Niche overlap and dietary resource partitioning in an African large carnivore guild

Abstract

Understanding and quantifying a large carnivores’ feeding behaviour is a key component in determining its functional significance in an ecosystem, both in terms of its top‐down influence on prey species, but also its relationships with sympatric carnivores. Dietary overlap is one of the numerous niche dimensions used to characterize resource partitioning and potential competition within a community. We characterize the diet, potential dietary niche overlap and prey preference of a large African carnivore guild on small fenced protected areas. To quantify the potential inter‐ and intraspecific foraging competition, we analysed 5,128 kills, representing 35 prey species made by African wild dogs Lycaon pictus (n = 553), cheetahs Acinonyx jubatus (1,427), lions Panthera leo (2,648) and leopards P. pardus (500). Our results show that large African carnivores in small protected areas are exposed to considerable overlap in dietary resource utilization. At the interspecific level, African wild dogs and cheetahs displayed the greatest vulnerability to potential dietary competition. Lions exhibited marked differences in prey preference, mass and species utilization compared to the other carnivores. African wild dogs and cheetah females with dependent offspring occupied the greatest potential for dietary competition within the large carnivore guild. Using a case study based on the preferred biomass of prey available, we estimate the sustainable density of large carnivores at a small fenced prospective African wild dog reintroduction site. African wild dogs displayed the lowest mean predicted density compared to all sympatric predators with an expected population size of 7 individuals. Our research highlights the need to assess the influence of competitive forces in structuring and restoring large predators to portions of their historical range by identifying species most vulnerable to a potential reintroduction attempt. In the absence of controlled experiments, elucidating the influences of exploitation competition is challenging, and only through manipulating sympatric species presence and densities can these complex interactions be fully understood.

Facilitation or Competition? Effects of Lions on Brown Hyaenas and Leopards

“…However, as with potential facilitative interactions between lions and brown hyaenas, it is unclear if such competitive interactions resulted in any broader effects on leopard ecology, since we did not detect differences in either abundance, habitat use or ungulate prey selection. Weak dietary competition has previously been suggested between leopards and lions [22], and we highlight that identifications of the conditions under which intra-guild processes influence carnivore communities should be a prioritised component of further carnivore community studies.…”

“…Since lions are specialised predators on medium-sized and large vertebrates [20], we can expect facilitative interactions between lions and brown hyaenas due to carcass provisioning, and competitive interactions between lions and leopards due to both species' predatory habits. However, recent studies suggest that leopards may be unaffected by lions in terms of their abundance, space use, activity and prey utilisation [21][22][23], although some observations suggest spatial avoidance of lions by leopards [24]. Relationships between lions and brown hyaenas are less well documented, but facilitative interactions have been suggested [18,25].…”

Spatial heterogeneity facilitates carnivore coexistence

“…Competitively dominant carnivore species can limit the population sizes and behavior of inferior competitors through interspecific competition and direct killing, sometimes leading to the local extinction of subordinate predator populations Strand 2000, Swanson et al 2014). Key mechanisms enabling the coexistence of multiple carnivore species include spatial and temporal avoidance of dominant predator species by subordinates Slotow 2009, Vanak et al 2013), and dietary niche separation Mills 2008, du Preez et al 2017; but see Vogel et al 2019). However, most large carnivores are threatened by human-induced habitat loss and fragmentation, Manuscript received 4 September 2020; revised 25 November 2020; accepted 6 December 2020.…”

Community‐level responses of African carnivores to prescribed burning

“…In our study area, sympatric large carnivores (spotted hyena Crocuta crocuta, leopard Panthera pardus and cheetah Acinonyx jubatus) consume several prey species that responded positively to burning (e.g. impala, wildebeest zebra; Vogel et al, 2019) and, therefore, could have benefited from burn-induced prey availability. Our observed lack of positive responses to fire by subordinate large carnivores suggests that they might not be able to fully exploit increased prey availability in postfire landscapes.…”

“…Although there is some level of diet overlap among large carnivores in the system, lions prefer several prey species that increased the use post-burn (wildebeest, zebra, warthog, buffalo), which are less preferred prey or selected infrequently by other large carnivores in the system (Vogel et al, 2019). Meanwhile, some small-and mediumsized ungulates such as nyala, grey duiker Sylvicapra grimmia and red duiker Cephalophus natalensis that did not strongly increase the use in burned areas comprise a larger proportion of sympatric large carnivore diets compared to lion diets (Vogel et al, 2019). Thus, the lack of response to prescribing burning by subordinate large carnivores might be related to their prey preferences, rather than their avoidance of lions.…”