Small, mouse-like bird found mainly in the Bolivian Andes. Despite the name, it also ranges over the border into far southeastern Peru, but does not reach Manu. The small white patch on the crown is distinctive, but can be hard to see from some angles and may be absent on some birds. Plumage is otherwise mostly grayish-brown with rusty barring on the lower underparts. Adult males are darker than females and juveniles. Does not occur together with the similar White-crowned Tapaculo. Inhabits the understory of humid forest, and usually very hard to see. Vocalizations include a long, very rapid trill and a slower series of sharp chips.