The casque on a rhinoceros hornbill's beak is not just decoration - it acts like a sound box, making the bird's loud calls echo further through the forest. When two hornbills call to each other in the jungle canopy, the sound is so loud and strange that it carries a very long way. Indigenous people of Borneo have long considered the hornbill a sacred and important bird.
Hornbills are famous for their extraordinary nesting behaviour. When the female is ready to lay her eggs, she seals herself inside a hollow tree using mud, droppings, and fruit pulp, leaving only a tiny slit. The male feeds her through the slit for weeks while she incubates the eggs. The 'prison' protects the nest from snakes and other animals.
Rhinoceros hornbills eat mainly fruit - especially figs - which makes them very important for the forest. Every seed they swallow and later drop in their droppings has a chance to grow into a new tree, sometimes far from where it started. They are sometimes called the 'farmers of the forest' for this reason.