Why leopards commit infanticide

Abstract

Infanticide is a widespread but seldom observed behaviour that has been shown to convey strong selection forces on some social mammals. However, infanticide in nonsocial species is less clearly understood, particularly the evolutionary function of infanticide. Here we present direct and indirect evidence of infanticide in a large, solitary felid, the African leopard, Panthera pardus, and determine its likely causes in light of six explanatory hypotheses. Observed and inferred rates of infanticide for leopards were among the highest recorded for mammalian carnivores, accounting for almost half of juvenile mortality and nearly a third of all offspring. Our results demonstrate that infanticide in leopards is mainly an adaptive behaviour which provides reproductive benefits to perpetrators. Infanticidal males were typically unrelated to their victims, the death of unweaned offspring shortened the interbirth intervals of mothers, and perpetrators increased their chances of mating with and siring the mother's subsequent litter. Female leopards also appear to have developed a profusion of strategies to counter the risk of infanticide, providing further support for the sexual selection hypothesis. Cannibalism may provide some incentive for infanticide (perpetrators usually consumed their victims) but this is probably an added, minor benefit rather than the primary driver for the behaviour. Our findings suggest that infanticide is a key factor shaping the sociospatial ecology of leopards. They also highlight the importance of accounting for functional components of population dynamics when managing large carnivores, particularly for invasive activities that artificially elevate adult male turnover.