 None of the African species of hornbills are seriously threatened, but many Asian hornbills are threatened by hunting and habitat loss, as they tend to require primary forest.Among these threatened species, only the plain-pouched hornbill and rufous-necked hornbill are found on the Asian mainland; all others are insular in their distribution.In the Philippines alone, one species (the Palawan hornbill) is vulnerable, and two species (the Mindoro and Visayan hornbills) are endangered.