This is a first-winter Dark-sided Flycatcher. It lacks pale lores and has a poorly-defined moustachial stripe and hence has the classic plain-faced and hooded appearance of Dark-sided. The streaking below is too well defined for Asian Brown and the bill is too narrow. There appear to be dark marks on the under-tail coverts which only Dark-sided shows. The retained juvenile greater coverts are tipped pale buff which neither Asian Brown nor Grey-streaked show (first-winter Dark-sided does not always show this, but if present it is diagnostic of Dark-sided). Primary projection seems long for Asian Brown.
Grey-streaked can further be eliminated as the wings/primary projection are too short, the streaks below are too diffuse and it lacks a well-defined sub-moustachial and malar stripe (which gives Grey-streaked its’ more marked head pattern).
