(MSc at the University of Pretoria)
Ligand specificity of uterine oestrogen and progesterone receptors in the sub adult African elephant
A study looking at the ligand specificity of uterine oestrogen and progesterone receptors in the African elephant in view of developing techniques to potentially control the reproductive output of elephants.
Influence of gestation on uterine endometrial steroid receptor concentrations in the African elephant
Estrogen and progesterone receptor concentrations were determined from uterine biopsies obtained from both pregnant and non-pregnant females of African elephants. Concentrations of estrogen and progesterone receptors were inversely correlated to gestational stage with evidence of down regulation of progesterone receptors with progressing gestation.
Download Article (1997)
Download Article (1998)
(PhD at Wits)
Sex and age related distinctions in the feeding ecology of the African elephant
Within the Associated Private nature Reserves of South Africa, plant based surveys on woody species were conducted at the feeding sites of both bull groups and family units of elephants during the dry season. Although similar in terms of plant species composition, the diets of bull groups and family units differed in the plant parts ingested. Chemical analyses of plant and fecal samples support the Body Size Hypothesis according to which bulls maintain diets of lower nutritional quality than smaller bodied females, who may or may not be pregnant. These results support observed sex and age related distinctions in vegetation impact levels and could also drive sexual segregation in elephants.
Download Thesis
Analysis of five year’s annual surveys of trees used as nesting sites found that elephant damage did not directly affect the persistence of the nest over the monitoring period. However, the presence of insects and fungus on large trees were negatively related to their survival, thereby indicating that elephant impact could indirectly facilitate insect and fungus attack and thus potentially shorten the lifespan of a tree. However, a healthy age structure of Acacia nigrescens was found, the tree species most frequently used as the nesting sites for both vultures and raptors, indicating that there is potentially sufficient regeneration of this species to replace the current trees.
Analysis of five year’s annual surveys of trees used as nesting sites found that elephant damage did not directly affect the persistence of the nest over the monitoring period. However, the presence of insects and fungus on large trees were negatively related to their survival, thereby indicating that elephant impact could indirectly facilitate insect and fungus attack and thus potentially shorten the lifespan of a tree. However, a healthy age structure of Acacia nigrescens was found, the tree species most frequently used as the nesting sites for both vultures and raptors, indicating that there is potentially sufficient regeneration of this species to replace the current trees.
Landowners or game reserve management are often faced with the decision whether to undertake consumptive and/or non-consumptive use on their properties. Hunting is a wildlife consumptive use whilst tourism is non-consumptive. The study uses a theoretical model to examine cases where the game reserve management decides on how much land to devote to hunting and how much to tourism or a combination of both. Three scenarios are used to analyze the effects of these decisions: (1) hunting area separate from tourism area but wildlife is shared; (2) hunting and tourism done in the same area; and (3) hunting area and tourism area separated by a fence. The model suggests that the outcome would depend on a number of conditions including which use dominates the economic or ecological aspects of the production process and the main objectives of the game reserve management.
This study on the history of megafaunal fruit dispersion, made use of the GPS tracking data of elephants in the Kruger National Park and the Associated Private Nature Reserves. Elephants’ influence on seed dispersion was studied by determining the distances and areas that they could potentially carry seeds based on their gut retention rates.
