Wildebeest
Both species of wildebeest are even-toed, horned, greyish-brown ungulates resembling cattle. Males are larger than females and both have heavy forequarters compared to their hindquarters. They have broad muzzles, Roman noses, and shaggy manes and tails. The most striking morphological differences between the black and blue wildebeest are the orientation and curvature of their horns and the color of their coats. The blue wildebeest is the bigger of the two species. In males, blue wildebeest stand 150 cm tall at the shoulder and weigh around 250 kg, while the black wildebeest stands 111 to 120 cm tall and weighs about 180 kg. In females, blue wildebeest have a shoulder height of 135 cm and weigh 180 kg while black wildebeest females stand 108 cm at the shoulder and weigh 155 kg. The horns of blue wildebeest protrude to the side, then curve downwards before curving up back towards the skull, while the horns of the black wildebeest curve forward then downward before curving upwards at the tips. Blue wildebeest tend to be a dark grey color with stripes, but may have a bluish sheen. The black wildebeest has brown-coloured hair, with a mane that ranges in color from cream to black, and a cream-coloured tail. The blue wildebeest lives in a wide variety of habitats, including woodlands and grasslands, while the black wildebeest tends to reside exclusively in open grassland areas. In some areas, the blue wildebeest migrates over long distances in the winter, whereas the black wildebeest does not. The milk of the female black wildebeest contains a higher protein, lower fat, and lower lactose content than the milk of the blue wildebeest. Wildebeest can live more than 40 years, though their average lifespan is around 20 years.
Black wildebeest
The black wildebeest is a gregarious animal with a complex social structure comprising three distinct groups, the female herds consisting of adult females and their young, the bachelor herds consisting only of yearlings and older males, and territorial bulls. The number of females per herd is variable, generally ranging from 14 to 32, but is highest in the densest populations and also increases with forage density. A strong attachment exists among members of the female herd, many of which are related to each other. Large herds often get divided into smaller groups. While small calves stay with their mothers, the older ones form groups of their own within the herd. These herds have a social hierarchy, and the females are rather aggressive towards others trying to join the group. Young males are generally repelled by their mothers before the calving season starts. Separation of a young calf from its mother can be a major cause of calf mortality. While some male yearlings stay within the female herd, the others join a bachelor herd. These are usually loose associations, and unlike the female herds, the individuals are not much attached to each other. Another difference between the female and bachelor herds is the lesser aggression on the part of the males. These bachelor herds move widely in the available habitat and act as a refuge for males that have been unsuccessful as territorial bulls, and also as a reserve for future breeding males.