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Are Cape Cormorants (Phalacrocorax capensis) losing the competition? Dietary overlap with commercial fisheriesMasiko, Oyena B 21 February 2019 (has links)
Characterisation of the diet of pelagic feeders can be regarded as key to development of ecosystem-based management plans, conservation of predators as well as understanding of ecological and trophic interactions. Therefore, long term studies on dietary changes provide insights into the nature of competition and overlap between seabirds and fisheries. The Cape Cormorant Phalacrocorax capensis breeds in the Benguela upwelling region of southern Africa. Its population has decreased by over 50% in the three most recent generations resulting in the species being listed as Endangered in the IUCN Red Data List. Its decline has previously been postulated to result from reduced prey availability. In this thesis, I examined and reported on the spatio-temporal distribution of Cape cormorant diet obtained from different colonies over two decades (1988 – 1997 and 1998 – 2007). I further investigated the extent of overlap between the diet composition and sizes of fish eaten by Cape Cormorants and those caught by the purse-seine fishery. Epipelagic fish (Anchovy, Sardine, Horse Mackerel and Redeye) dominated the diet of Cape cormorants at all sites. Anchovy was the most important in the diet in all years except in 1992 and 1993, when Sardine dominated the diet, and in 2007 when ‘other’ fish species (mainly Cape Silverside Atherina breviceps and Southern Mullet Chelon richardsonii) became the most frequently eaten fish. There were decadal variations in the relative numerical abundance of different prey species. Over both decades investigated, the diet was largely dominated by Anchovy and Sardine, with Horse Mackerel contributing more in the second than first decade. There was, however, an increase in the contribution of Anchovy relative to Sardine from the first decade to the second. At all colonies, Cape Cormorants mostly preyed on Anchovies of sizes between 5 and 11cm. Sardines eaten were larger than Anchovies (mostly 11 – 23 cm), with a bimodal distribution in the first decade. However, the few Sardine eaten in the second decade were smaller (4 – 7 cm) perhaps reflecting the length of fish available. There was an overlap in the distribution of fish sizes caught by the fishery and those found in the diet of Cape Cormorants especially in the first decade. However, increased sampling of Cape Cormorant diet is required to more fully understand the extent of competition and overlap with fisheries.
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Cheetah (Acinonyx jubatus) mortality and survival in fenced reserves as part of a managed metapopulation across South AfricaSchroeder, Michelle M. 21 February 2020 (has links)
Large carnivores require expansive habitat to meet their life history needs making them vulnerable to the loss and fragmentation of natural habitat. This, in addition to human persecution has led to substantial population and range reductions of most of the world’s large carnivores over the past century. Cheetahs are no exception, occupying only 12% of their historic range in South Africa. Reintroduction programs have attempted to re-establish cheetahs to parts of this historic range, and increasingly the potential exists for their conservation in smaller fenced game reserves. However, this requires managers to maintain demographic and genetic diversity. In 2011, the Endangered Wildlife Trust initiated a project which coordinates movements between reserves using a metapopulation framework. This coordinated management approach is still in its infancy and little data exist on how reintroduction success varies amongst individuals and reserves. This study aims to examine the causes of mortality and the factors influencing cheetah survival on 20 reserves using individual life history records from 1993-2018. We assessed demographic, environmental, and management factors that are predicted to influence cheetah survival using a Cox proportional hazard model. Predation, mostly by lions (Panthera leo) accounted for 39% of known mortalities. However, the presence of spotted hyena (Crucota crucuta) posed the greatest threat to survival. Contrary to my prediction, translocation improved survival when controlling for age. Survival has also improved with time since the coordinated metapopulation approach was initiated in 2011. We created a nomogram which can be used by practitioners to predict cheetah survival within the metapopulation. Our study shows the importance of monitoring reintroduction efforts and encourages similar methods be used for other species of conservation concern that are managed within a metapopulation framework.
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The preservation of the Cape flora : status, causes of rarity, ideals and prioritiesRebelo, Anthony G January 1992 (has links)
Includes bibliographies. / The Cape Floristic Region (CFR), covering 90 000 km2, comprises one of the world's six floral kingdoms. With 8600 species, of which 68 per cent are endemic, it ranks amongst the richest of temperate and tropical floras. Although 19 per cent of the CFR occurs in nature reserves, by far the majority of the preserved area comprises Mountain Fynbos. Only 0.5 and 3 per cent of the original extent of Renoster Shrub/and Lowland Fynbos is preserved, respectively. In this study Fynbos vegetation is identified as the richest habitat for Red Data Book (RDB) plant, freshwater fish, amphibian, butterfly, and reptile species in southern Africa. The greater Cape Town metropolitan area is identified as containing by far the highest richness of RDB plant, butterfly, reptile and amphibian species in the CFR Thus, this area ranks globally as one of the most urgent conservation priorities. The study also illustrates that previously used methods for evaluating priority conservation areas have under-rated species-poor areas containing a high proportion of RDB species. By collecting for species richness, a far more realistic picture of threatened areas can be obtained from RDB taxa. This study predicts, using a priori hypotheses based on ecological traits, and finds, that seed dispersal and regeneration strategies are most strongly correlated with rarity, most specifically with distributional area. Using distributional data for the Proteaceae, this study estimates that 95 per cent of all vascular plant species in Fynbos can be preserved in 16 per cent of the area. It also identifies the sites that require preservation if the maximum protection of floral diversity is to be realized. Two null models for evaluating the efficiency of a spatial configuration of reserves are proposed. Utilizing an iterating selection procedure, this study explores various algorithms, based on species richness and rarity, to construct ideal reserve configurations. This study provides the first empirical confirmation that the ideal approach to designing a reserve configuration is to identify areas of high endemism and richness in distinctive vegetation types within particular biogeographical regions. Thus, this study pioneers the use of RDB data to identify priority conservation regions, provides one of the first assessments of the causes of rarity in plants and establishes useful null models and algorithms for the identification and testing of ideal reserve locations in the design of integrated reserve networks. Not only does this study contribute towards theoretical reserve selection procedures, but it provides one of the most advanced frameworks for the preservation of a top conservation priority in the world, the CFR.
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Assessing sea turtle, seabird and shark bycatch in artisanal, semi-industrial and industrial of fisheries in the Cabo Verde ArchipelagoMontrond, Gilson 16 February 2021 (has links)
Firstly, I am very grateful to Birdlife International for the MSc scholarship. I am also very grateful to Professor Peter Ryan of the FitzPatrick Institute of African Ornithology, University of Cape Town, for agreeing to supervise this project and for his guidance, insights and comments on the write-up. I am grateful to Sarah Saldanha, for all the support during this MSc. Many thanks also to Dr Ross Wanless, Dr Rima Jabado and Ruben Rocha for all support, guidance and advice. I want to thank a lot Andy Angel for their accommodation and all support in South Africa. I am grateful to all the UCT staff and BirdLife Senegal Staff for all the support during this study. Many thanks to my family for all the encouragement and support. I want to thank to all the Cabo Verde fishers for their willingness to share their knowledge and experience. Finally, many thanks to the Conservation Biology class of 2019, for all their support.
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Factors influencing the timing of breeding in a range expanding raptor at two spatial scalesSebele, Lovelater January 2012 (has links)
Includes abstract. / Includes bibliographical references. / Range shifts and expansions have been recorded in a number of species and it is expected that as climate change proceeds it will result in more species joining this trend. A major concern with these shifts is the suitability of the receiving novel environments, for example, if these areas experience different climatic conditions or prey phenology. One way to evaluate how expanding populations adapt to the environment is through evaluating their breeding patterns. In southern Africa, the Black sparrowhawk (Accipiter melanoleucus) originally existed in Botswana, Mozambique, North Eastern and South Eastern South Africa and Zimbabwe.
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Human networks of tetrapod translocations in the Western Cape, South Africa: trends and potential impacts on biodiversityGoss, Jeremy R January 2012 (has links)
Includes abstract. / Includes bibliographical references. / Global trends show an increase in wildlife trade associated with the process of globalisation and increased international trade. In addition, biodiversity managers are increasingly turning to species translocations to achieve conservation goals. These human induced movements of wildlife have a number of potential impacts, one being the introduction of non-native species that may establish and become invasive. Although the underlying mechanisms are debated, it is accepted that invasive species are having detrimental effects on biodiversity worldwide.
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The historical exploitation of chondrichthyans in False Bay, South Africa and assessment of their conservation statusBest, Lauren Nicole January 2012 (has links)
Includes abstract. / Includes bibliographical references. / Commercial fishing in False Bay, South Africa, began in the 1600s. Today chondrichthyans are regularly taken in multiple fisheries throughout the Bay. Using time series data and life history information I assessed the vulnerability of chondrichthyans to exploitation in False Bay. Extensive time series from five fishing methods, between 1897 and 2011, enabled catch trend analyses for chondrichthyans as a whole as well as for specific species. Commercial linefish, beach seine, and recreational angling provided the best source of data because they cover the range of habitats found in the Bay and are the least selective methods.
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Human safety and shark conservation: an analysis of surfer risk perceptions and attitudes towards shark managementSheridan, Katherine 27 February 2021 (has links)
South Africa has a history of human conflict with sharks and shark safety management. Management of this conflict differs throughout the country, with Cape Town opting for a non-lethal approach in the form of the Shark Spotters programme, and Kwa-Zulu Natal (KZN) opting for a lethal approach using shark nets and drumlines. Lethal management of sharks stems from a belief that without it, people would be too afraid to go in the water, leading to adverse effects on tourism and other associated industries. I assessed surfers' perceptions of risk from sharks, how they value sharks, their knowledge of sharks, and their attitudes towards shark management. I surveyed surfers at Muizenberg Beach in Cape Town, and North Beach and Bay of Plenty Beach in Durban by asking them to answer questions in a questionnaire. A conjoint analysis assessed how likely respondents were to go in the water under various scenarios using situational factor levels related to shark presence, surf/sea and spotting conditions, and whether other people were in the water. The questionnaire results showed no support for lethal shark control and only 8.3% of respondents were aware the nets used in KZN were a lethal form of shark control. Respondents had good knowledge of shark ecology and a positive perception of sharks, both of which have been shown to benefit shark conservation in previous studies. A multiple linear regression model showed a positive correlation between perception of shark risk and perception of other risks, such as car accidents and natural disasters, with respondents perceiving other risks as greater than shark risks. In the conjoint analysis, shark presence was the most influential factor for surfers deciding to go in the water, but respondents were more likely to go in under good surf conditions and spotting/sea conditions even if a shark had been seen recently. Overall, sharks do not deter people from going in the ocean. Implications of these results undermine the longstanding argument that lethal shark management is necessary to protect tourism. Furthermore, the lack of knowledge that lethal shark control is being practised in South Africa coupled with the opposition to lethal management found in this study highlights a clear disconnect between water users and shark managers in KZN.
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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 ReserveTaylor, Johanna 01 March 2021 (has links)
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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Biogeochemical niche construction in the forest-fynbos mosaic of Jonkershoek Nature Reserve, South AfricaDalwai, Raheem January 2014 (has links)
Includes bibliographical references. / The south-western Cape of South Africa is dominated by fynbos vegetation with patches of forest restricted to rock screes and stream banks owing to the more favourable moisture status of these microhabitats. A detailed analysis of soil underlying forest and fynbos vegetation in Jonkershoek Nature Reserve was investigated. A total of nine soil pits were dug in forest and on fynbos slopes with high and low gradients. Pits were analysed by depth examining texture while soil was also sent for x-ray fluorescent analysis and carbon and nitrogen analysis. Evidence for dust deposition varied spatially, although this could be a result of the rapid erosion experienced during winter. Soil properties, mainly texture and nutrient concentration differed distinctly between forest and fynbos. I argue that these differences are caused by topographical diversity and maintained by vegetation which influences nutrient enrichment via dust accumulation and plant litter decomposition. Thus I concluded that soil texture favours nutrient retention in forest soil more than in fynbos soil enhancing the disparity between nutrients in the respective environments. By influencing litter decomposition and aeolian inputs of dust, vegetation is responsible for modifying its niche increasing the difference between fynbos and forest patches.
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