The rufous hornbill, also known as the Philippine hornbill and locally as kalaw, is a large species of hornbill endemic to the Philippines. They are referred by locals as the "clock-of-the-mountains" due to its large booming call which typically occur of every hour. It occurs in moist tropical lowland forest. They are now considered to be a threatened species and its reasons for decline being habitat destruction, hunting and poaching for the illegal pet trade.

Bucerotiformes is an order of birds that contains the hornbills, ground hornbills, hoopoes and wood hoopoes. These birds were previously classified as members of Coraciiformes. The clade is distributed in Africa, Asia, Europe and Melanesia.