Big competition for small spots? Conspecific density drives home range size in male and female leopards

Variation in home range size exists among and within wildlife populations. Home range size variation may be driven by both intrinsic and extrinsic factors, including sex, food and reproductive resources, density and competition. In this study, we investigated the sex-specific impacts of prey and reproductive resources, conspecific density and competition on leopard Panthera pardus home range size at two spatio-temporal scales in the Sabi Sand Game Reserve, South Africa. Male leopard home ranges were more than twice the size of those of females, in line with expectations for a solitary, polygamous species. Both male and female leopard space-use were primarily driven by short-term changes in intra-sexual conspecific density. Females were influenced by both short and long-term drivers, with long-term prey availability (home range and core) and refugia (core) further impacting size. Males were almost exclusively influenced by short-term drivers; home range size was further impacted by short-term changes in female leopard and prey density, and age. Long-term prey availability contributed to male leopard core size. The difference in impact of short- and long-term drivers between the sexes likely relates to tenure expectations; males may be forced out of their territories at any time and should therefore optimize their space-use based on present conditions. Female leopards, however, must secure a home range that maximizes their reproductive success in the short- and long-term in order to raise cubs to independence. Our findings challenge expectations that space-use is primarily resource-driven and demonstrate the critical role of social factors in saturated populations of solitary species. Furthermore, we illustrate the importance of considering temporally variable factors across different timescales to fully understand their impact on mammalian spatial organization.