Great Myna

The great myna, also known as the white-vented myna, is a starling whose range extends from Sikkim across north-east India and Indochina. It is black with elongated forehead feathers forming a frontal crest that may curl backwards, with a yellow beak and feet, white from the vent to the tip of the tail, and a white wing patch (Wikipedia, general species account).

That short account is the only source read for the Bhutan guide. It gives no habitat, size, diet or breeding information, so none is stated.