hornbill

 

common name for members of the family Bucerotidae, Old World birds of tropical and subtropical forests, named for their enormous down-curved bills surmounted by grotesque horny casques. From 2 to 5 ft (61–152.5 cm) in length, they are the largest of an order that also includes the kingfishers. Hornbills are black and dark brown with patches of white or cream on the body, wings, and tail. The bill is usually brownish, though in some species it is black, red, or yellow. Omnivorous, hornbills eat fruits, berries, insects, and small animals. They have loud, far-carrying voices and a variety of calls, including brays, toots, bellows, and cackles. They are noted for their unusual nesting habits; presumably as a defense against monkeys and snakes, the female is sealed into the nesting cavity by the male, who feeds her through a bill-sized aperture for a period of from 6 weeks to 3 months while she incubates the eggs. This practice, and the fact that hornbills mate for life, has made them the subject of superstition among native tribes, who use them (or representations of them) in religious rituals as symbols of purity and fidelity. The great hornbill, Buceros bicornis, ranges from India to Indochina and Sumatra. Hornbills are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Coraciiformes, family Bucerotidae.

Hornbills
Abyssinian Ground-hornbill Bucorvus abyssinicus
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Coraciiformes (but see text) Family: Bucerotidae Rafinesque, 1815
Genera
Aceros Anorrhinus Anthracoceros Buceros Bucorvus Ceratogymna Ocyceros Penelopides Tockus

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
  • Writhed 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 leadeateri

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.

References

• Johansson, Ulf S. & Ericson, Per G. P. (2003): Molecular support for a sister group relationship between Pici and Galbulae (Piciformes sensu Wetmore 1960). J. Avian Biol. 34(2): 185–197. doi:10.1034/j.1600-048X.2003.03103.x PDF fulltext

• Kemp, Alan C. & Woodcock, Martin (1995): The Hornbills: Bucerotiformes. Oxford University Press, Oxford, New York. ISBN 0-19-857729-X

• Maclean, Gordon Lindsay & Roberts, Austin (1988): Roberts' Birds of Southern Africa (Revised Edition). Hyperion Books. ISBN 1853680370

• Wallace, Alfred Russel (1863): "The Bucerotidæ, or Hornbills". The Intellectual Observer June 1863: 309–316.

• Zimmerman, Dale A., Turner, Donald A., & Pearson, David J. (1999): Birds of Kenya and Northern Tanzania (Field Guide Edition). Princeton University Press. ISBN 0-691-01022-6

External links

• Hornbill videos on the Internet Bird Collection
• ITIS Taxonometric Report Data
• Birds of India website

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