The wildebeest's mating season or "rut" usually coincides with the beginning of their mass migration to the woodlands at the end of the wet season in mid-May or early June. After six months of feeding on nutritious vegetation, the wildebeest are in prime condition to endure the rigors of rut, which last three to four weeks.
The timing of rut is critical to [G 36 / peak calving] but it is not certain what actually triggers the sexual activity in male wildebeest. Scientists suspect the exact timing of rut is triggered by the influences of the lunar cycle combined with seasonal changes. Many animals begin breeding in response to the lengthening of daylight hours, but none other than the wildebeest is thought to be influenced by the moon.
As rut begins, bulls chase through the herds, tossing their heads and bucking, then paw at the dirt and [V 005 / begin challenging one another]. One challenge can involve up to 30 distinct moves including dropping to their knees and butting horns, snorting, and staring eyeball to eyeball. After five or ten minutes of action and counteraction, the loser breaks away and the challenge ends. The challenges are highly ritualized but not violent and usually do not result in bloodshed.
The victor establishes his territory and begins rounding up as many rutting females as possible to mate with. The territorial male is constantly deflecting advances of other males while frantically trying to prevent the females from straying out of his territory and into another's. As the herd shifts during the continuing migration, territories are abandoned and reestablished many times. As a result, rutting females mate with a number of territorial males, increasing the chances of conception. Typically, 95 percent of all females over two years old give birth annually.
Territorial males only make up 15 percent of the population and are the only males to mate. Non-territorial males and yearlings are chased from mating grounds. This ensures that only the strongest and most dominant breed. Because rut only occurs as the wildebeest migrate from the plains, mating is limited by time and space which ensures peak calving.
