Hornbills nest in cavities that develop naturally in old and dead trees. These birds are not capable of excavating them, maybe only in enlarging the entrance and the inside. However, such trees are never plentiful in a healthy forest. In urban areas dead trees are not tolerated as they pose a danger to life and limbs. Old trees with naturally developing large cavities are also deemed potentially dangerous. Due to this shortage in nesting cavities, there is always a fierce competition whenever there is one available.
On the offshore island of Pulau Ubin where most of our Oriental Pied Hornbills (Anthracoceros albirostris) are found, and there are about 20 birds or so, there seems to be no problem at the moment. With an increase in population, competition for nesting cavities will invariable develop.
The Singapore Hornbill Project has been experimenting with nesting boxes at the Jurong Bird Park. Because these birds are caged, they are receptive to these boxes and are breeding inside. These boxes are now being tried in Pulau Ubin under natural conditions (top).
In Thailand, nesting cavities are excavated from pieces of tree trunks to specifications, hauled up along the trunk to be firmly attached to the tree (below left). These have proven successful. The image below (right) shows the Great Hornbill (Buceros bicronis) making use of such a contraption to breed.
Input by YC Wee; image of nesting box at Pulau Ubin by Angie Ng, those from Thailand courtesy of Prof Pilai Poonswad, Hornbill Research Foundation.