It is so similar in morphology and habits to the carrion crow ("Corvus corone"), for many years they were considered by most authorities to be geographical races of one species. Hybridization observed where their ranges overlapped added weight to this view. However, since 2002, the hooded crow has been elevated to full species status after closer observation; the hybridisation was less than expected and hybrids had decreased vigour. Within the hooded crow species, four subspecies are recognized, with one, the Mesopotamian crow, possibly distinct enough to warrant species status itself.