Black Hornbill with white hair, Sarawak, Malaysian Borneo (1 Viewer)

[dixonlau]

Location: Sibu (lowland), Sarawak, Malaysian Borneo
Date: 7-Nov-2021

May I know why this Black hornbill has a white hair on its head? Is it sub/split or Black Hornbill can be with/without white hair?

Both pic below are same bird.





Comparing to one without white hair taken a week ago.



Many thanks.

 

[MacNara]

According to Robson, 'Birds of South-east Asia', where it is illustrated, it's a 'male variant'.

 

[dixonlau]

According to Robson, 'Birds of South-east Asia', where it is illustrated, it's a 'male variant'.

Thank you.