Black-breasted Thrush

The black-breasted thrush is found from north-eastern India to northern Vietnam, and tends to live in forests at high altitude. It is 22 to 23.5cm long including the tail. The lower parts are the same colour in both sexes, but the upper part of the male is mostly black while the female is mostly grey-brown (Wikipedia, general species account).

The call has been described as 'sweet mellow' and 'melodious', with musical phrases spanning three to eight notes. The timing of breeding differs between countries. The source read does not name Bhutan, so its occurrence there is flagged for checking.