The population of the wildebeest has fluctuated in response to changes in rainfall and disease. But it was not until 1959, when the first census in the Serengeti was done, that scientists had an accurate accounting of wildebeest in the region.
At that time the wildebeest population was estimated at 100,000. It was suffering high mortality from [G 40 / rinderpest], a highly contagious disease found in [G 41 / ruminants] such as cattle, wildebeest and buffalo. Since its introduction to the region in 1890, rinderpest had periodically taken heavy tolls on these populations. Cattle, the carriers of the disease, were immunized in the late 1950s. By 1962, rinderpest had died out of the wildlife populations.
The census of 1961 revealed the wildebeest population was nearly triple that of 1959. The dramatic difference was largely attributed to the reduction of rinderpest. However, between the two surveys, the method of census taking was refined resulting in the development of the [L3 104 / photographic census]. The method employed in the 1959 census was an [L3 105 / aerial counting] of each animal.
With rinderpest completely eradicated, the populations of the wildebeest and buffalo grew steadily through the early sixties, while the population of the zebra and other non-ruminant [G 45 / ungulates] remained the same. By the late sixties, the wildebeest population leveled off because of lack of food in the dry season. However, 1971 marked the beginning of a series of higher than average dry season rainfalls which produced an abundance of food. By the late seventies, the population had dramatically increased to 1.3 million, while the [L3 106 / population of resident ungulates] remained relatively stable.
The wildebeest population has not changed significantly in the past fifteen years, having reached an equilibrium between birth and death. [L3 107 / Accidents], disease, [L3 108 / malnutrition] and predation all contribute to the mortality rate, thus the balance. [L3 109 / Poaching] has also become a factor in the mortality of the wildebeest. Although the figures are increasing annually, the overall toll is relatively small at this time.
The current wildebeest population in the Serengeti-Mara ecosystem is estimated at 1.4 million, reflecting nearly a six-fold population increase in 30 years. However, these numbers could change dramatically and quickly with a reduction in rainfall, affecting the availability of food during the dry season. Additionally, wildebeest have long since lost what immunity they had developed to rinderpest; therefore, any reappearance of the disease could have a serious affect on the population.
