not sure about ID, only saw the pair briefly, but it seemed like Buceros and does not seem to have B. bicornis white coloration on wings bottom
1200 m; caught and released for research with permission of the Malaysian government and Sarawak Forestry Department.
1000 m; caught and released for research with permission of the Malaysian government and Sarawak Forestry Department.
Video available for this observation: https://www.youtube.com/watch?v=MmL3EAa-tac
Four seen, flying north.
10 or so seen as usual flying north in the early morning.