The second bird can be ID'ed as lugens based on the shape of the eye-stripe (broader behing the eye) and the extensive white in the wing coverts. (Be careful of the second feature - ocularis can also have extensive white in the wing, especially males in spring). I think the slightly blue tone to the mantle probably also favours lugens but this may be related to light conditions.
I suspect that lugens is under-recorded in HK because female birds like this are so similar to ocularis - and similarly I wonder if ocularis may be over-recorded in winter!
