Assessing the status of leopard in the Cape Fold Mountains using a Bayesian spatial capture–recapture model in Just Another Gibbs Sampler

Trophic downgrading of an adaptable carnivore in an urbanising landscape

Urbanisation critically alters wildlife habitat and resource distribution, leading to shifts in trophic dynamics. The loss of apex predators in human-transformed landscapes can result in changes in the ecological roles of the remaining mesocarnivores. Decreased top-down control together with increased bottom-up forcing through greater availability of anthropogenic foods can result in a predation paradox. Understanding these changes is important for conserving ecological function and biodiversity in rapidly urbanising systems. Here, we use stable isotope analysis to provide insight into longer term changes in trophic position, niche width and overlap of an elusive, medium-sized urban adapter, the caracal (Caracal caracal) in and around the city of Cape Town, South Africa. Using fur samples (n = 168) from individuals along a gradient of urbanisation we find that overall caracals have a broad isotopic dietary niche that reflects their large variation in resource use. When accounting for underlying environmental differences, the intensity of anthropogenic pressure, measured using the Human Footprint Index (HFI), explained variation in both food subsidy use (δ13C values) and trophic status (δ15N values). The significantly higher δ13C values (P < 0.01) and lower δ15N values (P < 0.001) of caracals in more urbanised areas suggest that predator subsidy consumption occurs via predictable, anthropogenic resource subsidies to synanthropic prey. These prey species are predominantly primary consumers, resulting in shifts in diet composition towards lower trophic levels. Further, caracals using areas with higher HFI had narrower isotope niches than those in less impacted areas, likely due to their hyperfocus on a few lower trophic level prey species. This pattern of niche contraction in urban areas is retained when accounting for caracal demographics, including sex and age. The removal of apex predators in human-transformed landscapes together with reliable resource availability, including abundant prey, may paradoxically limit the ecological influence of the remaining predators, and bring about a degree of predator trophic downgrading. The dampening of top-down control, and thus ecosystem regulation, likely points to widespread disruption of trophic dynamics in rapidly developing areas globally.

Leopard density and the ecological and anthropogenic factors influencing density in a mixed-use landscape in the Western Cape, South Africa

Large carnivores face numerous threats, including habitat loss and fragmentation, direct killing, and prey depletion, leading to significant global range and population declines. Despite such threats, leopards (Panthera pardus) persist outside protected areas throughout most of their range, occupying diverse habitat types and land uses, including peri-urban and rural areas. Understanding of leopard population dynamics in mixed-use landscapes is limited, especially in South Africa, where the majority of leopard research has focused on protected areas. We use spatially explicit capture-recapture models to estimate leopard density across a mixed-use landscape of protected areas, farmland, and urban areas in the Overberg region of the Western Cape, South Africa. Data from 86 paired camera stations provided 221 independent captures of 25 leopards at 50 camera trap stations with a population density estimate of 0.64 leopards per 100 km2 (95% CI: 0.55-0.73). Elevation, terrain ruggedness, and vegetation productivity were important drivers of leopard density in the landscape, being highest on elevated remnants of natural land outside of protected areas. These results are similar to previous research findings in other parts of the Western Cape, where high-lying natural vegetation was shown to serve as both a refuge and a corridor for leopard movement in otherwise transformed landscapes. Given the low leopard density and the prevalence of transformed land intermixed with patches of more suitable leopard habitat, prioritising and preserving connectivity for leopards is vital in this shared landscape. Ecological corridors should be developed in partnership with private landowners through an inclusive and multifaceted conservation strategy which also incorporates monitoring of and rapid mitigation of emerging threats to leopards.

Leopard density and interspecific spatiotemporal interactions in a hyena-dominated landscape

Scavenging is widespread in the carnivore guild and can greatly impact food web structures and population dynamics by either facilitation or suppression of sympatric carnivores. Due to habitat loss and fragmentation, carnivores are increasingly forced into close sympatry, possibly resulting in more interactions such as kleptoparasitism and competition. In this paper, we investigate the potential for these interactions when carnivore densities are high. A camera trap survey was conducted in central Tuli, Botswana, to examine leopard Panthera pardus densities and spatiotemporal activity patterns of leopard and its most important competitors' brown hyena Parahyaena brunnea and spotted hyena Crocuta crocuta. Spatial capture-recapture models estimated leopard population density to be 12.7 ± 3.2 leopard/100 km², which is one of the highest leopard densities in Africa. Time-to-event analyses showed both brown hyena and spotted hyena were observed more frequently before and after a leopard observation than expected by chance. The high spatiotemporal overlap of both hyena species with leopard is possibly explained by leopard providing scavenging opportunities for brown hyena and spotted hyena. Our results suggest that central Tuli is a high-density leopard area, despite possible intense kleptoparasitism and competition.