White-thighed hornbill (Bycanistes albotibialis)
|Synonyms:||Bycanistes cylindricus albotibialis, Ceratogymna albotibialis|
|Size||Head-body length: 60 - 70 cm (2) (3)|
Male weight: 1.2 - 1.4 kg (2) (3)
Female weight: 0.9 - 1.1 kg (2) (3)
Classified as Least Concern (LC) on the IUCN Red List (1).
The white-thighed hornbill is a large and highly vocal bird, with a long, slightly decurved beak, topped with a large and distinctive growth known as a casque. The function of this strange structure is debated, though it may provide support for the long beak, help in attracting a mate, or serve to amplify the bird’s raucous call (4).
The white-thighed hornbill is considered by some to be a subspecies of the brown-cheeked hornbill, Bycanistes cylindricus (2) (3) (5), although it occupies a distinct range (2) and differs in its colouration. Like B. cylindricus, the body is glossy black, and the rump, belly, tail coverts and tips of the wings are white, with a broad black band across the centre of an otherwise white tail. However, the white-thighed hornbill lacks the brown cheek and throat feathers of B. cylindricus, and has white on its thighs, giving the species its common name. Males have a brown beak, slightly grooved at the base of the lower mandible, with a cream-coloured tip, and a cream-coloured casque that also has slight grooving. The beak is darker and the casque more elongated than in B. cylindricus. The bare skin around the eye is pale yellow, the eye itself is brownish, and the legs and feet are black. Females are smaller, with much smaller beaks and casques, while juveniles lack the casque altogether (2) (3).
Western and central Africa, from Benin east to Sudan and Uganda, and south to the Democratic Republic of the Congo and northern Angola (2) (3) (5).
The white-thighed hornbill is found in extensive areas of primary forest, mainly in lowlands, but also recorded up to elevations of 4,054 metres. It is also occasionally found in adjacent areas of secondary forest and in plantations (2) (3).
Fruit makes up about 90 percent of the diet of the white-thighed hornbill, though it also takes insects and the eggs and nestlings of other birds (2) (3). Most feeding takes place high in the canopy, where large groups may gather at fruiting trees. The long distances travelled in search of fruit mean this hornbill is likely to be an important seed disperser, playing a key role in forest regeneration (2) (4) (6).
Hornbills have a unique form of nesting behaviour. The female uses mud or her own droppings to seal herself inside a tree cavity, leaving only a narrow slit through which the male feeds both her and the chicks until the time comes for the chicks to leave the nest (4). In Bycanistes hornbills, the male swallows mud, forming it into pellets which are regurgitated to the female while she is inside preparing the nest. For this reason, the males are often encountered beside pools or termite mounds prior to nesting (7). However, little else is known about the breeding behaviour of the white-thighed hornbill (2). Up to two nestlings have been recorded, but usually only a single offspring is seen flying with the parent birds after fledging (2) (3). Like other hornbills, the white-thighed hornbill is likely to be monogamous (4), and usually moves around in pairs or small family groups (2). There is no obvious breeding season (2), but reproduction may be timed to coincide with peak fruit availability and may even be abandoned in years when this is low (8).
The white-thighed hornbill is threatened by habitat loss and fragmentation, and is among the first of the large hornbill species to be affected by forest disturbance, although it does sometimes occur in disturbed areas (2). Little information is available on whether, like other hornbill species (4), the white-thighed hornbill is hunted, for example for food or as a pet. However, it has been reported that some areas have local taboos against eating white-thighed hornbills (3).
The white-thighed hornbill is not currently considered globally threatened, though population trends have yet to be quantified and there is some evidence that they are in decline (5). There are no known specific conservation measures in place for the species, but, as it is often treated together with B. cylindricus, further research may be needed to better understand the conservation needs of each as separate species.
For more information on hornbill research and conservation see:
Coraciiformes Taxon Advisory Group:
The Hornbill Research Foundation:
For more information on this and other bird species please see:
- BirdLife International:
Authenticated (20/07/09) by Dr Alan Kemp, retired Curator, Transvaal Museum (now Ditsong National Museum of Natural History), and Research Associate, Percy FitzPatrick Institute of African Ornithology, University of Cape Town.
- Coverts: small feathers concealing the bases of larger flight feathers, usually on the wings or tail.
- Monogamous: having only one mate during a breeding season, or throughout the breeding life of a pair.
- Primary forest: forest that has remained undisturbed for a long time and has reached a mature condition.
- Secondary forest: forest that has re-grown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
IUCN Red List (November, 2008)
- del Hoyo, J., Elliott, A. and Sargatal, J. (2001) Handbook of the Birds of the World. Volume 6: Mousebirds to Hornbills. Lynx Edicions, Barcelona.
- Kemp, A.C. (1995) The Hornbills: Bucerotiformes. Oxford University Press, Oxford.
- Grzimek, B. (2003) Grzimek’s Animal Life Encyclopedia. Second Edition. Volume 10: Birds III. Gale Group, Farmington Hills, Michigan.
BirdLife International (November, 2008)
- Holbrook, K.M., Smith, T.B. and Hardesty, B.D. (2002) Implications of long-distance movements of frugivorous rain forest hornbills. Ecography, 25(6): 745 - 749.
- Kemp, A. (2009) Pers. comm.
- Stauffer, D.J. and Smith, T.B. (2004) Breeding and nest site characteristics of the Black-casqued Hornbill Ceratogymna atrata and White-thighed Hornbill Ceratogymna cylindricus in south-central Cameroon. Ostrich, 75(3): 79 - 88.