The bill of the Oriental Pied Hornbill (Anthracoceros albirostris), like in all hornbills, is long, decurved and topped with a protruding casque. The casque is hollow and extremely light, supported internally by bony ridges and rods. The hollow structure functions as a resonance chamber to amplify the hornbill’s call.
In the juvenile, the bill and casque are poorly developed, especially at fledging. These increase in size until the fledgling becomes an adult. As with most, if not all species, the male has a larger casque than the female.
According to Kinnaird & O’Brien (2007), the long bill is an important feeding tool. Because of its size and weight, the bird is not always able to reach the outer branches of its food plants. The long bill thus comes in useful here.
The tips of the two mandibles meet precisely as in a pair of forceps. This allows the bird to pick food items like an egg or a fig without breaking or squashing it. The ability to see its own bill tip that most birds cannot do, also helps it to manipulate food – picking it at the bill tip and then tossing it down the throat.
The mandibles can also exert enough force to crush the skull of a chick or break open a fruit. The inner surfaces are serrated and this allows the bill to grip objects efficiently as well as to carry the items in the tip. At the same time the serrated surfaces of the two mandibles do not meet to form sharp cutting edges – there is always a gap between them.
Wang Luan Keng & YC Wee
(Image by Wang Luan Keng)
1. Kemp, A. C. (2001). Family Bucerotidae (Hornbills). In: del Hoyo, J., A. Elliott & J. Sargatal (eds.). Handbook of the birds of the world. Vol. 6. Mousebirds to Hornbills. Lynx Editions, Barcelona. Pp. 436-523.
2. Kinnaird, M. F. & O’Brien, T. G. (2007). The ecology and conservation of Asian hornbills: Farmers of the forest. University of Chicago Press.