thinfor

Yes, should be a yellow-crested cockatoo (小葵花鳳頭鸚鵡).  It's very common in northern HK island.  I just saw a flock of over 10 of them just south above HK park yesterday.

thinfor

Thanks for your comment.  I always could not measure the size of birds in the photo without any solid references (I think the tree branches could tell that this cockatoo is much greater than a yellow-crested.)
I'm going to search the internet to have a look at white cockatoo.