DEMOGRAPHY OF THE SERENGETI CHEETAH (ACINONYX-JUBATUS) POPULATION - THE FIRST 25 YEARS

Data are presented on the demography and reproductive success of cheet ahs (Acinonyx jubatus) living on the Serengeti Plains, Tanzania over a 25-year period. Average age at independence was 17.1 months, females gave birth to their first litter at approximately 2.4 years old, inter birth interval was 20.1 months, and average litter size at independenc e was 2.1 cubs. Females who survived to independence lived on average 6.2 years while minimum male average longevity was 2.8 years for those born in the study area and 5.3 years for immigrants, with a large pro portion of males dispersing out of the Plains population. Females prod uced on average only 1.7 cubs to independence in their entire lifetime and their average reproductive rates were 0.36 cubs per year or 0.17 litters per year to independence. Variance in lifetime reproductive su ccess in the cheetah is similar to that of other mammals. No significa nt negative correlations were found between adult cheetah population s ize and numbers of cubs reaching independence, implying that the Plain s population had not reached carrying capacity. Annual numbers of adul t female cheetahs only were correlated with rainfall. Adult female che etah numbers were not correlated with adult female lion numbers on the Plains, however, reproductive rates of cheetahs were negatively corre lated with the presence of lions while cheetahs had cubs. Moreover, ch eetah reproductive success was lower during the period of high lion ab undance (1980-1994) than during the earlier period of relatively few l ions (1969-1979). Litter size at independence dropped from 2.5 to 2.0, lifetime reproductive success declined from 2.1 to 1.6 cubs reared to independence, and the reproductive rate (cubs/year) decreased from 0. 42 to 0.36 from the earlier to the later period. Cheetah reproductive success showed little association with the presence of Thomson's gazel le at sightings except for a negative correlation between large number s of gazelle (200-500) and reproductive success possibly because hunti ng success decreases with increasing prey herd size, or because cheeta hs always lose in direct competition with other predators which are at tracted to large congregations of prey. In addition, cheetah reproduct ive success was negatively correlated with the presence of Grant's gaz elles (11 or more) perhaps because Grant's gazelles were more likely t o occur consistently in dry areas.