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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A landscape approach to elephant conservation in Mozambique

Ntumi, C.P. (Cornelio Pedro) 25 May 2012 (has links)
People and elephants share landscapes throughout Mozambique. Here elephant conservation management focuses on protected areas but fails to address the conflict that exists between elephants and people. In this thesis I develop a landscape approach to conflict mitigation that is designed to accommodate the needs of people and of elephants in human-dominated landscapes. Mozambique faces a dilemma: politically it is required to reduce poverty while at the same time adhere to international agreements and requirements to protect biodiversity with relatively scarce financial resources. Reactive mitigation of human-elephant conflict (HEC) at the site-specific scale have proven to be costly and with low efficacy. A shift from reactive to proactive HEC mitigation approaches at the county-wide scale (e.g. a district level, the administrative planning body) may provide opportunities to reconcile such apparent contrasting requirements in Mozambique. The elephant population of Mozambique is fragmented and remnant sub-populations are limited to clusters of protected areas in a matrix of human-dominated landscapes. A meta-population perspective may accommodate this spatial structuring and allow for a conservation plan that ensures population persistence and moderate impacts with other species in the landscape. I assessed HEC throughout human-dominated landscapes of Mozambique to examine some assumptions associated with the landscape approach advocated here. I used spatially explicit human activity data, landscape features and elephant distribution at the grid cell of 25 km2 and at the district scale to test the practicality of landscape approaches to elephant conservation and mitigating HEC in the human-dominated landscapes of Mozambique. I then tested whether human activities have significant impacts on elephant numbers and distribution across Mozambique. Furthermore I tested if the costs and benefits of sharing space with elephants influenced HEC. Thereafter, I explored at the grain scale of 25 km2 if the degree of overlap between them on the use of resources can be used to predict the likelihood of HEC across the landscape. Direct and indirect human activities explained trends and rates of elephant population changes in Mozambique. Because most rural households of Mozambique rely on subsistence farming by extracting or cropping from the land, primarily for their own purposes, living close to elephant refuge areas represented a potential risk to humans. However, conflict with elephants does not centre on food security, but on lifestyle being affected by the presence of elephants, which itself was a function of human density. Rodents and insects are the primary agents responsible for food loss during food storage. HEC was not a function of elephant density – a combination of human density, percent cultivated area and human population growth rate best explained HEC incidences. Although at human densities beyond 60 people/km2, elephants disappeared, at low levels of land transformation and low human densities people and elephants co-existed, which may induce higher incidences of HEC. Proximity to roads and suitable land for agriculture were the best predictors for HEC in the rural areas of Mozambique. These results imply spatially driven causes of HEC. These findings supported assumptions that conservation landscapes embedded in different land uses that accommodate ecological needs of people and elephants as well as the likelihood of severity of HEC can ensure elephant conservation without forcing people into poverty. While reactive HEC mitigation actions at site-specific scales are attractive for local communities, proactive measures at the landscape scale may be more effective in the rural context of the distributional range of elephants in Mozambique. HEC can be mitigated proactively through an effective land-use planning that involves zonation and implementation. To address this I extrapolated the relevant findings from resources selection functions models at the 25 km2 grain scale for study locations to a country-wide scale and proposed a model of a likelihood of HEC. The country-wide HEC model yielded high predictive power and confirmed protected areas as sites of high elephant dependability. These models indicate focal areas for short to medium term reactive HEC mitigation measures and local community programs at specific site level. This dissertation suggests that human and elephant co-existence is possible in Mozambique. The apparent increase of HEC is not a function of numbers of elephants but of improper land use planning. In this thesis I argue in favour of a landscape approach to mitigate conflict between elephants and people. This approach should be considered in all national plans that aim to reduce conflict and enhance conservation. / Thesis (PhD)--University of Pretoria, 2012. / Zoology and Entomology / unrestricted
32

Dispersal and dispersion of southern elephant seals at Marion Island

Hofmeyr, G.J. Greg (Gordon John Gregory) 09 February 2006 (has links)
This study focused on the dispersal and dispersion of southern elephant seals, Mirounga leonina, at Marion Island in relation to their natal site, and to their site of first reproduction. Movements from the natal site to terrestrial haulouts used for reproduction, and between successive reproductive sites, were defined as dispersal, while movements from the natal site to sites used for purposes other than reproduction, were defined as dispersion. Some 33000 records collected over 12 years, of haul outs at 54 different sites of 5700 tagged seals, formed the database analysed. Both male and female seals were found to use sites closer to their natal site than expected, for reproductive, moult and winter haulouts. However, breeding seals used sites closer to their site of first reproduction than their natal site, on subsequent reproductive haulouts. No difference was found between the mean distances dispersed to moult sites and to winter haulout sites, but distances of dispersal were significantly less than distances of dispersion. Female seals dispersed further than males to reproductive sites, but no difference between the sexes was apparent for moult and winter dispersion. While the number of male seals hauling out to reproduce was too small to assess the effects of various factors on the dispersal of males, a number of factors influenced the dispersion of male seals, and dispersion and dispersal of female seals. These included age, isolation of natal site, anthropogenic disturbance, natal harem size and natal harem pre-weaning mortality. A number of hypotheses are proposed to explain the reasons behind the results found, and the direction of future research concerning the movements of southern elephant seals and their choice of terrestrial environment is suggested. / Dissertation (MSc (Zoology))--University of Pretoria, 2006. / ab2013 / Zoology and Entomology / unrestricted
33

Megaherbivores in succulent thicket: resource use and implications

Landman, Marietjie January 2012 (has links)
This study aims to develop a predictive understanding of the resource use, impacts and interactions of elephant Loxodonta africana and black rhinoceros Diceros bicornis in the succulent thickets of the Eastern Cape, South Africa. While these megaherbivores typically dominate the biomass, elephant are more abundant, such that their impacts off-set that of all other herbivores. Consequently, this thesis has three main foci: first, developing a mechanistic understanding of the influences of elephant; second, developing predictive insights into elephant impacts on plant communities; finally, an understanding of the knockon-effects of the impacts for coexisting rhinoceros. Thus, by documenting the diet and dietary preferences of elephant, I firstly show that only about 18 percent of the species previously thought vulnerable to herbivory, occur in the diet. This refutes the generally held belief that elephant herbivory is the primary driver of decline among plants, and emphasizes the likely contribution of other mechanisms (e.g. trampling, knock-on-effects, etc.). Thus, the accurate prediction of the impacts caused by elephant requires an understanding of previously marginalized mechanisms. From here, I quantify >50 years of impacts on the thicket shrub community and test their spatial and temporal extent near water. I confirm the vulnerability of thicket to transformation (particularly near water) as the accumulated influences of elephant reduce community composition and structure, and predict that these impacts will eventually bring about landscape-level degradation and a significant loss of biodiversity. Importantly, results show an uneven distribution of effects between elements of this community: from community composition and structure, to the structure of individual canopy species and ecological functioning. While these findings confound our interpretation of the extent of the impacts, it demonstrates the importance of explicitly recognizing biodiversity and heterogeneity for the conservation management of elephant. Finally, I test the consequences of the impacts for coexisting rhinoceros. While I show that this causes rhinoceros to change their foraging strategies in the presence of elephant at high densities, I also show that elephant may facilitate access to food for rhinoceros at reduced densities. These findings indicate the importance of elephant in driving the structure and composition of the thicket shrub community and the consequences of this for coexisting large herbivores. Thus, developing a predictive understanding of the spatial and temporal variations of elephant impacts between elements of biodiversity and the mechanisms driving these changes are key to their management. This implies that the effective conservation management of elephant can only be achieved through the careful, scientific design of monitoring programmes.
34

The influence of genetic relatedness on sociality and demography of female African elephants

Munishi, Linus Kasian January 2011 (has links)
Many elephant populations across Africa were or are being devastated by poaching and habitat loss, making population and range size for the species important issues of conservation concern in elephant ranging areas, including Tarangire National Park (TNP). Poaching and/or overhunting are known to have direct effects on the demography of elephant populations. The current understanding of the indirect effects of poaching on the sociality and demography of elephant populations is relatively poor, both at the group and an individual level. In this thesis the importance of genetic relatedness (as influenced by poaching) on sociality and demography of the female elephants was studied, using a combination of genetic, observation of behaviour and two decades of demography data collected from the northern subpopulation of TNP. I investigated and characterized the relatedness categories within elephant groups. Using a conceptual model for group size analysis in aggregation economies, I hypothesized that elephant populations subject to social disruptions due to poaching would exhibit characteristics of the free entry model, whereas more stable, closed populations would better fit the group-controlled model. I present a rare quantitative analysis of genetic relatedness and group size patterns among groups of adult female elephants in two wild populations: one in Tarangire National Park (TNP), Tanzania, and another in Addo Elephant National Park (AENP), South Africa. I demonstrate that the group size in African elephant populations is governed by genetic relatedness, and that poaching/overhunting has a significant influence upon the apparent group formation and size in elephants. I then focused on the effect of relatedness on agonistic interactions between adult females. I hypothesized that individual-based aggressive interactions among adult female African elephants would vary according to degree of kinship, with closely related dyads showing less aggression towards each other in resource-limited environments, thereby leading to indirect fitness benefits for individuals. As predicted, females did not show agonistic interactions to their close kin most often, and the frequency and intensity of aggressive interactions was inversely related to the degree of relatedness of the interactants. The effect of group relatedness and structure on reproductive success of individual female African elephant in TNP was also investigated. Adult female reproductive success was significantly influenced by within- group relatedness and structure. Higher reproductive success (with higher frequency of calf production and survival and more female calves produced) were more evident in the closely related groups than groups with low relatedness, suggesting that females from genetically disrupted groups are less likely to be reproductive than those in closely related groups. The possibility of negative effects of poaching on the subsequent generation of poached adult females and the alternative of a positive demographic response through reduced density was assessed by analysing the demographic patterns of the first generation (F1) females of prime-aged adult female African elephants in TNP using within- group relatedness and size. I also compared vital rate (age of first birth and interbirth interval) responses of first generation (F1) cows from Tarangire (poached) elephants with other females from poached (Northern Luangwa National Park, Zambia) and unpoached (Amboseli National Park, Kenya and Addo Elephant National Park, South Africa) populations. Group relatedness had no significant effect on sex ratio of the F1 cows‟ calves. There was a significant difference between the mean age of first birth and interbirth interval of F1 cows from the two (poached, Tarangire and unpoached, Amboseli National Park) elephant populations, suggesting that elephant populations reduced by poaching to low levels show an increase vigour through release from density constraints. Based on these results, the broader implications of secondary effects of poaching on elephant populations are critically evaluated. Also the importance of understanding the consequences of these effects is highlighted in light of other elephant conservation and management approaches. This understanding is useful in making conservation and management decisions for elephants and other biodiversity.
35

A clinical assessment of the morphometrics of African elephant tusks

Steenkamp, Gerhardus 04 August 2008 (has links)
No abstract available. / Dissertation (MSc)--University of Pretoria, 2008. / Zoology and Entomology / unrestricted
36

Endocrine correlates of free-ranging African elephant (Loxodonta africana) treated with porcine zona pellucida vaccine

Bates, Melodie Joy 04 January 2011 (has links)
Due to overpopulation of African elephants in South Africa and the consequent threat to biodiversity, the need for a method of population control has become evident. The potential use of the porcine zona pellucida (pZP) vaccine as a safe and effective means for population control is explored. While potential effects of pZP treatment on social behaviour of African elephants have been investigated, no examination of the influence of pZP vaccination on the endocrine correlates in treated females has been undertaken. The ovarian activity of freeranging, pZP-treated African elephant females was monitored non-invasively for one year duration by measuring faecal progestagen concentrations via enzyme immunoassay. Behavioural observations were recorded for comparison with progestagen concentrations and to determine any behavioural changes surrounding the pZP vaccine darting event. Each elephant under study showed progestagen concentrations rising above baseline at some period during the study indicating luteal functionality. Average progestagen concentrations were 1.61 ± 0.46 ìg/g. Within sampled females, 42.9% exhibited oestrous cycles within the range reported for African elephants, 14.3% had irregular cycles, and 42.9% did not appear to be cycling. Average oestrous cycle duration was 14.72 ± 0.85 weeks. Behavioural oestrous coincided with the onset of the luteal phase and a subsequent rise in progestagen concentrations. Focal sampling to determine activity budgets before and after the darting event revealed no significant change in behavioural activities. In the week following immunization, individual progestagen concentrations decreased significantly from overall average concentrations. Average progestagen concentrations positively correlated with rainfall and with herd dominance. No association between average individual progestagen concentrations or cyclicity status with age, lactation, or parity were detected. Earlier determination of efficacy was made indicating reproductive control was established 22 months post-treatment. Results indicate the presence of ovarian activity amongst pZP-treated female African elephants in two years following initial immunization. Further study should be aimed toward studying the long term effects of pZP vaccination on the reproductive function of female African elephants. / Dissertation (MSc)--University of Pretoria, 2010. / Production Animal Studies / unrestricted
37

DNA fingerprinting analysis of captive Asian elephants, Elephas maximas

Bischof, Laura Louise 01 January 1990 (has links)
This thesis examined the effectiveness of DNA fingerprinting analysis for paternity ascertainment and the establishment of relatedness of captive Asian elephants (Elephas maximas). Eighteen Asian elephants from three North .American zoos were examined. Thirteen of these elephants were wild caught. Relationships between these elephants and the remaining elephants born in captivity were known.
38

Sex and age related distinctions in the feeding ecology of the African elephant

Greyling, Michelle Deborah 29 January 2010 (has links)
Thesis (Ph.D.), Faculty of Science, University of the Witwatersrand, 2004
39

Digital Infrared Thermal Imaging and its use in Domestic and Non-Domestic Species

Bowers, Susan Denise 15 December 2012 (has links)
Digital infrared thermal imaging (DITI) is a non-invasive diagnostic technique that is used to detect symmetry and asymmetry of surface temperature gradients. DITI can examine many different aspects of thermal physiology and diagnose injury and disease. The objectives of this study were (1) to investigate the use of DITI to determine whether differences in temperature gradients exist between late gestation and non-pregnant mares, (2) to evaluate whether velvet antler (VA) temperature gradients, as measured by DITI would pattern VA growth, and (3) to determine if “normal” temperature gradients of the foot exist among elephants as detected using DITI. To investigate these objectives, three experiments were conducted to determine the value of DITI for research on mammals. Results obtained from the first study indicate DITI was able to detect pregnancy in the horse during late gestation. In the second study DITI successfully patterned the growth and hardening of VA. While in the third study DITI demonstrated its value as a tool to increase overall welfare for captive elephants. In summary these studies suggests that DITI may have value in conducting research with domestic and non-domestic species that are not able to be restrained.
40

ANALYZING THE DISTRIBUTION OF THE AFRICAN ELEPHANT (LOXODONTA AFRICANA) IN TSAVO, KENYA

Mukeka, Joseph M. 20 July 2010 (has links)
No description available.

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