The Walden's hornbill (Aceros waldeni) locally called dulungan, also known as the Visayan wrinkled hornbill, rufous-headed hornbill or writhed-billed hornbill, is a critically endangered species of hornbill living in the rainforests on the islands of Negros and Panay in the Philippines. It is closely related to the writhed hornbill, but can be recognized by the yellow throat and ocular skin in the male, and the blue throat and ocular skin in the female (both throat and ocular skin are deep orange or red in both sexes of the writhed hornbill). Its binomial name commemorates the Scottish ornithologist Viscount Walden.