Casuariidae

(vertebrate zoology) The cassowaries, a family of flightless birds in the order Casuariiformes lacking head and neck feathers and having bony casques on the head.

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(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

Resources

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.

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.

Birds Australia. 415 Riversdale Road, Hawthorn East, Victoria 3123 Australia. Phone: +61 3 9882 2622. Fax: +61 3 98822677. E-mail: mail@birdsaustralia.com.au Web site:

Bredl, Rob. "Cassowaries." Barefoot Bushman. 5 Dec. 2001

"The Cassowary." The Living Museum: Wet Tropics. Wet Tropics Management Authority Official Web Site. 5 Dec. 2001

"Double-wattled cassowary." Zoo Discovery Kit. Los Angeles Zoo. 5 Dec. 2001

[Article by: S.J.J.F. Davies, ScD]

Casuariidae
Emu
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Struthioniformes Family: Casuariidae Kaup, 1847
Genera
Casuarius Dromaius For fossil forms, see article

The bird family Casuariidae has four surviving members: the three species of cassowary, and the only remaining species of Emu. The emus were formerly classified in their own family, Dromaiidae, but are regarded as sufficiently closely related to the cassowaries to be part of the same family.

All four members of the family are very large flightless birds native to Australia-New Guinea. The characteristics of the family are those of its members.

Systematics and evolution

The emus form a distinct subfamily, characterized by legs adapted for running. As with all ratites, there are several contested theories concerning their evolution and relationships. As regards this family, it is especially interesting whether emus or cassowaries are the more primitive form: the latter are generally assumed to retain more plesiomorphic features, but this does not need to be true at all; the fossil record is also ambiguous, and the present state of genomics does not allow for suffiently comprehensive analyses. A combination of all these approaches with considerations of plate tectonics at least is necessary for resolving this issue.

The number of cassowary species described based on minor differences in casque shape and color variations is quite large^{[citation needed]}. In recent times, however, only 3 species are recognized, and most authorities only acknowledge few subspecies or none at all.

The fossil record of casuariforms is interesting, but not very extensive. Regarding fossil species of Dromaius and Casuarius, see their genus pages.

Some Australian fossils initially believed to be from emus were recognized to represent a distinct genus, Emuarius^[1], which had a cassowary-like skull and femur and an emu-like lower leg and foot. In addition, the first fossils of mihirungs were initially believed to be from giant emus^[2], but these birds were completely unrelated.

Southern Cassowary

Subfamily Casuariinae - cassowaries

• Genus Casuarius
  • Southern Cassowary, Casuarius casuarius
  • Dwarf Cassowary, Casuarius bennetti
  • Northern Cassowary, Casuarius unappendiculatus

Subfamily Dromaiinae - emus

• Genus Dromaius
  • Emu, Dromaius novaehollandiae
    • Tasmanian Emu, D. n. diemenensis (extinct)
    • South Eastern Emu, D. n. novaehollandiae
    • South Western Emu, D. n. rothschildi
    • Northern Emu, D. n. woodwardi
  • Kangaroo Island Emu, Dromaius baudinianus (extinct)
  • King Island Emu, Dromaius ater (extinct)

• Genus Emuarius - "emuwaries" (fossil)
  • Emuarius guljaruba (Late Oligocene - Late Miocene)
  • Emuarius gidju (Wipajiri Early Miocene of Lake Ngapakaldi)

References

• Boles, Walter E. (2001): A new emu (Dromaiinae) from the Late Oligocene Etadunna Formation. Emu 101: 317–321. HTML abstract

Footnotes

1. ^ From "Emu" + "Casuarius". Describer W. E. Boles commonly refers to the genus as "emuwaries" or "cassomus".
2. ^ The vernacular name "mihirung" is derived from mihirung paringmal, which means "giant emu" in the Chaap Wuurong language

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