clutch of eggs for each of her partners. The chicks stay with the male for up to nine months.

conservation status

The status of the southern cassowary is uncertain. It requires large areas of undisturbed rainforest to flourish. As these are logged or disturbed by roadmaking and settlement, the bird's future is put at risk. Some are killed on the roads. Feral animals such as pigs and dogs disturb the nests in their search for eggs, causing the population to shrink. In New Guinea the bird is hunted and snared for food, but while large tracts of forest remain, it is secure.

significance to humans

Both in Australia and New Guinea the southern cassowary is incorporated into the mythology of the indigenous peoples, but it is still hunted by them, and the chicks captured, to be kept in pens in the villages until they are large enough to eat.


Bennett's cassowary

Casuarius bennettii

taxonomy

Casuarius bennettii Gould, 1857, New Britain.

other common names

English: Dwarf cassowary, little cassowary, mountain cassowary; French: Casoar de Bennett; German: Bennettkasuar; Spanish: Casuario Menor.

physical characteristics

Height 39–53 in (99–135 cm); weight 39 lb (about 18 kg). A small cassowary with a flat, low casque and a less colorful neck than the other species. A distinctive form lives on the west side of Geevink Bay, West Irian, and may merit recognition as a species, C. papuanus.

distribution

New Guinea, New Britain, and Japen Island.

habitat

Lives in forest and secondary growth, favoring hilly and mountainous country to 10,800 ft (3,300 m). On New Britain, where other species are absent, it lives in lowland forest as well.

behavior

Usually solitary or in small family groups, traversing steep slopes and thick vegetation. Its call is higher pitched than that of the other species.

feeding ecology and diet

Bennett's cassowary feeds mainly on fallen fruits in the rainforest but also takes fungi, insects, and small vertebrates.

reproductive biology

The clutch consists of four to six eggs. Incubation 49–52 days.

conservation status

Not threatened. Although it is hunted extensively it remains widespread at low densities.

significance to humans

Widely kept as a pet and, when small, traded between localities.


One-wattled cassowary

Casuarius unappendiculatus

taxonomy

Casuarius unappendiculatus Blyth, 1860, aviary in Calcutta.

other common names

English: Northern cassowary; French: Casoar unicaronculé; German: Einlappenkasuar; Spanish: Casuario Unicarunculado.

physical characteristics

Height 65–69 in (165–175 cm); weight females 128 lb (58 kg); males 81 lb (about 37 kg). A large cassowary with coarse black plumage, a tall casque, a colorful neck, and one central wattle.

distribution

Northern New Guinea, from western Vogelkop, West Irian, to Astrolabe Bay, Papua New Guinea, and on Satawati, Batanta, and Japen islands.

habitat

Mostly lowland areas of rainforest and swamp forest, up to 1,600 ft (490 m).

behavior

Assumed to be similar to other cassowaries.

feeding ecology and diet

Feeds on fallen forest fruits.

reproductive biology

Birds in breeding condition have been collected in May and June, but nothing else has been reported about its breeding.

conservation status

The status of the cassowary is uncertain. It requires large areas of undisturbed rainforest to flourish. It is hunted and snared for food, but where large tracts of forest remain, it is secure.

significance to humans

The cassowary is incorporated into the mythology of the indigenous peoples, but it is still hunted by them, and the chicks captured, to be kept in pens in the villages until they are big enough to eat.


Resources

Books

Coates, B. J. The Birds of Papua New Guinea. Alderly, Australia: Dove, 1985.

Davies, S. J. J. F. Ratites and Tinamous. Oxford: Oxford University Press, 2002.

del Hoyo, J., A. Elliott, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 1, Ostrich to Ducks. Barcelona: Lynx Edicions, 1992.

Marchant, S., and P. J. Higgins. Handbook of Australian, New Zealand and Antarctic Birds. Vol. 1, Ratites to Ducks. Oxford: Oxford University Press, 1990.

Periodicals

Crome, F. H. J. "Some Observations on the Biology of the Cassowary in Northern Queensland." Emu 76 (1976): 8–14.

Davies, S. J. J. F. "The Natural History of the Emu in Comparison with That of Other Ratites." Proceedings of the Sixteenth International Ornithological Congress (1976): 109–20.

Organizations

Birds Australia. 415 Riversdale Road, Hawthorn East, Victoria 3123 Australia. Phone: +61 3 9882 2622. Fax: +61 3 98822677. E-mail: [email protected] Web site: <http://www.birdsaustralia.com.au>

Other

Bredl, Rob. "Cassowaries." Barefoot Bushman. 5 Dec. 2001 <http://www.barefootbushman.webcentral.com.au/cassowaries.htm>

"The Cassowary." The Living Museum: Wet Tropics. Wet Tropics Management Authority Official Web Site. 5 Dec. 2001 <http://www.wettropics.gov.au/lm/The_Cassowary.htm>

"Double-wattled cassowary." Zoo Discovery Kit. Los Angeles Zoo. 5 Dec. 2001 <http://www.lazoo.org/learnfiles/ZooDiscoveryKit/Cassowaryfacts.html>

S.J.J.F. Davies, ScD

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