Mesocarnivore community structuring in the presence of Africa’s apex predator

Apex predator reintroductions have proliferated across southern Africa, yet their ecological effects and proposed umbrella benefits of associated management lack empirical evaluations. Despite a rich theory on top-down ecosystem regulation via mesopredator (<20kg) suppression, a knowledge gap exists relating to the influence of lions (Panthera leo) over Africa’s diverse mesocarnivore communities. We investigate how geographical variation in mesocarnivore community richness and occupancy across South African reserves is associated with the presence of lions.  An interesting duality emerged: lion reserves held more mesocarnivore-rich communities, yet mesocarnivore occupancy rates and evenness-weighted diversity were lower in the presence of lions. Human population density in the reserve surroundings had a similarly ubiquitous negative effect on mesocarnivore occupancy. The positive association between species richness and lion presence corroborated the umbrella species concept but translated into small differences in community size. Distributional contractions of mesocarnivore species within lion reserves, and potentially corresponding numerical reductions, suggest within-community mesopredator suppression by lions, likely as a result of lethal encounters and responses to a landscape of fear. Our findings offer empirical support for theoretical understanding of processes underpinning carnivore community assembly and are of conservation relevance under current large-predator orientated management and conservation paradigms.

Methods
We used camera-trap data on mesocarnivore species collected across R=17 reserves and S = 33 reserve-by-year surveys in NE South Africa. We summarized mesocarnivore daily encounter frequency data to implement the multi-region community occupancy model used to jointly describe geographical variation in mesocarnivore community richness and occupancy.