brendank

I have had 4 Blue-and-white Flycatchers on Po Shan Road this November and December and had the last one December 2.  I would say it is likely to be a Blue-and-white Flycatcher.

brendank

I suppose it's not totally possible to rule out either Fujian Niltava or Blue-and-white Flycatchers (or Rufous-bellied) from these photos. It seems adult female Fujian should have a blue half collar but this bird I would guess is a first winter bird so I don't know that it would show that mark.

Behavior should be different.  If it was near the ground most of the time, that should favor Fujian Niltava.