Demography of the Serengeti cheetah (Acinonyx jubatus) population: the first 25 years

Abstract

Data are presented on the demography and reproductive success of cheetahs (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 ®rst litter at approximately 2.4 years old, interbirth interval was 20.1 months, and average litter size at independence 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 proportion of males dispersing out of the Plains population. Females produced 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 success in the cheetah is similar to that of other mammals.No signi®cant negative correlations were found between adult cheetah population size and numbers of cubs reaching independence, implying that the Plains population had not reached carrying capacity. Annual numbers of adult female cheetahs only were correlated with rainfall. Adult female cheetah numbers were not correlated with adult female lion numbers on the Plains, however, reproductive rates of cheetahs were negatively correlated with the presence of lions while cheetahs had cubs. Moreover, cheetah reproductive success was lower during the period of high lion abundance (1980±1994) than during the earlier period of relatively few lions (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 gazelle at sightings except for a negative correlation between large numbers of gazelle (200±500) and reproductive success possibly because hunting success decreases with increasing prey herd size, or because cheetahs always lose in direct competition with other predators which are attracted to large congregations of prey. In addition, cheetah reproductive success was negatively correlated with the presence of Grant's gazelles (11 or more) perhaps because Grant's gazelles were more likely to occur consistently in dry areas.

Factors affecting life and death in Serengeti cheetahs: environment, age, and sociality

“…First, an individual's time of death was assumed to be equal to time of last sighting plus two standard deviations of that individual's intersighting interval (Caro, 1994). Second, time of death was assumed to correspond to the age at which an individual was last seen (Kelly et al, 1998). The former method overestimates time of death, whereas the latter underestimates it.…”

“…Although we now have sufficient observational data on several environmental and social factors influencing cheetah reproduction or the correlates of reproduction, the consequences of these factors on fitness have received little attention (but see Kelly et al, 1998). This is unfortunate because the importance of these factors as selection pressures cannot be critically assessed without long-term data on individual reproductive success (Clutton-Brock, 1988a).…”

Reintroduction of Top‐Order Predators: Using Science to Restore One of the Drivers of Biodiversity

“…Top-order predator populations that exceed 500 individuals are rare in today's world of fragmented landscapes. Indeed, the Vulnerable category of the IUCN Red List requires >1000 mature individuals (IUCN, 2001), which means that supposedly natural populations, such as the cheetahs, Acinonyx jubatus, of the Serengeti Plains (~60 adult females, which are 25% more common than males) (Kelly et al, 1998), would be deemed unsuccessful had they stemmed from a reintroduction. Thus, in the short term, reintroduction success can be more satisfactorily defi ned as breeding by the fi rst wild-born generation or a 3-year breeding population with natural recruitment exceeding mortality (Griffi th et al, 1989), particularly in small, enclosed reserves (Hayward et al, 2007b).…”

Population Genetic Consequences of the Allee Effect and the Role of Offspring-Number Variation

“…However, deviations from the Poisson distribution have been detected in the distributions of lifetime reproductive success in many natural populations. Distributions can be skewed and multimodal (Kendall and Wittmann 2010) and, unlike in the Poisson distribution, the variance in the number of surviving offspring is often considerably larger than the mean, as has been shown, among many other organisms, for tigers (Smith and Mcdougal 1991), cheetahs (Kelly et al 1998), steelhead trout (Araki et al 2007), and many highly fecund marine organisms such as oysters and cod (Hedgecock and Pudovkin 2011).…”

“…However, deviations from the Poisson distribution have been detected in the distributions of lifetime reproductive success in many natural populations. Distributions can be skewed and multimodal (Kendall and Wittmann 2010) and, unlike in the Poisson distribution, the variance in the number of surviving offspring is often considerably larger than the mean, as has been shown, among many other organisms, for tigers (Smith and Mcdougal 1991), cheetahs (Kelly et al 1998), steelhead trout (Araki et al 2007, and many highly fecund marine organisms such as oysters and cod (Hedgecock and Pudovkin 2011).The number of offspring surviving to the next generation (for example the number of breeding adults produced by any one breeding adult) depends not only on the sizes of individual clutches, but also on the number of clutches produced and on offspring survival to adulthood. Therefore, a variety of processes acting at different points in the life cycle contribute to offspring-number variability, for example, sexual selection or variation in environmental conditions.…”