Red Knobbed Hornbill. Photo taken at Tangkoko National Reserve in Sulawesi Indonesia. It is also known as the Sulawesi Wrinkled Hornbill. An Indonesian endemic, the Knobbed Hornbill is distributed in the tropical evergreen forests of Sulawesi, Buton, Lembeh, Togian and Muna Island. As with other hornbills, the Knobbed Hornbill is believed to be a monogamous species. The diet consists mainly of fruits and figs. The female sealed itself inside a tree hole for egg-laying. During this time, the male will provide foods for the female and the young. The Knobbed Hornbill is evaluated as vulnerable on the IUCN Red List of Threatened Species.