Thanks to all for your help. Sorry that I have no more photos of the bird because of the dense vegetation. I think it is not a Pale Thrush, Dusky Warbler or Common Tailor Bird. Yes, I agree it might be a Brownish-flanked Bush Warbler or Manchurian Bush Warbler. Does it fit Radde's Warbler or Yellow-streaked Warbler?
To Russcath, I think you have already found the Po Shan Road birding directory from other thread of this forum. The bird was found on the slope by the Po Shan Road near a monitoring station in the afternoon (the lowest section of Po Shan Road on the Brendan's birding map).
