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.

Longer-term ecosystem level dynamics are often neglected in conservation studies involving single species. In this study, a retrospective analysis is presented on the feeding performance of African wild dogs Lycaon pictus in the Serengeti in relation to a competing species, the spotted hyena Crocuta crocuta, to test whether hyenas had an effect on feeding performance of wild dogs in this ecosystem. Our analysis is based on observations of over 700 wild dog kills recorded over a 20-year period (from 1964 to 1987) during which time there was a decline in wild dog numbers (ending with their local extinction in 1991) and a twofold increase in hyena density. Overall, the amount of time that dogs had access to the kill (access time) decreased with increasing numbers of hyenas attending kills, but access time increased with increasing hunting-group size of dogs and carcass mass. In addition, in the 1980s, dogs spent longer at kills than in the 1970s for a given set of conditions, including when hyenas were absent. Our analysis demonstrates a greater potential for group benefits than was found in a previous study (Carbone, Du Toit et al., 1997). Hunting-group sizes of between two and six dogs performed best when hyenas attended dog kills because the benefits of increased defence outweighed the costs of having to share the carcass with more dogs. Hunting-group sizes of wild dog and levels of hyena attendance at the kill broadly paralleled the population trends in these species, with hunting-group sizes of wild dog declining, followed by hyena attendance increasing. Despite the combined effects of increased hyena attendance and reduced hunting-group size, dogs in the 1980s typically spent longer feeding and consumed more of the carcass including the poorest sections. This suggests that dogs in the 1980s may have been under greater energetic stress.

Abstract... African wild dogs were studied ilrcm 1967 ru 1978 or, tile Ser$:ngeti Plains in northern ianzania. The mzin ubjectives werc to dererinine the status ci t1:e sub-population and ro elucidate the eiology and behavior of this social carnivore. Thi: paper describes the decline of the sub-pcpulation, the dynamics of pack composition, and pncterns of dispersal.

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Summary Black rhinoceroses on the Serengeti Plains were surveyed from February 1974 through January 1978. Sex and age composition of the sixty‐seven individuals identified was 30% adult males, 36% adult females and 34% immatures and calves. Social groupings were described for 140 sightings (237 rhinos), of which 38% were lone males. The sex ratio was 1:1 for all age classes combined. Of the adult females, 79% had calves. Two observed calving intervals were approximately 3‐3 years. The ratio of adult females to young is not significantly different from ratios reported elsewhere in East Africa. Rhinos did not use the short grasslands of the Serengeti Plains. In the medium grasslands they used mainly the drainage lines where there was food and water, but only minimal cover. Most rhinos on the plains were found along the woodland edge. Near the Seronera River, on the edge of the plains, there was a density of one rhino per 19 km2. Home ranges varied from 43 to 133 km2, with much overlapping. Some male, female, and male‐female dyads shared the same home ranges. An estimated 700 black rhinos live within the 12 920 km2 Serengeti National Park. Management for black rhinos in the park requires primarily that woodlands and abundant watering places be maintained and that poaching be minimized. Résumé Les rhinocéros noirs des plaines du Serengeti furent surveillés de février 1974 jusque janvier 1978. La distribution par sexe et par âge des soixante‐sept individus identifiés fut de 30% de mâles, 36%, de femelles adultes et 34% d'immatnres et de jeunes. Les groupements sociaux furent décrits à partir de 140 observations (237 rhinos), dont 38%étaient des mâles solitaires. Toutes classes d'âge combinées, le sex‐ratio était de 1/1. 79% des femelles adultes étaient suitées. Deux observations donnent un intervalle de 3,3 ans entre deux naissances. La proportion femelles adultes/jeunes n'est pas significativement différente de celles décrites ailleurs en Afrique de 1'Est. Les rhinos n'utilisent pas les pâturages ras des plaines du Serengeti. Dans les páTturages moyens, ils fréquentent surtout les sillons d'écoulement où ils trouvent nourriture et eau mais peu d'abri. La plupart des rhinos des plaines se trouvent en lisière forestiere. Prks de la rivière Seronera, en bordure des plaines, il y a une densité de I rhino par 19 km2. Les domaines vitaux varient de 43 à 133 km2 avec beaucoup de

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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.