Landscape heterogeneity as a determinant of range utilization by African elephants (Loxodonta africana) in mesic savannas

Landscapes are inherently heterogeneous. However, some portions of a landscape are more heterogeneous than others and are therefore not equally suitable for resource extraction by elephants. Elephants have large energy demands to meet and should spend the majority of their time in areas where they are able to forage optimally. Identifying the determinants of home range location and area may therefore provide insight into aspects of landscape utilization by elephants. Using vegetation structure as a surrogate, I investigated whether landscape heterogeneity explains the variability home range size and location of elephants occurring in the mesic savannas of Zambia and Malawi. I developed a landscape map for each of five study areas. Using these maps, I applied four FRAGSTATS metrics to quantify different aspects of landscape heterogeneity within the study areas, as well as elephant home ranges and randomly located ranges delineated using a 95% Kernel estimation. I placed similar study areas into comparable groups for each of the landscape heterogeneity metrics. Elephant home range size was not a function of landscape heterogeneity metrics and may therefore be explained by other factors. Landscape complexity and diversity of elephant home ranges varied within groups of similar study areas, suggesting that these metrics were important descriptors of home range location. Within study areas, with the exception of patch density, landscape heterogeneity metrics supported the expectation that wet season ranges would be more heterogeneous than those of the dry season. In addition, female ranges were more heterogeneous than those of males during the wet seasons with respect to both patch density and landscape diversity. In most cases, greater landscape heterogeneity within home ranges was only shown during the wet season and this suggests that water requirements preclude selection for more heterogeneous landscapes during the dry season. However, elephants of the Zambian study areas, besides Kafue, selected for metrics indicative of landscape complexity and diversity during both dry and wet seasons. I therefore concluded that elephants favoured complex landscapes with more vegetation types in irregularly arranged patches and landscape heterogeneity therefore determines the location of elephant home ranges. At a regional scale, a landscape comprises habitats of varying suitability to elephants. In a metapopulation framework, such areas may form sources or sinks and therefore contribute to driving elephant movements. The ability to identify areas of importance to elephant range utilization is therefore an essential tool to apply within the megaparks for metapopulations conservation framework.Dissertation (MSc (Zoology))--University of Pretoria, 2007.Zoology and Entomologyunrestricte

The response of biological communities to spatial and temporal changes in a regenerating coastal dune forest along the north-east coast of South Africa

Ecological restoration that aims to reinstate indigenous processes may be constrained by regional and local conditions, especially those that drive dispersal and colonisation. Local conditions can be managed, while regional conditions cannot. The management of costly rehabilitation programmes is considered best practice when scientifically informed. My thesis documents the responses of biological communities to a range of local conditions developing in coastal dune habitats in response to ecological restoration. Here, landscape-level (spatial structure of patches of tree canopies) local conditions were distinguished from site-level (topography, soil nutrient content, woody plant community richness, microclimatic variables) local conditions. The spatial structure of tree canopies varied over time and differed between the mining lease site and the relatively undisturbed benchmark site prior to (1937- 1970), and after (1990-2006) mining. For example, approximately 20% of the mining lease site and 40% of the benchmark site was covered by tree canopies prior to mining. However, after mining and rehabilitation, the structure of tree canopies began to converge towards that of the benchmark. The topographic profile of coastal dunes was less heterogeneous after mining and rehabilitation than before. Aspect, elevation and gradient of dune slopes were also different and had shifted in space. Variability in the structure of tree canopies could not explain variability in species richness, forest-associated species richness and proportion of benchmark species for the millipede, dung beetle and bird communities ashad been expected. However, species composition did change (though idiosyncratically) with age-related changes in soil nutrient availability and tree species diversity. Temperature, relative humidity and light intensity varied with dune topography, but soil nutrient content (C: N ratio and pH) was better accounted for by the age of the regenerating forest than by dune topography. Similarly, analysis of covariance suggested that tree canopy density, woody plant richness and millipede species richness only responded to the aspect, elevation and gradient of restored coastal dunes when age was taken into account as a covariate. However, the response of keeled millipedes to dune topography, regardless of regeneration age, suggested that the microclimatic variability brought about by topographic heterogeneity may provide these specialists with suitable microhabitats. Throughout my thesis, the age of regenerating patches of indigenous canopies was often more important as an explanatory variable than habitat conditions per se. Age itself is not a determinant of biological communities, but merely the axis along which habitat conditions change with succession, and later, patch dynamics. Therefore, as elsewhere, my thesis has highlighted age as a useful proxy for the response of biological communities to local conditions. It seems that managing local variables such as those considered in my assessment is not an avenue through which to enhance restoration. After kick-starting initial conditions, best practice rehabilitation management should therefore focus on minimizing external disturbances rather than interfering with natural processes.Thesis (PhD)--University of Pretoria, 2013.Zoology and Entomologyunrestricte

Coastal dune topography as a determinant of abiotic conditions and biological community restoration in northern KwaZulu-Natal, South Africa

Topography is rarely considered as an independent goal of restoration. However, topography determines microenvironmental conditions and hence living conditions for species. Restoring topography may therefore be an important first step in ecological restoration. We aimed at establishing the relative importance of topography where coastal dunes destroyed by mining are rebuilt as part of a rehabilitation program. We assessed the response of (1) microclimatic and soil conditions, and (2) woody plant and millipede species richness and density, to locationspecific topographic profiles. We enumerated the topographic profile using variables of dune morphology (aspect, elevation, and gradient) as well as relative position on a dune (crest, slope, and valley). Temperature, relative humidity, and light intensity varied with aspect, elevation, gradient, and position. However, regeneration age was a better predictor of soil nutrient availability than these topographic variables. Age also interacted with topographic variables to explain tree canopy density and species richness, as well as millipede species richness. The density of keeled millipedes (forest specialists) was best explained by topographic variables alone. The transient nature of these new-growth coastal dune forests likely masks topography-related effects on communities because age-related succession (increasing structural complexity) drives the establishment and persistence of biological communities, not habitat conditions modulated by topography. However, our study has shown that the microhabitats associated with topographic variability influence specialist species more than generalists.Department of Trade and Industry and Richards Bay Minerals and the National Research Foundationhttp://link.springer.com/journal/11355hb2014ab201

Inferred spatial use by elephants is robust to landscape effects on GPS telemetry

Global Positioning System (GPS) telemetry provides data to study spatial utilization patterns of animals. Spatial uncertainty due to poor accuracy and fix rates, however, may detract from inferences based on such data. The exclusion of two-dimensional (2D) locations may improve such inferences, but the prevalence of 2D locations may be a factor of landscape properties. In trials conducted using GPS units stationed at known positions, fix rate decreased significantly with increased canopy cover, but was unaffected by slope. Most (75%) of the locations recorded in closed woodland were 2D locations, suggesting that the exclusion of 2D locations may reduce estimates of the utilization of such habitats. Excluding 2D locations from records obtained for GPS units deployed on free-ranging elephants (Loxodonta africana) increased daily displacement distances, and changed the number of locations per habitat. However, selection ratios and estimates of home range area were not influenced by filtering location data. We concluded that although the exclusion of 2D locations improved the accuracy of locations per se, it resulted in significant data loss. This loss could alter inferences on patterns of spatial utilization

Preliminary observations on the diet of leopards (Panthera pardus) from a conservation area and adjacent rangelands in the Baviaanskloof region, South Africa

Pastoralists on rangelands adjacent to the Baviaanskloof Provincial Nature Reserve, Eastern Cape, report stock losses through predation by leopards (Panthera pardus). This leads, in certain cases, to persecution of the leopards. This study attempted to quantify livestock depredation by leopards by comparing leopard diet within and  outside the reserve. Leopard scats from both areas were analysed for prey items. A total of 18 prey taxa was identified, including small to medium-sized ungulates, rodents, birds and a felid. The mountain reedbuck was the most frequently utilized prey, followed by vlei rat, bushbuck, rock hyrax and grysbok. Baboons, although abundant throughout the study area, were not utilized by these leopards. There was a significant difference in the frequency of prey items between the reserve and the rangeland samples in terms of the relative contribution of the prey taxa.  Medium-sized and small ungulates were heavily utilized in the reserve, whilst the diet in rangelands was composed largely of small mammals (including small  ungulates). Only two scats contained the remains of domestic animals, indicating that<5%of the diet comprised this prey category, and suggesting that leopards in the study area do not preferentially prey on livestock.Keywords: leopards, diet, scat analysis, livestock predation, rangelands, conservation areas