An entirely dark boubou found in thickets and dense vegetation. Widespread, but can be surprisingly rare and local in many parts of its range. A distinctively nondescript medium-sized skulking forest bird whose most obvious field mark is a lack of field marks, as it is wholly dark all over. The scientific name, which means “white-billed,” refers to young birds, whose bills start out white and darken with age. Similar to other species of sooty boubou, but Lowland Sooty Boubou is found at lower elevations and has a distinctive voice: a series of drawn out, ringing hoots or whistles, given singly or in short groups. Calls are harsh, sometimes mechanical chatters.