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Casuarius bennettidwarf cassowary

By Stephanie Jones

Geographic Range

Casuarius bennetti is found on the island of New Guinea. The majority of the population resides in Papua New Guinea, on the eastern side of the island. These birds are also found on the islands of New Britain and Yapen but their presence on these islands is likely due to extensive trade in cassowaries from New Guinea. ("Family Casuariidae-Dwarf Cassowary", 1990; "Cassowary", 1985)

Habitat

Dwarf cassowaries are regarded as high altitude birds in relation to other cassowaries. Their habitat is steep mountainous terrain up to 3000 m (10000 ft) that is thickly vegetated with subtropical to tropical forests. ("Cassowaries-Bennett's cassowary", 2003; "Family Casuariidae-Dwarf Cassowary", 1990; "Cassowary", 1985)

  • Range elevation
    3000 (high) m
    9842.52 (high) ft

Physical Description

Dwarf cassowaries are the smallest of the cassowaries (Casuariidae). They stand about 99 to 135 cm (39 to 53 in) tall when measured to the top of the head and weigh around 18 kg (39 lb). Their plumage is black and coarse, while their feathers are similar to drooping bristles. Dwarf cassowaries have wings that are much reduced and they are flightless. The head and neck are lacking in feathers and are blue and red in color. The top of their head is crowned with a horny “casque,” which is similar to a bony helmet. Dwarf cassowaries, unlike their near relatives, do not have colored wattles of flesh hanging from their necks. Their legs do not have feathers and are solid and powerful. Dwarf cassowaries have three toes and the innermost toe has an enlarged claw, which can be up to 10 cm (4 in) in length. Females and males are monomorphoric, although females are larger than males. ("Family Casuariidae-Dwarf Cassowary", 1990; "Cassowary", 1985)

  • Sexual Dimorphism
  • female larger
  • Average mass
    18 kg
    39.65 lb
  • Range length
    99 to 135 cm
    38.98 to 53.15 in

Reproduction

Little is known about the mating system of Casuarius bennetti. However, more research has been completed on a related species, Casuarius casuarius, commonly known as southern cassowaries. Female southern cassowaries will become more tolerant of males as the breeding season approaches. Eventually, pairs of male and female cassowaries will form. When the female is ready to lay eggs, the pair will find a nesting site. The male will dance around the female in circles while his throat trembles and swells and he emits a series of low booming calls. Finally, the male will lead the female a short distance from the nest where the female will squat and allow the male to mount her. The eggs will be laid shortly after copulation. In captivity, C. casuarius has been known to copulate between the laying of each egg. After the eggs have been laid, the female will leave to mate with other males. ("Cassowary", 1985; Richard, 1996; "Cassowary", 1985)

In the genus Casuarius, the breeding season begins in May or June and lasts until October or November. Breeding is an annual occurrence. Females may mate with more than one male during a season and must be healthy and well-nourished in order to lay multiple clutches of eggs. The clutch size of dwarf cassowaries is between 4 and 6 eggs. The incubation period lasts between 49 and 52 days. Young become independent in 7 to 16 months and sexually mature at around 4 years old. ("Cassowary", 1985; "Wet Tropics Management Authority", 2006)

  • Breeding interval
    In the genus Casuarius females generally breed 1 to 3 times during an annual breeding season.
  • Breeding season
    The breeding season for Casuarius begins in May or June and lasts until October or November.
  • Range eggs per season
    4 to 6
  • Range time to hatching
    49 to 52 days
  • Average fledging age
    9 months
  • Range time to independence
    7 to 16 months
  • Average age at sexual or reproductive maturity (female)
    4 years
  • Average age at sexual or reproductive maturity (male)
    4 years

In the genus Casuarius, mating with males and laying eggs are the only responsibilities of the female birds with regard to reproduction. Once the female has laid a clutch of eggs, she will move on to find another male with which she can mate. The eggs are incubated by the male, who is also responsible for raising and defending the chicks. The chicks will follow their father but are responsible for feeding themselves. Young fledge after about nine months and are driven out of the home range of their father. (Rand and Gilliard, 1986; "Community for Coastal and Cassowary Conservation", 2006)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male
  • pre-weaning/fledging
    • protecting
      • male
  • pre-independence
    • protecting
      • male

Lifespan/Longevity

Members of the genus Casuarius have been known to live up to 40 years in captivity and possibly to 60 years in the wild, although these claims of age in the wild are unconfirmed. Age can be estimated using the appearance of the casque, the size of the footprint, and the presence of wrinkles on the neck. Lifespan in dwarf cassowaries has not been documented. ("Community for Coastal and Cassowary Conservation", 2006)

  • Average lifespan
    Status: captivity
    26 years
    AnAge

Behavior

Dwarf cassowaries are shy birds that are rarely seen in the wild. They are active during the day, spending their time searching for food. They are usually found alone or in pairs and occasionally in small groups. If these birds are cornered, they will defend themselves with powerful kicks. Dwarf cassowaries have reportedly killed both humans and dogs when they were provoked. (Diamond, 1972; "Family Casuariidae-Dwarf Cassowary", 1990; Ramel, 2005; "Cassowary", 1985)

  • Range territory size
    1 to 5 km^2

Home Range

The home range of members of Casuarius is roughly 7 square kilometers and the territory size varies from 1 to 5 square kilometers. The size and shape of the range change based on the food supply and the occurrence of the annual breeding season. Female cassowaries tend to have home ranges that overlap the home ranges of several males. ("Wet Tropics Management Authority", 2006)

Communication and Perception

The call of dwarf cassowaries consists of low, booming tones that resonate at a frequency near the lower end of human hearing. This low-frequency communication is ideal for solitary birds that occur at low densities in thick forests, as dwarf cassowaries do. Little is known about communication when dwarf cassowaries meet to mate, although visual cues may be involved. (Mack and Jones, 2003)

Food Habits

Dwarf cassowaries feed mainly on fallen fruits or fruits that they pluck from shrubs. Dwarf cassowaries also use the crest on their head to sort through leaf litter and reveal other sources of food, such as fungi, insects, plant tissue, and small vertebrates, including lizards and frogs. ("Cassowaries-Bennett's cassowary", 2003; Gould, 1970; "Family Casuariidae-Dwarf Cassowary", 1990; "Cassowary", 1985; "Community for Coastal and Cassowary Conservation", 2006)

  • Animal Foods
  • amphibians
  • reptiles
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • Other Foods
  • fungus

Predation

Dwarf cassowaries have a large claw on their innermost toe and a powerful kick that they use to defend themselves when provoked. Dogs are considered predators of Casuarius species, particularly older birds, hatchlings, and sub-adults. Feral (introduced) pigs are also predators of Casuarius because they eat the eggs of these birds and are potential predators of hatchlings and young birds. Humans occasionally hunt cassowaries for their meat and feathers. Dwarf cassowaries have no natural predators; dogs, pigs, and humans are not endemic to New Guinea. ("Family Casuariidae-Dwarf Cassowary", 1990; "Cassowary", 1985; "Community for Coastal and Cassowary Conservation", 2006)

Ecosystem Roles

Members of the genus Casuarius are responsible for the distribution of large fruits for about 70 species of trees. The fruits of these trees are too large for many other forest dwelling fruit eaters to disperse. They also play a role in the dispersal of smaller seeds for about 80 plant species. These seeds are often toxic, but can be consumed by members of Casuarius because of their rapid digestive system. Members of Casuarius are considered keystone species. ("Community for Coastal and Cassowary Conservation", 2006)

Economic Importance for Humans: Positive

Dwarf cassowaries are kept in captivity as pets and sometimes traded locally. Cassowaries are sometimes hunted by local tribes for their meat and feathers. ("Cassowary", 1985)

Economic Importance for Humans: Negative

Dwarf cassowaries have been known to attack humans when provoked. Using their strong legs and sharp claws, several deaths of humans have been recorded as the result of cassowary attacks. ("Cassowaries-Bennett's cassowary", 2003; "Cassowary", 1985)

  • Negative Impacts
  • injures humans

Conservation Status

Dwarf cassowaries are hunted extensively but populations seem to be stable at this time. Habitat destruction and excessive hunting could threaten populations. ("The IUCN Red List of Threatened Species", 2004)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Stephanie Jones (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

2003. Cassowaries-Bennett's cassowary. Pp. "75-81" in M Hutchins, J Jackson, D Olendorf, eds. Grzimek's Animal Life Encyclopedia, Vol. 8-11, 2nd Edition. Farmington Hills: Thomson Gale.

The British Ornithologists' Union. 1985. Cassowary. Pp. 82 in B Campell, E Lack, eds. A Dictionary of Birds, Vol. 1, 1st Edition. Vermillion, South Dakota: Buteo Books.

Wet Tropics Management Authority. 2006. "Community for Coastal and Cassowary Conservation" (On-line). Cassowary. Accessed October 14, 2006 at http://www.cassowaryconservation.asn.au/noframedocs/Cassowary.html.

Marshall Editions Developments Limited. 1990. Family Casuariidae-Dwarf Cassowary. Pp. "43-44" in C Perrins, ed. The Illustrated Encyclopedia of Birds, Vol. 1, 1st Edition. New York: Prentice Hall Press.

International Union for Conservation of Nature and Natural Resources. 2004. "The IUCN Red List of Threatened Species" (On-line). Casuarius bennetti. Accessed October 14, 2006 at http://www.iucnredlist.org/search/details.php/4010/summ.

Wet Tropics Management Authority. 2006. "Wet Tropics Management Authority" (On-line). Birds - The Cassowary. Accessed October 14, 2006 at http://www.wettropics.gov.au/pa/pa_casso.html.

Diamond, J. 1972. Avifauna of the Eastern Highlands of New Guinea. Cambridge: Nuttal Ornithological Club.

Gould, J. 1970. Birds of New Guinea. Great Britain: Methuen & Co Ltd.

Mack, A., J. Jones. 2003. Low-Frequency Vocalizations By Cassowaries. The Auk, 120/4: "1062-1068". Accessed October 14, 2006 at http://www.bioone.org/perlserv/?request=get-document&doi=10.1642%2F0004-8038%282003%29120%5B1062%3ALVBCCS%5D2.0.CO%3B2.

Ramel, G. 2005. "Struthioniformes" (On-line). Earthlife Web. Accessed November 12, 2006 at http://www.earthlife.net/birds/struthioniformes.html.

Rand, A., E. Gilliard. 1986. Handbook of New Guinea Birds. Garden City: The Natural History Press.

Richard, R. 1996. "Cassowary Husbandry Workshop" (On-line). The Sonoma Bird Farm. Accessed November 12, 2006 at http://www.cassowary.com/workshop.html.

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