Heterophasia pulchella
Habitat
Subtropical or tropical moist montane forest
Range
China, India and Myanmar
The beautiful sibia is a member of the family Leiothrichidae found in China, India and Myanmar. Its natural habitat is subtropical or tropical moist montane forest (Wikipedia, general species account).
That short account is the only source read for the Bhutan guide. It does not name Bhutan, so its occurrence there is flagged for checking, and it gives no plumage, size, diet or breeding information.