Chestnut-crowned Bush Warbler

The chestnut-crowned bush warbler is a species of warbler found in South Asia. Its overall population size has not been quantified, but it is one of the species declining through habitat destruction, though not rapidly. It split from the chestnut-headed tesia about five million years ago (Wikipedia, general species account).

That short account is the only source read for the Bhutan guide. It does not name Bhutan, and gives no plumage, size, habitat, diet or breeding information, so none is stated.