The influence of vegetation on lion Panthera leo group sizes in the Hluhluwe-Umfolozi Park, South Africa (In English)

摘要

Lions Panthera leo live in fission-fusion groups, with the size of the sub-groups being related to the original pride size and social factors, such as group-size-specific foraging success, cooperative cub defense and group territoriality. We analyzed lion group sizes in the Hluhluwe-Umfolozi Park , a small reserve in South Africa for a period of fifteen years. Group sizes of adult female and adult male lions differ significantly within the reserve. Larger groups of adult females are found in open habitat, whereas in thick vegetation, female groups are small. Male group sizes do not correlate with the type of vegetation, but larger male groups are found in areas with large female groups. Surprisingly, cub group sizes and the number of cubs per female, an estimate for cub survival, do not significantly differ across the reserve. We postulate that differences in adult female group sizes are adaptations to the differences in vegetation structure: in open habitat, large female groups are essential for cooperative hunting, for rearing and protecting their cubs communally and to cope with higher inter-group competition when defending their territory. In contrast, in thick vegetation, inter-group competition is lower, dense cover improves the hunting success and compensates for reduced cub defense of small female groups. As the number of cubs per female is the same throughout the reserve, we suggest that both, open habitat and thick vegetation are of similar quality for lions when they adjust their group size [ Acta Zoologica Sinica 53(1): 15 – 21, 2006].