Sooty black bird with a large, heavy bill that is bone-white in males, dark in females. Some males have a bright white eyebrow, while others have an entirely black head. Females have reddish skin around the eye and a weaker, paler eyebrow stripe. Inhabits lowland mature forests. Travels singly, in pairs, or in small flocks, typically at lower levels in the forest than the large hornbills. Gives distinctly un-birdlike growling calls.