 The word "colobus" comes from Greek ("kolobós", "docked", "maimed"), so named because the thumb is stump-like.Colobuses habitats include primary and secondary forests, riverine forests, and wooded grasslands; they are found more in higher-density logged forests than in other primary forests.Their ruminant-like digestive systems have enabled them to occupy niches that are inaccessible to other primates