Hornbill
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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Coraciiformes (but see text)
Family: Bucerotidae

[Photo] Red-billed Hornbills (Tockus erythrorhynchus). The Red-billed Hornbill has a black stripe on the back of its head. Public domain from USFWA

Hornbills (family Bucerotidae) are a group of birds characterized by a long, down-curved bill, sometimes with a casque on the upper mandible. Frequently, the bill is brightly coloured. Both the common English and the scientific name of the family refer to the shape of the bill, "buceros" being "cow horn" in Greek. In addition, they possess a two-lobed kidney. Hornbills are the only birds in which the first two neck vertebrae (the axis and atlas) are fused together; this probably provides a more stable platform for carrying the bill.

Composition and relationships
The Bucerotidae include some 57 living species, about 10 of them endemic to the southern part of Africa. Their distribution ranges from Africa south of the Sahara through tropical Asia to the Philippines and Solomon Islands. Most are arboreal birds of dense forest, but the large ground-hornbills (Bucorvus), as their name implies, are terrestrial birds of open savanna.

There are two subfamilies: the Bucorvinae contain the 2 ground-hornbills in a single genus, whereas the Bucerotinae contain all other taxa. In the Sibley-Ahlquist taxonomy, hornbills are separated from the Coraciiformes as a separate order Bucerotiformes, with the subfamilies elevated to family level. Given that they are almost as distant from the rollers, kingfishers and allies as are the trogons (Johansson & Ericson 2003), the arrangement chosen is more a matter of personal taste than any well-established taxonomic practice. All that can be said with reasonable certainty is that placing the hornbills outside the Coraciiformes and the trogons inside would be incorrect.

Characteristics
Hornbills are omnivorous birds, eating fruit, insects and small animals. They cannot swallow food caught at the tip of the beak as their tongues are too short to manipulate it, so they toss it back to the throat with a jerk of the head. They range in size from the Black Dwarf Hornbill (Tockus hartlaubi), at 102 grams (3.6 oz) and 30 cm (1 foot), to the Southern Ground-hornbill (Bucorvus leadbeateri), at up to 6.2 kg (13.6 lbs) and 1.2 m (4 feet). Males are about 18% larger than females on average, and some species have sexual dichromatism. In the Abyssinian Ground-hornbill, for example, pure blue skin on the face and throat denotes an adult female, and red and blue skin denotes an adult male.

Hornbills generally form monogamous pairs. The female lays up to six white eggs in existing holes or crevices, either in trees or rocks. Before incubation, the females of all Bucorvinae???sometimes assisted by the male???begin to close the entrance to the nest cavity with a wall made of mud, droppings and fruit pulp. When the female is ready to lay her eggs, the entrance is just large enough for it to enter the nest, and after she has done so, the remaining opening is also all but sealed shut. There is only one narrow aperture, big enough for the male to transfer food to the mother and the chicks. During the incubation period the female undergoes a complete moult. When the chicks and the female are too big to fit in the nest, the mother breaks out, then both parents feed the chicks. In some species the mother rebuilds the wall, whereas in others the chicks themselves rebuild the wall unaided. The ground-hornbills are conventional cavity-nesters instead.

Species List in Taxonomic Order
Subfamily Bucorvinae

Genus Tockus
White-crested Hornbill Tockus albocristatus
Black Dwarf Hornbill Tockus hartlaubi
Red-billed Dwarf Hornbill Tockus camurus
Monteiro's Hornbill Tockus monteiri
Red-billed Hornbill Tockus erythrorhynchus
Eastern Yellow-billed Hornbill Tockus flavirostris
Southern Yellow-billed Hornbill Tockus leucomelas
Jackson's Hornbill Tockus jacksoni
Von der Decken's Hornbill Tockus deckeni
Crowned Hornbill Tockus alboterminatus
Bradfield's Hornbill Tockus bradfieldi
African Pied Hornbill Tockus fasciatus
Hemprich's Hornbill Tockus hemprichii
African Grey Hornbill Tockus nasutus

Genus Ocyceros
Pale-billed Hornbill Ocyceros pallidirostris
Malabar Grey Hornbill Ocyceros griseus
Ceylon Grey Hornbill Ocyceros gingalensis
Indian Grey-Hornbill Ocyceros biostris

Genus Anthracoceros
Malabar Pied Hornbill Anthracoceros coronatus
Oriental Pied Hornbill Anthracoceros albirostris
Black Hornbill Anthracoceros malayanus
Palawan Hornbill Antracoceros marchei

Genus Buceros
Rhinoceros Hornbill Buceros rhinoceros
Great Hornbill Buceros bicornis
Rufous Hornbill Buceros hydrocorax
Helmeted Hornbill Buceros vigil

Genus Anorrhinus
Brown Hornbill Anorrhinus tickelli
Bushy-crested Hornbill Anorrhinus galeritus

Genus Penelopides
Luzon Hornbill Penelopides manillae
Mindoro Hornbill Penelopides mindorensis
Tarictic Hornbill Penelopides panini
Samar Hornbill Penelopides samarensis
Mindanao Hornbill Penelopides affinis
Sulawesi Hornbill Penelopides exarhatus

Genus Aceros
White-crowned Hornbill Aceros comatus
Rufous-necked Hornbill Aceros nipalensis
Wrinkled Hornbill Aceros corrugatus
Writhed-billed Hornbill Aceros waldeni
Knobbed Hornbill Aceros cassidix
Wreathed Hornbill Aceros undulatus
Narcondam Hornbill Aceros narcondami
Sumba Hornbill Aceros everetti
Plain-pouched Hornbill Aceros subruficollis
Blyth's Hornbill Aceros plicatus

Genus Ceratogymna
Trumpeter Hornbill Ceratogymna bucinator
Piping Hornbill Ceratogymna fistulator
Silvery-cheeked Hornbill Ceratogymna brevis
Black-and-white-casqued Hornbill Ceratogymna subcylindricus
Brown-cheeked Hornbill Ceratogymna cylindricus
White-thighed Hornbill Ceratogymna albotibialis
Black-casqued Hornbill Ceratogymna atrata
Yellow-casqued Hornbill Ceratogymna elata

Subfamily Bucerotinae

Genus Bucorvus
Abyssinian Ground-Hornbill Bucorvus abyssinicus
Southern Ground-Hornbill Bucorvus leadbeateri

Cultural significance
Most species' casques are very light, containing a good deal of airspace. However, the Helmeted Hornbill has a solid casque made of a material called hornbill ivory, which is greatly valued as a carving material in China and Japan. It is often used as a medium for the art of netsuke.

A Tockus hornbill was the model for Zazu from the movies The Lion King, The Lion King 2, and The Lion King 1 1/2.

http://en.wikipedia.org/wiki/Hornbill

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