Pied Imperial Pigeon (Ducula bicolor)
found a breeding pair in school!! they're building a stick nest just off the 2nd floor corridor! :) found out from my bird guide book that they are Pied Imperial Pigeons (Ducula bicolor)
This distinctive coastal and island pigeon is a target for hunters but can still occur in huge flocks. Creamy to ivory-white, often sullied by food, with black flight feathers and tip of tail; bill and feet blue-grey. Juveniles are greyer. Forms big breeding colonies on offshore isalnds, where fig trees are abundant; noisily clucking hoo-hoo-hoo. Also seen singly or in small groups, especially at dawn and dusk over the coast. Found on small islands, in mangrove and other coastal forest. Occurs from South Burma to New Guinea; resident, but with long-distance movements and interchange between islands.
hoo hoo hoo.... :p (though according to Wikipedia, "Calls made by the birds are a deep "mrrrooooo", "roo-ca-hoo" and "up-ooooo"...)