Thermoregulatory patterns, the use of rest-phase heterothermy, the energetic significance of clustering behaviour, and the role of sunning behaviour in thermoregulation were assessed in the white-backed mousebird Colius colius, an southern African arid zone species. I hypothesised that C. colius makes significant rest-phase energy savings by means of clustering behaviour, and has the ability to reduce diurnal energy costs by utilising solar radiation. I tested these hypotheses using indirect calorimetry and surgically implanted temperature-sensitive telemeters, and by simulating solar radiation in a constant-environment chamber. Rest-phase body temperature (T[b]s) was highly labile, with rest-phase T[b]s of down to 26 °C being recorded. During the rest-phase, T[b] was not regulated with respect to a setpoint temperature, as typically occurs in endotherms. Rather, rest-phase T[b] patterns were characterised by periods of linear decreases (passive cooling) at a rate dependent on ambient temperature and the number of individuals in a group. I did not observe any instances of torpor, as described in the literature. When T[b] depression did occur, it appeared to be the result of passive heat loss, and not the metabolic down-regulation which typically precedes a torpor bout. These findings, together with the phylogenetic position of the Coliidae, raise questions regarding the evolution of torpor. The inability of individual mousebirds to maintain a rest-phase setpoint T[b] suggests that in C. colius the physiological mechanism responsible for the defence of a rest-phase setpoint T[b] is replaced by a behavioural mechanism, namely clustering behaviour. The birds in this study showed a basal metabolic rate 40% below the predicted allometric values, and a circadian amplitude of body temperature (T[b]) of 5.2°C, 195% of the predicted value. The use of linear independent contrasts revealed that these deviations from the expected allometric values are not due to the phylogenetic relationships of the Coliiformes, and hence are likely to represent adaptation. These conservative metabolic traits offer opportunities for significant energy savings and are presumed to be adaptive in the unpredictable habitat of this species. The birds were able to make significant energy savings by means of huddling behaviour. At an ambient temperature of 15°C, the energy expenditure of birds in a group of six was 50% of that of single birds. The energy savings the birds were able to make were dependent on ambient temperature and the number of birds in the group. The ability to lower energy requirements by means of huddling behaviour is likely to be highly adaptive when dealing with low nocturnal temperatures in an environment where food supplies are spatially and temporally unpredictable. When allowed access to simulated solar radiation, individual mousebirds showed 15 - 30% reductions in their energy expenditure, while maintaining a constant body temperature. These reductions in energy expenditure hence represent thermoregulatory savings. My results support the hypothesis that solar radiation may be important in the energy budgets of some bird species. The ability to reduce food requirements by means of absorbing solar radiation is likely to be strongly selected for in the arid areas inhabited by C. colius, which are characterised by large circadian fluctuations in ambient temperature, in addition to resource unpredictability. Thermoregulation in C. colius appears to involve an interaction of behavioural patterns and physiological traits. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Sexual selection is usually invoked to explain the evolution of elaborate epigamic characters in animals. However, the mechanism by which female choice operates is poorly understood, and it is not clear whether female choice is purely aesthetic or related to male genotypic quality. It has been suggested that Moller's fluctuating asymmetry (FA) hypothesis may resolve the 'arbitrary trait'-'good gene' debate. However, tests of this controversial hypothesis have yielded equivocal results. I examined the allometric patterns of FA in the redcollared widow in order to test the FA hypothesis. In addition, I documented intrapopulation variation in trait size to determine whether females could distinguish between males on the basis of ornament size and/or symmetry. Male tail length was found to be more variable in size than other traits, suggesting that sufficient variation exists in ornament size for females to distinguish between males on this basis. In addition, the prediction of the FA hypothesis that ornaments would display higher degrees of asymmetry than non-ornamental traits was supported. However, no significant linear or second-order polynomial relationship was found between trait size and asymmetry for tail, wing and tarsus length. Furthermore, neither tail length or symmetry was correlated with indices of body condition. Although this might suggest that the FA hypothesis is invalid, I argue that the assumptions of the hypothesis are too simplistic for it to hold true for all species without taking the basic biology of the species into account. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

Dragonfly assemblages and their biotope preferences in the National Botanical Gardens, Pietermaritzburg, South Africa were investigated. The information served as background for increasing public awareness and education by designing a dragonfly observation trail. Multivariate analyses of data, classified 20 a priori selected sampling units into four ecologically meaningful biotope types, each with characteristic dragonfly assemblages. These biotopes were: 'waterfall', 'forested river', 'shaded pond/stream' and 'open ponds/dam'. Species-environmental variables correlations were significantly high for six out of twelve, measured environmental variables: pH, percentage shade, vegetation (structural and compositional), ambient temperatures, water temperatures, and water depth. Sunlit ponds/dam had higher species richness and diversity than the other water bodies. The months of November to April were significantly high in species richness and diversity, and were characterized by both rare and abundant, and both localized and widespread species. The winter months (May to October), in contrast, were characterized by only the widespread and abundant species. Questionnaire responses were used to test the popularity of the concept of a dragonfly trail, and showed a high level of awareness and commitment on the part of respondents (visitors to the botanical gardens) across all age groups. There was a strong response to knowing more about dragonflies (using a trail) and to become involved in conserving them. The scientific results, the responses to the questionnaire, and practical feasibility, all indicated that the instigation of a trail was possible. After some preliminary trials, a full trail was designed, which is now being installed by the National Botanical Gardens for the benefit of a wide sector of the public and for heightening public awareness of the need for dragonfly and other invertebrate conservation. This study was partly in response to the IUCN Status Survey and Conservation Action Plan: Dragonflies, and to widen the value and appeal of the botanical gardens, which are an already well-established public asset. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1999.

The African wild dog (Lycaon pictus) was reintroduced into Hluhluwe Umfolozi Park (HUP) in 1980/81 after an absence of over 50 years. A 'hands off' management approach was applied. Although the reintroduction is regarded as successful, the population has not increased significantly and still only consists of a single pack. Various aspects which may affect this population were investigated to compile an active management strategy. Home range analyses identified extensive use of a home range which covered only 22.7 % of HUP and was situated entirely in Hluhluwe Game Reserve. The extensive movements of the dogs within their home range were primarily dictated by the movements and distribution of their prey species, especially nyala (Tragelaphus angasu) and impala (Aepyceros melampus). Forest habitats were preferred, but all available habitat types were utilised extensively by the wild dogs. Space and habitat were both considered to have no limiting effect on this population and HUP has sufficient space and suitable habitat to support a larger population of L. pictus. A number of potentially pathogenic antigens were identified in the population, indicating that it had been exposed to these at some time. Domestic dogs in the areas surrounding HUP were identified as the most likely source of these diseases which pose a threat to the wild dogs. Some genetic considerations are discussed in terms of their effect on the population status and management of the wild dogs. A number of management proposals based on the results of the project were formulated. It is suggested that an active management approach be adopted for the population. This includes managing it as part of a metapopulation which primarily involves the exchange of genetic material among similar wild dog populations on a regular basis. The immediate supplementation of the population with new genetic material is proposed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

Considering the high rate of endemism in Madagascan organisms, which are mostly restricted to forest ecosystems, and the accelerating rate of deforestation affecting the island, it is critical to understand the effects of forest fragmentation on Malagasy biota to allow for better management of species within ecosystems. Ecological and human-induced changes have led to the disappearance of forest from vast areas of the island, including on the central High Plateau. The Ambohitantely Special Reserve, located on the central High Plateau at 1500 m asl, was selected as the study site for research on the effects of forest fragmentation on forestependent bird species in Madagascar. The Ambohitantely special Reserve covers 5600 ha of which 50% are natural forest, 35% are anthropogenic grassland savannah and 15% are exotic plantations. The forest, described as East Malagasy moist montane forest, is 2737 ha in area, of which 1487 ha are comprised of 513 forest fragments scattered around the largest block totalling 1250 ha. To investigate the effects of forest fragmentation on forest-dependent bird species, seven forest fragments were selected, ranging from 0.64 ha to 136 ha, in addition to the largest block, referred to as the control site. The bird species composition and relative abundance in different-sized fragments were assessed in reference to the control site, by using a combination of two standardized sampling methods: mistnetting and point-counts. A total of 1804 mistnet-days were accrued, 1026 in the control site and 778 in the seven forest fragments, leading to the capture of 491 birds of 26 species. A total of 160 point-counts was made at 39 different sample plots totalling 53 h 29 min of censusing, and a record of 30 species. A total of 72 bird species including 54 breeding forest affinities of the avifauna of Ambohitantely were defined with reference to 32 forest sites scattered across Madagascar. The species composition in all fragments are fully nested subsets of the control site and the species distribution in the fragments does not represent random subsets of the control site. The analysis of the bird communities in different size fragments indicates that the occurrence of bird species reflects a regular pattern of species extinction in relation to decreasing size of forest fragment. Species composition is discussed in reference to Ambohitantely's long history of isolation that may have led to extirpation of bird species from this site. The higher bird taxa decrease in number or totally disappear as a result of their ecological specialization. Equally, they are the most affected by edge effects (e. g. Atelornis pittoides). The main ecological trends in disappearance or extinction of species is a decrease in the number of small-bodied insectivorous understorey species and mid- and upper-stratum small-bodied insectivorous and nectarivorous species. Insectivorous species are particularly affected by forest fragmentation and three forest-dependent species found in Ambohitantely Forest are particularly sensitive to forest fragmentation: Newtonia amphichroa, Calicalicus madagascariensis, and Cyanolanius madagascarinus. The biological (flora species composition and forest structure) and the physical (temperature, moisture, and light) changes generated by the fragmentation of the forest have a greater impact on highly specialized foraging guilds and this explains the pattern of current bird species composition in Ambohitantely Forest. The influence of forest fragmentation on the altitudinal migration process is debated and conservation measures such as the establishment of forest corridors are proposed to improve the protection of biota found in the Ambohitantely Special Reserve. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

The small population size of wild dog Lycaon pictus (10) in Hluhluwe-Umfolozi Park (HUP) and the decline in their numbers since 1992, has caused concern for their survival and consideration of further introductions. In the light of many failed wild dog relocation and reintroduction programmes, this study contributes towards an understanding of the ecology of the HUP wild dog pack. Wild dog prey preference was determined from scat analysis and personal observations, and their potential impact on the primary prey species was modelled. The choice of physical habitat features by wild dog and their ranging behaviour within the Park were correlated with the distribution of their primary prey and other predators. To determine the susceptibility of prey to predation in three reserves with different predator diversities and densities, prey vigilance and prey response to playback recordings of predator calls were recorded. The results showed that wild dog preference for females, adult nyala Tragelaphus angasi and juvenile impala Aepyceros melampus, was a function of prey abundance, profitability calculated using a diet choice model, and ease of capture. Based on the overall lack of association of wild dog and their primary prey species and predators, and the overall lack of similarity of wild dog and prey choice of physical habitat features, predator presence was the most important determinant of wild dog ranging behaviour. Prey vigilance differed significantly between reserves and was inversely correlated with predator density. Prey response to predator calls did not differ significantly between reserves but prey did, however, react sooner to those calls unfamiliar to them. Nyala were more vigilant and responded sooner to playbacks than impala suggesting that nyala may experience greater levels of predation pressure. There was no evidence to suggest that the prey preference, habitat preference and ranging behaviour of the wild dog were influenced by the susceptibility of prey to predation. Models of prey population dynamics determined that although the introduction of an additional wild dog pack would result in a reduction of current prey population growth rates and an increase in prey population extinction probabilities, their predicted impact would be slight. Since emigration and population viability were identified as the primary causes of the HUP wild dog population decline, the introduction of two groups of wild dog individuals into Hluhluwe was suggested to boost population numbers and stimulate breeding and dispersal within the Park. The importance of future monitoring and proactive management was stressed to ensure the survival of this valuable species in the Park. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

Rodents cause damage in commercial forests by gnawing at the bark of the trees. It is currently estimated that rodent damage in commercial forestry costs the industry R50 million per annum. The species of rodents which cause the damage are not known, neither is the reason behind this behaviour. Through stomach analysis it has been established that 3 species are involved Otomys irroratus, Rhabdomys pumilio and Mastomys natalensis, however this behaviour is confined to the winter. Chemical analysis of the bark reveals that the percentage concentration of nitrogen varies seasonally. The period of high concentration correlates with periods when the natural food of the rodents is restricted and when bark gnawing is most prevalent. In the past the industry's response to the damage has been to treat the areas with rodenticides. Using standard CMR methods, the two commercially-licensed rodenticides and raptor perches were tested to examine their efficacy as rodent control strategies. It was found that at a lower application of I block of rodenticide every third tree there is little difference in the effectiveness of the rodenticide brands and there is also little reduction in the abundance of the rodents. At a higher application rate of I block per tree, the abundance of rodents is reduced but termination of the treatment results in the rodent numbers quickly recovering, indeed they surpassed their original population numbers within 4 months. Apart from the environmental dangers of applying such concentrations of poison, this is clearly an uneconomic solution. My results indicate that at first planting, the sites should be provisioned with raptor perches at a density of 16 ha⁻². Contrary to accepted policy the perches do not require cross pieces, which add to the expense and offer no advantage in raptor residency time. In areas of very high rodent abundance the provisioning of tree collars provide physical protection to the trees. An additional benefit of the collars is that the collars cause a beneficial microclimate around the tree which enhances its growth rate. When the tree is around 2 years old it should be pruned to a height of I ffi, the slash being left in the inter-row. Results show that trees treated in such a way experience no further attack and the rodents browse on the prunings. As the cost of the perches is reduced and the cost of pruning is non-recurring the recommendations provide an economical and environmentally sympathetic alternative to rodenticide application. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

Invasions of ecosystems by alien species is a worldwide problem. Man, with his constant travelling, introduces organisms to places they have never occurred in before. The introductions may be accidental or deliberate. Some of the introduced organisms become invasive and some of these also become pests. Two aquatic pulmonate snails, Physa acuta (Physidae) and Lymnaea columella (Lymnaeidae), were introduced to South Africa probably through the aquarium industry in the 1940s and have now spread to most of the country's freshwater systems. A third invasive pulmonate, and second physid provisionally called Aplexa cf. marmorata, has recently been found in South African freshwaters. Comparison between A.. cf. marmorata found in Durban and P. acuta from Pietermaritzburg as an example of the genus Physa, confirmed that they belong to different genera and are therefore different species. Features compared were the shell, radula, foot, mantle, male genitalia and sperm morphology. Aplexa cf. marmorata is characterized by its foot having a pointed posterior end with a dark mid-dorsal stripe while that of P. acuta does not have these features. The mantle edge ofA.cf. marmorata has short triangular dentations while that of P. acuta has long finger-like projections. Aplexa cf. marmorata does not have an externally visible preputial gland whereas P. acuta does. The penis of A.cf. marmorata has a lateral opening while that of P. acuta has a sub-terminal outlet. TEM sections of the spermatozoon of A.cf. marmorata showed that it has a maximum of two glycogen helices around the mid-piece while P. acuta is known to have three. A study of the population dynamics of A.cf. marmorata in Durban showed it to produce three overlapping generations within a 14 month period whereas P. acuta has been shown to produce as many as eight over a similar time period. Further comparisons between South African A. cf. marmorata and similar material from the West Indies, Nigeria and St Lucia (KwaZulu-Natal) showed that they shared the same features with the specimens collected in Durban and are therefore considered to belong to the same species , Aplexa marmorata (Guilding, 1828). This species is indigenous to the Caribbean and northern parts of South America. The picture is however complicated by the fact that Dr L Paraense, doyen of the Brazilian school of freshwater malacology, does not recognize the genus Aplexa and redescribed this species under the name Physa marmorata in 1986. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

Ten species of shallow water echinoid are found on the subtropical east coast of South Africa. Although their distributions are patchy, the most common species, Echinometra mathaei, stomopneustes variolaris and Diadema savignyi, are nontheless conspicuous components of intertidal communities on this coast. As little was known about these three species, the overall intention of this study was to provide some fundemental information on their biology and ecology. For the purposes of achieving this aim a life history approach was adopted, where the relative investments by each species in growth, maintenance and reproduction were investigated and compared. These patterns of investment were then related to the habitat occupied by each species, in an attempt to identify the selective forces which may have been implicated in shaping their life histories. It was apparent from the results of investigations conducted between January 1991 and June 1993 that there were distinct differences in the patterns of investment in growth, maintenance and reproduction between the three species. The life history of S. variolaris, which occupied exposed habitats in the lower intertidal, was characterised by a large investment in maintenance, lower reproductive output, slower growth and a longer lifespan, relative to the other two species. In contrast, Q. savignyi, which inhabited less exposed mid-shore pools, had a relatively higher reproductive output, more rapid growth, a smaller investment in maintenance and a shorter lifespan. While selection ln S. variolaris and Q. savignyi appears to favour survival and reproduction respectively, the life history of E. mathaei, a species which also occupies mid-shore pools, was balanced between these two extremes, allocating sufficient resources to maintenance to permit tolerance of harsh physical conditions while still making a moderate investment in reproduction over a lifespan of intermediate duration. The predictions generated by the r-K selection and "bet hedging" theories of life history evolution, were applied in the process of speculating on the selective forces which may have shaped these life histories. However, it was found that neither set of predictions and associated selective forces could adequately explain the observed life histories. Rather, it seemed that the life histories of the three species represented evolved responses to the direct and indirect effects of exposure to wave action and sand movements which dominate the intertidal environment on the South African east coast. In the exposed lower intertidal, unpredictable recruitment, drag and impact forces associated with wave action, which impose limits to body size and necessitate a large investment in maintenance to ensure survival, select for slow growth, low reproductive output and high longevity. In contrast reproduction and growth of species occupying the more sheltered mid-shore pool habitats would be less effected by the demands of maintenance investment or limits to body size. In addition predictable recruitment in the mid-shore, would obviate the need for long life in order to ensure a contribution to future generations. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

Conservation of streams involves an understanding of their physical , chemical and biological entities. SASS5 is a biomonitoring method developed to monitor the habitat quality of a water body. It is based on differential scores attributed to various macroinvertebrate families with varying degrees of sensitivity to anthropogenic impact. This method , however, does not assess impacts on particular species. Odonata are good candidates for study at the species level as they are well researched and males are easily identified . As adults, they are known to be sensitive indicators of both riparian and river conditions. Yet Odonata cannot be an umbrella taxon for all other taxa . Therefore, the main aim of this study is to determine the complementarity of the two metrics (Odonata assemblages and SASS5), establishing whether Odonata assemblages offer additional information on, or insight into, riverine habitat quality as portrayed by SASS5. To accomplish this, certain objectives were addressed . 1) The variation of SASS5 scores and 2) Odonata assemblages between river systems, structural habitat types (open or closed canopies) and compositional habitat types (indigenous or alien vegetation). 3) Whether SASS5 scores vary to the same extent, and, 4) on the same spatial scale (river system and point localities) as Odonata abundance and species richness . The relationship between these two metrics was determined along three rivers in the Pietermaritzburg basin. Sampling units (SUs) with extremes in vegetation structure (sunlight and shaded SUs) and vegetation composition (alien or indigenous) were selected. Using this range of environmental conditions placed environmental extremes on the macroinvertebrate populations at point localities and having three different river systems added the dimension of variation over a broader scale, thus stretching the two metrics to investigate whether both responded similarly or in different ways. Results indicated that both metrics provide a similar portrait of overall river conditions. At the smaller spatial scale, the Odonata assemblage, unlike SASS, was highly sensitive to the riparian vegetation. Odonata species were less sensitive to vegetation composition but differentially sensitive to vegetation structure. However, landscape context is also important, with point localities being affected by the neighboring dominant habitat type. Larval Odonata alone did not provide this information. Overall, aquatic macroinvertebrates and adult Odonata provide a highly complementary pair of metrics that together provide large spatial scale (river system) and small spatial scale (point localities) information on the level of impact of stressors such as riparian invasive alien trees. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.