The Marble-faced Bristle-Tyrant is most readily found in mid-elevation cloud forests, although its overall altitudinal range encompasses at least 750 to 2400 m; it is only rarely found at edges. The ‘grizzled’ black-and-white ear-coverts from which this species’ derive its vernacular name arguably represent its most striking plumage feature, but for many observers this is a typically nondescript tyrant-flycatcher. Three subspecies have been described, which vary principally in the intensity of yellow coloration on the face, but perhaps surprisingly it is the southernmost taxon, P. o. ottonis, which has occasionally been considered to represent a separate species, rather than the even more geographically disjunct P. o. purus of the coastal mountains of northern Venezuela. The Marble-faced Bristle-Tyrant is typically seen alone or in pairs, and it often forages within mixed-species flocks. Like a great many, small, Andean flycatchers, comparatively little information is available concerning this species’ natural history, with virtually nothing known about breeding, despite the Marble-faced Bristle-Tyrant being a relatively common bird throughout much of its range.