3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The influence of hunting activity on African elephant (Loxodonta africana) movements(2015) Nobrega, Catherine Elizabeth PinhoAfrican elephants (Loxodonta africana) are still being poached and hunted and this could potentially affect their movement. As a keystone species, crucial to maintaining ecosystem function and therefore food webs, it is important to understand the effects hunting may have on their movements. This study was undertaken in the Associated Private Nature Reserves adjacent to the Kruger National Park, where elephants are hunted. I looked at changes in daily displacement distance and distance from hunting and natural mortality events to determine if elephants were affected by hunting events, up to what distance, and to determine whether elephants reacted in the same way to hunting and natural mortality events. I found that elephants are only affected by hunting events when within 1 km of the event, which is consistent with the literature. When considering natural mortality events, they actually diverted movements towards the event location, which is also consistent with literature. These results, however, are based on a very small sample size. In addition, the time of day of the events was not recorded by the wardens of the reserve, and this provided a further limitation for the data analysis and interpretation.Item Sexual segregation in African elephants, Loxodonta africana, in the Associated Private Nature Reserves, Limpopo, South Africa(2015-05-25) Chapman, TarrynThe African elephant, Loxodonta africana displays sexual segregation, a phenomenon which describes males and females of the same species living separately, except during the mating season. Despite it occurring in many sexually dimorphic species, the factors that govern sexual segregation are still poorly understood. The aim of my study was to investigate whether or not African elephants in the 1825 km2 Associated Private Nature Reserves (APNR), Limpopo Province were sexually segregated as a result of habitat segregation. I tested the Forage Selection Hypothesis (FSH) which, based on the Jarman-Bell principle, predicts that smaller females are more selective foragers as a result of their high energy demands and poor digestive capabilities in comparison to the larger males. Using the GPS location data of 18 collared adult elephants (12 male and 6 female) from November 2008 to November 2010, I plotted both the total (95% isopleth) and core (50% isopleth) home ranges of individual elephants. I used these home ranges to i) confirm sexual segregation in the APNR, ii) determine whether or not there was a difference in vegetation composition of the home ranges between males and females, and iii) to establish how frequently male and female elephants were associated with each of the vegetation types located within their home ranges. All analyses were done at both the total and core home range level. Home range overlaps were rare between male and female home ranges, particularly at the core home range level, confirming sexual segregation of elephants in the APNR. The vegetation composition data of the home ranges as well as the frequency of association by elephants with each of the available vegetation types (using GPS locations) revealed no significant difference between male and female elephants. Therefore, habitat segregation did not explain sexual segregation by elephants in the APNR. I propose that future studies should consider: i) temporal distribution of elephants to assess how much time each sex spends in each of the available vegetation types; ii) other resources, particularly the availability of water, in addition to the availability of forage, since water limits elephant movements; and iii) social segregation in conjunction with habitat segregation, since elephants display sex-specific differences in social organisation. A comprehensive understanding of the factors that govern sexual segregation of elephants might contribute to conservation management of elephants in the APNR and other small reserves.Item Habitat selection of African elephants (Loxodonta Africana) after reintroduction in Dinokeng Game Reserve(2014-07-31) De Hoog, JeanetteConservation has led to African elephants (Loxodonta africana) being reintroduced to small game reserves. However, only a few studies have been done on how elephants react to their new environment after a translocation. Dinokeng Game Reserve introduced a herd of 10 elephants (Loxodonta Africana) in October 2011. Using Global Positioning System collar locations of one female elephant, I aimed to determine whether an elephant’s exploration resulted in an expansion of its home range as the elephant settled in its new environment. Secondly, I aimed to determine how the use of resources and conditions in an elephant’s environment changed from release to the end of the study period. To achieve my first objective, I calculated the elephant’s daily distance movement distances and home ranges over 16-day and seasonal periods. I used logistic regression to assess the habitat selection of the elephant over the study period. The results of the research demonstrated that the elephant slowly explored its new environment, which resulted in an expansion of its home range over time. However, it took almost two years before the elephant displayed signs of settling in its home range. The elephant used habitats further away from buildings, closer to fence boundaries and water sources, with low elevation and high greenness at the start of the study. Over time, the elephant’s habitat selection was no longer constrained by buildings and it demonstrated stronger evidence of using habitats with lower elevation towards the end of the study period. The findings suggest that elephants do not necessarily explore extensively before finding an area to remain in, and it may take longer than a year for them to settle. Furthermore, human settlements seem to limit elephant’s habitat selection a translocation, but this influence decreases as the elephant settles in its new environment.Item Effects of enclosure on home range and resource selection: a comparison of two African elephant herds (Loxodonta Africana Africana)(2014-06-12) Leonard, ArmandEnclosed game reserves are at risk of local vegetation over-utilization and homogenization by elephant. Understanding how the elephant spatial distribution is coupled to their seasonal resources use can aid future management given the threat of climate change. A comparison of home ranges and core area sizes across seasons and years was made between an elephant herd outside in an open system, compared to the elephant inside Limpopo Lipadi Game and Wilderness Reserve (LLGWR). Location data, obtained by GPS-GSM technology, was used to determine seasonal home ranges and core areas by local convex hull (LoCoH) methods and to generate seasonal General Estimating Equations (GEE). Remote sensing data was used to determine habitat variables. The home ranges of the elephant herd outside as expected, was twice as large during summers and a third larger during winters than the elephant herd inside the fenced reserve. The influence of seasonal rainfall on home range size was reflected at home range scale for the outside herd and for the core area scale for the herd inside the reserve. Increased rainfall overcomes the ‗magnet effect‘ of artificial waterholes on elephant distribution in the landscape only in the open system. Inside the reserve, contrary to expectation the winter home ranges were non-significantly larger than summer home ranges due to space limitation induced by fencing and permanent artificial waterhole density. Resource use was evaluated by using GEE models at a scale larger than established home ranges and therefore would reflect as home range determinants. The study confirms that elephant do not use resources randomly. A scale in resource selection of elephant cows exists, with distance to drainage lines at small scale preferred during winter, with aspect, slope, elevation, and NDVI at larger scales. Fencing furthermore, affects the scale at which selection occurs by limiting resource availability, especially during resource restrictive periods and limits range expansion during resource abundant periods. Elephant cows prefer gentle terrain, close to permanent water [<1.77km (SD inside the reserve, and <2.33km ( outside the reserve], moderately high NDVI, riparian vegetation during late winter and early summer if available. Generally, during lower rainfall periods lower elevations are preferred along the elevation gradient, and during higher rainfall periods, higher elevations. The elephant herd outside the reserve, furthermore prefer aspects in the landscape during hot summers that are cooling and cool winter aspects that are warming to facilitate energy saving and thermoregulation. Key words: Elephant home range, core areas, fencing, seasonal, artificial waterholes, open system, NDVI, elevation gradient, distance to water, seasonal GEE modelling.Item Do anthropogenic and natural features act as barriers to African elephant (Loxodonta africana) space use?(2014-01-09) Robertson, KristyThe degree that different landscape features influence elephants use of space in the Kruger National Park and surrounding private game reserves (Balule, Timbavati, Klaserie and Umbabat) is not known. The aim of my study was to assess landscape features which influence elephant space use at two different spatial scales: at a large scale representing home range selection within the landscape and a small scale representing core area selection within the total home range. I investigated the space use of 15 male and 6 female adult elephants over a three year period (June2007-May 2010), using GPS data and satellite mapping analysis. The features selected for analysis as possible barriers to elephant space use were anthropogenic (fences, roads, railway lines and infrastructure) and natural features (rivers, geological features and vegetation). I also investigated the total and core home range size of elephants and whether elephant space use differed by sex and season. Males had larger total home ranges than females irrespective of season, but there were no size or seasonal differences of core home range size between the sexes. Elephants used features differently at the two spatial scales, differed in the use of features between seasons, and there was a difference between the sexes in the use of features. Fences, railways, rivers (in the wet season), geological features and vegetation types were the features that influenced elephant space use, and could be possible barriers at the large scale. Elephants occurred close to fences which possibly restricted their space use. Elephants also occurred close to railway lines but they might not have crossed the railway line. As expected elephants occurred less often at close distances to rivers in the wet season which could possibly be as a result of higher rainfall in this season, preventing elephants from crossing their usual riverbed corridors. Male and female elephants differed in the use of vegetation types found on particular geological features: males selected basalt and females selected granite areas for both the dry and wet seasons. Both male and female elephants were associated with a wider variety of vegetation types in the dry season, possibly because the limited food availability causes elephants to cover larger areas in search of food. Elephant space use was therefore governed by several features that may or may not restrict space use. My study, using satellite mapping analysis, can suggest what hinders movements of elephants and what is essential for assisting elephant space use, which could help conservation efforts for reserve design and corridor formation between reserves.Item A study of the subcortical anatomy of the brain of the African elephant (Loxodonta africana)(2013-08-06) Maseko, Busisiwe ConstanceAfrican elephants are one of the iconic mammalian species of the continent, and are the largest terrestrial mammals on the planet. While being a well-known species, with intensive behavioural studies having been undertaken, studies of the elephant brain are limited. Given that elephants do show a unique and interesting set of behaviours, including infrasonic communication, unique control of the trunk, and that they eat around 500 kg of low quality plant matter each day, the current study aimed to investigate the neural underpinnings of these and many other behaviours exhibited by elephants. While not all aspects of elephant neuroanatomy are covered in the current set of studies, the results have provided a great deal of data for regions of the brain that have not been examined for almost 50 years, and applied modern neuroanatomical methods to this task. This thesis outlines how to obtain elephant brains amenable to modern neuroanatomical study, demonstrates that the ventricles are of a size predictable for a mammal with a 5 kg brain, and that the cerebellum is relatively the largest mammalian cerebellum studied to date. A microscopic examination of the cerebellar cortex revealed that the elephants have a greater amount of a potentially more complexly organized cerebellar cortex. In addition, an architectonic study of the diencephalon and brainstem revealed that elephants, while having a mostly standard mammalian diencephalon and brainstem, do show unique features that correlate to control of specialized behaviours. In summary, the current study shows that the system for motor timing, infrasound production and reception, and the systems for satiety and wakefulness are specialized in the elephant, all of which correlate to the overt behaviours previously studied. In addition, the current studies indicate potential paths to follow for the study of behaviour in these species that will hopefully lead to a better understanding of these animals. There is still much to explore and learn about the elephant brain and it is hoped this thesis creates a platform that provides the impetus for many future studies