The dark-sided one

 It's generally not easy to distinguish the migrant flycatchers especially between the asian brown and the Dark-sided Flycatcher.  On closer scrutiny of images taken so far I finally discovered that I've already shot the dark-sided much earlier.

What distinguished it is its shorter and totally black bill, its longer wing tips reaching to its tail, darker greyish/brown flanks and dark undertail covert centre.

15/2020

CMCO Day 25/26

My first sighting that I thought was an asian brown flycatcher.

The distinct black bill.

Later shots that revealed even clearer its features, being longer and all of the above-mentioned features on closer examination.

And this could possibly be a first winter.

In comparison the Asian Brown Flycatcher.