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1
Bigwood, Taryn. "Geomorphic impacts of Loxodonta Africana (African elephants) in Tembe Elephant Park." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/30370.
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Humans are modifying animal populations, indirectly accelerating or reducing the geomorphic alterations caused by animals. Species have been monitored and studied with focus on domesticated animals but little research has been undertaken on wild animals. This study analyses the geomorphic impact of elephants on Tembe Elephant Park, so that the changes they cause to the landscape may be quantified. To conduct this research four sites were chosen: an area where elephants had been excluded for twenty-five years, where excluded for five years, where elephants exist at present and where elephants mud wallow. Three of the four study sites were classed as sand forest (twenty-five-years exclusion, five-years exclusion and where elephants exist) and were analysed and compared to determine the similarities and differences in climate, microclimate, vegetation and the soil’s physical and chemical properties. The wallow site was not compared to any other study site, but was observed and mapped to quantify the geomorphic impact of elephants wallowing. When the sand forest sites were compared the climate, vegetation type and soil were found to be similar. Where elephants were present: the vegetation was inconsistent in basil cover, canopy height, structure and class. Soils were more compacted with a low infiltration rate, higher temperature, lower soil moisture, higher pH and a lower electric conductivity and air relative humidity was the highest. Where elephants have been excluded for twenty-five years, the opposite trends arose from the data analysis. The vegetation was consistent in basil cover, canopy height, structure and class, and the soils were less compacted with a high infiltration rate, low temperature, higher soil moisture, lower pH and a higher electric conductivity. The microclimate showed a trend where the air relative humidity was the lowest. At the elephant wallow site data showed that the wallows were in general circular in shape, 52.5m3 of soil was removed per month for the last nine months and the surface area of the wallows increased by 165.5m2 per month for nine months from April to December 2008. All the results from this study show that the elephant activity in Tembe Elephant Park has geomorphic consequences. From the results, it is possible to conclude that the geomorphic impacts of elephants on Tembe Elephant Park are contributing to a nutrient cycle shift in the sand forest biome, as they change aspects of the vegetation, microclimate, soil and landscape, which are the foundation of the cycle.Dissertation (MA)--University of Pretoria, 2011.
Geography, Geoinformatics and Meteorology
MA
Unrestricted
2
Jacobs, Zoe M. "African Elephant (Loxodonta Africana) Conservation in Tanzania." Scholarship @ Claremont, 2015. http://scholarship.claremont.edu/scripps_theses/568.
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Increasing human population and development in Africa restricts land and resources for African elephants (Loxodonta africana) and threatens the preservation of the species. Despite the importance of conservation for many governments in Africa, many local communities have negative views of elephants and exhibit anti-conservation behavior. By looking at the history of wildlife policy in Tanzania, this paper seeks to understand these opinions through a historical context. Three case studies of conservation initiatives were evaluated to determine what aspects of conservation initiatives promote long-term pro-conservation behavior on the part of the local community. Ultimately, conservation initiatives should establish a framework whereby local communities are empowered through conservation.
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Munishi, Linus Kasian. "The influence of genetic relatedness on sociality and demography of female African elephants." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/d1011612.
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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.
4
Hook, Margaret Rose. "Effect of Lion Calls on African Elephants (Loxodonta Africana) in Addo Elephant National Park, South Africa." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1196.
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Perceived predation risk alters animals’ behavior. This shift in behavior often comes at the cost of attaining resources. Generally, African elephants (Loxodonta africana) experience little predation pressure; however, the risk of predation by lions (Panthera leo) increases other prey species are less abundant. In elephant herds, related females and their offspring travel together in family groups, led by the eldest female. Response to predation pressure was examined by playing lion calls to the population of 437 elephants at the Main Camp Section of Addo Elephant National Park (AENP) in South Africa. Unfamiliar lion calls from a single male and two males, static, and running water were played from a remote speaker to elephants at waterholes. These trials were recorded by video. Behaviors of elephants were then extracted from video into focal observations of thirty second segments before, during and after a sound was played. I analyzed these data using parametric t-tests and non-parametric randomization tests. When no sound was played, elephants did not alter their behavior. Water elicited low levels of distress behaviors. Elephants behaved in a threatened or annoyed manner toward static. Elephants changed their behavior more in response to lion calls than to the controls, namely by decreasing drinking and increasing walking and distress behaviors. I also examined how individuals differed in their responses to the lion calls based on a number of demographic factors. Adult and subadult females performed more social behaviors after lion calls when the matriarch was absent than when she was present. Furthermore, when group size was larger and more calves were present, females decreased drinking and increased time exhibiting distress behaviors. Based on this and other studies it can be concluded that elephants of different demographics perceived similar levels of elevated risk when hearing lion calls. Landscape of fear models are useful for assessing habitat use by prey species in response to real and perceived predation risk. The present study corroborates findings from a study in East Africa that elephants perceive threat from lions based on calls alone and appear to distinguish levels of threat by the number of lions calling.
5
Selier, Sarah-Anne Jeanetta. "The social structure, distribution, and demographic status of the African elephant population in the central Limpopo River Valley of Botswana, Zimbabwe, and South Africa." Connect to this title online, 2007. http://upetd.up.ac.za/thesis/available/etd-06112008-154746/.
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Nasseri, Nabil A. "The relationship of herpetofaunal community composition to an elephant (Loxodonta africana) modified savanna woodland of northern Tanzania, and bioassays with African elephants." Click here to access thesis, 2009. http://www.georgiasouthern.edu/etd/archive/spring2009/nabil_a_nasseri/Nasseri-Nabil-200901-ms.pdf.
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Thesis (M.S.)--Georgia Southern University, 2009."A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Directed by Bruce A. Schulte. ETD. Includes bibliographical references (p. 25-45, 64-87) and appendices.
7
Guldemond, Robert Abraham Rene. "The influence of savannah elephants on vegetation a case study in the Tembe Elephant Park, South Africa /." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08242006-124305.
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Gough, Katie F. "Relatedness, social behaviour, and population dynamics of the elephants (Loxodonta africana) of Addo Elephant National Park, South Africa." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/3569.
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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.
9
Hyatt, Charles Winton. "Discrimination learning in the African elephant." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/28887.
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Wood, Jason Donald. "Communication and spatial cohesion of the African elephant, Loxodonta africana /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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King, Lucy E. "The interaction between the African elephant (Loxodonta africana africana) and the African honey bee (Apis mellifera scutellata) and its potential application as an elephant deterrent." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543016.
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De, Beer Yolandi-Mari. "Determinants and consequences of elephant spatial use in Southern Africa's arid savannas." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-08122008-141848.
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Wall, Jacob C. "Geospatial analysis of African elephant movement (Loxodonta africana and L. cyclotis)." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/51929.
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African elephants (Loxodonta africana and L. cyclotis) are important species for geospatial study given their ecological role as megaherbivores, their large home ranges which pose challenges for conservation, and the ongoing ivory crisis. Using GPS tracking data, I address five research topics that contribute new information to the geospatial analysis of tracking data, to elephant movement ecology, and conservation :
1. What is an appropriate method to collect, store, disseminate, visualize and analyze elephant tracking data? I present a system (Loxobase) designed to provide an efficient and scientific basis for the treatment of wildlife tracking data. I demonstrate its utility by analyzing tracking datasets collected from 247 elephants (Chapter 2).
2. Can we leverage real-time tracking data for management and conservation? I present a monitoring system that implements continuous analysis of elephant GPS tracking data streams to identify positional and movement-based geospatial alert conditions. Four algorithms identify when wildlife slow or stop moving or cross into or near to spatial objects (Chapter 3).
3. Can we estimate wildlife space-use from tracking data? I develop the Elliptical Time-Density model to estimate an animal's utilization distribution from tracking data where parameters are directly linked to species biology. I demonstrate its performance in relation to other space-use estimators (Chapter 4).
4. What does tracking data tell us about the movement patterns of the Sahelian elephants in Mali? I use GPS tracking to study elephants in the Gourma, Mali to understand this unique and important population. The Gourma elephant's range was found to exceed those reported elsewhere in Africa and movements were correlated with patterns of rainfall and vegetation phenology. I also identified corridors and core areas of conservation priority (Chapter 5).
5. What does tracking data tell us about the factors influencing elephant range size across Africa? I present a comparative analysis of elephant range area measured in West, Central, East and Southern Africa. Using mixed effects models, I test hypotheses about elephant range size in relation to sex, species, region, vegetation phenology and quantity, protected areas, human footprint and terrain (Chapter 6).Arts, Faculty of
Geography, Department of
Graduate
14
Gillson, Lindsey. "Vegetation change in East African elephant habitat." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396163.
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Wood, JD, B. McCowan, R. Langbauer, J. Viljoen, and L. Hart. "Classification of African elephant Loxodonta Africana rumbles using acoustic parameters and cluster analysis." Bioacoustics, The International Journal of Animal Sound and its Recording, 2005. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001005.
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It has been suggested that African savanna elephants Loxodonta africana produce 31
different call types (Langbauer 2000). Various researchers have described these calls
by associating them with specific behavioural contexts. More recently Leong et al.
(2003) have attempted to classify elephant call types based on their physical
properties. They classified 8 acoustically distinct call types from a population of
captive elephants. This study focuses on one of these call types, the rumble, in a wild
population of elephants in Kruger National Park, South Africa. A single family group
of elephants was followed to record group behaviours and vocalizations from January
through August 2001. By measuring the physical properties of 663 rumbles and
subjecting these to cluster analysis, we present evidence that shows that rumbles can
be categorized by their physical properties and that the resulting rumble types are
associated with specific group behaviours. We characterize three types of rumbles that
differ significantly by ten acoustic parameters. Two rumble types were associated with
the elephant group feeding and resting, while the third was associated with socializing
and agitation.
16
Karimi, Rebekah R. Schulte Bruce A. "An assessment of perceived crop damage in a Tanzanian village impacted by human-elephant conflict and an investigation of deterrent properties of African elephant (Loxodonta africana) exudates using bioassays." Diss., Statesboro, Ga.: Georgia Southern University, 2009. http://www.georgiasouthern.edu/etd/archive/fall2009/lyndsay_a_itoh/Itoh_Lyndsay_A_200908_MS.pdf.
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"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Title from PDF of title page (Georgia Southern University, viewed on June 19, 2010). Bruce A. Schulte, major professor; Lissa M. Leege, J. Michelle Cawthorn, committee members. Electronic version approved: December 2009. Includes bibliographical references (p.76-78).
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Mukeka, Joseph M. "ANALYZING THE DISTRIBUTION OF THE AFRICAN ELEPHANT (LOXODONTA AFRICANA) IN TSAVO, KENYA." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1278655589.
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Rooney, Brigit. "Tourism and African Elephant (Loxodonta Africana) Behavior in Zambezi National Park, Zimbabwe." TopSCHOLAR®, 2019. https://digitalcommons.wku.edu/theses/3123.
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As charismatic megafauna and a flagship species, African elephants (Loxodonta africana) are vital to the African tourist economy. Conversely, high levels of wildlife tourism can induce behavioral shifts that push desired animals into less frequented areas and disrupt natural behaviors. In order to examine this trade-off, tourism levels and African elephant behaviors were studied in Zambezi National Park (ZNP) near Victoria Falls, Zimbabwe. Over the course of 14 weeks, in-person observations and camera traps in ZNP were used to collect geographic, demographic, and behavioral data from elephant sightings. As a proxy for human presence, geo-locational data were collected for each vehicle sighted in ZNP. These data of vehicles and elephants were mapped in ArcGIS to show a visual representation of their spatial relationship and identify high density and hotspot locations. Analyses from physical observations found that elephants were more frequently sighted in the park region with less vehicle traffic, as expected, but surprisingly also expressed more vigilance behaviors in that region. These results imply that elephants in high traffic regions become accustomed to vehicles but still avoid them when possible. Analyses from camera trap data revealed that only two of the six waterholes monitored had inversely related elephant and human presence, as predicted. There was no clear relationship between elephant and human presence. Future studies should account for habitat type differences in behavioral observations and compare elephant waterhole use in more heavily visited parks.
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Landman, Marietjie. "Megaherbivores in succulent thicket: resource use and implications." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1007956.
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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.
20
Potgieter, Mary-Lee. "Long-term monitoring of elephant impact on the woody vegetation in the Tembe Elephant Park, South Africa." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/30940.
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The African Elephant is a key component of the savanna ecosystem. They contribute to the
generation of habitat for smaller vertebrates, as well as invertebrates, by the breaking of
branches or uprooting of trees. Elephants also play a role in seed dispersal, germination and
sapling recruitment. All these functions are advantageous to the ecosystem if the elephant
population size is acceptable for the size of the reserve and the amount of available forage.
The Tembe Elephant Park covers an area of 30 013 ha and is situated in northern KwaZulu
Natal. This reserve has a diversity of vegetation types and is part of the Maputaland Centre
of Plant Endemism and the Maputaland-Pondoland-Albany Hotspot of Biodiversity. Elephant
numbers in the park are currently high and the elephant population is still increasing. This is
threatening, especially to the endemic Sand Forest communities within the park.
The extent of elephant impact in Tembe Elephant Park, South Africa, was investigated and
compared to data collected six years prior to the current study. Elephant impact was
determined in 44 transects within nine communities across the park. Percentage canopy
removal was calculated for the woody individuals found in sites and with this data the
targeted size classes and species could be identified. The preferences of elephants for
specific woody species were determined by three electivity indices.
Elephant utilisation in Tembe Elephant Park, as reflected by percentage canopy removal,
increased since 2004 as the elephant population increased. Communities that experienced high values in 2010 of elephant utilisation were the Closed Woodland 1, Mature Sand
Forest, Open Woodland 1 and the Closed Woodland 3. Not only did the actual canopy
volume removed by elephant increase with approximately 57%, but the total canopy volume
available for browsing decreased extensively since 2004.
The size classes targeted by the elephants remained approximately the same from 2004 to
2010 although the 2010 results showed that elephant canopy removal percentage increased
in the large size classes. This was expected as elephants target individuals with large stem
diameters.
A change in the selection for woody species by elephants was clear, but the change in
species preference made future projections of canopy removal problematic. Elephants seem
to utilise a species at extreme levels until the species is almost extirpated, then they move
onto the next target species. This routine is evident in the results as highly preferred species
in 2004, with high canopy volumes available and removed, had low canopy availability and
electivity ratios in 2010, consequently the elephants moved on from these species as
individuals became scarce.
It was clear that the structure of individuals, populations and communities were being
altered, selected species were facing extirpation and composition of communities was
changed through the browsing manners of elephants. Management actions should be
implemented to prevent irreversible damage to the vegetation and to conserve the woody
species currently under threat.Dissertation (MSc)--University of Pretoria, 2012.
Plant Science
MSc
Unrestricted
21
Derham, Kelly. "Wire Netting Reduces African Elephant (LOXODONTA AFRICANA) Impact to Selected Large Trees in South Africa." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1358.
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African elephants (Loxodonta africana) are ecosystem engineers in that they substantially alter the environment through their unique foraging and feeding habits. At high densities, elephants potentially have negative impacts on the environment, specifically to large trees. Because of this, recent increases of elephants in the Associated Private Nature Reserves (APNR) on the Western Boundary of Kruger National Park, South Africa have caused concern regarding the health of several species of tree. My objective was to assess the effectiveness of wrapping protective wire netting around the trunk of the tree in preventing and reducing bark stripping by elephants. 2,668 trees, 1352 marula (Sclerocarya birrea), 857 knobthorn (Acacia Nigrescens), and 459 false marula (Lannea schweinfurti), were assessed for elephant impact in the APNR, 1387 (52%) of which had previously been wrapped in protective wire netting (789, 548, and 50 respectively). For knobthorn and marula, wire netting significantly decreased the number of the trees that were bark stripped. For all trees, wire netting decreased the level of bark stripping especially for the highest impact levels. No trees wrapped with wire were ringbarked, compared to 23 unwired trees. In addition, wire netting had an effect on the distribution of damage for the highest impact class incurred regardless of type. A higher relative frequency of wired trees were found in lower impact categories compared to unwired trees. Wire netting is a low maintenance and ecologically valuable technique that alleviates bark stripping for some species. The judicial use of wire netting on trees could serve to maintain elephant and trees populations in areas of heavy confinement with locally high densities of elephants.
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Holdgate, Matthew Robert. "Applying GPS and Accelerometers to the Study of African Savanna (Loxodonta africana) and Asian Elephant (Elephas maximus) Welfare in Zoos." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2234.
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African savanna elephants (Loxodonta africana) and Asian elephants (Elephas maximus) are a focus of welfare research in zoos due to their high intelligence, complex social structure, and sheer size. Due to these challenges, some argue that zoos are inherently incapable of providing appropriate care for elephants, while others believe that zoos can fulfill the needs of these species with improved husbandry. There is a general consensus from both within and outside of zoos, however, that zoos must improve their elephant programs or cease exhibiting these animals altogether. Now more than ever, applied research on zoo elephant welfare is needed to provide context for this debate.
Researchers are interested in how far zoo elephants walk due to the potential health and welfare benefits of walking in these highly mobile species. Zoo researchers recently adopted GPS technology to study elephant walking, and preliminary evidence suggests that African elephants in large zoo exhibits walk distances that correspond with wild elephants under non-extreme conditions. However, data are limited from Asian elephants and from elephants in more typically-sized exhibits. In Chapter Two, I discuss important methodological considerations of utilizing GPS in a zoo environment, including an introduction to the technology, sources of error and mitigation, methods to improve GPS performance, and possible effects of GPS device attachment on animal behavior. This review shows GPS performance is adequate for tracking zoo elephant walking when proper methodological techniques are applied, and should serve as a useful reference for zoo researchers considering using GPS.
In Chapter Three, I used GPS anklets to measure outdoor daily walking distance in 56 adult female African (n = 33) and Asian (n = 23) elephants housed in 30 zoos. I collected 259 days of data and found that elephants walked an average of 5.34 km/day with no significant difference between species. Multivariate regression models predicted that elephants with more dynamic feeding regimens (more diverse feeding types and frequencies; unscheduled feeding times) will walk more. Distance walked was also predicted to be higher in elephants that spend time in a greater number of different social groups. Distance walked was predicted to decline with age. Finally, I found a significant negative correlation between distance walked and nighttime space experience. The results of the analysis suggest that zoos that want to increase walking in their elephants need not rely solely on larger exhibits, but can increase walking by adding quality and complexity to exhibits. However, my results failed to establish a definitive link between walking distance and other validated measures of elephant welfare. Thus, the direct health and welfare benefits of walking in zoo elephants remain unresolved.
Resting behaviors are an essential component of animal welfare, but have received little attention in zoological research. In Chapter Four, I used accelerometers in anklets to complete the first large-scale multi-species investigation of zoo elephant recumbence. I collected 344 days of data from 72 adult female African (n = 44) and Asian (n = 28) elephants at 40 zoos. I found that African elephants are recumbent an average of 2.14 hours/day, which is significantly less than Asian elephants at 3.22 hours/day. Multivariate regression models predicted that African elephant recumbence increases when they experience more space at night, and Asian elephant recumbence increases when they spend time housed alone. Both species showed a similar response to substrate, such that African elephants spending time on all-hard substrates are predicted to be recumbent less, while Asian elephants spending time on all-soft substrates are predicted to be recumbent more. The discovery that occasional non-recumbence is a common behavior in zoo elephants also introduces a new area of research that may have important animal welfare consequences. Finally, this study established that zoos should continue their efforts to replace hard substrate with soft substrate in order to provide zoo elephants with environments that facilitate recumbence.
Overall, this work assessed walking and recumbence in zoo elephants, which will allow zoos to gauge the prevalence of these behaviors in their elephants as compared to the sub-population studied here. A variety of factors that are associated with these behaviors were also identified. With this information, zoos can prioritize modifications to their facilities and animal management programs to create an environment that encourages zoo elephants to express walking and recumbence behavior, should they choose to do so.
This work is one component of the Elephant Welfare Project, the largest zoo animal welfare project ever undertaken, and is unprecedented in both scope and scale. The project was funded by the Institute of Museum and Library Services (IMLS), an independent, U.S., federal, grant-making agency that supports libraries, museums, and zoos. At the time of this writing, the first manuscripts from this project are being submitted to academic journals. These papers will describe the prevalence and distribution of a variety of elephant behaviors and welfare indicators, serve as a benchmark for future elephant welfare studies, and aid in decision making with regard to best practices in elephant management.
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Smet, Anna F. "A comparative cognition perspective on the production and use of visual signals by African savannah elephants (Loxodonta africana)." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/11860.
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Elephants' complex societies, well-developed communication systems, evolutionary history and close working relationship with humans make them an important species for studies of cognition but research on elephant cognition is sparse. In this thesis I aim to illuminate the social cognition involved in the interpretation and production of visual signals by African elephants (Loxodonta africana). My results are intended to contribute to the cross-species literature on social cognition and help to elucidate wild elephant social behaviour. I studied captive elephants, housed at an elephant-back safari company in Victoria Falls, and wild elephants in Hwange National Park, both in Zimbabwe. Wild elephants display a vast array of postures, actions and signals. I found that elephants recognise visual attentiveness in others when they signal silently, producing more signals when their audience can see them, and using the body and face orientation of an audience to judge their attention. When responding to typically human visual signals, elephants immediately responded correctly to deictic gestures, including variants of pointing that they were unlikely to have already experienced. These results indicate elephants' astonishing sensitivity to even subtle social cues. I found no indication that elephants reason about mental states such as false beliefs, or rationality; however, limitations of the experimental design meant I was unlikely to find such an ability even if it is present in elephants. Furthermore, I discovered that elephants have a form of referential indication in their natural communication in the wild. Elephants match their direction of attention with a type of trunk action produced by a group member. Attending to human-like signals, and interpreting them as communicative is an advantage for any animal working with humans and that ability might explain the choice of species that are ancestors of today's domestic animals.
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Chelopo, Ngwako David. "Physiological responses of African elephant (Loxodonta africana) immobilised with a thiafentanil-azaperone combination." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/77443.
Full textAbstract:
Objective To determine the cardiopulmonary and blood gas status of elephants during
chemical capture (immobilisation) with a thiafentanil-azaperone drug combination kept in
lateral recumbency.
Study design Prospective descriptive study.
Animal population Ten free-ranging adult African elephant bulls (estimated weight range
3000 to 6000 kg).
Methods Elephants were immobilised using a thiafentanil (15-18 mg) and azaperone (75-90
mg) by darting from a helicopter. Once recumbent, the tidal volume, minute volume, end-tidal
carbon dioxide, arterial blood pressure and pulse rate were recorded immediately after
instrumentation and at five-minute intervals until T20. Arterial and venous blood gases were
analysed at the time of initial instrumentation and at 20 minutes. On completion of the data
collection, the thiafentanil was antagonised using naltrexone (10 mg mg-1 thiafentanil). A
stopwatch was used to record time to recumbency (dart placement to recumbency) and time
to recovery (administering antagonist to standing). Data was checked for normality and was
found to be parametric. Data were compared using a one-way analysis of variance and
reported as mean (± SD).
Results All elephants were successfully immobilised and all physiological variables remained
constant with minimal non-significant variation over time. Average time to recumbency was
12.5 minutes. The estimated expiratory tidal volume was 21 (± 6) L breath-1 or 4.8 ± 0.8 mL
kg-1, and the measured minute volume was 103 (± 31) L minute-1. The heart and respiratory rates were 49 (±6) beats and 5 (± 1) breaths minute-1, respectively. The mean arterial blood
pressure was 153 (± 31) mmHg. The elephants were acidaemic (pH 7.18 ±0.06; bicarbonate
ion 20 ±4 mmol L-1; lactate 11 ± 4 mmol L-1), mildly hypoxemic (PaO2 68 ± 15 mmHg) and
mildly hypercapnic (PaCO2 52 ± 7 mmHg). Average time to recovery was 2.2 minutes.
Conclusion and clinical relevance African elephant bulls can be successfully immobilised
using thiafentanil-azaperone. Recumbency was rapid, the cardiopulmonary variables were
stable and within acceptable ranges, and recovery was rapid and complete. Mild hypoxaemia
and hypercapnia were evident, but does not necessarily require oxygen supplementation.Dissertation (MSc)--University of Pretoria, 2020.
Companion Animal Clinical Studies
MSc
Unrestricted
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Eggert, Lori S. "The evolution and conservation of the African forest elephant /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3013708.
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Goodyear, Sarah Elizabeth. "Habituation to Auditory Stimuli by Captive African Elephants (Loxodonta Africana)." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1481.
Full textAbstract:
Elephants are cognitive species that exhibit many types of learning. Associative, social, and insight learning have been investigated with elephants, but one of the simplest forms, habituation, has not. As an individual learns that a stimulus is neither harmful nor beneficial, it will decrease its response to the stimulus through the process of habituation. Elephants possess a well-developed sensory system and may habituate to stimuli that could be used for enrichment and/or management. The aim of this study was to examine the habituation process of elephants in response to repeated presentations of two auditory stimuli –buzzing by a disturbed beehive and the sound of banging on pots and pans, as these sounds invoke alert and avoidance behaviors in wild elephants as part of humanelephant conflict mitigation. I hypothesized that elephants would initially exhibit strong reactions to both sounds, but these responses would diminish over repeated trials. I also hypothesized that their responses to the bee sound would decrease more slowly than to the pot/pans sound because bee buzzing represents a biological cue that a threat is nearby. This study was conducted using four female African elephants (Loxodonta africana) at the Nashville Zoo. Elephants received each stimulus for a 10-day period. On the first sound presentation, the elephants reacted by exhibiting distress, avoidance, and vigilance behaviors. Over repeated presentations, the elephants stopped responding to the stimuli, suggesting habituation had occurred. They also seemed to generalize their habituation between the first and second sound, resulting in a faster habituation to the second sound. Although a preliminary study, the results suggest that elephants learn which stimuli are non-threatening and subsequently stop responding to them, most likely through habituation. Specifically, the elephants habituated to bee buzzing and banging pots and pans, two deterrents used to stop elephants from entering farmlands and eating crops. Habituation is a major concern for the development of effective human-wildlife conflict mitigation and zoo enrichment programs. The results from this study indicate that habituation is an important learning process that should be considered during the implementation of captive and wildlife management, even for highly intelligent species such as elephants.
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Ekobo, Atanga. "Conservation of the African forest elephant (Loxodonta africana) in the Lobeke, south-east Cameroon." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262645.
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Benavides, Valades Gabriela. "Induction of anoestrus in free-ranging African elephant (Loxodonta africana) cows using a gonadotrophin-releasing hormone vaccine." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/24985.
Full textAbstract:
The GnRH vaccine may offer an alternative to the current immunocontraceptive method in elephant cows which uses native porcine zona pellucida proteins derived from abattoir slaughtered pigs as the immunogen, greatly limiting its availability. The pZP vaccine is stored at -20 °C and must be mixed with an adjuvant before use. The GnRH vaccine Improvac® is commercially available, already contains the adjuvant and can be stored at 4 °C. The aim of this study was to evaluate the efficacy of the gonadotrophin releasing hormone (GnRH) vaccine Improvac® (Pfizer Animal Health, Sandton, South Africa) in the induction of anoestrus in elephant cows. The Improvac® was administered to eight adult, female, healthy, free-ranging elephants, located in Entabeni Private Game Reserve in the Limpopo Province, South Africa. Another four cows were left untreated and served as controls. The monitoring of the experimental population was conducted over a twelve-month observation period via non-invasive faecal steroid analysis. Progesterone metabolites in extracted samples were measured by Enzyme Immunoassay (EIA) to determine luteal activity and thus the effect of the GnRH vaccine on the endocrine correlates. This study started with a three-month control period prior to vaccination when faeces were collected from each study animal, as soon as possible after defecation to ensure positive identification of the individual with its sample. The three-month period was followed by the immunization protocol. The elephants all received a primary, followed by a booster vaccination dose five weeks later. Each dose of 3 ml contained 600 ìg of RnRF-protein conjugate; both treatments were applied via remote delivery. Monitoring continued until the end of the twelve-month observation period. Observations of oestrous behaviour during the twelve-month period were also recorded. The results showed no statistical difference between treated and control females. There was, however, marked individual variation in response to GnRH immunization. This was possibly influenced by physiological and environmental factors such as age, where the youngest cows showed a better response in terms of reduced progestagen secretion; as well as season, where progestagen levels increased 1.3 times during the rainy season compared to the dry season. There was no association between average progestagen concentration and social hierarchy ranking. A high percentage (86.48%) of behaviours that could be related to oestrus coincided with the onset of the luteal phase and a subsequent rise in progestagen concentrations. All the females (treated and control) showed some evidence of ovarian cyclicity during the study, although 75% of the cycles did not fall within the normal 13-17 week oestrous cycle range reported, suggesting that abnormal cycles are a common reproduction irregularity inherent to non-pregnant wild African elephants. Further research to determine the optimal vaccination protocol is indicated in order to obtain consistent responses to the vaccine that will provide an efficient and safe contraceptive for use in female African elephants. CopyrightDissertation (MSc)--University of Pretoria, 2011.
Production Animal Studies
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Prinsloo, Dominique. "Impacts of African elephant feeding on white rhinoceros foraging opportunities." Thesis, Nelson Mandela University, 2017. http://hdl.handle.net/10948/13768.
Full textAbstract:
In this study, I investigated the interaction between two megaherbivores, the African elephant and white rhinoceros, that has the potential to impact grazing lawns of which white rhino are the creators and maintainers and elephants are potentially the modifiers. I hypothesized that as elephants browse, they discard a variety of coarse woody debris onto the ground; should this woody debris (of varying amounts and sizes) fall onto grazing lawns, white rhino either move them, consume grass around the woody debris or abandon the lawn entirely. If high levels of woody debris are deposited here, grazing by white rhino is likely to be prevented, at which time I predicted that mesoherbivores would have a competitive advantage in accessing forage that white rhino cannot. I examined the mechanistic links between different levels of elephant-deposited woody debris and grass response at a point scale and feeding patch spatial scale of grazing lawns in an African savanna. In addition, I assessed the response of mesoherbivores in terms of vigilance behaviour with increasing levels of predation risk posed by increasing levels of woody debris. I present the first evidence of an indirect effect of elephant on white rhino foraging behaviour. I demonstrate how increasing levels of woody debris lead to a decreasing probability of foraging by white rhino. I also demonstrate how the probability of foraging by mesoherbivores increases as the amount of forage increases. However, since this study took place during a severe drought where resources are extremely limited, I was unable to properly separate the effects of elephant-deposited woody debris from the severe lack of rainfall on grass response and subsequently herbivore foraging behaviour. Due possibly to the drought, mesoherbivores responded less or not at all to risk factors such as woody debris therefore woody debris was not a predictor of vigilance behaviour in my study. This study contributes to our understanding of how the impacts of elephants, as ecosystem engineers, have cascading effects on savanna ecosystems. My study showed that elephant impact mediates the foraging behaviour of white rhino during a drought. However, under average rainfall periods, my original hypothesized effect of the indirect impacts of elephants on white rhino foraging and grazing lawn dynamics could still hold. This key hypothesis that I was unable to test under ‘normal’ conditions due to the drought is still valid and functionally important for understanding the ecosystem processes driving grazing lawn formation, persistence and composition in African savannas where elephants and white rhinos coexist.
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Bates, Melodie Joy. "Endocrine correlates of free-ranging African elephant (Loxodonta africana) treated with porcine zona pellucida vaccine." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/25181.
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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
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Lee, Tamara Ann. "Determinants of protected area boundary crossings by savannah elephants, Loxodonta africana." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/28764.
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When elephants leave primary protected areas (PPAs), such as national parks and game reserves, they may come into conflict with people residing on the adjoining land. In this study, I attempted to determine why African savannah elephants leave the PPAs in which they were collared. To accomplish this, I used telemetry locations of collared elephants in PPAs throughout southern Africa and investigated whether a range of intrinsic and extrinsic variables could explain why elephants crossed the boundaries of the PPAs. Adjoining many of the PPAs were secondary protected areas (SPAs), which consisted of community conservancies, and collectively with the PPAs formed clusters of protected areas. Most (45 of 49) elephants roamed beyond the PPAs but they remained within the clusters of protected areas. The elephants utilised both the PPAs and the SPAs and appeared to not feel threatened when using the SPAs. The reasons for elephants leaving PPAs varied both seasonally and between the sexes. The females roamed beyond the PPAs more during the wet season than the dry season, whereas, for males there was no seasonal difference. During the wet season, female and male habitat selection was similar within and beyond the PPAs. During the dry season, more females and males beyond the PPAs selected for areas close to people, which could be indicative of water. The proportion of male and female home ranges beyond PPAs did not increase with increasing density of elephant populations within the PPAs, nor did the proportion of female home ranges beyond PPAs increase with increasing population growth rate of elephant populations within the PPAs. Therefore, high numbers of elephants within the PPAs did not drive elephants beyond the boundaries. Contrastingly, the proportion of male home ranges beyond the PPAs did increase with increasing population growth rate. However, the results were inconclusive due to small sample size. This study confirms that elephants are utilising the SPAs as well as the PPAs. Therefore, the importance of including the SPAs in conservation actions for elephants cannot be over-emphasized.Dissertation (MSc)--University of Pretoria, 2013.
Zoology and Entomology
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Ott, Theresia. "Landscape heterogeneity as a determinant of range utilization by African elephants (Loxodonta africana) in mesic savannas." Diss., Pretoria : [S.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-0522208-131027/.
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Braby, Justine. "The Efficacy of Downlisting the African Elephant under CITES: A Critical Assessment." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/4466.
Full textAbstract:
International trade in wildlife and endangered species is an extremely lucrative business, bringing in an estimated five billion US dollars annually. This makes it one of the world's largest industries. Nearly one third of this trade is illegal. Millions of animals suffer and die each year at the hands of man, often due to human greed and vanity. This international market for animals has led to drastic declines in the populations of many species, including such exotic animals as the rhino, leopard, tiger, and the African elephant. The African elephant's plight has arguably been the most popular. Due to trade in its ivory, African elephant populations declined so dramatically that experts claimed the elephant would be extinct by 2010. This paper examines the steps taken by international law to protect the African elephant, and specifically looks at the two strategies adopted by the African countries to ensure this protection.
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Evans, Kate Elizabeth. "The behavioural ecology and movements of adolescent male African elephant (Loxodonta africana) in the Okavango Delta, Botswana." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431629.
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Smit, Hanneline Adri. "Phylogeography of three Southern African endemic elephant-shrews and a supermatrix approach to the Macroscelidea." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/21442.
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Thesis (PhD)--Stellenbosch University, 2008.ENGLISH ABSTRACT: The order Macroscelidea has a strict African distribution and consists of two extant subfamilies, Rhynchocyoninae with a single genus that includes three species, and the Macroscelidinae represented by the remaining three genera, Elephantulus that includes 10 species, and the monotypic Macroscelides and Petrodromus. On the basis of molecular, cytogenetic and morphological evidence, Elephantulus edwardii (Cape rock elephant-shrew), the only strictly South African endemic species, was shown to comprise two closely related taxa. A new Elephantulus taxon, described here is reported for the first time. It has a restricted distribution in the central Nama Karoo of South Africa. Apart from important genetic distinctions, Elephantulus sp. nov. has several relatively subtle morphological characters that separate it from E. edwardii. Molecular sequences from the mitochondrial cytochrome b gene and the control region of E. edwardii sensu stricto suggests the presence of a northern Namaqua and central Fynbos clade with four evolutionary lineages identified within the latter. The geographic delimitation of the northern and central clades corresponds closely with patterns reported for other rock dwelling vertebrate species indicating a shared biogeographic history for saxicolous taxa in South Africa. Elephantulus rupestris (western rock elephant-shrew) and Macroscelides proboscideus (round-eared elephant-shrew) are two taxa with largely overlapping distributions that span the semi-arid regions of South Africa and Namibia. Based on mitochondrial DNA sequence data E. rupestris has a structured genetic profile associated with a habitat of rocky outcrops compared to M. proboscideus that inhabits gravel plains, where the pattern is one of isolationby– distance. Chromosomal changes, apart from heterochromatic differences, are limited to variation in diploid number among elephant-shrew species. These range from 2n=26 (E. edwardii; E. rupestris; Elephantulus sp. nov.; E. intufi; E. brachyrhynchus and M. proboscideus) to 2n=28 in both Petrodromus tetradactylus and E. rozeti to 2n=30 in E. myurus. Cross-species chromosome painting (Zoo-Fluorescence in situ hybridization or zoo-FISH) of E. edwardii flow-sorted probes that correspond to the five smaller sized autosomes (8-12) and the X chromosome showed no evidence of synteny disruption among Elephantulus sp. nov., E. intufi, E. myurus, P. tetradactylus and M. proboscideus, and reinforced the G-banding observations underscoring the conservative karyotypes in these species. A comprehensive phylogeny including all described elephant-shrew species is presented for the first time. A multigene supermatrix that included 3905 bp from three mitochondrial (12S rRNA, valine tRNA, 16S rRNA) and two nuclear segments (Von Willebrand factor [vWF] and exon 1 of the interphotoreceptor retinoid binding protein [IRBP]) was analysed. Cytogenetic characters, previously described morphological, anatomical and dental features as well as allozyme data and penis morphology were evaluated and mapped to the molecular topology. The molecular findings did not support a monophyletic origin for the genus Elephantulus and suggests that both the monotypic Petrodromus and Macroscelides should be included in Elephantulus. Molecular dating suggests that an arid-adapted Macroscelidinae lineage dispersed from east Africa at ~11.5 million years ago via the African arid corridor to southwestern Africa. Subsequent speciation events within the Macroscelidinae are coincidental with three major periods of aridification of the African continent.
AFRIKAANSE OPSOMMING: Die orde Macroscelidea het ’n verspreiding beperk tot Afrika en sluit twee bestaande subfamilies in, die Rhynchocyoninae wat drie spesies binne ’n enkele genus insluit en die Macroscelidinae verteenwoordig deur drie genera, Elephantulus (10 spesies) en die monotipiese Macroscelides en Petrodromus. Gebaseer op molekulêre, sitogenetiese en morfologiese bewyse, bestaan E. edwardii, tot op datum die enigste streng endemiese Suid- Afrikaanse klaasneusspesie, uit twee nabyverwante taksa. Die nuwe Elephantulus takson, hierin beskryf, het ’n beperkte verspreiding in die sentraal Nama Karoo van Suid-Afrika. Afgesien van belangrike genetiese bewyse wat die beskrywing van die nuwe spesie ondersteun, word Elephantulus sp. nov. gekenmerk deur ’n aantal subtiele morfologiese karakters wat dit onderskei van E. edwardii. Binne E. edwardii sensu stricto, het mitochondriale molekulêre volgordes beduidende substruktuur aangedui regoor die spesies se verspreiding. Die data het die teenwoordigheid van ’n noordelike Namakwa en sentrale Fynbos klade aangetoon met vier evolusionêre lyne binne die laasgenoemde. Die geografiese skeiding van die noordelike en sentrale klades stem grootliks ooreen met patrone in ander rotsbewonende vertebraat spesies, wat op ’n gedeelde biogeografiese verlede in Suid-Afrika dui. Elephantulus rupestris (westelike klipklaasneus) en Macroscelides proboscideus (ronde-oor klaasneus) is twee taksa met verspreidings wat grootliks oorvleuel in die semi-woestyn streke van Suid-Afrika en Namibië. Mitochondriale DNS volgorde-bepaling dui op ’n gestruktueerde genetiese profiel binne E. rupestris, geassosieer met ’n habitat van rotskoppies, in vergelyking met ’n isolasie-deur-afstand patroon wat M. proboscideus, wat op gruisvlaktes aangetref word, karakteriseer. Chromosoom verandering, afgesien van heterochromatiese verskille, is beperk tot ’n strukturele verandering van ‘n diploïede getal van 26 (E. edwardii; E. rupestris; Elephantulus sp. nov.; E. intufi; E. brachyrhynchus en M. proboscideus) tot 2n=28 in beide Petrodromus tetradactylus asook E. rozeti en 2n=30 in E. myurus. Kruis-spesies chromosoom fluoressent hibridisasie (“zoo-FISH”) van die vloei-sorteerde merkers toegewys tot die vyf kleiner grootte outosome (8-12) asook die X chromosoom van E. edwardii tot metafase chromosome van Elephantulus sp. nov., E. intufi, E. myurus, P. tetradactylus en M. proboscideus het geen bewyse getoon van sintenie-verbreking nie en versterk G-bandbepaling waarnemings wat die konserwatiewe kariotipes in hierdie spesies ondersteun. ‘n Volledige evolusionêre filogenie, verteenwoordigend van alle erkende klaasneusspesies, word vir die eerste keer voorgestel. As sulks is ’n multigeen supermatriks wat gebaseer is op 3905 bp van drie mitochondriale (12S rRNA, valien tRNA, 16S rRNA) en twee nukluêre segmente (Von Willebrand faktor [vWF] en ekson 1 van die interfotoreseptor-retinoïed-bindende proteïen [IRBP]) ingesluit. As toevoeging, is nuwe sitogenetiese data, voorheen beskryfde morfologiese, anatomiese en dentale karakters sowel as data van allosieme-analises en penis morfologie ge-evalueer en nie-molekulêre ondersteuning aangedui op die molekulêre topologie. Die molekulêre bevindinge ondersteun nie ’n monofiletiese oorsprong vir Elephantulus nie en stel voor dat beide die monotipiese Petrodromus en Macroscelides ingesluit moet word in die genus Elephantulus. Molekulêre datering stel voor dat ’n dor-aangepasde Macroscelidinae lyn versprei het vanaf oos Afrika ~11.5 miljoen jaar gelede deur die “droeë Afrika korridor” tot in suidwestelike Afrika. Verdere spesiasie gebeurtenisse binne die Macroscelidinae kan nouliks geassosieer word met drie groot periodes van verdorring in Afrika.
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Kelling, Angela Swilley. "An examination of salivary cortisol concentrations and behavior in three captive african elephants (loxodonta africana) at zoo atlanta." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26586.
Full textAbstract:
Salivary cortisol is becoming an effective method with which to quantify cortisol levels, including the ability to track diurnal patterns and acute stress fluctuations. The purpose of this study was to validate salivary cortisol for use in African elephants (Loxodonta Africana), establish baseline cortisol values in three African elephants at Zoo Atlanta and explore the relationship between cortisol and various behaviors and husbandry events. Elephant salivary cortisol was found to be a valid measure based on correlations with serum cortisol and serial dilution results. Salivary cortisol also decreased across the day, but no definitive patterns were revealed. Using baseline values, salivary cortisol was used to examine the effects of enrichment, maintenance and novel training, and a mild stressor. Maintenance training was found to lead to lower cortisol values than novel training. Salivary cortisol after enrichment did not differ from individual overall means. The mild stressor initiated a rise in salivary cortisol. The final focus of this study was to investigate the link between salivary cortisol and stereotypic behavior. Stereotypies are described as repetitive behaviors with little variance and no discernible function or goal. There is not a straightforward relationship between stereotypies and welfare. Analysis of salivary cortisol at various durations into swaying bouts established that swaying appears to decrease cortisol levels. Additionally, behavioral data were collected. Behavioral data confirmed anecdotal reports of circular dominance in these animals. Behavioral data also revealed that although these individuals spend the majority of their time consuming food, one individual in particular devotes a significant amount of her time to swaying, a percentage much higher than that found when Wilson, Bloomsmith, and Maple (2004) examined stereotypic swaying rates in these same animals. Results of this study have direct ramifications for the current management requirements for captive elephants around the world. It helps tap into aspects of psychological well being of captive elephants to elucidate factors influencing welfare and stereotypic behavior. Research of this nature is a critical endeavor if we are to appropriately manage these magnificent animals in captivity.
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Codron, Jacqueline. "Annals of ivory : perspectives on African elephant Loxodonta africana (Blumenbach 1797) feeding ecology from a multi-decadal record." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4169.
Full textAbstract:
Includes abstract.Includes bibliographical references (leaves 202-256).
This thesis explores the dietary responses of African elephants (Loxodonta africana) to environmental change by testing the hypothesis that diet switching (from predominantly browse-based to more grass-rich diets) is driven by cyclical patterns of climate and habitat change in a southern African savanna. Elephants are thought to have substantial impacts on their environments, primarily because they consume large amounts of vegetation over sustained periods. However, the woody plant composition of their diet varies considerably across space and through time, so that in some instances they have been found to be almost pure grazers. Tracking these changes by traditional approaches (e.g. field observations) is difficult because of the geographical and temporal constraints inherent to these methods. Stable light isotope tracking of diet allows diet switching to be studied over multiple space/time scales. Here, I use stable isotope data from elephant faeces, tail hair, and ivory to record short- (monthly), medium- (seasonal to annual), and long-term (decadal) ecological variability, respectively, of elephant diets in the Kruger National Park, South Africa. Results from faeces collected at monthly resolution for one year confirm findings of a previous study (based on biannually-collected samples over two years) that elephants generally consume more grass in the more wooded habitats of the northern Kruger Park, but that there is a greater degree of seasonal diet switching in southern Kruger Park habitats. Moreover, diet changes also relate to changes in underlying bedrock across Kruger Park. Isotopic time-series produced by serial profiling of tail hairs confirm patterns observed in faeces. Long-term diet histories of individuals are derived from serial isotope sampling of ivory, yielding records that represent several decades of an animal’s life, at sub-annual (seasonal) resolution. Overlaying individual ivory series in time produces the first, to my knowledge, multidecadal record of African elephant diet, dating from 1903 to 1993. Contrary to expectations, stable carbon, nitrogen, and oxygen isotope records from ivory do not correlate well with cyclical climate trends for the study region. Rather, pronounced diet shifts are observed during extreme climatic events (floods and droughts), and the greatest levels of intra- and inter-annual variability coincide with significant changes in park management policy during the 20th century, i.e. the introduction of water provision programs after the mid 1930s, and the onset of elephant population control in 1967. It is proposed that such direct intervention has played the biggest role in disturbance of elephant-plant equilibria during the 20th century, and further studies to improve our understanding of this phenomenon will be instrumental to development of appropriate management strategies for the 21st century.
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Jansson, Lina. "How to stop the African elephant population from extermination; Causes, Achievements and Consequences." Thesis, Södertörn University College, School of Life Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-747.
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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.
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Cimadori, Ilaria <1994>. "BIODIVERSITY, WILDERNESS AND THE PROTECTION OF THE AFRICAN ELEPHANT POPULATION IN INTERNATIONAL LAW." Master's Degree Thesis, Università Ca' Foscari Venezia, 2020. http://hdl.handle.net/10579/16568.
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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.
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Olsson, Linnea. "Human-elephant conflicts : A qualitative case study of farmers’ attitudes toward elephants in Babati, Tanzania." Thesis, Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-24091.
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It is widely recognized that human-wildlife conflicts can reduce farmers’ support for long-term species conservation. The subject of human-elephant conflicts is highly relevant in villages around Babati District in North Central Tanzania because of the closeness to Tarangire National Park. The purpose of this study is therefore to examine local farmers’ attitudes toward elephants and the attitudes’ effects on conservation efforts. Primary data was collected through a qualitative approach of semi-structured interviews with twelve farmers in four villages around Babati, with Wildlife Officer Nashon Macokesha at Babati District Council and with Allan Carlson, Nature Conservation Expert at WWF. A thematic analysis was done to make comparisons between the answers from farmers, Macokesha and Carlson. The Theory of Planned Behavior and the Value-Belief-Norm theory were also used to analyze the underlying factors of the farmers’ attitudes. The results of this study show that around half of the farmers have positive attitudes toward elephants, while the other half think negatively of them. Elephants were identified as the most problematic species and crop-raiding as the most problematic type of human-elephant conflict. The problems that farmers experience do to crop-raiding and other types of human-elephant conflicts include the direct effects of lost livelihood and income and indirect effects like health impacts and security issues. The result also indicates that factors affecting farmers’ attitudes toward elephants include: 1) the proportion of available land affected by elephants, 2) the closeness of farmers’ fields to Tarangire National Park, 3) the lack of compensation, 4) the ability to affect the decision-making concerning the human-elephant conflicts and 5) the information about and knowledge of elephants and their importance. The underlying cause of the human-elephant conflicts is identified to be the spatial overlap of the two species. To prevent human-elephant encounters in the first place, thereby reducing the risk of human-elephants conflicts, better land use planning can be used to avoid settlement and cultivation close to protected areas. Buffer zones can be established around national parks and reserves to reduce the overlap between humans and wildlife. Mitigation through preventive and deterrent methods like lighting fires, making noises, using chili-dung or chili-grease to scare elephants off farmers’ fields can also be used. Another alternative is to switch from growing high-risk crops that elephants prefer to crops like chili or sesame which rarely gets eaten by elephants.Att konflikter mellan människor och djurliv kan minska bönders stöd för artbevarande åtgärder är välkänt bland forskare. Konflikter mellan människor och elefanter är vitt förekommande i byar i Babati-distriktet i norra Tanzania på grund av närheten till nationalparken Tarangire. Syftet med denna studie är därför att undersöka bönders attityder till elefanter och attitydernas effekter för bevarandeåtgärder. Primärdata samlades in genom ett kvalitativt upplägg med semistrukturerade intervjuer med tolv bönder i fyra byar i Babati, med Wildlife Officer Nashon Macokesha på Babati District Council samt med Allan Carlson, naturvårdsexpert på WWF. En tematisk analys utfördes för att jämföra svaren mellan bönderna, Macokesha och Carlson och the Theory of Planned Behavior samt the Value-Belief-Norm theory användes för att analysera de underliggande orsakerna bakom böndernas attityder. Resultatet från denna studie visar att ungefär hälften av bönderna har positiva attityder till elefanter, medan den andra hälften har negativa åsikter om dem. Elefanter identifierades som den mest problematiska arten för bönderna och förstörandet av grödor som den mest problematiska typen av konflikt mellan människor och elefanter. Problemen som bönderna upplever till följd av dessa konflikter inkluderar direkta effekter som förlorad inkomst och försämrade försörjningsmöjligheter, men också indirekta effekter som hälso- och säkerhetsproblem. Faktorer som enligt resultaten i denna studie kan påverka böndernas attityder till elefanter innefattar: 1) andelen tillgänglig mark som påverkas av elefanter, 2) närheten från böndernas mark till nationalparken Tarangire, 3) bristen på kompensation, 4) möjligheten att påverka beslutsprocessen gällande konflikten mellan människor och elefanter samt 5) information och kunskap om elefanter och deras betydelse. Den underliggande orsaken till konflikterna mellan människor och elefanter identifieras vara överlappet i användningsområden mellan de båda arterna. För att förhindra möten mellan människor och elefanter, och därmed minska risken för konflikter, behövs bättre markanvändningsplanering så att bosättning och jordbruk undviks i närheten av skyddade områden. Buffertzoner kan också anläggas runt nationalparker och reservat för att minska överlappet mellan människor och djur. Avskräckande åtgärder, som att tända eldar, göra oväsen, tända chilibriketter eller sätta upp chili-rep, för att hålla elefanter borta från böndernas åkrar kan också användas. Ett annat alternativ är att bönderna byter från att odla högriskgrödor som elefanter föredrar till att odla grödor som chili eller sesam, vilka sällan eller aldrig äts av elefanter.
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Mueller, Jenni Elizabeth. "Seasonal Changes in Behavior and Exhibit Use of Captive African Elephants (Loxodonta africana) and Black Rhinoceroses (Diceros bicornis)." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1215524414.
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Knott, Edward Joseph. "The effect of elephants (Loxodonta africana, Blumenbach, 1797) on Xeric Succulent Thicket." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1005359.
Full textAbstract:
This study looks at the impact of elephant feeding on the Xeric Succulent Thicket component of Eastern Cape Subtropical Thicket (ECST) in Addo Elephant National Park (AENP). Observations of elephant feeding were carried out and vegetation transects were surveyed for impact of elephant feeding. The results indicated that the Nyati elephants spent the majority of their time grazing (nearly 90%), particularly the cow-young herds, and especially when the herd gathered in larger numbers. Browsing events were concentrated on Acacia karroo (81%) and there was no significant difference between the sexes in their preference for this species. Despite being subjected to most of the browsing, the majority of A. karroo trees were undamaged and the effect of elephants was generally light. It appears unlikely that, three years after re-introduction to Nyati, the elephants have had an effect on community structure of the vegetation. Surveys were conducted on stands of the alien invasive weed prickly pear Opuntia ficus-indica, and it was recorded that elephants in Nyati have had a dramatic effect on prickly pear, utilising all adult plants assessed and destroying 70% of them. This level of destruction in such a short period of time suggests that prickly pear is a highly favoured species. The results from the present study suggest that elephants can play a role in the control of prickly pear. Results are discussed in terms of elephants as both megaherbivores and keystone species, and as agents of intermediate disturbance.
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Castelda, Stacie Marie. "Waterhole dynamics and chemical signals of African elephants (Loxodonta aficana) by Stacie M. Castelda." Click here to access thesis, 2008. http://www.georgiasouthern.edu/etd/archive/fall2008/stacie_m_castelda/Castelda_Stacie_M_200808_MS.pdf.
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Thesis (M.S.)--Georgia Southern University, 2008."A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Directed by Bruce A. Schulte. ETD. Includes bibliographical references (p. 69-88) and appendices.
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Rose, Matthew Calvin. "A critical analysis of the socioeconomic impact assessments of the Addo Elephant National Park." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1002698.
Full textAbstract:
Impact assessment is a requirement for development in many countries across the globe, seeking to inform the decision-maker as to the environmental, social and economic impact of an ongoing or proposed project. Socioeconomic impact assessment (SEIA) is a means of informing decision-makers as to the socioeconomic effects a project could have, or is having, thus contributing to informing adaptive management practices. However, the tendency of socioeconomic impact assessment to highly quantitative economic methods of analysis raises the question of whether the desired results are achieved by the process. The purpose of the research was to determine whether highly quantitative forms of economic analysis are suitable for measurement of impacts in a social context where distributive as well as net impact is important; to critically analyze the method utilized in achieving highly quantitative economic impact assessment results; and lastly to draw conclusions and make recommendations regarding the efficacy of monitoring processes used to inform adaptive management practices. The research was conducted by means of a case study focusing on three SEIAs carried out on the same entity, namely the Addo Elephant National Park. Managed by South African National Parks (SANP), it began expanding its borders in the early 2000s. Funded by the World Bank, SANP was required to carry out a comprehensive Strategic Environmental Assessment (SEA) in 2003 to ensure the expansion did not have negative environmental, social and economic repercussions, and where such consequences were unavoidable, to ensure that mitigation and management thereof was informed by useful monitoring exercises. Given the need for resettlement and issues of economic distributive concern raised in the 2003 SEA, the three socioeconomic impact assessments conducted from 2005 – 2010 as part of the ongoing monitoring exercises formed an ideal framework for answering the primary research questions. The findings indicate that despite consistent terms of reference, different assessors interpret mandates from the commissioning body in different ways, leading to varied applications of the same theory, some methodologically better than others. Economic multiplier analysis was found to be inadequate as a measure of the distributive effects of economic impact. Moreover, a lack of consistency, accountability and transparency in the monitoring process led to three sets of results that were incomparable over time and thus inadequate as a means to inform adaptive management practices. Asymmetries of and between power and expertise in the commissioning body and the assessors led to breakdowns of the assessment process in terms of accountability and integrity and resulted in a failure to properly define the scope of the study and measure the relevant indicators. The following recommendations were made: that the economic multiplier method be complemented by additional methods of analysis when utilized in disparate social contexts where distribution of economic benefit is important; that monitoring practices be systematized at an early stage of the process to ensure comparable results useful in informing ongoing management practices; and that what an assessment measures and how it measures it be clarified with reference to an objective source. Finally, the number of factors for consideration in any impact assessment means that measurement of the full picture suffers resource constraints, emphasizing the need for impact assessment oversight to recognize the deficiencies of the process whilst still acknowledging that ‘some number is better than no number’.
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Gaugris, Jerome Yves. "The impacts of herbivores and humans on the utilisation of woody resources in conserved versus non-conserved land in Maputoland, northern KwaZulu-Natal, South Africa." Connect to this title online, 2008. http://upetd.up.ac.za/thesis/available/etd-06052008-162658.
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Von, Hagen Rebecca Lynn. "An Evaluation of Deterrent Methods Utilized to Prevent Crop Raiding by African Elephants (Loxodonta Africana) in the Kasigau Wildlife Corridor, Kenya." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/3068.
Full textAbstract:
Escalating human elephant conflict (HEC) continues to be a contributing factor
towards elephant decline, and crop raiding is the most common form of negative
human-elephant interactions. For communities that cannot reverse or prevent crop
raiding, it is necessary to contain HEC events through deterrent measures. Few
deterrent measures exist that combine practicality and affordability while also
preventing habituation by elephants. This project focused on comparing the efficacy of
deterrent methods to assess which was the most successful at preventing elephants
from entering crops in the farming community of Sasenyi, Kenya. In this paired-control
study, four deterrent methods were evaluated: acacia fences, chili-pepper fences, a
new metal strip fence, and a combination of a chili and metal strip fence. Of the over
400 visits by elephants to individual fields containing crops recorded during two field
seasons, elephants entered farmer fields in the experimental area on 33 occasions
(<10%). Analysis of incidents when elephants approached at less than 50 m revealed
that the chili + metal fence and the metal fence were significantly more effective than
no deterrent. Following further verification of its effectiveness, this new deterrent
method could be a powerful new tool to alleviate elephant crop raiding and reduce HEC.
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Roever, Carrie Lynn. "Spatial determinants of habitat use, mortality and connectivity for elephant populations across southern Africa." Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/28661.
Full textAbstract:
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
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Ferry, Nicolas. "Processes involved in the functioning of large mammal communities : the role of the African elephant in the ecology of predator-prey relationships." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1054/document.
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Les communautés écologiques sont connues pour être des systèmes complexes composés de multiple espèces entrant en interaction les unes avec les autres. De nombreux modèles théoriques ont été développés pour étudier les communautés. Certains ont souligné l'importance des effets indirects que les espèces pouvaient avoir les unes sur les autres, tels que les chaînes d'interactions et les modifications d'interactions (par modification du trait d'une des espèces en interaction ou de l'environnement où se déroule l'interaction). Bien que la science expérimentale vienne confirmer le rôle fondamental que pourrait avoir ces effets indirects, peu d'études à l'échelle des communautés en milieu naturel ont été conduites, et encore moins chez les grands mammifères. Le Parc National de Hwange, au Zimbabwe, est un écosystème de savane arborée semiaride caractérisé par une quasi-absence d'eau de surface naturelle (point d'eau, rivière) pendant la saison sèche, et ce n'est qu'avec la création de points d'eau artificiels pompés que la richesse spécifique des communautés de grands mammifères et les fortes abondances animales sont maintenues. De plus, cet écosystème a la remarquable particularité à la fois d'abriter l'une des plus fortes densités d'éléphants, et d'être considéré comme l'un des bastions africains pour sa population de lions. Le lion est connu comme étant un chasseur à l'affût, utilisant les éléments de son habitat (fourrés, souches, hautes herbes, etc.) pour se rapprocher au maximum de sa proie et lui bondir dessus par surprise. De plus, cette espèce semble profiter de l'agrégation des herbivores aux points d'eau pendant la saison sèche pour chasser autour de ces points d'eau. L'éléphant d'Afrique quant à lui est capable d'aménager son milieu et est ainsi susceptible de favoriser l'accès à certaines ressources pour les autres espèces, telles que des abris ou au contraire une meilleure visibilité. En revanche, de par sa masse corporelle exceptionnelle et son régime alimentaire généraliste, il est possible qu'il soit un compétiteur clé pour les autres herbivores. Enfin, étant très nombreux dans l'écosystème étudié, nécessitant de grandes quantités d'eau, et devenant de plus en plus agressifs au fil de la saison sèche, les éléphants influencent l'utilisation des points d'eau par les autres herbivores. Cette thèse porte donc sur le rôle que peuvent avoir les éléphants sur les interactions trophiques entre les lions et leurs proies, via des mécanismes d'effets indirects. Différents axes de recherche sont abordés. Le premier porte sur l'effet des éléphants sur la communauté de grands herbivores aux points d'eau, et plus particulièrement comment ils peuvent influencer leur distribution spatiale, et à terme leur vulnérabilité vis-à-vis des prédateurs. Un évitement spatial des éléphants par les autres herbviores en début de saison sèche suggère fortement que les éléphants sont de potentiels compétiteurs. Cependant, à la fin de la saison sèche, le phénomène s'inverse et certaines espèces d'herbivores se rapprochent fortement des éléphants. Deux scénarios portant sur les mécanismes pouvant expliquer ce patron ont été explorés, sans succès : une nécessité croissante d'accéder à de l'eau de meilleure qualité au niveau des pompes des points d'eau, et une augmentation du risque de prédation qui pourrait rendre les éléphants « attractifs » aux yeux des herbivores, les éléphants adultes étant invulnérables à la prédation et capables de les faire fuir par des comportements de harcèlement. Le deuxième axe de recherche porte sur l'effet des éléphants sur la distribution spatiale des herbivores à l'échelles du paysage et de l'habitat, et sur les conséquences possibles que cela peut avoir sur l'écologie spatiale des prédateurs. L'absence de ségrégation entre éléphants et herbivores ne supporte pas l'hypothèse d'un effet de compétition par exploitation, et l'investigation quant à l'effet sur les prédateurs n'a pas été poussée plus avant... [etc]Species can indirectly affect other species and their interactions. The trophic interaction between a predator and its prey can be modified by the presence of a third species either through chain interactions (e.g. successive predation link) either through interaction modification. However, these indirect received few attentions in theorical modelling of food web, and fewer studies tried to explore this phenomenon at the scale of natural complex communities of large mammals. The role of the elephants as modifier of lion’s trophic interaction is explored in the semi-arid woodland savannah ecosystem of Hwange National Park, Zimbabwe. African elephants, as key competitor (male body mass ~ 4000 kg with aggressive behaviour) shape the behaviour of herbivores at waterholes results do not allow to state on the elephant mediation of lion trophic interaction at waterholes. In addition, elephants seem to facilitate the availability of food resources for impalas, possibly by increasing regrowth of shoots by breaking twigs and stem, as these last select habitats used by elephants. However, not effect of facilitation or competition were observed for the other herbivores, which lead to think that elephants do not influence lion trophic interaction in that way. Finally, by altering the physical environment (i.e. engineer species) the elephants affect the visibility and ambush sites for lions in the woody vegetation and ultimately seem to influence the lion kill site selection. This study suggests that indirect effects may act at the community level even if their observation and quantification are difficult in natural communities. Moreover, it supports the observation that it is important to take into account these indirect effects in order to have a thorough understanding and have a better ability to predict the consequences that disruptions may have on the structure and functioning of communities
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O'Kane, Christopher Anthony John. "Elephant versus other browsers' long-term influences on savanna woodland dynamics : synergistic influences of elephant and other large mammalian herbivores on the structure and composition of woody plant communities in Hluhluwe-iMfolozi Park, South Africa." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:abf97429-a044-4a62-9e29-be45b9d689d6.
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A crucial question in the debate about reintroducing elephant culling is whether the long-term effects of elephants and mesobrowsers on woodlands are similar. Sufficiently high biomass-densities of mesobrowsers may, following reduction or removal of elephants, continue to heavily impact earlier life-history stages of a similar suite of woody plants that elephant impacted, preventing these species from maturing. Thus a similar end-point for woodland structure and composition is achieved. No study exists in the literature where woody plant and habitat utilisation of the savanna browser guild has been determined in the same locality over the same period. A review of 49 years of literature implied that the two groups impact the same core woody-species in the same habitats. Dietary and habitat utilisation of guild members was determined in Hluhluwe-iMfolozi Park, South Africa. A small suite (n = 8) of woody species formed the core diet of all guild members. Herbivores’ densities were determined using a novel GIS approach; all members of the guild showed extensive overlap in habitat use. GPS collars and a GIS were then used to detect zones of different density of impala in the landscape, thus defining, for the first time, a natural fine-grain browsing gradient. Densities of woody seedlings were significantly less (average 48% reduction) in areas of high versus low impala density. A simple browse-browser model, incorporating, in a novel approach, functional groups of plant species, was parameterised from these results and an extensive review of the literature. Outputs suggest that over the long-term (100 years), impala will have a similar impact on woodland structure as elephant. An apparently strong synergistic effect between impala and elephant impact, suggests that reduction or removal of either impala or elephant will radically reduce long-term destruction of woodlands. In smaller or medium sized reserves, where control of mesobrowser populations is practical, profitable and more acceptable than elephant culling, these findings imply a re-direction of management efforts. Management should consider the biomass-density of both groups, rather than just focus on the system’s perceived ‘keystone’ species. Such principles may also apply to temperate and other systems.
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Fishlock, Victoria L. "Bai use in forest elephants (Loxodonta africana cyclotis) : ecology, sociality & risk." Thesis, University of Stirling, 2010. http://hdl.handle.net/1893/2758.
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Forest elephant (Loxodonta africana cyclotis) sociality is relatively little-studied due to the difficulties of making direct observations in rainforests. In Central Africa elephants aggregate at large natural forest clearings known as bais, which have been postulated to offer social benefits in addition to nutritional resources. This thesis explores the role of these clearings as social arenas by examining bai use within three main themes; ecology, sociality and risk factors. Seasonal changes in elephant use of the Maya Nord bai (Republic of Congo) are described, along with the demography of the visiting population. Elephant visit rate was highly variable; the number of elephants using Maya Nord in an observation day ranged from 0 to 117 animals. This variability was unrelated to local resource availability and productivity suggesting that bai use occurs year round. Elephants in Odzala-Kokoua do not show high fidelity to a single clearing; 454 elephants were individually identified and re-sighted an average of 1.76 times (range 1-10) during the twelve month study period. Previous bai studies have yet to quantify how elephants associate with one another within the bai area. This study examines socio-spatial organisation and associate choice using two measures of association within the 0.23 km2 bai area; aggregations (all elephants present in the clearing) and parties (elephants spatially co-ordinated in activity and movement) and distinguishes these from parties that range together (i.e. arrive and leave together). Social network analyses (SocProg) were used to describe inter- and intra-sexual multi-level organisation in the bai environment, and to illustrate the non-random nature of elephant aggregations and parties. Bais were shown to function as social arenas; female elephants showed active choice of certain associates and active avoidance of others when creating parties, whereas males were less discriminatory. Parties formed in the clearing (mean size= 3.93, SE= 0.186) were larger than ranging parties (mean size= 2.71, SE= 0.084) and elephants stayed for 50% longer in the clearing when they associated with individuals from outside their ranging party. Inter- and intra-sexual relationships were maintained within the clearing, and these are suggested to offer elephants essential opportunities for social learning. The patterning and nature of the relationships observed at the Maya Nord clearing indicates that forest elephants use a fission-fusion social structure similar to that of savannah elephants (Loxodonta africana africana); relationships are significantly structured by age- and sex- and underpinned by individual identity. Old experienced females hold key roles for forest elephants, and male relationships are superimposed on the network of female associations. Odzala-Kokoua elephants use bais to maintain their social relationships despite being highly sensitive to the anthropogenic risks involved in using these open areas. The results of this study suggest that forest and savannah elephants lie on the same social continuum, balancing social “pulls” to aggregate against the ecological “pushes” that force groups to fission. Previous models of savannah elephant sociality construct levels of association and social complexity upwards from the basic mother-calf unit (e.g. Wittemyer & Getz 2007). My results suggest that it may be more appropriate to consider elephant sociality and associations as in dynamic equilibrium between social and ecological influences acting at all levels of grouping, and to explicitly test how these underlie the opportunity costs that elephants are willing to pay in order to maintain social groupings.