When in flight, dark underwing and breast can be seen, while its neck is held straight out. Tail is black, with white beneath the tail. Chicks are white and downy with a black bill and a black, bald crown. Chicks are incubated and tended to by both parents. Gives out a throaty karau and also claps bill.
Chicks give out loud, harsh and repeated krack calls.
Hunts alone or in small loose groups, commonly under the forest canopy, feeding in margins of swampy forest, and appears at salt licks. Feeds by probing their long bills into shallow water for fish, frogs, molluscs and crustaceans. Frequently soars on rising thermals and roosts high up in forest trees. Core habitat is the floodplains of large rivers, including the riverine swamp forest along lower Perak, now being cleared for agriculture. Poaching Conservation Protection of habitat in parks such as Taman Negara, Kerau Wildlife Reserve and Kinabatangan Wildlife Sanctuary.