Browsing by Author "Mann, Gareth"
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- ItemOpen AccessA camera trap assessment of factors influencing leopard (Panthera pardus) habitat use in the Nouabalé-Ndoki National Park, Republic of Congo(2018) Mavinga, Franck Barrel; O'riain, Justin; Mann, Gareth; Breuer,ThomasLeopards (Panthera pardus) are faced with increasing levels of anthropogenic pressure resulting in population declines across much of their historical range. While there is relatively limited knowledge of leopards occurring in African rain forests, their abundance and distribution is assumed to be impacted by a combination of several anthropogenic factors, most notably loss of prey and habitat conversion. In this study I used a long-term camera trap array that forms part of the Tropical Ecology, Assessment and Monitoring (TEAM) project - Terrestrial Vertebrate (Camera Trapping) Monitoring Protocol, to estimate the species richness of mammals, the relative abundance of leopard prey species and leopard habitat use in the Nouabalé-Ndoki National Park (NNNP) in the Republic of Congo. I investigated the impact of different environmental and anthropogenic factors on leopard occurrence at two camera trap arrays (a northern and southern cluster) within the NNNP using occupancy modelling. While there were no significant differences in mammalian species richness between the two clusters there was a higher relative abundance of the preferred prey species of leopards in the northern cluster. A total of 106 leopard photographic events were recorded across all camera traps and all survey years. The top occupancy model produced an average probability of site use (ψ) over all sites of 0.52 ± 0.14 (SE). The covariate specific β-coefficient estimate suggests that leopard occurrence and detectability were positively correlated with both the relative abundance of the blue duiker (Philantomba monticola) and the distance to the nearest river (β =0.062 ± SE 0.053 and 6.55 ± SE 10.84, respectively). Therefore there was no support for the prediction that the probability of leopard habitat use increases with a higher relative abundance of all potential prey species, nor was there support for the prediction that leopard habitat use would be higher further away from human settlements (β =3.42 ± SE 2.94). 2 Leopard habitat use was higher in the southern cluster which may be linked to the denser understory that would provide greater cover which is important for improved hunting success in leopards. Together, these results suggest that both the prey species and leopards appear to be thriving within the NNNP with limited evidence of anthropogenic impacts despite an increase in commercial logging and the itinerant bushmeat hunting in the peripheral area. It would be worth expanding the existing camera trap arrays to cover a greater spatial extent within NNNP and hence allow for a more detailed analysis of edge effects and to detect the potential impacts of anthropogenic activities which are predicted to increase in selected villages in the periphery of the park.
- ItemOpen AccessEstimating leopard density in a coastal protected area of the Western Cape, South Africa(2022) Hargey, Ayesha; O'riain, Justin; Mann, GarethLeopards (Panthera pardus), like many other large carnivores, are facing increasing threats including habitat degradation, illegal hunting, and persecution for perceived or actual livestock depredation. Protected areas remain the cornerstone of conservation efforts throughout the world but they are not a panacea and recent studies have shown declining populations within many protected areas of South Africa. Efforts to improve leopard conservation are hampered by a lack of reliable and repeated estimates of population size across their distribution, which limits an understanding of population dynamics and the potential drivers of declines. Monitoring efforts that produce density estimates are invariably the most informative for reserve managers who work with endangered species and are responsible for regional conservation planning – especially in cases where both predator and prey are of vulnerable populations. A small coastal area within the De Hoop Nature Reserve has been fenced off from the reserve with the goal of establishing a mainland breeding colony for the endangered African penguin (Spheniscus demersus). The fence is designed to reduce the threats posed by terrestrial predators, particularly leopard and caracal (Caracal caracal). Both feline species engage in supernumerary killings of penguins due to their poor predator response and are thus of special relevance to reserve managers and NGOs committed to their conservation. In this study, I conducted a camera trap survey in the De Hoop Nature Reserve, along the south coast of the Western Cape with the primary objective of estimating the density of leopards and the secondary goal of understanding the distribution, abundance, and activity patterns of leopard and caracal relative to the proposed penguin colony. I deployed 40 paired camera trap stations over 2457 trap nights and captured 312 independent images of the target taxa. A sample-based species accumulation curve revealed a clear asymptote indicating adequate sampling effort and a total of 24 medium and large mammal species. Both leopard and caracal had high relative abundance indices at camera stations close to the designated penguin colony. I recorded 111 independent images of leopards, of which six males and one female could be reliably identified. I derived a density estimate of 0.18 ± 0.07 individuals per 100km2 which is lower than estimates for protected areas in the eastern and northern regions of South Africa, and lower too than other estimates obtained from the fold mountains of the Western Cape. Coastal fynbos has low productivity and supports a low prey biomass relative to other biomes in South Africa, and thus the density may be justifiably lower than in other more productive habitat types. Of immediate concern is the heavily skewed sex ratio (6M:1F) and low total population size which — together with a permeable boundary fence and known persecution of leopards on neighbouring farms — makes this population vulnerable to both stochastic events and edge effects. Lethal management of leopards that threaten penguins would not be sustainable and thus it is important that a non-lethal barrier has been implemented as it offers the prospect of coexistence between two endangered and charismatic species.
- ItemOpen AccessFrom 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, GarethServals (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.
- ItemOpen AccessLandscape utilisation by an introduced pack of African wild dogs (Lycaon pictus) in eastern Botswana(2018) Mottram, Phoebe; O'riain, Justin; Mann, Gareth; Snyman, AndreiAfrican wild dogs (Lycaon pictus) are one of the most endangered carnivores in southern Africa. Direct persecution, prey decline and habitat loss and fragmentation all contributed to a rapid decline in this species’ population size and distribution during the 20th century. Following a thorough population viability analysis in the late 1990s the decision was taken to manage the South African population as a metapopulation. This involved the reintroduction of packs to small, fenced protected areas and the subsequent transfer of individuals or small groups between reserves to avoid inbreeding. A key component of successful metapopulation management is post-release monitoring to provide data on the determinants of reintroduction success and failure, particularly when establishing new populations. This study aimed to provide information on the post-release behaviour and movements of a pack of eight African wild dogs introduced to the Northern Tuli Game Reserve in eastern Botswana in February 2017. Two individuals from the introduced pack were fitted with GPS collars. A total of 933 GPS locations were recorded between February 2017 and October 2017. Movement data was used to analyse home range, habitat resistance and resource utilisation by this pack across a range of spatial and temporal scales. Monthly 95% kernel density estimations revealed a mean home range of 330.02 km2 . A reduction in home range size to 37% of the average monthly 95% kernel density estimations revealed that the pack commenced denning in May 2017. However, this denning attempt failed, as shown by the home range size increasing only a month after it initially contracted, which is less than the expected contraction period required to produce a successful litter. Habitat resistance analysis revealed that the pack readily crossed fences but not rivers, with the Limpopo river serving as a very hard barrier that consistently deflected pack movement parallel to its course. Resource utilisation functions showed a preference for sites far from riverine areas, with low elevation and rough and rocky terrain. I propose that this may reflect a predator avoidance pattern, with lions (Panthera leo) in particular preferring riverine habitat with a less rough terrain in this area. The persistence of this pack in the landscape nine months post-release indicates that this reintroduction has been a partial success. Large perennial rivers provide important barriers to the movement of this pack and may thus be important for mitigating local human-wild dog conflict. Fences, however, were readily traversed and therefore communities outside of fenced areas are likely to experience conflict with this pack and any future packs re-introduced to this area.
- ItemOpen AccessMesocarnivores 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, GarethProtected 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.