Abstract: Pup mortality of southern elephant seals at Marion Island from 1990 through 1999 ranged from 1.6 to 7.3%, averaging 3.8%. Pup mortality was density independent and dismissed as being a major population regulating agent at Marion Island. Juvenile survival over two periods, one during the population decline and the other after the population had stabilised, was assessed and compared using mark-recapture models. Survival was age- but not sex-related and on average, the probability of ...
Abstract: The house mouse (Mus musculus) was introduced to Marion Island by sealers in the early 1800’s and was found abundantly over the entire Island as early as 1818. Despite the abundance of this rodent, little information is known about the invasive house mouse from Marion Island with regards to its genetics and infectious disease potential. Therefore, this study aimed to determine the genetic diversity of the house mouse Mus musculus on Marion Island, as well as the prevalence of thr...
Abstract: Faecal analysis (n = 806 scats) was employed to examine the diet of the Subantarctic fur seal Arctocephalus tropicalis at Marion Island (46° 54’S, 37° 45’E) over a period of six years (April 2000 – March 2006). Identifiable prey remains (fish otoliths, cephalopod beaks) were extracted from the faeces and analyzed. The number of individuals of each prey group identified was determined, and the size of individuals was estimated by applying appropriate regression formulae to m...
Abstract: Life-history theory is based on the notion that resources are generally limited in nature, and that organisms have to allocate these resources amongst different physiological systems to maximise their survival and fitness. Therefore life-history traits such as maintenance, growth and fecundity are very often negatively associated with each other. Since the immune system plays a prominent role in fitness and survival of an organism it often features in life-history trade-offs partic...
Abstract: An analysis of the social behaviour of the roan antelope (Hippotraqus equinus equinus Desmarest, 1804) is presented in this thesis. The study commenced in A herd of 10 animals in an enclosure - 1,6 kilos square and simulating natural conditions - provided ideal opportunities for intensive study: Further observations were made on free-roaming herds in the main roan habitat of the Park i.e. the Lebombo flats north of the Letaba river, The basic discipline regulating the interactions ...
Abstract: The present study investigates trap success, species richness, community structure, capture-recapture ratios, sex, population estimates, climatic effects, diversity, age structure, signs of reproduction, and seasonal changes in the body biomass in seven broad vegetation communities in the Bankenveld Grasslands of Telperion in Mpumalanga Province, and Ezemvelo Nature Reserve in Gauteng Province, South Africa. This study focuses on the effect of past management influences on diversit...
Abstract: Habitat loss and fragmentation drives the current extinction crisis. The processes through which it affects biodiversity, however, are complex and poorly understood. This is especially true for spatially complex regions that comprise a mosaic of land-use types, which often range from protected areas to dense human settlements. In such human-modified landscapes, it is important to determine the extent and impact of changing land-use patterns on biodiversity if we are to meet conserv...
Abstract: Since the energy available to an animal for cell growth, thermoregulation, reproduction and other physiological functions is highly dependent on seasonal environmental changes many small mammals breed seasonally during times when environmental conditions are most favourable for growth and survival of the young. In the tropics and sub-tropics, seasonal rainfall appears to be the main reason for seasonal breeding. In order to maximize fitness, it is important for an animal to be able...
Abstract: Recent studies of heterothermy in free-ranging mammals have revealed that solar radiation is an important variable influencing torpor patterns. The interaction between solar radiation (SR) and arousal costs can be thought of as a continuum from passive increases in body temperature (Tb) (rewarming at a slower rate but energetically less costly), to supplementation of endogenous heat production (rewarming more rapidly but with costs similar to that in the absence of solar radiation)...
Abstract: Foraging forms the cornerstone of an animal’s life-history. An individual's foraging success shapes the demography and health of a population. Understanding key facets of maternal foraging behaviour are crucial to get a holistic picture of both regional and local environmental factors that drive foraging behaviour. This study aimed to measure the maternal foraging behaviour of a marine top predator, the Subantarctic fur seal (Arctocephalus tropicalis), from Marion Island (MI) ove...
Description: Thesis (PhD)--University of Pretoria, 1992.
Abstract: Ten Cape porcupines were radiotracked for one year in a savanna ecosystem at Nylsvley Nature Reserve, Transvaal, South Africa. Social organisation was characterised by family groups comprising a monogamous adult pair and immature offspring. Pair members usually shared the same burrow and utilised similar home range areas. Group size is probably determined by the time of offspring dispersal which is dependent upon population density and resource dispersion and abundance. Total home ...
Abstract: Earlier studies investigated the genetic structure of fragmented or isolated elephant populations by comparing the genetic characteristics of pre-defined populations. This study aimed to determine if there was genetic evidence for spatial structuring in a continuous elephant population in the Kavango-Zambezi Transfrontier Conservation Area (KAZA-TFCA). I sequenced one mtDNA gene region for 88 individuals and genotyped 100 individuals for 10 nuclear microsatellite loci. Bayesian Clu...
Abstract: 4 Summary Seasonal metabolic adjustments and partitioning of evaporative water loss in Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi Student: Ingrid A. Minnaar Supervisor: Prof. A. E. McKechnie Co-supervisors: Prof. N. C. Bennett, Prof. Christian T. Chimimba Department: Zoology and Entomology, University of Pretoria Degree: MSc: Zoology The capacity to thermoregulate over a wide range of TaS is critical for maintaining homeostasis in endotherms. Several aspects of the th...
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