This is a forest species, occurring at a variety of elevations, but mainly in the mountains. It is highly variable with dark and pale subspecies, some with white faces and some with gray. The white-faced and blackish groups have been considered full species in the past. This individual is of the sooty group also sometimes considered a separate species.
The 14 subspecies currently recognized by HBW differ significantly from the subspecies named in Robson. Following the descriptions in HBW, I tentatively assigned this individual to D. l. mouhotii based on its neutral gray coloration, blackish forehead, long deeply notched tail, and lack of white in the face. It breeds in Southern Myanmar and Northern Thailand; and migrates to Indochina. However Robson's plate shows this race as much darker, almost black which seems at odds with other sources. Furthermore this race intergrades with D. l. hopwoodi and D. l. bondi, both of which are migratory, so any subspecies assignment away from known breeding areas should probably be tentative. More information at Birdforum Opus.
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