The Knobbed hornbill (Aceros cassidix), also known as Sulawesi wrinkled hornbill, is a large species of hornbill with a yellow bill, white tail feathers, pale blue skin around eye, blackish feet and bare dark blue throat. The male has rufous/buff face and neck, orange-red eyes, and a high reddish casque on the top of his bill. The female has a black face and neck, a yellow casque, and brownish eyes. An Indonesian endemic, the knobbed hornbill is distributed in the tropical evergreen forests of Sulawesi, Buton, Lembeh, Togian and Muna Island.