Dissertations / Theses on the topic 'African elephant populations'

This study presents an investigation into the population dynamics and social structure of a small, closed elephant population. Specifically, it examined population growth rates for evidence of density-dependent regulation. It also quantified the association patterns of female elephants groups, and male elephants groups. Social structure was examined using Hamilton’s kinship theories of inclusive fitness, and age. Male-female patterns of association were also examined for inbreeding avoidance behaviours. The study population was located in Addo Elephant National Park, South Africa. Density-dependence was assessed using a long-term data set. Densities were considerably higher than estimated carrying capacities. Population growth rate was positively correlated with increasing density. No relationship between birth rate, the age of first calving or calf sex ratio and elephant density was detected but there was a positive relationship between birth rate and rainfall during conception year. Mortality rates, particularly for juveniles, were low, and mean inter-calf interval was 3.3 years. There is no evidence of density dependent regulation in this population. These findings indicate that density dependence should not be considered as an option in the control of elephant numbers in this Park, or where elephant resources are not seasonally limited. Examination of association patterns of the adult female component revealed that associations were not random at the population, family or individual scale. This is the second study on African elephants to confirm previous behavioural studies that predicted that preferred associates were close maternal relatives. This supports many studies showing that social species preferentially associate with their kin. The adult males in this population were found to have a well differentiated society with non-random associations. Generally, males were found to have weak associations with most other males and strong associations with only a few males. This association pattern was found to be persistent over the time frame of the study, as indicated by the time lag analysis. Males returned to their natal family, even when maternally related females were in oestrus. Oestrous females directed positive behaviours towards musth males. It appears that behavioural inbreeding avoidance mechanisms in this small, closed population are inhibited: musth status seems to override inbreeding avoidance. General principles from this case study were interpreted in terms of their applicability to other small, closed populations.

Southern Africa contains 58% of the world’s savannah elephant population, yet 72% of their range occurs outside of protected areas. It is, therefore, important to develop management guidelines that satisfy the needs of both elephants and people while maintaining environmental heterogeneity and ecosystem processes. Managing elephants as a metapopulation may provide the solution. The goal of this thesis was then to use a habitat-based approach to identify landscape characteristics which could contribute to the functionality of a metapopulation for elephants. Using resource selection function models, I identified habitat suitability for elephants across southern Africa and used these models to evaluate whether current habitat configurations allow for the assumptions of connectivity and asynchronous population dynamics required by a metapopulation. I found that water, tree cover, slope, and human presence were important predictors of elephant habitat selection. Furthermore, functional responses in habitat selection were present across space and time for water and tree cover, showing the adaptability of this generalist species to resource heterogeneity. Using habitat selection along with circuit theory current flow maps, I then found a high likelihood of connectivity in the central portion of our study area (i.e. between the Chobe, Kafue, Luangwa, and Zambezi cluster). Main factors limiting connectivity were the high human density in the east and a lack of surface water in the west. These factors effectively isolate elephants in the Etosha cluster in Namibia and Niassa clusters in Mozambique from the central region. Models further identified two clusters where elephants might benefit from being managed as part of a conservation network, 1) northern Zambia and Malawi and 2) northern Mozambique. Incorporating information on elephant mortalities in northern Botswana into habitat selection estimations, I found that source habitats for elephants occurred within the central Okavango Delta region and sink habitats were associated with periphery of the study area where human use was highest. Eighty percent of elephant mortalities occurred within 25 km of people. The protected designation of an area had less influence on elephant mortality than did the locations of the area in relation to human development. To exacerbate human-elephant conflicts, people tended to settle in areas of high-quality elephant habitats, creating resource competition between elephants and people. Consequently, elephant mortality near humans increased as a function of habitat suitability, and elephants responded by using less suitable habitats. While humans occupied only 0.7% of the study area, mortality and behavioural effects impacted 43%. Based on the habitat factors examined here, elephants in southern Africa could be managed as a metapopulation if (1) connectivity is maintained and encouraged and (2) spatial heterogeneity in resources and risks serves to stabilize elephant demography. This habitat-based system of management could serve to alleviate unstable elephant populations in southern Africa and create more natural, self-sustaining regulatory mechanisms.
Thesis (PhD)--University of Pretoria, 2013.
Zoology and Entomology
unrestricted

African savannah elephants play a vital role in the Serengeti ecosystem with the opportunity to alter the entire ecosystem by its sheer number. Management of these animals are therefore of high importance, but little genetic research has been done thus far in the ecosystem. Their recent traumatic history of poaching serves as a template for intriguing evolutionary theories and further understanding of elephant behavior. In this study it was investigated on the genetic structure and spatial differentiation of the elephants in Serengeti using a mitochondrial DNA (mtDNA) marker. A widespread sample size of 55 elephants were collected in three zones of the Serengeti National Park (West, North and Seronera) and analyzed for genetic diversity. The results gave the impression of a slightly outbreeding population with no ongoing subdivision (FST = -0.04864, p = 0.92082). A total of 7 haplotypes were obtained with one clearly being dominant (78.2 %). All collected haplotypes were compared to earlier studies using the same mitochondrial marker and having a wider perspective, with samples ranging across the sub-Saharan Africa. Results show that there is a possibility that the elephants now inhabiting the Serengeti are primary descendants of Northern populations coming from Kenya and Uganda, with additional individuals giving the impression that the Serengeti elephants are a mixture of individuals with historical connections from all over sub-Saharan Africa.

Humans’ hunting for ivory has had a serious impact of the African elephant population. Ivory has throughout history been a symbol of manhood and status. As the market of ivory expanded to the rest of the world, the market demand for ivory became higher than what the elephants could manage to provide. In the 1980’s, the African elephant population was threatened by extension and it was reduced with 50 percent in ten years. For this reason, CITES placed the African elephant population under a ban, which made it an illegal act to trade ivory and other elephant parts.

The protection of biodiversity and of particular animal species and their habitats has become increasingly relevant at an international level. For this reason, several Conventions have been created over the years, each dealing with different issues to enhance animals, habitat and biodiversity protection. Unfortunately, although these instruments highlight the increasing awareness of the importance to enhance conservation and the efforts that the international community is taking to improve the protection of animals, habitats, and biodiversity, in many cases these tools do not afford adequate protection. The aim of my thesis is to study in depth animal and biodiversity protection in international law, taking into consideration four major biodiversity-related Conventions to foster conservation. In particular, I will deal with the Convention on Biological Diversity (CBD), the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Convention on the Conservation of Migratory Species of Wild Animals (CMS), and the Convention concerning the protection of the World Cultural and Natural Heritage (UNESCO Convention), discussing the limitations of this branch of international law to identify possible solutions. To do so, I will carry out an analysis of the current status of the African Elephant population as a case study in four African range states that have signed the above mentioned Conventions, which are Gabon, Democratic Republic of Congo, Tanzania and Zimbabwe. The management and protection of elephants is very complex because it involves various issues like poaching, habitat loss, human population growth which worsen human-elephant conflict, poverty, corruption, national development needs and lack of funding, all elements that make conservation very difficult, with subsequent countries difficulties in the Conventions application.

Thesis (M.F.A.)--Georgia Southern University, 2006.
"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science" ETD. Includes bibliographical references (p. 54-58) and appendices.

The common warthog (Phacochoerus africanus) has recently been recognised as an alien invasive species in the Eastern Cape and their population is increasing rapidly within the region. This then raises a concern as it is recorded that invasive species have negative impacts on both economic and ecological aspects of biodiversity in the receiving community. There are few studies that have documented the impacts of this species in the Eastern Cape. This study therefore seeks to determine the diet and population trends of this species in the Addo Elephant National Park (AENP) Main Camp and the results obtained can be correlated with previous studies and used to quantify the impacts of this species in the Eastern Cape. Warthogs are specialized grazers, it was therefore hypothesized that they will have potential impacts on grazing resources in the AENP Main Camp. The diet of common warthogs in the AENP Main Camp was determined through microhistological analysis of faecal material of samples collected seasonally. Population trends of common warthogs were determined in relation to the effects of predation on the population growth and population age structure of these animals within the AENP Main Camp. The results were compared with the findings for common warthog population growth and population age structure of Great Fish River Nature Reserve (GFRNR), a predator free population. It was hypothesized that the population growth rate of common warthogs in the AENP Main Camp before the introduction of lions and hyaenas in the AENP would not differ from the population growth rate of common warthogs in GFRNR. Secondly, the post-lion/hyaena common warthog population in the AENP Main Camp would differ from both the AENP Main Camp pre-lion/hyaena and GFRNR common warthog populations due to the presence of large predators in the AENP Main Camp. For population age structure it was hypothesized that the two populations, AENP Main Camp and GFRNR would differ because of predators increasing mortality. The diet of common warthogs was dominated by grass (87.4 percent), with Cynodon dactylon being the dominant grass species. Common warthogs in the AENP Main Camp should be properly managed because they have potential impact on grasses. The population growth of common warthogs in the AENP Main Camp showed no effect of predation, with population growth not differing from that of GFRNR. Predation had an effect on common warthog population age structure with AENP Main Camp and GFRNR populations differing, particularly in terms of adult structure. Thus, population growth of common warthogs in the AENP Main Camp is not determined by the presence of predators. These findings highlight the status of common warthog as an invasive species in the AENP Main Camp and potentially impacting on grass species and show little effects of top-down population regulation. These results show a need of monitoring common warthog population as well as their potential impacts in the area.

Les savanes soudano-sahéliennes d’Afrique occidentale témoignent du plus fort taux d'extinction de grands mammifères, résultant principalement de l’emprise croissante des activités anthropiques. Le Parc Régional du W (PRW - Bénin, Burkina Faso et Niger) abrite la dernière grande population d’éléphants de savane (Loxodonta africana), pour laquelle peu d’informations sont disponibles. Les objectifs de ce travail de thèse sont alors de (1) proposer un diagnostic global des caractéristiques de cette population (taille et composition des groupes) et (2) d’identifier les déterminants écologiques et anthropiques de sa distribution spatio-temporelle, en adoptant une approche combinant plusieurs échelles spatiales et temporelles, et en appliquant des protocoles complémentaires de suivis directs (aérien et pédestre) et indirects (relevés d’indices, radio télémétrie). La taille de groupe moyenne est estimée à 13. 44 (95% CI=3. 94) avec les données aériennes et à 5. 01 (95% CI=0. 94) d’après les observations réalisées au sol. La population d’éléphants du PRW comprend une proportion d’adultes légèrement plus élevée (c. 56%) que celle d’immatures. D’avril à juillet 2004, deux éléphants femelles ont été suivis par radio télémétrie. Les tailles de domaine vital sont estimées à 2 572 et 1 970 km². Des mouvements transfrontaliers depuis le Niger jusqu’à la partie centrale du Parc (Burkina Faso) via le Nord de la partie béninoise sont décelés au début de la saison des pluies. A l’échelle du Parc, la disponibilité en eau de surface, la présence d’activités humaines en périphérie et au sein de l’aire protégée (transhumance illégale) ainsi que la productivité primaire constituent les principales variables écogéographiques influençant la répartition spatiale et temporelle des pachydermes. Ces mêmes déterminants se révèlent également influents à une échelle plus fine, celle du site alimentaire. Ces résultats forment une première base de données pour le suivi ultérieur de cette dernière grande population d’éléphants de savane ouest africaine
West sudano-guinean savannahs show the highest extinction rate of large mammals, mainly caused by growing human pressure. The W Regional Park (WRP - Benin, Burkina Faso and Niger) shelters the largest remaining West African savannah elephant population, for which only few data are available. Then, objectives of this PhD work are: (1) proposing a global diagnosis of this population characteristics (group size and composition) and (2) identifying ecological and human factors of its spatio-temporal distribution at several spatial and temporal scales and with complementary protocols such as direct surveys (both aerial and pedestrian) and indirect monitoring (i. E. Radio tracking). The WRP elephant population mean group size was estimated at 13. 44 (95% CI=3. 94) with aerial surveys data and at 5. 01 (95% CI=0. 94) with ground surveys data. Adult class (c. 56%) in recorded groups was systematically more represented than young’s. From April to July 2004, two elephant females were radio-tracked. Home range sizes were estimated at 2572 sq. Km for one female and 1970 sq. Km for the other. Transfrontier movements from Niger to the central part of the park (Burkina Faso) through northern Benin were observed at the beginning of the rainy season. At the park scale, surface water availability, human activities, both around and within the protected area (i. E. Illegal pastoralism) as well as primary production are the main ecogeographical variables that influence the spatio-temporal distribution of elephants. Those factors are also important at a smaller scale, the feeding site. Results represent a first data base for further monitoring of this West African last large elephant population

By 2001, elephants had been translocated (mainly from Kruger National Park) to 58 small, fenced reserves in South Africa. All but two introductions took place since 1989. We document important aspects of the population dynamics of elephants in these reserves using data collected in a survey conducted in 2001. The mean population size was 45 elephants, with an average density of 0.25 elephants/km2. Populations have a female bias with 0.79 males to females. Populations have 19% adult males, and 31% adult females. On average, almost 50% of the population comprises adult and subadult females, indicating an immanent potential for large population growth. Births were not significantly different froma 1:1 sex ratio. When two extreme populations were removed, mean mortality rate was 0.4% per annum.Population growth rates averaged 8.3%,but five reserves had growth rates above 13%, and the highest annual growth rate was 16.5% per annum. Twenty-seven populations already have densities above 0.2 elephants/km2, and eight reserves have densities above 0.4 elephants/km2. Assuming a 12% per annum growth (feasible given the data presented), over half the reserves will have densities above 0.33 elephants/km2 within five years. These results indicate that the translocation of elephants has been successful, with most populations reproducing at a rate far exceeding expectations. This has serious implications for owners and managers, as some form of population control (contraception, removals, culling etc.) needs to be urgently planned for implementation as soon as possible in most, and probably all small reserves.

Earlier studies investigated the genetic structure of fragmented or isolated elephant populations by comparing the genetic characteristics of pre-defined populations. This study aimed to determine if there was genetic evidence for spatial structuring in a continuous elephant population in the Kavango-Zambezi Transfrontier Conservation Area (KAZA-TFCA). I sequenced one mtDNA gene region for 88 individuals and genotyped 100 individuals for 10 nuclear microsatellite loci. Bayesian Clustering Algorithms incorporated in the program Geneland were used to identify groups of genetically similar individuals. An Analysis of Molecular Variance (AMOVA) determined if these groups (henceforth referred to as subpopulations) were significantly differentiated. I used a Geographic Information System (GIS) landscape genetic toolbox to identify areas in the landscape with high genetic divergence between individual samples to determine if there were identifiable genetic barriers in the landscape. There were three significantly differentiated mtDNA sub-populations (Fst = 0.787), and two nDNA sub-populations that were not significantly differentiated (Fst = -0.02; Rst = -0.045), implying obstructed mtDNA, but high nDNA gene flow across the study region. Also, gene flow was apparent between Chobe and Kafue National Parks, where telemetry data has as of yet not recorded inter-population movements between these parks. The three mtDNA sub-populations were geographically differentiated and followed political boundaries as apparent sub-populations in Botswana, Zambia and Zimbabwe. The differences between mtDNA and nDNA genetic structuring may be explained by i) historical events that shaped the current genetic structure (e.g. through founder-effects and persistent poaching hotspots) and ii) intrinsic variables that influence genetic structure at a local scale (e.g. through resource dependencies and social behaviour). The KAZA elephant population has a genetic diversity (mtDNA diversity as the pairwise number of differences (π) = 2.59; nDNA diversity as the mean alleles/locus and He = 7.5, 0.71) higher than other southern African populations, and inter-population movements may be responsible for maintaining this genetic diversity. I recommend continued support for conservation initiatives that aim at maintaining and restoring connectivity between populations through landscape linkages, which in so doing may ensure inter-population gene flow and uphold the current genetic state of the KAZA-TFCA elephant population.
Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Zoology and Entomology
unrestricted

The conservation of leopards in the Eastern Cape Province requires a holistic approach that considers both predator-human interactions as well as the biology of the carnivore. Numerous studies have been conducted on leopards within protected areas; however more information regarding the species is needed outside these areas to facilitate effective management of predators. The spatial ecology of the leopard (Panthera pardus) were studied in the Baviaanskloof and GAENP in the Eastern Cape. The Baviaanskloof is an extensive area of mountainous terrain (approximately 2665km²) which has a mosaic of land uses, and leopards move from conservation areas to farmland where they come into contact and conflict with farmers. This study examined the spatial ecology of leopards living on farmlands adjacent to protected land. The space utilization and activity patterns of six leopards were analysed. These animals were caught and released on farmlands in the Baviaanskloof (n=4) or translocated (n=2) when not possible to release on site. The animals were caught by means of fall-door, walk-in traps and fitted with Vectronic GPS collars that facilitated the collection of high quality GPS fixes from each animal. Data was collected using VHF and UHF telemetry to download data. An understanding of spatial requirements in areas with different land use, and the extent of overlap of space use with other leopards allow, for the first time in the region, the calculation of possible maximum population size. Analysis of range size was carried out using two methods: minimum convex polygon, and Kernel Utilization Distribution. Finally, a key predictor of space use is prey availability. I assessed the prey base using a grid of camera traps. The studied leopards revealed large range utilization with minimal overlap. The activity patterns suggest there is no preference between diurnal and nocturnal activity patterns and the population density was estimated between 0.3 - 1.3 leopards per 100km². Large home range sizes and low population densities suggest that leopards require large areas of suitable habitat, and that conservation efforts need to be extended beyond protected areas to ensure the long-term viability of leopard populations in such areas.

Depuis le milieu des années 1980, les populations de grands herbivores ont diminué dans le Parc National de Hwange, au Zimbabwe. Cette thèse explore l'un des scénarios avancés pour expliquer de telles chutes, à savoir le rôle des éléphants puisque leur population a connu une forte croissance. Deux mécanismes ont été explorés : les conséquences des modifications de la végétation par les éléphants sur la sélection des habitats par les autres herbivores et la compétition par interférence pour l'accès à l'eau entre les éléphants et les autres herbivores. Certaines réponses comportementales à court terme ont été mises en évidence mais nos résultats ne suggèrent pas que celles-ci puissent se traduire en réponses démographiques à long terme. La présente étude exclut donc les hypothèses basées sur l'effet de la modification des milieux par les éléphants et sur l'interférence aux points d'eau entre les éléphants et les autres espèces pour expliquer le déclin des grands herbivores.

The elephant debate deals largely with population size, how elephant numbers change over time, how they may affect vegetation, and how their populations should be managed. Trends in elephant numbers frequently motivate management decisions, and past efforts to alleviate elephant impact aimed at controlling population size. However, methodological and statistical constraints may influence interpretation of trends and lead to incorrect management decisions. Furthermore, inferences about the response of elephant populations to specific management actions are seldom based on scientific evidence. In this thesis I assess the consequences of survey design and monitoring features on the interpretation and statistical reliability of population trends as well as the effect of population management on elephant densities and population growth rates. To do this, I collated information on elephant population estimates and past management actions across Africa. I used information from the northern Botswana elephant population to clarify temporal trends in elephant densities and numbers. Elephant numbers in northern Botswana increased from 1973 to 1993 while densities remained relatively stable. This difference in trends is due to an associated increase in survey area during the same time. In contrast, from 1996 to 2004 surveyed areas remained constant in size and neither elephant numbers, nor densities changed significantly during this time. This apparent stabilisation in numbers may have resulted from density-related elephant dispersal. This case study suggests that in open populations movements may complicate the interpretation of trends, and that differences in the rates of change in numbers and densities may have different management implications. The precision of population estimates, sample size, population size, and the magnitude of the annual rate of population change to be detected, affect power to identify trends. Two-thirds of the 156 time series that I assembled apparently were stable, and only 30 % of these had sufficient statistical power to detect population changes. These apparent stable trends without sufficient statistical power are inconclusive and should not be used to inform management decisions. Past elephant population management practices may have increased densities and growth rates in African elephant populations. Case studies of populations that were exposed to different management actions indicated that fencing of populations and water supplementation may have enhanced growth rates probably by influencing dispersal patterns. Thus, past management practices may have contributed to the ‘elephant problem’ by enhancing local elephant densities and population growth rates. In this thesis, I showed that trends based on elephant numbers may be misleading when the area over which elephants were counted, increased in size. Second, despite much effort and resources devoted to the monitoring of elephant populations for more than 50 years, population estimates and time series including such estimates had low quality, thereby reducing statistical power to detect trends in population change. Third, population growth rates were associated with management, where elephant population densities grew at faster rates when managed. Future conservation efforts should take into account the methodological and statistical constraints that may influence trend analyses of elephant populations and take cognizance of the fact that management decisions need to be evaluated against expected outcomes. Copyright
Dissertation (MSc)--University of Pretoria, 2009.
Zoology and Entomology
unrestricted

The successful conservation management of African elephants depends largely on understanding the fundamental processes driving the population regulation of this species. Southern Africa’s increasing populations have raised concern over the impact of high elephant densities on the system, in stark contrast against the elephant’s more precarious position in other parts of Africa. As we search for solutions from the processes of historical elephant regulation, we realise that there is a decided lack of empirical evidence to explicitly direct our efforts. In this PhD, I attempt to investigate the application of the classic pattern of large herbivore population limitation, which mainly involves high juvenile mortality in response to stochastic environmental events, to African elephant population dynamics. Firstly, I evaluated the magnitude and frequency of mortality events that would be required to prevent elephant population growth. The death of 85 % of infants and weaned calves would need to occur twice a generation, while a single severe mortality event (causing the death of all infants and weaned calves and 10 % of the rest of the population) once a generation would be sufficient. However, the severity of these events is not matched in natural occurrence in Africa today and only a single recorded event in Tsavo National Park, Kenya, in the 1970’s has come close when more than 7 000 died during a very severe drought. Secondly, I evaluated the potential role of fire as a stochastic, massmortality event limiting elephant populations. I found that fire functions in a similar manner to other environmental catastrophes and primarily causes high juvenile mortality. However, this catastrophic event also highlighted the extreme behavioural and physiological impacts experienced by the elephant population involved. The potential role of these types of events on long-term female fecundity needs further investigation. In isolation, this type of mortality event would need to occur with high frequency to prevent population growth. However, in combination with a decrease in female fecundity, these stochastic events may have a much greater impact on population demography than first thought. Thirdly, I investigated a potential mechanistic link between stochastic mortality events and juvenile susceptibility to resource limitation. Allometric relationships dictate that juveniles select a diet of higher quality than adult elephants. We found that this was achieved by weaned calf selection of higher quality plant parts, although use of plant types and plant species was similar to that of adult females, who they move across the landscape with. The strong sexual dimorphism exhibited by this species was reflected in adult male use of lower quality forage than adult females (or juveniles) in both dry and wet seasons. Diet quality scaled negatively with body size, but adult females consistently selected a higher quality diet than adult males, irrespective of body size. The nutritional and reproductive demands placed on an individual during different life-history stages therefore influence foraging strategies, together with nutrient requirements, e.g. phosphorus for pregnancy/lactation selected consistently by females when unrestricted in the wet season, protein for growth selected consistently by weaned calves. Competitive displacement of adult females to feed at higher levels in the canopy by calves also influenced feeding behaviour. Therefore intraspecific body size, nutritional requirements (in terms of nutrients and energy) and competition had a strong influence on foraging strategy employed by age-sex classes of elephants in response to seasonal environmental change. More selective juvenile foraging requirements means that juveniles are most susceptible to resource limitation, for example during stochastic environmental events such as droughts. In small, closed systems, juvenile mortality is likely to have a strong influence on elephant population regulation, with a slight, temporary decrease in female fecundity possibly acting in conjunction with juvenile mortality effects. Therefore, stochastic environmental events such as drought and fire may be the only natural incidence of population regulation to occur in these systems, where populations continue to grow exponentially and there is no evidence of density-dependence (as in the case of many small, fenced reserves in South Africa). In large, open, high-density systems in other parts of southern Africa, density dependence acts strongly on female fecundity and causes low levels of juvenile mortality in areas of local population aggregation. Therefore, in isolation, natural juvenile mortality is unlikely to regulate African elephant populations, but in conjunction with decreased female fecundity in response to density-dependent feedbacks and stochastic environmental events, population regulation may occur. The management of long-lived megaherbivore species with similar demographic drivers must include an appreciation of the complexity of population response to manipulation of mortality or fecundity effects. Small changes can potentially result in large shifts in population dynamics. Further insight into the mechanisms driving these processes will allow sound scientific support of megaherbivore management decisions to be made throughout Africa.
Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2008.

The savanna elephant is a flagship species for conservation in Maputaland, a biologically diverse centre of endemism. At present Maputaland’s elephants are fragmented into two sub-populations, those confined to the Tembe Elephant Park (TEP) and those roaming across the Maputo Elephant Reserve (MER) and along the Futi Corridor. Fragmentation may have affected the sub-populations by skewing age and sex ratios, decreasing survival, isolating the sub-populations, and restricting landscape selection. My evaluation of historical population estimates suggest that the size of the elephant populations has been under estimated both before and after the construction of an electrified fence that fragmented the population. The application of a series of mark-recapture models to sight-resight data collected in TEP resulted in a population estimate of 179 (95% CI=136-233). The Bowden’s estimator was the most suitable model under prevailing conditions. My results confirmed that small populations of elephants are difficult to census in closed habitats. Estimates derived from aerial counts significantly under-estimated minimum population size determined from a registration count.Estimates derived from mark-recapture models approach or exceed those from registration counts. Both population fragments are increasing in numbers: TEP’s at 4.6% per year, MEP’s at 3.1% per year. Demographic variables are significantly different, age at first calving is 11.5 years and 9.9 years, and calving interval is 4.2 years and 2.2 years for TEP and MER respectively. Age distribution was similar for females but not for males, as TEP showed a bias for adult males. At the population level bulls in TEP favoured sand forests while breeding herds preferred reedbeds, but these preferences did not prove to be statistically significant. Individual bulls appeared to select for closed woodland landscape type but no statistical significance could be determined. My study highlights the inconsistencies inherent in using historical data to determine population trends. Caution must be used when management decisions are based on such estimates. Sight-resight models are suitable for the enumeration of elephant populations. My results do not support landscape selection in elephants. The differences between population variables for the sub-populations are probably due to age and sex ratios imposed when the population was fragmented and the different levels of protection afforded to the sub-populations.
Thesis (PhD (Zoology))--University of Pretoria, 2007.
Zoology and Entomology
unrestricted

Elephant management traditionally centers on reducing ecological impact and human-elephant conflict by controlling numbers. However, such an approach only deals with symptoms, and ignores the causes of the problem. Planning for cases when a species is a nuisance in some areas, but threatened in others, could benefit from the application of metapopulation theory. The theory offers a framework that is elegant, and have ecological as well as political appeal. Applying classic metapopulation theory to long-lived species that are widely distributed in stochastic environments where they can resist extinctions is problematic. However, empirical evidence for metapopulation structure may exist when applying more lenient criteria. I examined the literature for empirical support of classic criteria set by Hanski (1999) and for a more lenient sub-set of criteria proposed by Elmhagen&Angerbjörn (2001) for specifically mammals. I propose that for small mammals (≤5kg) the full complement of classic criteria must be applied to yield perspectives on population regulation and conservation. However, for large (>100kg) and medium sized (>5≤100kg) mammals only habitat discreteness, potential of demographic asynchrony and the likelihood of dispersal among sub-populations must be evaluated. Metapopulation theory could then be useful when constructing conservation plans that ensure the persistence of a species and contribute to forces that stabilize populations regionally. I evaluated the applicability of metapopulation theory to southern Africa’s elephant sub-populations. I identified 51 discrete administrative sub-populations that occurred in six conservation clusters. Population growth rates varied across space and time within and among conservation clusters. Some sub-populations and conservation clusters increased or decreased while others remained stable. Therefore, elephant populations in southern Africa were in demographic asynchrony, both on a local and regional scale. I also suggest that dispersal may occur among sub-populations within clusters. Consequently, the regional population is stabilized by emigration to, or immigration from neighboring sub-populations as a result of demographic asynchrony across an ecological gradient. Elephant populations across southern Africa thus adhered to one and could possibly adhere to all metapopulation criteria. Observed changes in elephant numbers could also be the result of survey error. To gain an understanding of how survey error could affect estimates, I used dung counts and measurements to estimate population size and construct an age structure for the elephants living in the Maputo Elephant Reserve in Mozambique. I suggest that dung surveys can yield population estimates with known precision and can be used in monitoring programmes aimed at assessing population trends - despite the fact that it can be affected by observer bias. In this thesis I show that metapopulation theory provides the opportunity of applying a spatio-temporal approach to elephant conservation that is not obsessed with numbers. When implementing metapopulation theory, management no longer have to centre on elephants, but can focus on the landscape as a spatially and temporally dynamic area. Local fluctuations in elephant numbers could be construed within a regional context, rather than implementing management strategies on a local scale. Such an approach will focus on the causes rather than the symptoms of the elephant problem and may contribute to the persistence of elephants as well as other components of southern African biodiversity. AFRIKAANS : Die ekologiese impak van olifante en konflik tussen mense en olifante word tradisioneel hanteer deur olifant getalle te beheer. Ongelukkig los so ʼn benadering net die simptome en nie die oorsaak van die problem op nie. Gevalle waar ʼn spesie ʼn problem is in sommige areas maar bedreig is in ander, kan baat vind by die toepasing van die metabevolkings teorie. Die teorie bied ʼn elegante raamwerk wat op ekologiese en politieke gebiede aanklank vind. Die toepasing van die klassieke metabevolkings teorie op lang lewende spesies wat wyd versprei voorkom in stochastiese omgewings waar hulle weerstand kan bied teen uitsterwings skep egter probleme. Emperiese bewyse vir ʼn metabevolkings struktuur kan egter voorkom waneer meer gematigde kriteria ondersoek word. Ek het die literatuur ondersoek vir emperiese ondersteuning vir die klassieke kriteria wat Hanski (1999) voorgestel het, asook vir ʼn meer gematigte sub-groep van kriteria wat deur Elmhagen&Angerbjörn (2001) vir spesifiek soogdiere voorgestel is. Ek stel voor dat die klassieke kriteria aangewend kan word om bevolkings van klein soogdiere (5≤kg) te reguleer, beter te kan verstaan en dan te bewaar. Vir groot (>100kg) en medium groot (>5≤100kg) soogdiere kan die metabevolkings teorie net gebruik word as die bestaan van aparte habitate, demografiese asinkronie en die potensiaal van verstrooing tussen tussen subbevolkings bewys kan word. Die metabevolkings toerie kan dan gebruik word om bewarings inisiatiewe in te stel wat spesies in staat sal stel om voort te bestaan en oor die streek te stabiliseer. Ek het die toepasbaarheid van die metabevolkings teorie vir suidelike Afrika se olifant sub-bevolkings ondersoek. Ek het 51 aparte administratiewe sub-bevolkings geidentifiseer wat in ses ‘bewaringsklosse’ voorkom. Bevolkings groeitempos het binne in en tussen bewaringsklosse gewissel. Sommige het of toegeneem of afgeneem terwyl ander stabiel gebly het. Olifant sub-bevolkings in Suider Afrika was dus in demografiese asinkronie, op ʼn lokale sowel as op ʼn streeks vlak. Ek het ook voorgestel dat verstrooing kan voorkom tussen sub-bevolkings binne in bewarings klosse. Die olifant bevolking van die streek word dus deur emigrasie na, of immigrasie van naburige sub-bevolkings as gevolg van demografiese asinkronie oor ʼn ekologiese gradient gestabiliseer. Olifant bevolkings in Suider Afrika het dus voldoen aan een, en kan potensieel voldoen aan alle metabevolkings kriteria. Opmerklike veranderinge in olifant getalle kan ook wees as gevolg van foute wat tydens tellings gemaak word. Om beter te verstaan hoe sulke foute bevolking skattings affekteer, het ek olifant mis tellings en metings gebruik om ʼn bevolking skatting en ouderdomsstruktuur vir olifante in die Maputo Olifant Reservaat in Mosambiek saam te stel. Ek stel voor dat mis opnames bevolking skattings kan lewer wat bekende presiesie het en dat dit gebruik kan word in moniterings programme wat neigings in olifiant bevolkings ondersoek - alhoewel sulke skattings beinvloed kan word deur die vooroordeel van waarnemers. In hierdie tesis toon ek aan dat die metabevolkings teorie ʼn geleentheid skep vir ʼn ruimtelike-tydelike benadering in olifant bewaring wat nie net op getalle fokus nie. Wanneer die metabevolkings teorie toegepas word, kan bestuur op die landskap as ʼn ruimtelike en tydsgebonde dinamiese area fokus, in plaas van net op olifant getalle. Lokale wisselings in olifant getalle kan binne in ʼn streek konteks geinterpreteer word, eerder as om bestuurs inisiatiewe net op ʼn lokale vlak in te stel. So ʼn benadering sal fokus op die oorsprong in plaas van die simptome van die olifant problem en mag bydra tot die voorbestaan van nie net olifante nie, maar ook tot die biologiese diversiteit van Suider Afrika. Copyright
Dissertation (MSc)--University of Pretoria, 2010.
Zoology and Entomology
unrestricted

Tese de mestrado em Biologia Evolutiva e do Desenvolvimento, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2017
O elefante da savana africano (Loxodonta africana) é uma espécie altamente social, na qual é observável a separação de machos e fêmeas quando os indivíduos atingem a maturidade sexual. O número de elefantes desta espécie está a diminuir por todo o continente africano, devido à ocorrência histórica e actual de abate de indivíduos para controlo populacional em zonas de maior densidade de elefantes e de caça ilegal, bem como graças à crescente fragmentação do habitat e ocupação humana. Isto potencia o decréscimo da variabilidade genética, que, por sua vez, pode ter impactos negativos na sobrevivência das populações. De facto, aumenta a probabilidade de ocorrer um bottleneck genético, depressão de consanguinidade, e uma diminuição do tamanho populacional efectivo. Este problema pode ser exacerbado quando se tem em conta a presença de barreiras físicas e de populações humanas que impedem a migração de animais e, consequentemente, o fluxo genético. O isolamento populacional aumenta os efeitos da deriva genética e promove a diferenciação genética entre populações. Adicionalmente, os elefantes mais velhos são o principal alvo de caçadores furtivos por apresentarem maiores presas. Estes indivíduos não só têm posições mais centrais em redes sociais, como actuam como um repositório de conhecimento, tanto social como ecológico, para os elefantes mais novos. Remover estes indivíduos pode levar a alterações comportamentais duradouras, que podem mesmo conduzir à redução do fitness reprodutivo. Devido à importância da sociabilidade nesta espécie e do impacto que poderá ter sobre a sua sobrevivência, urge compreender como a semelhança genética e o comportamento estarão associados nos elefantes. É necessário, em particular, estudar este parâmetro entre machos. Estes não só são caçados com maior frequência devido ao tamanho das suas presas, como apresentam comportamentos conflituosos para com humanos. Além disto, enquanto os grupos de fêmeas estão altamente estudados a nível social e genético, ainda pouco se conhece sobre os laços sociais entre machos. Os grupos de fêmeas são matriarcais, formados por até vinte adultos aparentados e as suas crias. Os machos, ao atingirem a adolescência, dispersam do grupo natal. Os elefantes macho são geralmente solitários, pelo que a constituição de tais grupos é altamente variável em termos do número de indivíduos, da sua coesão, duração e composição. No entanto, não existem estudos que explicitem com alto grau de certeza o que determina a sua formação e manutenção, nem existem descrições completas das associações entre machos. Também não é sabido se estas associações têm impacto sobre a sobreposição de áreas vitais. De facto, apesar de os machos não serem territoriais, tendem a evitar outros machos durante a época de cio. É possível que demonstrem diferentes níveis de tolerância a outros machos dependendo da relação social entre eles estabelecida. Caso o parentesco genético seja um factor pertinente para a formação destas relações, espera-se que traga tais benefícios aos mesmos, como a diminuição da agressividade entre machos e um aumento de sucesso reprodutivo. Neste estudo, temos como objectivo primário estudar a genética populacional de uma população de elefantes da savana na África do Sul, mais especificamente nas Associated Private Nature Reserves (APNR), um conjunto de áreas privadas adjacentes ao Parque Nacional Kruger (PNK), na África do Sul, e ao Parque Nacional do Limpopo, em Moçambique. Até à década de 1990, as APNR encontravam-se cercadas, não havendo migração de indivíduos para dentro ou fora da região. Como tal, e tendo em conta a longa longevidade dos elefantes, é possível que ainda sejam visíveis os efeitos deste isolamento a nível genético. Por outro lado, observações efectuadas no campo indicam que se tem dado um aumento populacional. Porém, ainda não foi feita uma análise genética que permita compreender se o aumento populacional está a ser acompanhado por um incremento de diversidade genética. Caso este seja o caso e não seja detectada elevada consanguinidade ou um bottleneck genético, a população da APNR poderá ser ideal para futuros estudos relativos ao impacto do parentesco genético na formação e manutenção de associações sociais entre machos, visto não ser esperado um grande impacto da caça furtiva na população. Logo, é expectável que as associações e comportamentos demonstrados sejam representativos de grupos sociais não perturbados. Para realizar este estudo, foram genotipadas amostras fecais não invasivas de 80 fêmeas e 168 machos da APNR, dos quais 68 são juvenis e 180 são adultos, com um painel de 18 marcadores de microssatélites autossómicos, suplementados por três marcadores de microssatélites para confirmação da identificação sexual. Comparámos ainda os resultados obtidos com 46 elefantes do PNK. Analisámos o nível de diversidade genética e estimámos o tamanho populacional efectivo (Ne = 394.4). Não encontrámos evidências para a existência de um bottleneck genético ou de consanguinidade. Também não foi observável estrutura genética, quer entre os elefantes das APNR e PNK, quer dentro de cada população, para ambos os sexos. O nível de diferenciação genética entre a APNR e o PNK foi igualmente baixo (Fst = 0.0038). Calculámos ainda o nível de parentesco entre os machos e criámos uma rede genética. De seguida, mapeámos esta rede sobre índices preliminares de associação entre 16 machos, não tendo sido obtida uma correlação entre associação social e parentesco genético. No entanto, obtivemos uma correlação entre a proximidade de amostras e parentesco genético, sendo que, a distâncias inferiores a 500 metros, os animais eram mais aparentados geneticamente do que o esperado. Tal demonstra que indivíduos aparentados apresentam pelo menos sobreposição parcial de áreas vitais. Note-se que a componente social deste trabalho carece de uma maior quantidade de observações e de um maior número de machos observados de modo a permitir tirar ilações robustas dos resultados obtidos. Esperamos, assim, obter mais dados sociais no futuro. Os resultados obtidos indicam que esta população apresenta uma boa saúde ao nível da diversidade genética. No entanto, estes resultados poderão advir em parte da existência de migração entre regiões, que poderá introduzir novos alelos na população, e consequentemente encobrir a assinatura genética do isolamento populacional histórico, bem como aumentar o nível de variabilidade genética e o tamanho populacional efectivo. Igualmente, a migração poderá ter sido suficiente para diminuir o nível de diferenciação genética entre os elefantes amostrados nas APNR e no PNK. Como tal, é importante que a população continue a ser protegida, de modo a que a caça furtiva no sul de África não leve à redução da variabilidade genética e à disrupção de grupos sociais. A conservação desta população torna-se ainda mais importante quando se tem em conta o acentuado decréscimo populacional da espécie ao nível do continente africano. Este estudo piloto caracteriza geneticamente uma população de elefantes sul-africana que demonstra a importância do fluxo genético para manter a diversidade genética e mitigar os efeitos nocivos da caça furtiva e do abate de animais. Como tal, a manutenção de conectividade entre parques nacionais e reservas naturais é vital para garantir a migração de elefantes entre populações. Este estudo é ainda um primeiro passo para uma caracterização pormenorizada do modo como o parentesco genético pode explicar tais comportamentos de machos como a escolha de indivíduos com quem se associar e padrões de dispersão.
The African savannah elephant (Loxodonta africana) is a highly social species that builds fission-fusion societies, characterized by sex-biased dispersal and complex hierarchies. Elephant numbers have been decreasing throughout Africa due to historic culling and current poaching, as well as habitat fragmentation. This potentiates a decrease of genetic diversity, which can have negative impacts in the population. Moreover, older individuals, which act as repositories of knowledge for younger elephants, are often targeted by hunters. The removal of kin and social associates can lead to lasting behavioral changes, by diminishing strong bonds and reducing reproductive output. We studied a South African savannah elephant population in the Greater Kruger region on the border of Mozambique to determine the genetic and relationship ties that bind individuals, and compared our results to 46 Kruger Park elephants. Our sampled elephants include 80 females and 168 males, of which 68 are juveniles and 180 are adults. We assessed the level of genetic diversity, and found no evidence of a genetic bottleneck, inbreeding or of genetic structure either within or between populations or for each sex. We also estimated the effective population size. We analyzed the pairwise genetic relatedness between males in the study sample to create a genetic network, which we mapped against preliminary association data obtained from field observations of sixteen individually identified bulls. Genetic relatedness and associations were not correlated for these individuals. However, we found evidence that related bulls have at least partially overlapping home ranges. Overall, our results indicate a good genetic health for this population, conducive for the observation of male behaviors of an undisrupted population. This pilot study offers a first genetic characterization of a South African elephant population, and is a stepping stone towards a thorough characterization of how genetic relatedness can explain such behaviors as males’ dispersal and choice of associates.

The continual increase in elephant numbers across southern Africa raises concern, though the interventions to manage these populations are more contentious. Within small, enclosed reserves active management is necessary to limit elephant impact. Various management tools exist with which to control fluctuations in elephant population numbers or density and simulate natural large stochastic events to control population growth. During this study, undertaken in the Munyawana Conservancy, KwaZulu-Natal, and Pilanesberg National Park, North West Province, South Africa, several management options were implemented. In order to lower the population numbers, family groups were translocated from the Munyawana Conservancy to other reserves, while to reduce population growth rate an immunocontraception was implemented. Both conservation areas introduced older bulls to normalise the bull population age structure, and expanded the conservation area by inclusion of new land to reduce population density. The influence of these management interventions on the elephant population were measured by their social, behavioural, spatial and movement responses. The older bull introduction was successful as bulls set up exclusive bull areas. There was a quick, subtle affect on the bull groups' size immediately after the older bull introduction, while there was no immediate change within the resident bulls' musth behaviour or duration. During area expansion, elephants appeared to perceive the new unexplored area as a threat although this threat became reduced through time as they became more familiar with it. The spatial scale of response was relatively small, while the temporal scale of response was relatively large. Rotational immunocontraception was shown to be a successful tool to alter herd structure by aging the population and maintaining a low population growth rate. The process of immunocontraception darting had no significant effect on herd associations and movement rates, accordingly the duration of the disruption effects were short lived. During multi-management interventions, no differences were found within the elephant social grouping. Management interventions may pose unforeseen social risks and different populations may respond differently to management induced stress. Therefore, interventions need to be considered for each elephant population which will achieve the conservation area's objectives with the most effective outcome, but with lowest holistic impact.
Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2017.
With an increase in opportunistically-collected data, statistical methods that can accommodate unstructured designs are increasingly useful. Spatial capturerecapture (SCR) has such potential, but its applicability for species that are strongly gregarious is uncertain. It assumes that average animal locations are spatially random and independent, which is violated for gregarious species. I used a data set for African elephants (Loxodonta africana) and data simulation to assess bias and precision of SCR population density estimates given violations in location independence. I found that estimates were negatively biased and likely too precise if non-independence was ignored. Encounter heterogeneity models produced more realistic precision but density estimates were positively biased. Lowest bias was achieved by estimating density of groups, group size, and then multiplying to estimate overall population density. Such findings have important implications for the reliability of population density estimates where data are collected by unstructured means.
LG2017

The Central Limpopo River Valley elephant population is a cross border population on which very little scientific data pertaining to numbers, distribution and demographic status is available. The total range was determined using published literature, reports, postal questionnaires and interviews. Numbers and dry season distribution were determined by means of three total aerial counts in 2000, 2001 and 2004 of the sections of the total range in which elephants were reported. Totals of 1388, 1424 and 1339 were recorded with the highest numbers in all counts in the Botswana section of the study area. Four sub groups within the population were identified. Human settlements and the distribution of rivers and fencing appeared to be the major factors influencing distribution and movement. The population is highly mobile within the total range, and numbers fluctuate markedly in any given section, but numbers in the total range appear to have been increasing slowly at below 2% per annum and the range expanding slightly over the last 30 years. Additional range is being provided by the creation of a Trans Frontier Conservation Area. Movements were determined through ground observations within the study area and seem to follow the major rivers namely the Shashe, Ramokgwabane, Simukwe, Shashani, Tuli, Umzingwane and Limpopo rivers. The social and demographic status of the population was determined through ground observations as well as total aerial counts conducted within the Northern Tuli Game Reserve from 1976 to 2004. The study has shown that group sizes increase with an increase in rainfall (average mean group size of 56.524, SDE 77.388) and decrease during low rainfall periods (mean group size of 24.157, SDE 22.223). The age structure was determined from aerial photographs during August 2000 and showed a high percentage of adults and sub adults, with infants estimated at 3%. The approximate birth rate (1.5%) calculated for 2000 is balanced by an average natural mortality determined between 1999 and 2004 of 1.8%. The inter calf interval determined from known herds observed in the Northern Tuli Game Reserve was estimated at 3.94% and suggests that the long-term birth rate for the population should be higher than that for the year 2000. The difference between the combined natural and human induced mortality rates (~4%) and the birth rate suggested by the age structure and the inter calf interval (~6%) gives the ~2% long-term increase observed in the numbers. Human elephant interactions within the study area were determined through published literature and interviews with local residents. Elephants and humans interact in both a positive and negative manor and interactions are related to human land use practices within the area. Elephants were indicated as the major problem animal in farming areas, but the major draw card within tourism operations.
Dissertation (MSc (Wildlife Management))--University of Pretoria, 2008.
Animal and Wildlife Sciences
unrestricted

Thesis (M.Tech.: Information Technology)-Durban Institute of Technology, 2005 iii, iii, 85 leaves
Throughout Africa, growing human populations and resulting loss of wildlife habitat is a critical issue for most animal species. It is more and more common for privately owned small or medium sized farms to reintroduce wildlife on their land and such protected areas are fast becoming the only refuges available to wild animals. However a comprehensive understanding of the complex ecological processes taking place is vital for the effective management of restricted areas and the conservation of biodiversity. Due to the enormous complexity of an ecological system and the long periods of the related dynamics, it is very difficult to analyse the interaction between animals and plant populations without suitable computer models. In this thesis, the dynamics between elephant and trees (a major food source) are considered using computer simulations.

The present study compared Sand Forest bird assemblages found in a communal land area with that of the Tembe Elephant Park, and determined the habitat preference and status of selected herbivore species within the park. The study forms part of the Maputaland Conservation-based and Integrated Rural Development Programme of the Centre for Wildlife Management from the University of Pretoria and is linked to the activities of the Lubombo Transfrontier Conservation Area (LTFCA). The main purpose of the study was to compare Sand Forest bird assemblages found in the Tshanini Community Conservation Area, which is characterised by low levels of human utilisation, with that of the Tembe Elephant Park, which is characterised by wildlife utilisation. This approach was used to determine the biological importance of this communal land area in contributing towards the conservation of the rare Sand Forest habitat. Visual and auditory bird surveys revealed that the communal land area contains unique Sand Forest bird assemblages, which demonstrated the biological importance of the communal land for Sand Forest conservation, especially from an avian perspective. The second purpose of the study was to identify possible competition between selected herbivore species within the Tembe Elephant Park and/or a decrease in numbers of rare species. Herbivores that might be adversely affected by the destruction of the Sand Forest, or who may themselves have a destructive effect on the Sand Forest were also identified. Target herbivores included the nyala Tragelaphus angasii, impala Aepyceros melampus, Burchell’s zebra Equus burchellii, greater kudu Tragelaphus strepsiceros, red duiker Cephalophus natalensis and suni Neotragus moschatus. Road transects were used to record the spatial distribution of the target herbivores, and the vegetation types that were used more or less often than expected were subsequently determined. None of the target herbivores showed a preference for the Sand Forest or appeared to have a destructive effect on the Sand Forest. The suni, however, reached its highest density within the Sand Forest and the destruction of this habitat will therefore negatively affect the suni population. In several parks and reserves that aim to conserve a variety of species, it has been necessary to control the populations of highly competitive species. Both the nyala and the impala are highly competitive and occur in relatively high numbers within the Tembe Elephant Park, and consequently their population numbers should be kept sufficiently low in order not to have a negative influence on the vegetation or the survival of less competitive ungulates. Total aerial counts and transect distance sampling counts indicated an increase in the numbers of all the target herbivores. It is important to protect a viable portion of the preferred habitat of every target species within a reserve, and to keep competition with rare species to a minimum for the long-term survival of the regional biodiversity. Key aspects of wildlife and their habitat should be monitored so that trends are noted in time, and management adjustments can be made accordingly.
Dissertation (MSc (Wildlife Management))--University of Pretoria, 2007.
Centre for Wildlife Management
unrestricted

Balancing increasing elephant numbers with biodiversity conservation in small reserves has become a concern for many protected area managers. Elephants are considered important agents of disturbance creating heterogeneity and thus contributing to the maintenance of biodiversity. However elephants also damage vegetation through their destructive feeding habits, and this has led to pressure to reduce elephant populations in many reserves. Quantitative data on the impact of elephants on invertebrates, the main component of biodiversity at the species level, are lacking. The aim of this project was to assess the effect that habitat alteration by elephants has on the diversity of selected ground-dwelling invertebrates (ants, centipedes, millipedes, spiders, scorpions and termites) through the provision of logs and dung as a potential refuge niche for these invertebrate communities, and to determine the effect of spatial (vegetation types) and temporal (season and age of dung) variation on the invertebrates using these refugia. Variation in impacts was considered important because savanna is not homogenous and the impact of the refugia is likely to be dynamic in terms of seasonal trends in invertebrate populations, and in terms of changes in the environmental conditions offered by the refugia. Elephant impact on vegetation, quantity of refugia (logs and dung) produced and invertebrate diversity associated with refugia were determined for 115 transects within Madikwe Game Reserve in the North Western Province, South Africa. Invertebrate abundance, species richness and diversity were always higher under refugia than in areas without refugia. Vegetation utilisation, frequency of refugia production and invertebrate diversity showed strong temporal variation (seasonal); elephant impact and production of logs were higher in winter than in summer because elephants are more likely to feed on woody vegetation in winter when grass nutrient levels are low. Invertebrate diversity under the logs was higher in summer than in winter, and this probably reflected the higher abundance and diversity of invertebrates that are usually associated with the warmer, wetter summer months. The effect of adding refugia to three vegetation types on invertebrate diversity was tested experimentally at Makalali Private Game Reserve in the Limpopo Province, South Africa. Logs and elephant dung were set out in five plots each measuring 20m x 20m within Govender - iii mixed bushveld, riverine and mopane woodland. Significant differences were observed in invertebrate abundance, species richness and diversity between the refugia and control plots that lacked refugia and between the three vegetation types sampled. Similarity between invertebrate communities utilising the different refugia types and between the three different vegetation types were tested using the Jaccard similarity coefficient. The three vegetation types shared fewer than 50% of their species, as did the logs, dung and control sites. However the results obtained do illustrate a higher degree of similarity between the refugia substrates (logs and dung) than the control sites and between the more heterogeneous vegetation types (mixed bushveld and riverine) than the mopane veld. This indicated that invertebrate communities associated with refugia were not uniform, but were influenced by vegetation type. An experimental test of temporal changes in invertebrate community composition illustrated the importance of elephant dung as a microhabitat for different invertebrate groups over different ages of dung (three days, two, four, 12 and 32 weeks old). Colonisation of the dung, by dung beetles was immediate but as the microclimate of the dung changed with time, the new conditions were ideal for other invertebrate taxa. Over a period of eight months, the change of invertebrate communities utilising the dung included dung beetles, followed by millipedes and [mally ant and termite communities. The results of this study illustrated the importance of refugia (logs and dung) produced by elephants for ground-dwelling invertebrate species in the savanna environment. The extent of the influence of the refugia varied both spatially and temporally and this should be considered in future monitoring or in measuring impacts. While further research on a broader range of organisms and at larger scales is necessary, elephants do have a positive impact on at least some components of biodiversity, through the process of facilitation of refugia.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.