The wildebeest, also known as a gnu, inhabit the savanna, grassy plains, and open woodlands of central, southern, and eastern Africa - especially the Serengeti of Tanzania and Kenya. They have a heavy build with a massive head and broad muzzle. There is a beard of stiff black or white hair under the throat, and a shaggy mane. The tail is long and black with a tuft of hair at the tip. Both sexes have horns with a distinctive curved shape. They stand at between 3 to 4½ feet and weigh between 500 to 600 lbs.
They are active both day and night and are constantly on the move in search of grass. They generally live in herds that can number several thousand. During periods of drought they remain close to watering holes, but during the rainy season will scatter to new areas. The migration of the wildebeest is the largest animal migration in the world, with thousands of animals moving in an annual pattern that is dependent on the rainfall. They are often accompanied by large numbers of zebras, gazelles, and impalas.
During mating season the males will gather the females into a harem where they will remain until mating is through. They will then rejoin the main herd. A single calf is born in February and March and will be up and walking within 30 minutes of birth. They are able to follow the herd within days. Since most calves are born at around the same time their numbers swell which greatly increases their chances of surviving those critical first few months when they are easy prey for predators. Their main predators are lions, cheetahs and wild dogs.
The wildebeest populations have declined everywhere in Africa due to land development. It is only in the Serengeti that they remain stable.