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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Carnivore intra-guild competition in Selati Game Reserve, Limpopo Province, South Africa
- Authors: Comley, Jessica
- Date: 2020
- Subjects: Hyenas -- Behavior -- South Africa , Hyenas -- South Africa , Hyenas -- Ecology -- South Africa , Top predators -- South Africa , Top predators -- Ecology -- South Africa , Animal communities -- South Africa , Animal behavior -- South Africa , Mutualism (Biology) -- South Africa , Coexistence of species -- South Africa , Game farms -- South Africa , Selati Game Reserve (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115558 , vital:34163
- Description: Carnivore intra-guild interactions can be important drivers of carnivore community composition and ecosystem functioning. Large carnivores are particularly important since they occupy the highest trophic levels and can exert extensive influences on subordinate carnivores and prey species. Given Africa’s rapidly expanding human population, enclosed reserves such as those found in South Africa, may become increasingly important for carnivore conservation. A major concern, however, is that the interactions and co-existence of multiple carnivores in these systems is poorly understood. Additionally, the majority of reserves in South Africa are small ( 400km²), potentially increasing the likelihood of competition. My research aimed to provide insight into the interactions and co-existence of a multi-carnivore community within a small, enclosed reserve in South Africa (Selati Game Reserve). I tackled this task by using a combination of field techniques including camera trap surveys, ungulate transect surveys, aerial count surveys, location data collected from collared large carnivores and scat and kill site analyses. I found that carnivore-carnivore interactions, and their associated impacts, varied within the carnivore guild and that co-existence may be due to trade-offs between various risks (i.e. interference and exploitative competition) and benefits (i.e. resources such as food and space). My findings also revealed that large carnivores, such as lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus) do not have homogenous effects and that site-specific research on multiple-carnivores is integral for conserving biodiversity and ecosystem dynamics. Lions were the dominant large carnivore (in terms of intra-guild predation, space use and resource use) despite being outnumbered seven to one by spotted hyaenas. Leopard occupancy was negatively influenced by lions and leopard diet overlapped almost completely (91%) with spotted hyaenas, suggesting increased kleptoparasitism of leopard kills by spotted hyaenas. While my study provides valuable insight into the complexity of carnivore intra-guild competition in a small, enclosed reserve it also highlights major research gaps and emphasises the need for ecosystem-based research throughout southern Africa to fully understand how multiple sympatric carnivores co-exist in these systems.
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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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Population assessment and feeding ecology of brown hyenas (hyaena brunnea) in Mountain Zebra National Park, Eastern Cape, South Africa
- Authors: Comley, Jessica
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2862 , vital:20336
- Description: The development of many small (<400 km2), enclosed game reserves in the Eastern Cape Province of South Africa over the past 25 years has contributed greatly to the conservation of large carnivores. However, the brown hyena (Hyaena brunnea) is one of the least studied large carnivores in South Africa. Nevertheless, the reintroduction of this species (n=3 in 2008) into Mountain Zebra National Park (MZNP) provided the perfect opportunity to broaden our understanding of the role that this carnivore plays in an enclosed system. Camera trap data was collected for just over a year from April 2014 to April 2015 and brown hyena density estimates were calculated using spatially explicit capture-recapture analysis. Left-side images of brown hyenas were used in the analysis and 12 individuals were positively identified. The best model to estimate brown hyena density included a road covariate and estimated brown hyena density to be 6-10 individuals/100 km2 (an absolute abundance of between 12 and 21 individuals), which is higher than densities calculated for brown hyenas in other arid, open systems. In, addition, brown hyena scat samples were collected over a five year period from April 2011 to June 2015 and standard techniques for scat analysis were used to identify prey items. Cheetah (Acinonyx jubatus) and lion (Panthera leo) kill site data were used to investigate the impacts of these species on the diet of brown hyenas. Before the release of lions brown hyenas predominantly scavenged on medium-sized mammals, which was what the cheetahs mainly killed. However, after the release of the lions, brown hyenas predominantly scavenged on large mammals, which was what the lions primarily killed. The results from my study indicate that brown hyenas are most likely reaching high densities in enclosed systems, due to increased scavenging opportunities provided by other large predators. The rapid increase of brown hyena densities from small founder populations in enclosed reserves could result in inbreeding. Therefore, in order to successfully conserve brown hyenas and other large carnivores in South Africa, continual post-release monitoring and possible implementation of meta-population management schemes is required.
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