Browsing by Author "O'riain, Mannus Justin"

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    From big spots to little spots: Influence of camera trap deployment on spatial capture-recapture estimates of servals (Leptailurus serval) in Ithala Game Reserve
    (2020) Taylor, Johanna; O'riain, Mannus Justin; Mann, Gareth
    Servals (Leptailurus serval) face a range of threats which can impact their populations, but we have little information on their conservation status across much of their range. Repeated population density estimates are the most useful parameter for assessing population trends and the impacts of anthropogenic changes (e.g. habitat loss and poaching) on serval densities. These could further be used to establish a correlation between any changes in this population and relevant highlighted anthropogenic influences that may exist with relevance to their conservation vulnerability. However, such surveys for small cryptic carnivores are rare, largely because funding and hence research is heavily biased towards large, charismatic and threatened species. Fortunately, servals and other mesocarnivores are frequently recorded as by-catch in camera trap surveys designed for larger carnivores which offers a unique opportunity to explore the viability of using these 'bi-catch' data for the determination of population estimates of cryptic carnivores. Spatial capture-recapture models are the most robust means of estimating the densities of individually identifiable species like servals. In this study, I investigate whether the ongoing leopard (Panthera pardus) surveys in Ithala Game Reserve can be used to accurately estimate serval density and thus provide the first long term assessment of serval population trend within a protected area in South Africa. To achieve this, I designed a camera trap array to estimate serval density specifically (i.e. smaller intertrap distances and the inclusion of wetland habitat) and ran it simultaneously with a less intensive survey designed to estimate leopard population density in Ithala. The leopard array produced an estimate of 1.73 ± 0.80 (0.76-3.97) servals/100 km2 compared to an estimate of 2.49 ± 0.81 (1.24-4.63) servals/100 km2 from the serval array. In line with standard analysis of the results, the approximately 75% overlap in the 95% confidence intervals suggests the two density estimates are comparable. The inclusion of vehicle traffic (as a measure of anthropogenic disturbance) and vegetation (as a proxy for habitat suitability) as covariates did not improve the serval specific density estimate. Based on these findings I proceeded to use the long-term leopard survey data to produce annual density estimates for serval over a seven-year period (2013-2019). Serval density has decreased from the high of 9.66 (± 2.1) servals/100 km2 recorded in 2014 to a low of 1.42 (± 0.6) in 2018. A similar decline was evident in the leopard density estimates, suggesting that both these two carnivore species are facing some form influence that is threatening their population numbers in Ithala. Recent social surveys in nearby neighbouring communities reveal that snaring and hunting with dogs are both common methods of illegal hunting and such activities may be greatly facilitated in the northern section of Ithala owing the absence of a boundary fence. This study suggests that serval density can be reliably estimated using data collected as part of ongoing leopard surveys in protected areas throughout South Africa. Given the paucity of such data the approach used in this study should be expanded to provide a more comprehensive assessment of serval population status and the generality of the finding that serval density is declining within a protected area previously considered to be a stronghold for this species.
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    Land use influence on biodiversity and activity patterns of predators and prey in the semi-arid drylands of South Africa
    (2024) Ayinla, Oluwaseun; O'riain, Mannus Justin; Woodgate, Zoe
    The unprecedented rise in anthropogenic activity worldwide has left wildlife with no other choice but to find means to coexist with humans across a range of different land uses. While some animals have developed strategies to adapt to the gradual and long-term modifications to the environment as a result of anthropogenic disruptions, rapid and pervasive changes often result in drastic reduction in species abundance causing local extirpation and posing a threat to ecosystem sustainability. Some behaviourally plastic species may be able to cope in real time to changes brought about by anthropogenic disruptions in their habitat, but they may have to compete with humans directly for space and food prompting negative interactions between people and wildlife which in turn lead to conflicts between conservation bodies on how best to mitigate these interactions. Understanding these interactions and how they influence ecosystem level functions, community interactions and the long-term persistence of wildlife is essential to achieving biodiversity goals. Most studies on wildlife in South Africa have focussed on protected areas but given that most animals still persist outside protected areas, it is imperative to expand research to include human modified landscapes too. The goal of my study was to 1) explore how wildlife adjust their activity with land use and, 2) determine whether heavily persecuted species adjust their activity more in human modified landscapes compared to protected areas and 3) how prey species adjust their activity with and without apex predators and 4) whether lunar illumination influences the activity of heavily persecuted species on farmland and predator-prey interactions in protected areas. I used camera trap surveys conducted on farmland between September 2012 and March 2013, in Anysberg Nature Reserve between the end of September 2013 and May 2014 and in Sanbona Wildlife Reserve between the end of August and November 2015 to provide insights into the relationships between land use, biodiversity, and predator-prey dynamics in the semi-arid drylands of South Africa. My study showed that semi-arid drylands of South Africa are important refugia for wildlife which is evident in the high species richness found in my study. I found that the temporal overlap for the same species living in Anysberg Nature Reserve and the nearby small livestock commercial farmland of Koup were not dissimilar. However, heavily persecuted (e.g., black backed jackal) and harvested species (e.g., steenbok) exhibited greater nocturnality on farmland presumably to avoid the diurnal peaks in farm worker activity. The presence and absence of apex predators had minimal influence on the activity of both smaller predators and a large size range of potential prey. That said both plains zebra and kudu showed increased nocturnal behaviour in the absence of lion which typically hunt at night. The response of wildlife to moon phase in different land uses was mixed with no clear patterns in the proportion of activity at night with different moon phases in either Anysberg or the farmland. This dissertation highlights the complex interplay between human activities and wildlife populations and provides important baseline information on the relationships between land use, biodiversity, and predator-prey dynamics that can be used to explore future shifts in both land use and climate in the drylands of the Karoo.
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    Mesocarnivores in Protected Areas: ecological and anthropogenic determinants of habitat use in northern Kwa-Zulu Natal, South Africa
    (2019) Pretorius, Michelle; O'riain, Mannus Justin; Mann, Gareth
    Protected areas (PAs) form the cornerstone for most carnivore conservation strategies. However, climate change, increased isolation and human pressure along PA boundaries are together reducing the effectiveness of PAs to conserve carnivores. Mesocarnivores, in particular, frequently move beyond the boundaries of PAs where they threaten human livelihoods, and as a result, are often subject to chronic persecution. In South Africa, we know little about the conservation status of mesocarnivores both within and outside of PAs, as most research focuses on large, charismatic apex predators. The goal of my study was to leverage data collected from large carnivore studies to understand variation in mesocarnivore species richness within PAs. Camera trap surveys were conducted as part of Panthera’s 2015 national leopard monitoring programme in seven PAs across northern KwaZulu-Natal (KZN), South Africa. Using a multi-species extension of the Royle-Nichols occupancy model, my study explored environmental, interspecific and anthropogenic drivers of mesocarnivore habitat use and species richness. I found a surprisingly low number of detections (N = 356) for all five mesocarnivore species and considerable variation across PAs. Small PAs with a recent history of human disturbance supported more mesocarnivore species and at higher relative abundance. Mesocarnivore species richness was found to decline with increased vegetation and leopard abundance but increased towards the edge of PAs. Variation in species richness estimates decreased significantly with vegetation productivity and domestic dog abundance. Together these results suggest that (1) the edges may provide a refuge for mesocarnivores from more dominant species, (2) mesocarnivores exhibited resilience/adaptability to human disturbance, and (3) primary productivity and domestic dog abundance could mediate mesocarnivore distributions within PAs. My study showed that camera trap data derived from a single-species survey can be used to make inferences about non-target species to great success. Current PAs in KZN may not adequately conserve mesocarnivores, and as a result, emphasis should be placed on coexistence with mesocarnivores in marginal habitat outside of PAs.