Malayan Wreathed Hornbill


ORDER: Buceretiformes

FAMILY: Bucerotidae

GENUS: Aceros (Rhyticeros)

SPECIES: undulatus

DESCRIPTION:
Length 75 to 85 cm (30 to 35 in). Males are larger than females and weigh from 4 to 8 lbs; females weigh from 3 to 6 lbs. Birds are black with a white tail stained yellow with preen gland oil. Females have a black head and neck. Males have a rufous crown and white face and neck. The iris and bare skin around the eye are cherry-red. The extensive inflatable bare throat skin has an interrupted blue-black band across its center and is bright yellow in the male and blue in the female. Bill is dull white with a casque of low wreaths across the base of the upper mandible. Oakland Zoo also supports the Hornbill Nest Project.

GEOGRAPHICAL RANGE AND HABITAT:
Forested hill ranges of India, Myanmar, Thailand, Laos, Vietnam, Malaysia, Sumatra, Java, Bali, Borneo.

DIET:
Omnivorous and generalized feeder, eating mostly fruit. However, male feeds animal prey such as bats, reptiles, frogs, crabs, and insects to brooding female and developing chicks. Browses from the tree tops to the forest floor and even in water.

LIFE CYCLE/SOCIAL STRUCTURE:
Flocks of around twenty range far in flight, dropping down in response to calls or when spotting others below. They congregate at feeding and bathing sites, with up to 400 at communal roosts. These birds form life-long monogamous pairs. They nest in hollows excavated by the pair or already existing in tree trunks and may return to the same nesting hole for as many as nine years. After laying up to three white eggs, the female seals herself into the nest chamber with mud and dung, leaving a slit that just admits the male's beak. She is completely dependent on him for food during the 4 1/2 months that she incubates the eggs and broods the young. During this time, she also molts and re grows her feathers. She emerges with usually only one purple-skinned chick, any other chicks having died of starvation.

SPECIAL ADAPTATIONS:
Long flattened eyelashes. Long broad wings with short tails; loud "whooshing" wing beats are due to short underwing coverts that do not cover the flight quills. Hornbills are unique among birds in having a casque, the first two neck vertebrae fused and having two-lobed kidneys (all other birds have three.) Except for the two large ground hornbill species of Africa, all hornbills seal their nests, another unique attribute. The second and third toes are also partly fused (syndactyly), an aid to scrambling through tree top branches to find fruit.

INTERPRETIVE INFORMATION:
The hornbill's call from a perch is a repeated barking using an inflatable throat and jerking the bill upward with each note. The name hornbill stems from the tubular protuberance on the upper mandible of both sexes in many of the species. The protuberance, known as a casque, varies in size and configuration with different species of hornbill. Its function is unclear. It may act as a species recognition signal or to show gender and status or as a support for the long decurved upper bill or as a sound box for the hornbill's many calls. The Wreathed Hornbill's casque is just a flattened wrinkled wreath at the base of the bill. Its Javanese name "Anggang tahon" means "year bird", because of the cross ridges on the beak. Belief that a new ridge forms every year is not valid, as more than one ridge may form in a year, and some front ridges may even drop off. Up to nine ridges have been counted, but the birds may live twenty years or more.

OUR ANIMALS:

STATUS IN WILD:
In general, hornbill populations are decreasing throughout Southeast Asia, due to forest destruction. On appendix II (threatened) of CITES.

BIBLIOGRAPHY:

  1. Grzimek, Bernhard. 1973. Grzimek's Animal Life Encyclopedia. V.9, N.3. Van Nostrand Reinhold Co, New York.
  2. Kemp, Alan, 1995. The Hornbills. Oxford University Press, Oxford, New York, Tokyo
  3. Payne, Junaidi. 1990. Wild Malaysia. MIT Press, Cambridge, Mass.
  4. Proctor & Lynch. 1993. Manual of Ornithology: Avian Structure and Function. Yale University Press.
  5. Sibley & Moore. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press, New Haven, CT.
  6. Unk. 1991. The New Encyclopedia Britannica, 15th Edition.

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