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Understanding resource use of an invasive species: Diet of the common warthog in Eastern Cape succulent thicket

  • Authors: Mgqatsa, Nokubonga , Jama, Kanyisa , Landman, Marietjie , Kerley, Graham I H
  • Date: 2024
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462746 , vital:76331 , xlink:href="https://doi.org/10.1016/j.jaridenv.2024.105155"
  • Description: Understanding resource use of invasive species provides insights for predicting and mitigating their impacts on biodiversity. We explored the predictability of diet of the invasive common warthog by describing and comparing the diet of warthog populations from two semi-arid, invaded sites, Addo Elephant National Park (AMC), and Great Fish River Nature Reserve (GFRNR), Eastern Cape, South Africa. These sites are both dominated by the Subtropical Thicket biome, but differ in vegetation type. We used forage availability to estimate diet preferences at AMC. We predicted that warthog would consume grass in invaded landscapes. Additionally, we predicted that the diet at one invaded site would predict this at another invaded site. As predicted, warthog mainly consumed grass at both sites (AMC – 87.4%, GFRNR – 88.5%), eating few woody plants, succulents, and forbs. Cynodon dactylon was the most consumed species in AMC, in GFRNR this was Eragrostis curvula and Cymbopogon pospichilii. Our ability to predict the diet between sites was constrained by variation in the plant species consumed. We found strong relationships between the consumption of preferred plant species at AMC and their consumption at GFRNR. We show that warthogs are specialised grazers outside their native range and thus can be expected to impact grass communities in invaded areas, especially preferred grass species. Thus, conservation managers need to monitor grasses in areas invaded by warthog to better detect and manage their impacts.
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Using photo by-catch data to reliably estimate spotted hyaena densities over time

  • Authors: Mgqatsa, Nokubonga , Jama, Kanyisa , Landman, Marietjie , Kerley, Graham I H
  • Date: 2024
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462757 , vital:76332 , xlink:href="https://doi.org/10.1016/j.jaridenv.2024.105155"
  • Description: Protected areas are becoming increasingly isolated refugia for large carnivores but remain critical for their survival. Spotted hyaenas (Crocuta crocuta) are important members of the African large carnivore guild but, like other members of the guild, routinely come into conflict with people because of their large home ranges that are not always confined to protected areas. To effectively conserve spotted hyaena populations, it is paramount to monitor their abundance through reliable and cost-effective techniques. We estimated the density of spotted hyaenas in Hluhluwe–iMfolozi Park (HiP), South Africa using camera trap images and a spatially explicit capture-recapture (SECR) framework between 2013 and 2018. We estimated an average of 18.29 ± 3.27 spotted hyaenas per 100 km2 between 2013 and 2018, with an annual estimated high of 20.83/100 km2 in 2014 and a low of 11.98/100 km2 in 2015. Our results demonstrate that camera trap by-catch data can be used for estimating spotted hyaena densities over time. We believe that given the widespread use and deployment of camera traps across Africa, collaborative efforts to use existing data to improve regional and continental estimates and population trends for spotted hyaenas should be a priority.
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Count me in: Leopard population density in an area of mixed land‐use, Eastern Cape, South Africa

  • Authors: Bouderka, Safia , Perry, Travis W , Parker, Daniel M , Beukes, Maya , Mgqatsa, Nokubonga
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462591 , vital:76317 , xlink:href="https://doi.org/10.1111/aje.13078"
  • Description: Although the leopard (Panthera pardus) has the widest range of any felid in the world is designated as a vulnerable species, mainly because of human-induced conflict (Jacobson et al., 2016). Our study focuses on a population of leopards on privately owned, mixed-use farmland (Baviaanskloof Hartland–BH hereafter) which is adjacent to the Baviaanskloof Mega Reserve (BMR) in the Baviaanskloof UNESCO World Heritage Site of the Eastern Cape, South Africa. Given the unique make-up of the region, with sometimes conflicting management objectives, the status of leopards in the broader Baviaanskloof is of particular interest to a range of stakeholders. However, despite the need for management decisions to be based on reliable and regular population monitoring efforts (Elliot et al., 2020), the last formal assessment of the leopard population in the Baviaanskloof was performed in 2011/2012 but published 9 years later (Devens et al., 2018). The only other assessment of the status of leopards in the region was an unpublished Master's project (McManus, 2009). Here, we use photographic captures of leopards and a Spatially Explicit Capture Recapture (SECR) analytical framework in the mixed-use BH region of the Baviaanskloof to generate an up-to-date leopard population density estimate that can inform conservation management of the species in this important World Heritage Site.
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Puma (Puma concolor) sex influences diet in southwest New Mexico

  • Authors: Bernard, Kelly M T , Perry, Travis W , Mgqatsa, Nokubonga
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462647 , vital:76322 , xlink:href="https://doi.org/10.3398/064.083.0201"
  • Description: Puma (Puma concolor) is a wide-ranging, large felid species, and site-specific research on its diet is important for local management. Like the diets of other large felids, puma diets may differ between sex due to size dimorphism and between seasons due to changes in prey vulnerability and availability. We investigated the influence of sex and season on puma diet in southwest New Mexico in terms of prey species and size categories. Pumas (10 males, 6 females) were tracked with GPS collars for an average of one year per individual between February 2008 and July 2020. Puma location was recorded every 2 hours between 19:00 and 7:00, and kill sites were identified by a minimum of 2 GPS fixes occurring within 100 m and 100 hours of the first fix. Pumas specialized on mule deer (Odocoileus hemionus) and elk (Cervus elaphus) but also preyed upon a range of other species of different sizes. The probability of making a medium-sized kill such as a mule deer was higher for females than for males, while the probability of making an extra-large kill, such as an elk, was considerably greater for males than for females. There was substantial variation in prey species and size categories killed by individual pumas, particularly of smaller-sized prey like collared peccary (Pecari tajacu) and skunks (e.g., Spilogale gracilis, Mephitis mephitis). Our findings concur with previous research on the importance of mule deer and elk in puma diet, demonstrate individual variation in prey killed, and may have management implications.
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An assessment of the medium-term reproductive success of an extralimital white rhinoceros population

  • Authors: Truter, Anja , Mgqatsa, Nokubonga , Parker, Daniel M
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462570 , vital:76315 , xlink:href="https://doi.org/10.1080/15627020.2022.2132120"
  • Description: The white rhinoceros (Ceratotherium simum) is threatened primarily due to continued poaching for its horns. In South Africa, partly to promote the conservation of the species, white rhinos have been introduced into areas where they did not occur historically (i.e. where they are considered extralimital). Few studies have investigated the conservation contribution of extralimital white rhinos to the overall national herd. We aimed to determine whether the white rhinos introduced to a private game reserve in the Eastern Cape province have been successful from a reproductive perspective. We calculated inter-calving intervals, age at first calving, sex ratios of calves, and recruitment rates for white rhinos at a single site between 1992 and 2019. The average net annual population growth rate for the population was 10%, which is higher than the recommended 5% by the Biodiversity Management Plan for white rhinos. Trends in density-dependent parameters such as age at first calving and inter-calving intervals also indicated that the study population is still well below the density at which ecological constraints may manifest. We demonstrate that an extralimital white rhino population in the Eastern Cape can be successful from a reproductive perspective.
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Goat browsing does not induce physical defences but reduces leaf size in Vachellia trees

  • Authors: Nzimande, Amanda , Mgqatsa, Nokubonga , Kraai, Unathi M , Tsvuura, Zivanai , Kraai, Manqhai
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462624 , vital:76320 , xlink:href="https://doi.org/10.1016/j.actao.2022.103818"
  • Description: One aspect of plant-herbivore interactions in African savannas is the browsing impact of mammalian herbivores on plants, which may result in induced physical defences (spines) and changes in leaf morphology in trees experiencing intensive browsing. In these savannas, spinescence is considered to have evolved in response to herbivore pressure from large mammals. We assessed the impact of free-ranging domesticated goats on the spines and leaves of Vachellia karroo, V. nilotica and V. tortilis in Msinga, South Africa. We predicted that there would be fewer and smaller leaves, and longer spines occurring below compared to above 1.5 m for all tree species. We further predicted that the outer parts of the tree canopy would have smaller and fewer leaves, as well as more and longer spines compared to the inner part of the canopy. To determine the response of these trees to goat herbivory, 35 trees of each Vachellia species were selected, the number of leaves and spines found on two randomly selected branches below 1.5 m and one above 1.5 m were measured. We found that leaves were fewer and smaller below compared to above 1.5 m. Interestingly, we found the reduced leaf size to be equal to the size of spines below 1.5 m. We also found that V. karroo had more spines below 1.5 m compared to V. tortilis and V. nilotica. Along the branch segments, we found that spines were longer in the most accessible parts of the branch, the outer canopy. This study showed that browsing by goats, unlike wild herbivores, do not induce plant physical defences but rather limit available foliage. We also showed that physical defences (spine density) of Vachellia trees vary. This has implications for management and ecology of rangelands browsed by domestic mammals.
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Varying degrees of spatio-temporal partitioning among large carnivores in a fenced reserve, South Africa

  • Authors: Evers, Emma E M , Pretorius, Mariëtte E , Venter, Jan A , Honiball, Terry-Lee , Keith, Mark , Mgqatsa, Nokubonga , Somers, Michael J
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462779 , vital:76334 , xlink:href="https://doi.org/10.1071/WR21045"
  • Description: Context The spatio-temporal partitioning of large carnivores is influenced by interspecific competition and coexistence within small, enclosed reserves. Lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus) are the three largest African carnivores and have the greatest potential for intra-guild competition, particularly where space is limited.Aim To investigate the spatio-temporal partitioning between lions, spotted hyaenas and leopards in a small (~75 000 ha), enclosed nature reserve, Madikwe Game Reserve (Madikwe), South Africa.Methods We deployed 110 camera traps (baited n = 55 and unbaited n = 55) across Madikwe from 26 August 2019 until 6 May 2020. Von Mises kernel density plots were used to investigate daily temporal partitioning among the three species. A multiple-species, single-season occupancy model was used to investigate daily space use patterns.Key results We found both temporal and spatial exclusion between lions and spotted hyaenas on Madikwe. However, no evidence was found of spatio-temporal partitioning between lions and leopards, and spotted hyaenas and leopards.Conclusions Exploitative and interference competition on Madikwe might be high enough to warrant spatio-temporal partitioning between lions and spotted hyaenas to avoid the negative effects of intra-guild competition. Contrastingly, patterns observed between leopards and both lions and spotted hyaenas preclude the possibility of top-down control by superior carnivores.Implication These findings call for an adaptive management approach, where both carnivore and prey species compositions are constantly monitored. Management strategies such as these will allow for the conservation of valuable resources (i.e. prey species) to ensure the persistence of large carnivore populations across African ecosystems.
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Battle of the large carnivores: spatial partitioning in a small, enclosed reserve?

  • Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462581 , vital:76316 , xlink:href="https://hdl.handle.net/10520/EJC-2037326828"
  • Description: Interspecific competition among terrestrial carnivores can have widespread impacts on community structure and can ultimately determine which species are able to coexist. Within the carnivore guild, coexistence can be achieved through either spatial, temporal or dietary partitioning. The most effective method of avoiding competition may be spatial partitioning, as it removes the potential for negative interactions. The ways in which large carnivore species utilize and partition space in small, enclosed reserves in South Africa is currently poorly understood. This knowledge gap weakens our understanding of which mechanisms structure large carnivore communities in these systems. Thus, our aim was to use Global Positioning System (GPS) collars to investigate the spatial dynamics of large carnivores [four lions (Panthera leo), three leopards (Panthera pardus) and three spotted hyaenas (Crocuta crocuta)] on a small, enclosed reserve (Selati Game Reserve). Regarding home ranges, lions had considerable overlap among themselves (especially the females), leopards had minimal overlap, while spotted hyaenas had no home range overlap. Although we found no evidence for spatial partitioning amongst the collared large carnivores, differences in the habitat use patterns of the three large carnivore species is evident. The high prey abundance of Selati, carnivore predation strategies, behavioural adaptations and ecological separation could be facilitating the coexistence of lions, spotted hyaenas and leopards in Selati. We encourage future research to be aimed at investigating the interactions of multiple sympatric carnivores in an attempt to bridge the knowledge gap on which mechanisms structure carnivore communities.
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Do spotted hyaenas outcompete the big cats in a small, enclosed system in South Africa?

  • Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462603 , vital:76318 , xlink:href="https://doi.org/10.1111/jzo.12772"
  • Description: Carnivores are adapted to kill, meaning sympatric carnivores can have particularly aggressive and harmful competitive interactions. The co‐existence of multiple carnivores in an ecosystem could be restricted by their similarity in ecological niches (e.g. dietary overlap); however, high prey abundances could facilitate their co‐existence. Although the development of small, enclosed reserves (larger than 400 km2) in South Africa has reduced human–carnivore conflict, these systems may increase the likelihood of carnivore intra‐guild competition due to the clumping of competing carnivores into these restricted spaces. Using carnivore scat and kill site analyses, we determined the dietary preferences and overlap of sympatric large carnivores in a small, enclosed reserve, Selati Game Reserve (Selati). Large carnivores in Selati (lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus)) preferentially selected for varying combinations of prey size classes. Lions selected for large prey, leopards selected for small prey and spotted hyaenas did not prefer any particular prey size. Additionally, lions had the largest dietary breadth and the diet of leopards and spotted hyaenas overlapped considerably. Coupled with high prey densities in Selati, the predation strategies of the large carnivores could be facilitating their co‐existence. On the other hand, the high degree of dietary overlap among large carnivores suggests that there is strong potential for exploitation competition, particularly between spotted hyaenas and leopards as their diet overlapped extensively (91% and 93% for prey species and size class, respectively). Although spotted hyaenas are potentially outcompeting leopards in Selati, lions were the most dominant large carnivore. Our study reiterates the complexity of carnivore guild interactions and emphasizes how these interactions are subject to variation due to site‐specific circumstances (e.g. composition of prey and carnivore populations). We therefore encourage site‐specific, multi‐carnivore research throughout protected areas in southern Africa.
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Do spotted hyaenas outcompete the big cats in a small, enclosed system in South Africa?:

  • Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/150099 , vital:38940 , doi:10.1111/jzo.12772
  • Description: Carnivores are adapted to kill, meaning sympatric carnivores can have particularly aggressive and harmful competitive interactions. The co‐existence of multiple carnivores in an ecosystem could be restricted by their similarity in ecological niches (e.g. dietary overlap); however, high prey abundances could facilitate their co‐existence. Although the development of small, enclosed reserves (over 400 km2) in South Africa has reduced human–carnivore conflict, these systems may increase the likelihood of carnivore intra‐guild competition due to the clumping of competing carnivores into these restricted spaces. Using carnivore scat and kill site analyses, we determined the dietary preferences and overlap of sympatric large carnivores in a small, enclosed reserve, Selati Game Reserve (Selati).
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Lions do not change rivers: complex African savannas preclude top-down forcing by large carnivores

  • Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/149215 , vital:38816 , https://doi.org/10.1016/j.jnc.2020.125844
  • Description: Trophic cascade theories such as the ‘behaviourally-mediated trophic cascade hypothesis’ (BMTCH), have mainstreamed as ecological tools for conserving biodiversity and restoring ecosystems. The BMTCH relies on indirect negative effects of large carnivores through suppression of mesocarnivore activity and habitat use. Importantly, effects of top carnivores on mesocarnivores varies over time and space, is dependent on the species involved, and local context. In South Africa, there are very few free-ranging carnivores, as populations are often restricted to enclosed reserves. While predator-proof fences reduce human-wildlife conflict, they also influence space use within communities. We used an enclosed reserve with a relatively full complement of carnivores to test the generality of the BMTCH in the African context. Using single-species, multi-season occupancy models we investigated the spatial dynamics of multiple carnivores. We also investigated spatial partitioning by vegetation type and temporal partitioning.
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Lions do not change rivers: complex African savannas preclude top-down forcing by large carnivores

  • Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462634 , vital:76321 , xlink:href="https://doi.org/10.1016/j.jnc.2020.125844"
  • Description: Trophic cascade theories such as the ‘behaviourally-mediated trophic cascade hypothesis’ (BMTCH), have mainstreamed as ecological tools for conserving biodiversity and restoring ecosystems. The BMTCH relies on indirect negative effects of large carnivores through suppression of mesocarnivore activity and habitat use. Importantly, effects of top carnivores on mesocarnivores varies over time and space, is dependent on the species involved, and local context. In South Africa, there are very few free-ranging carnivores, as populations are often restricted to enclosed reserves. While predator-proof fences reduce human-wildlife conflict, they also influence space use within communities. We used an enclosed reserve with a relatively full complement of carnivores to test the generality of the BMTCH in the African context. Using single-species, multi-season occupancy models we investigated the spatial dynamics of multiple carnivores. We also investigated spatial partitioning by vegetation type and temporal partitioning. Our results revealed both support for and against the BMTCH. Lions and spotted hyaenas negatively influenced the detection probability of black-backed jackals and African wildcats, while leopards had a positive effect on these two mesocarnivore species. Additionally, lions positively influenced the detection probability of side-striped jackals. Although space use of carnivores in relation to vegetation type showed minimal evidence of spatial partitioning, each carnivore had a unique combination of abiotic and biotic factors influencing their spatial dynamics, which could facilitate co-existence. Temporal partitioning may also be promoting co-existence as activity patterns of smaller carnivores overlapped the least with sympatric carnivores, particularly lions. Extensive activity overlap between large carnivores does not promote co-existence. We suggest that applying the BMTCH as a universal law across ecosystems is unsupported and may lead to inappropriate conservation and management actions, and prevent protection of ecosystems.
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Elephant effects on treefall and logfall highlight the absence of megaherbivores in coarse woody debris conceptual frameworks

  • Authors: Landman, Marietjie , Mgqatsa, Nokubonga , Cromsigt, Joris P , Kerley, Graham I H
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/462614 , vital:76319 , xlink:href="https://doi.org/10.1016/j.foreco.2019.02.015"
  • Description: Despite the importance of coarse woody debris (CWD) in woody ecosystems, conceptual frameworks of its dynamics currently exclude the role of the megaherbivores, focusing instead on the role of insects, disease, fire, wind and droughts. However, recognizing the ecological roles of the megaherbivores is one of the most urgent contemporary issues, particularly as their decline will likely have unanticipated outcomes at the ecosystem-level. Here we used sites with and without elephants in a semi-arid woodland ecosystem in South Africa to test whether elephants changed the quantitative and qualitative features of the CWD profile in relation to other wood producers. We show that elephants increased the abundance of CWD, influenced its quality by toppling mostly maturing trees, and changed the distribution of large woody items along gentle hillslopes. Surprisingly, and despite the recognized importance of both CWD and elephants for biodiversity, there is almost no published data on the role of elephants in shaping wood-living communities by changing fallen woody debris dynamics. Our study contributes towards developing a broader conceptual framework of CWD dynamics that includes the role of megaherbivores and provides a novel view of the ecological consequences of the loss of the Pleistocene megaherbivores. Our findings have important implications for CWD restoration efforts in transformed systems that previously supported megaherbivores.
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