
Image 1: Hornbills’ typical habitat.
Hornbills are fascinating birds. Their large beaks and casques make these birds easy to recognise. The casque, the hollow structure on top of their beak, is a unique feature. It is believed to serve various purposes, including resonance for their calls, sexual display to attract mates, and sometimes even as a means of defence or protection.

Image 2: A pair of Plain-pouched Hornbill (Aceros subruficollis).
The casque is made of a substance called keratin (the same material that makes up human hair and nails). Although it is not solid bone, it can be very dense and can grow quite large in some species. Hornbills use their beaks and casques to forage for food, communicate, and defend themselves from predators.

Image 3: Helmeted Hornbill (Buceros vigil) – note its helmet-like casque
Helmeted Hornbills are hunted for their casques that are carved into intricate pieces of jewellery, ornaments, and other decorative items. Other species like Great and Rhinoceros Hornbills are hunted for tribal headdresses and feathers for tribal costumes. Most species are hunted for food. The status of many species of hornbills are thus becoming endangered or vulnerable. Conservation efforts are becoming all the more important to protect these extraordinary birds and their unique features.

Image 4: Black Hornbill (Anthracoceros malayanus).
Despite the challenges that come with having such large, seemingly cumbersome appendages, hornbills are well adapted to their environments, with a specialised lifestyle and behaviour that take full advantage of their unique anatomy.

Image 5: Bushy-crested Hornbill (Anorrhinus galeritus) at nest.
Many species are threatened into extinction due to poaching for their casques. Deforestation is another threat to their existence as they breed in natural cavities found on the trunks of large forest trees. When such holes are available, they are in high demand by insects (bees, wasps), birds (owls, woodpeckers), reptiles (monitor lizards) and mammals (bats). Sun Bears and Asiatic Black Bears tear the holes made by woodpeckers and used by bees to get at the honey.

Image 6: Rhinoceros Hornbill (Buceros rhinoceros) at nest.
Once a suitable cavity is located, the female will clean up the inside and seals the entrance from inside with mud and regurgitated food, leaving a narrow slit for the male to feed her and later, her chicks. Inside the cavity the female lays a clutch of eggs. Once the chicks develop feathers and are ready to leave the nest, the mud entrance is broken and the adults will stop feeding from outside the nesting hole. Feeding will then be from outside the hole to lure the chicks to leave the nest. Thereafter the adults will teach the juveniles how to forage for food, avoid predators and take shelter during the night.

Image 7: Great Hornbill (Buceros bicornis) feeding the adult female and chicks inside the nest.
Out of the 62 species of hornbills in the world, Thailand has 13 species.
Acknowledgement: Hornbill Research Foundation and Bee Choo Strange for information. Pictures credit: Thailand Hornbill Project and Morten Strange.