Who’s afraid of the big, bad predator? contrasting effects of apex predator presence on the behaviour of a mesopredator.

Abstract

Mesopredators experience top down pressure from apex predators, which may lead to behavioural changes such as spatial avoidance to reduce both interference and exploitative competition. However, apex predators may also facilitate mesopredators through the provision of carrion, so mesopredators should respond flexibly to the presence of apex predators. Aims. We aimed to investigate the drivers of black-backed jackal (Canis mesomelas) space use and detection in areas with and without lions (Panthera leo). We predicted that jackal detection and space use will be greater if apex predators facilitate rather than suppress them. Additionally, we predicted that in the absence of lions, the relative abundance of small ungulate species may become important drivers of space use and detection, because jackals can switch from scavenging to hunting. Comparatively, in the presence of lions, larger ungulate species will become important drivers of space use and detection as these species become accessible to jackals through scavenging. Methods. We used camera-trapping surveys, a single-species, single-season occupancy modelling approach, and the assessment of activity patterns to explore how apex predators influence the presence and probability of use of different sites in the Eastern Cape province of South Africa. Key results. Apex predators both positively and negatively affected the detection of jackals, indicating that these mesopredators show behavioural flexibility at the individual site level. There was high overlap between jackal activity patterns in the presence and absence of lions; however, at one site with lions, jackal activity did not peak at night as observed at other sites. Conclusions. Our results indicate that jackals demonstrate behavioural flexibility in the presence and absence of apex predators. Importantly, our results show that apex predators can both facilitate and suppress mesopredators, and that their behavioural responses are dependent on site-specific factors. Implications. Our findings highlight that sympatric predator behaviours should be based onsite-specific behaviours instead of the general patterns observed in more temperate systems.