Black wildebeest the hybrid as compared to either of its parents. In some animals, the auditory bullae are highly deformed, and in others, the radius and ulna are fused. Black wildebeest are sexually dimorphic, with females being smaller in size and more slender than males. The head-and-body length is typically between . Males reach about at the shoulder, while females reach . Males typically weigh and females . A distinguishing feature in both sexes is the tail, which is long and similar to that of a horse. Its bright-white colour gives this animal the vernacular name of "white-tailed gnu", and also distinguishes
Blue wildebeest of wildebeest existed 100 years ago, but currently, all but three migrations (Serengeti, Tarangire, and Kafue) have been disrupted, cut off, and lost. The blue wildebeest is preyed on by lions, leopards, African wild dogs, and hyenas, and predation is the main cause of death. They are also prone to outbreaks of disease, which may also lead to a decline in numbers. Major human-related factors affecting populations include large-scale deforestation, the drying up of water sources, the expansion of settlements and poaching. Diseases of domestic cattle such as sleeping sickness can be transmitted to the animals and take their toll.