Bamboo-loving wren of the Andes known for its beautiful song duets. Plumage and song vary geographically, and some forms may be treated as distinct species in the future. All birds are brown and gray overall with black and white face and mustache stripes. In most of Ecuador and in southwestern Colombia, it has black spots or speckles on its breast. Elsewhere it lacks breast markings and has a black crown or (only in central Peru) a brown crown. Pairs skulk in dense bamboo, and their loud, whistled song duets carry over long distances.