Coexistence among South African carnivores : spatial and temporal partitioning and their ecological correlates

Abstract

Carnivore species coexistence is shaped by niche partitioning that developed over evolutionary time through behavioural responses and adaptations to interspecific competition and risk. Minimising lethal and sub-lethal deleterious pressures from dominant species will aid the subordinate individual's fitness and survival.

This study aimed to test hypotheses concerning interspecific avoidance behaviour within carnivore communities and identify the potential for spatial and temporal partitioning as interspecific coexistence strategies used by South African Carnivora. Multi-seasonal data from large-scaled camera trapping networks in four South African protected areas were analysed. They are the Associated Private Nature Reserves (APNR) which encompasses Klaserie Private Nature Reserve (KPNR), Madikwe Game Reserve (MGR), Mountain Zebra National Park (MZNP), and the Tswalu Kalahari Reserve (TKR).

Spatial avoidance behaviour was analysed using occupancy modelling, selectivity of vegetation types, and quantitative spatial overlap using Pianka’s index. Only 21% of the species-pairs across all combinations and protected areas showed signs of spatial avoidance behaviour. In some cases among this minority, spatial partitioning could not be attributed to active avoidance behaviour with certainty due to a lack of biological reasoning supported by empirical evidence of competition and risk (e.g., genet associated species-pairs) and differences in vegetation type preferences (e.g., TKR’s Cape foxes Vulpes chama in relation to brown hyaenas Hyaena brunnea). No species-pairs in KPNR or MGR demonstrated clear evidence of spatial avoidance behaviour. Avoidance behaviour was observed among medium-sized and smaller carnivore species such as bat-eared foxes and aardwolves (Proteles cristata), but not among large predators (e.g., lions Panthera leo, leopards Panthera pardus, and spotted hyaenas Crocuta crocuta). Furthermore, TKR’s bat eared foxes appear to avoid areas used by brown hyaenas.

Temporal avoidance behaviour was analysed by comparing the kernel density estimates of each species’ diel activity patterns and core activity periods (50% isopleths). Furthermore, interspecific spatiotemporal behaviour was examined using time-to-event analyses. Most species-pairs (63%) across all combinations and protected areas showed no clear indications of using temporal avoidance behaviour as a coexistence strategy with the potentially riskassociated, dominant species. However, temporal partitioning was clearly observed in African wild dog (Lycaon pictus) and caracal (Caracal caracal) associated species-pairs due to their distinct temporal niche classifications (crepuscular and cathemeral, respectively). The potential for temporal avoidance behaviour was also evident between bat-eared foxes and aardwolves, particularly during the dry season. The remaining species-pairs that displayed potential temporal avoidance behaviour were primarily nocturnal and showed finer-scaled asynchronization of core activity periods (e.g., subordinate carnivore species appeared to avoid lions' core activity periods, and black-backed jackals also avoided spotted hyaenas).

This study shows that spatial and temporal avoidance behaviour among South African carnivores should be considered rare, at least on the scale conducted in this study. In addition, it is shown that these carnivore species coexist in fenced, space-restricted protected areas without requiring drastic behavioural adaptations to intraguild competition and risk. This study recommends that dietary aspects, seasonality at high latitudinal regions, and finer-scaled avoidance of, for example, core activity periods should be included and receive more focus in future analyses of interspecific avoidance behaviour among carnivores.