At first glance, hornbills appear as ancient creatures, the proportions of their features certainly not endowed with elegance. It is as if they were designed in an ancient style by an inexperienced designer, yet the awkward look of hornbills turns out to be a charm that attracts people to them at first sight.Their most striking features are their overly large and curved bill, and the large casque that decorates the top of the bill. The only hornbill in the world with a solid casque is the Helmeted Hornbill, where more than half of the front of its casque length is solid and resembles ivory.

Helmeted Hornbill ivory was traded by Chinese merchants at a price higher than jade during the Ming Dynasty. Hornbill casques come in different shapes and sizes. Some large,flat and broad, such as that of the Great Hornbill, some lie as a cylinder along the top of the elongated bill, even curve upward at the tip to form a ‘horn’ for the aptly named Rhinoceros Hornbill, but some are small, with corrugations on them like an elephant’s molar teeth, such as the casque of the Wreathed Hornbill.

Male hornbills are invariably larger than females, but the sexes can be distinguished when mature by certain features, such as the color of the bill and/or casque, the color of the head and neck feathers and the color of naked skin, especially on the bare gular pouch, orbital and facial skin.They have beautiful long eye lashes that young ladies would envy.  The structure of the hornbill’s wing differs from other birds in the lack of under wing coverts, which creates gaps between the bases of each of primary and secondary flight feather.

The sound produced when hornbills flap their wings and air passes through such spaces, and between the narrowed bases of the primary flight feathers makes such a noise that, in the silence of the forest, it many lead the listener to imagine all sorts of things happening above them.

In the rainy season at Khao Yai National Park, the choruses of insects and the sounds of rain drops, trapped on branches and foliage and then shed by a gust of wind, could provide the background, as that of a concert being performed.