Because of higher than usual rainfall in the seventies, the wildebeest population increased from an estimated 850,000 in 1972 to 1.3 million in 1977. During the same time, no notable difference was seen in the non-migrating or resident populations.
The wildebeest were consuming the excess vegetation but did not pose enough competition to cause a serious decline, rather it limited the population of resident grazers such as the [I 002 / buffalo], impala, [I 010 / kongoni] and kopi. This was significant to park management because it meant no artificial means was needed to control the wildebeest population.
Because the resident predators prey heavily on the migrating wildebeest when they are in the area, wildebeest actually relieve some of the predation pressure from the resident prey. This compensates somewhat for the increased vegetation consumed.
However, [I 011 / topis], which have similar grazing preferences as wildebeest, relocate to the floodplains when the wildebeest migrate to the Western Corridor. By moving, they avoid competition with wildebeest which outnumber them 30 to 1.
Since 1977, the only ungulates that have decreased in numbers significantly in the ecosystem are buffalo, elephants and [P 016 / rhinoceros] - all because of poaching.
