Habitat loss and fragmentation caused by tourist development along the eastern coast of the Yucatan Peninsula of Mexico represents a big threat to the survival of Nearctic-Neotropical migratory songbirds. This habitat plays a crucial role for successful migration for many migratory birds. However, the effects of habitat loss and fragmentation on these birds have not been well documented in the region. From September- December, 2006-2008, we mist-netted and conducted transect surveys to assess the variation in the avian community among three different levels of development (high, medium and low). The study area included two small reserves (10-20 ha) in the hotel zone associated with the Riviera Maya (high development), two sites with limited development within the Sian Ka’an Biosphere Reserve associated with small fishing camps (medium development), and two undeveloped sites located on a private ranch within Sian Ka’an (low development). I assessed species richness and abundance of four avian groups: the entire community, year-round residents, winter residents, and transients. Species richness and abundance decreased significantly with the greatest levels of disturbance. The high development level had the least species richness and abundance, whereas the medium development level had the greatest richness for all bird classes. However, my results suggest that small reserves in the hotel zone can be important compliments to the large, undisturbed reserves (Sian Ka’an) for both resident and migrant birds. Forty-six percent of all birds species captured in mist nets were Nearctic-Neotropical migrants; thus this group composed a significant component of the avian community. The dominance in the year-round resident community by the endemic Black Catbird (Dumetella glabrirostris) at medium and low development sites showed that coastal dune vegetation is also important in maintaining populations of endemic species, which are sensitive to levels of disturbance. The use of two different survey methods (mist-netting and transect surveys) produced complimentary descriptions of community composition. Because many year-round resident species and migrants depend on this scarce and discontinuous coastal habitat, and because of the intense development pressure on this coastal zone, better conservation strategies are needed to successfully sustain the avian community of this region.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Environmental Studies. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR39056

Thesis (Ph. D.)--University of Chicago, Dept. of Anthropology, August 2001. / Includes bibliographical references. Also available on the Internet.

Invasive species are considered an agent of ecological change with more significant effects than global warming. Exotic plant invasions threaten biodiversity and ecosystem viability worldwide. Their effects in the Sonoran Desert ecosystems are a growing concern among ecologists and land managers. We hypothesized that highly dynamic desert environments are unstable, therefore more vulnerable to invasion by exotic plant species. To test this hypothesis we used a multidimensional approach to assess the spatial distribution of two exotic species: Brassica tournefortii (Saharan mustard) and Schismus arabicus (Arabian grass), in a portion of 'El Pinacate y Gran Desierto de Altar' Biosphere Reserve (PBR) in northwestern Sonora, Mexico. This approach combined genetic algorithms, geographic information systems, field methods, statistical analysis, and remote sensing modeling at multiple spatial and temporal scales to predict and test the current and potential distribution of the invasives over dynamic landscapes.Predicted probability of invasion was influenced strongly by human factors: Road networks were the strongest predictors of presence, revealing the potential importance of humans as vectors of invasiveness. Dynamic landscapes, associated mostly with vegetation losses, were detected spectrally in the eastern portion of the study area, very likely associated with past agricultural and current grazing activity. Combined models of high probability for invasion by B. tournefortii and S. arabicus over dynamic landscapes were tested against confirmed locations of the invasives and land cover types associated with invasion. Results confirmed the hypothesis of the study and suggest that more dynamic landscapes are more prone to invasion by these two exotic plants in the PBR. B. tournefortii was found associated mostly with landscapes occupied by microphyllous desert scrub and grassland, as well as sarcocaulescent desert scrub. S. arabicus was found more abundantly in the flat low lands occupied by microphyllous and crassicaulescent desert scrub. These relationships cannot, however, be conclusive and require further investigation due to the complex ecology of these invasives.

White rhinos in the Umfolozi Game Reserve (UGR) are managed with a 'Sink Management Policy' which utilises natural dispersal patterns of white rhinos from an area of high density (the core), to areas of low density (vacuum zones). This study was initiated to determine how white rhinos utilised the vacuum zones, as the management staff of the UGR felt that white rhinos were not dispersing into them but utilising them only as areas of trophic resources. Significantly different white rhino densities were established in the Makhamisa and Masinda vacuum zones by removing white rhinos from Masinda. Changes in the density of white rhinos were monitored and the age and sex compositions determined. No significant changes in the density of white rhino groups were recorded during the study, however, the density of individuals in Makhamisa increased significantly in the dry season, while the density in Masinda did not change. The reason for this increase could not be determined, however, the most likely explanation was that rhinos moved toward the Makhamisa study area in search of surface water which was present in the White Umfolozi River. During the dry season the water level in the Umfolozi River was low so the white rhinos where able to cross into the study area. However, owing to the above average rainfall, resources were not limited in either study area, and most likely in most of the reserve. Thus, it could not be determined why white rhinos would need to enter the Makhamisa study area. Changes in grass height, grass colour, and the availability of water in pans and streams were monitored throughout the study. The grassland community compositions of the two study areas were found not to be significantly different. The total utilisation of the different grassland communities by white rhinos during the study were determined for both study areas. White rhinos in the two study areas utilised the grassland communities in a similar pattern throughout the study. During the wet and dry seasons, white rhinos primarily foraged in the short grassland community (Panicum coloratum & Themeda-Urachloa), their staple grassland community, and were not observed to switch and start foraging in the tall grassland community (Themeda & Themeda-Panicum). their reserve community. White rhinos in both study areas were able to forage in their stable grassland community throughout the dry season because of the above average rainfall experienced during the study The results of the study suggest that white rhinos outside the study areas did not utilise the vacuum zones for trophic resources. However, as the study was conducted in a year with above average rainfall, these findings may not represent how white rhinos utilise the vacuum zones in years with average or below average rainfall. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Subsistence harvesting pressure in most African countries focuses on the small and mostly unreproductive trees found in the understorey stratum and can have potentially insidious ecological effects. Harvest intensities at Ongoye Forest Reserve (OFR) vary significantly across the forest (range = 87 - 567 stumps ha-1), with harvesting focussed exclusively on poles from tree species that grow only in the understorey. Growing evidence indicates that seedling establishment from the pool of species available beneath a closed canopy is greatly influenced by the differential ability of species to take advantage of the short burst of resources in newly-created understorey gaps. Seedling dynamics in these gaps may determine forest tree diversity and dynamics and consequently harvest gaps have the potential to significantly affect natural forest dynamics. This study examined seedling establishment beneath intact understorey and within artificially created understorey gaps of different sizes (single stem gaps, two stem gaps, four stem gaps, eight stem gaps and control ‘gap’, where no stems were removed) that simulated different spatial scales of harvesting intensity of understorey trees. This experiment examined the proposition that successful seedling establishment and natural succession is strongly dependent on the scale of harvesting. Seedling abundance, species richness, irradiance (photosynthetically active radiation and the red to far-red ratio), soil nutrient composition and herbaceous layer cover was measured in each gap size in 2005 before harvesting, and again in 2007. The mean seedling abundance was not significantly different among gap treatments, although there was a trend towards more seedlings in 2005 than 2007. Seedling abundance in all gaps was greater than at control sites beneath the intact understorey. There was a continuous increase in seedling richness in 2007. An average species richness of 4.3 was recorded in the control sites, beneath a shaded understorey. Here, seedling richness increased by 18.24% with the removal of a single understorey tree (Gap 1). Species richness increased with increasing experimental gap size increased so that the greatest mean species richness (6.2 species) was recorded where eight neighbouring trees were removed (Gap 8). Light transmission reaching the seedling stratum was greater in larger gaps and there was a trend towards more seedlings and greater species richness in the higher light environments of such gaps. Soil nutrient levels did not influence seedling abundance and species richness in gaps. The herbaceous layer suppressed seedling establishment. In the largest gaps (115.4m2) created by harvesting, seedling composition was more deterministic than in small gaps where seedling establishment and density was random, accordingly there were more species in larger gaps from a more defined species assemblage. Current harvesting levels of pole-sized understorey trees, where only small gaps are created in the understorey, are unlikely to alter forest dynamics and species composition at OFR. This study demonstrates that harvesting eight adjacent trees crosses the harvest intensity threshold between sustainable natural tree dynamics and a potential successional shift to an alternative state. Clearly, for natural dynamics to be maintained harvesting intensities will have to be regulated. / http://hdl.handle.net/10413/631 / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

No description available.

Although the leopard (Panthera pardus) is one of the more successful large carnivores, challenges for leopard conservation emulate those of other more endangered carnivores, and they are a model species for investigating issues affecting carnivore persistence worldwide. This thesis represents a six year study of leopard on the Karongwe Game Reserve, South Africa, which provided a unique opportunity to observe various aspects of behavioural ecology in the absence of prey availability constraints or human persecution. Small, enclosed reserves such as Karongwe make up 16.8% of the total land in South Africa and undertaking sound ecological research in these areas provides valuable data for evidence-based conservation and management. The leopard is notoriously shy and difficult to study and I used free darting and habituation to enhance visual observation, in order to understand the ecological processes influencing leopard reproductive success and survival. My results show that leopard in the high prey area studied, consume almost double the number of ungulates as leopard in similar habitats elsewhere. This generalist predator improved its hunting success by selecting vulnerable prey and selectively hunted in habitats of intermediate density, where preferred prey were most abundant. Ample nutrition played a key role in reproductive health and reduced the duration of reproductive parameters below that previously recorded in the literature. Any additional nutritional input could not translate into increased population growth as females were already reproducing optimally. Female territorial size and habitat selection were determined by the availability of riparian habitat and resources of their preferred prey. Territoriality however was governed by prey biomass. Neighbouring leopards were territorial, sharing little space (average 11% territorial overlap) and hunting five times more often in the core than in the rest of their territory. During periods of prey richness, females became more territorial and there was a positive “bottom up” effect through subadult recruitment. Density-dependent intraspecific and interspecific competition for limited space regulated the population around carrying capacity, and constrained population growth. These results provide fundamental baseline data about leopard in the absence of human disturbance, or prey constraints. They highlight that, although the influence of optimal nutrition is important in the reproductive health and territoriality of leopard, habitat quality and quantity are ultimately what govern leopard carrying capacity and population size. I provide baseline reproductive, carrying capacity and territorial data for agencies developing policy, and for setting priorities in conservation and management, as well as habitat protection and restoration, for not only this species but other threatened species as well. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2013.

<p>This study investigated, within the context of Brain Reserve Capacity (BRC) theory, whether repeated concussions resulted in residual deficits in cognitive and academic functioning of early adolescent rugby players relative to non-contact sports controls.</p>

Indigenous forest resources are valuable to communities situated around them as they provide many different resources for their livelihoods. South Africa has only 0.5% of indigenous forest cover and most forests are surrounded by local communities who depend on them for resources. At Ongoye the forest was widely (91% of households) used for fuelwood. Community members denied harvesting the forest for either building or fencing poles, claiming they bought Eucalyptus poles from suppliers in the community. However, the harvesting intensities of pole size stems confirm that the user community does harvest timber from the forest. There is a high demand for fuelwood and pole-size stems are harvested not only for building but are cut and left to dry for later use as fuelwood. Although the harvesting intensity was greater than users were prepared to admit to, harvesting levels are thought to be sustainable. Local communities did not trade in products extracted from the forest. The use of resources was only for subsistence purposes, and therefore, forest resources were only valuable to users with respect to providing support to local livelihoods. Ensuring the protection and conservation of forest resources is critical for the survival of the user communities that are dependent upon them. Most local communities are not knowledgeable about managing forest resources adjacent to them, and the management of forest resources at Ongoye is currently in the hands of the state and also the influence of the Inkosi (local tribal chief). As part of the process of democratization post 1994, the government is devolving the management of natural resources to local communities. Several models of management institutions have been proposed and tested including community forest management (CFM), state forest management (SFM), and participatory forest management (PFM). Current trends are towards participatory management institutions. Using questionnaires, I determined that users preferred PFM over both SFM and CFM. However, the local community was in favour of more state involvement in the PFM than expected. Given a choice between CFM and SFM, the user community was more favourably disposed toward SFM. This was because they viewed CFM as vulnerable to resulting in open access to resources without any control. The devolution of powers to local communities can create problems in local governance. For most areas surrounding forest resources, traditional authorities are the important 'governing' leaders. In South Africa, events post 1994 have created tensions between democratically elected and hereditary governance institutions. On the one hand democratic institutions are supposed to be created at the local level, and on the other the constitution recognizes the existence of hereditary institutions. There is a power struggle over who the legitimate authority at the local level is between democratically elected councilors and chiefs. At Ongoye, the local chief was very powerful and had strong views on the ownership and control of Ongoye. He had a positive influence on maintaining current low to moderate levels of use of forest resources. However, because there are several dangers associated with concentrating power over management of natural resources in one individual, I recommend that a participatory natural resources management institution be developed that acknowledges the important role of the Inkosi, but also tempers his influence, so that continuity of management principles is maintained should traditional leadership changes hands. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.