For each ward, we determined the instantaneous rate of change of hunter density between 1978 and 2002. Results Total population numbers of buffalo in the protected area Figure 2 shows the changes in
total numbers of buffalo in the Serengeti National find more Park since 1965. At that time the population was recovering from the impacts of the viral disease, rinderpest, and numbers subsequently increased to a peak of 74,237 in 1975 (Sinclair 1977). Shortly after that, in 1977, anti-hunting activities were severely restricted by an economic crisis in Tanzania (Hilborn et al. 2006; Sinclair and Arcese 1995b) and widespread hunting on this species (and others) followed (Dublin et al. 1990a). By 1992 anti-hunting efforts had returned but the population had been reduced to 36,119 animals, some 49% of the peak number. The sharp decline to 21,186 buffalo in 1994 reflects the effect of a severe drought amounting to an additional mortality of 42% of the remaining population. Since 1998 the population has slowly increased. The most recent census (2008) of buffalo recorded 28,524 individuals in Serengeti National Park. Because these
are total counts there are no sampling SC79 cost errors associated with the data. However, bias errors have been calculated, accommodated by technique design and kept constant over the years (Mduma and Hopcraft 2008; Sinclair 1972). Fig. 2 Buffalo population trends for the Serengeti National Park. Data from Sinclair et al. (2007) Buffalo population trends by region Figure 3a, b presents the distribution of AICAR buffalo herds in 1970 before the main hunting period, and in 2003 during the recovery phase. These show that northern isothipendyl and western parts of the protected area have lost herds while the center and east have developed larger herds. Figure 4 shows the proportional changes in buffalo population in each zone (see Fig. 1), relative to 1970, the year when we have complete spatial
distribution of animals prior to the onset of hunting. By 1992 the north had lost 84% (±5% (95%CL)) the far west some 38% (±9%) and the center 29% (±7%) of their numbers. In contrast, the south had lost 23% (±10%) and the far east only 12% (±6%) of the population. Since the drought of 1993, the south has increased above the 1970 level (120% ±3%) and the far east is at 62% (±6%) of those levels. The far west and center, although just beginning to recover by 2008, are still only at 54% (±9%) and 40% (±8%) of their original numbers. The northern population has been unable to recover at all and remains at a mere 2% (±0.3%) of original numbers. In summary, the three regions with western borders had consistently lower recovery throughout the period 1970–2008 than the east and south. Fig. 3 The location of all buffalo herds in the park-wide censuses of (a) 1970, and (b) 2008 showing the loss of herds in the north and far west. Data from Sinclair (1977), S. A. R. Mduma unpublished. Dots represent the size of the buffalo herds at each location.