Browsing by Subject "Ecology and Conservation"

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    A multi-scale study on the movement ecology of Afrotropical waterbirds
    (2016) Henry, Dominic A W; Cumming, Graeme S
    Understanding the processes and mechanisms governing animal movement is a fundamental goal in ecology. Processes driving movement can occur across multiple spatiotemporal scales and have important consequences for the structure and dynamics of populations, communities and ecosystems. The study of movement provides insights into the ecological resources and habitats necessary for persistence of species and communities. It also provides a theoretical and applied basis from which to formulate informed conservation plans. Waterbirds in semiarid southern Africa are an ideal study group for understanding interactions between movement and environmental factors because they exhibit a wide range of movement strategies and are located within a landscape in which resources are characterised by high levels of spatiotemporal variability. Emphasis has been placed on understanding movement phenomena from individually-tracked animals, but cases which consider this approach in conjunction with traditional community ecology perspectives are rare. In this thesis I explored questions of movement in both individuals and communities, and argue that an integrated multi-scale approach is necessary to advance our broader understanding of movement in waterbirds. In the first part of the study I addressed an individual-level movement perspective. I used fine-scale telemetry data from 35 individually tracked Egyptian Geese Alopochenaegyptiaca and Red-billed Teal Anas erythrorhyncha with novel analytical techniques to explore questions of trade-offs in habitat selection, functional responses and whether movement responses to landscape resources are reactive or prescient. My findings suggested that, at the home-range scale, both forage optimisation and predation risk were limiting factors of movement and habitat selection of Egyptian Geese. I also showed for the first time that waterbirds exhibit functional responses in relation to changes in the availability of habitat types. I subsequently showed that the proximate drivers of waterfowl movement are the dynamics of rainfall and primary productivity. Egyptian Geese and Red-billed Teal were able to perceive and respond to temporal shifts in resource conditions prior to habitat patch occupation. This in turn suggested that their movements in semi-arid landscapes are underpinned by an intimate knowledge of the local environment and that waterfowl exhibit a complex behavioural movement strategy. In the second part of the study I used waterbird count data collected from wetlands in KwaZulu-Natal, South Africa, to address the community-level movement perspective.
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    Open Access
    Towards adaptive management of high-altitude grasslands: Ingula as a case study
    (2015) Maphisa, David Hlosi; Altwegg, Res; Underhill, Leslie G
    Eastern high - altitude grasslands of South Africa are centres for endemism and harbour fauna and flora of regional and international conservation concern. This area also provides important ecological services such as provision of water to communities downstream. Sweet and sour veld support beef livestock farming during summer months. The aesthetic beauty of the region makes the area a prime tourist destination too. More recently the area is becoming a target of other agricultural projects such man - made forests. Other new developments that need to be mitigated against are development of renewable energy projects such as pumped water schemes to generate electricity or wind farms. Additional habitat is lost when these projects are connected to the national grid. In this thesis, I use bird data and vegetation data to compare, contrast and suggest management tools to manage this area. I present data that I collected at Ingula Pumped Storage Scheme spanning five years from the beginning of the construction of the scheme to near its completion in 2012 as a case study to manage similar habitats. Chapter 1 presents a brief overview of ecological importance of this area and the history behind the construction of pumped storage scheme at Ingula. A literature review in Chapter 2 investigates management tools to manage these grasslands for avian diversity. Fire and grazing is a key management tool cited to make habitat suitable for birds. While few studies from this type of grassland exist, studies from outside South Africa suggest that fire and grazing supplement each other as management tool to make habitat suitable for species with contrasting ecological requirements. A mosaic of grass heights and cover across the landscape translates to species habitat suitability. Chapter 3 explores species richness through years, seasons and impact of grass height and cover on bird species richness. Species richness was highest in summer suggesting that management should make habitat for species suitable in summer when most priority species are likely to use the habitat. The main disadvantage of using bird species richness is that fieldworkers must know their species well. Secondly, use of species richness must be treated with caution because this method does not account for species detectability in time and in space. In Chapter 4 I use hierarchical distance sampling models which take into account both the detection and the biological process. To demonstrate this I used common grassland bird species which can easily be identified during monitoring. The downside of this approach is that because these species are common and therefore occur almost everywhere, they may not easily respond to lack of habitat heterogeneity. The technical disadvantage of using this method is to accurately allocate species to within distance bands, making this method challenging for fieldworkers. Chapter 5 presents random plot occupancy which records only detection - nondetection of birds during repeated plot surveys. This method accounts for observational and biological processes too and in addition implements rigorous statistical inferences to predict how birds respond to habitat variable s as influenced by management decision on fire and grazing. Finally, adverse weather conditions may hamper surveying all plots in some years. Through occupancy modelling it is possible to predict species occupancy on plots that were not surveyed during some years and finally this method has been improved to include rare species. This is my preferred method to monitor management effect on habitat suitability for birds at Ingula. Adaptive management, a pillar of which is adaptive monitoring is a new paradigm shift in conservation. In Chapter 6, I capture interactions between burning and grazing and effects on grass height and cover to predict habitat suitability for birds including large threatened Ingula birds using a simulation models. This model sets a stage for implementing adaptive management through experimental plots to capture a set of management uncertainties regarding the use of fire and grazing as management tools. Chapter 7 summarizes the thesis and acknowledges that Ingula consists of other equally important habitat and ecosystem such as cool moist mountain forest and matrix of grassland wetland that equally need to be conserved.