Resident herds of wildebeest must live in areas where the supply of food and water are adequate year around. Areas of higher rainfall in the east and the wooded grasslands in the north and west support the three separate resident herds found in the [M 003 / Serengeti-Mara ecosystem].
One herd is located in the Western Corridor on the Ndabaka Plains near Lake Victoria. Another is found to the northeast of the Serengeti in the Loliondo Controlled Area. The third population migrates on a small scale between the Mara and Loita areas of Kenya. They migrate between their dry season range in and around the [M 005 / Masai Mara National Reserve] and wet season range of the Loita Plains north of the Reserve. The short grass plains this area are the traditional calving grounds of the Loita wildebeest.
The resident and migrating wildebeest physically look the same and graze together during the dry season; however, there are some differences which keep the populations distinct from one another. They all breed at slightly different times of the year resulting in different birth periods.
[G 39 / Predation] plays a much larger role in limiting the population of the residents than it does in the migrating population. The latter escapes some predation pressure by migrating; whereas, intense predation pressure always exists for the former. As a result, the resident herds are primarily comprised of strong and healthy animals with very few old and sick. Also, males in resident herds hold territories for months, sometimes years, in contrast to migrating males which only hold territories during [G 42 / rut].
