Masters Degrees (Zoology)

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Aplexa marmorata (Guilding, 1828)(Basommatophora : Physidae) : an invasive freshwater snail in South Africa.
(2000) Dana, Pelisa.; Appleton, Christopher Charles.
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.
Arthropod diversity associated with fallen logs and woody litter on the forest floor on a small Seychelles island.
(2001) Kelly, J. A.; Samways, Michael John.
Cousine Island, Seychelles, is of major conservation significance as it is relatively pristine, and apparently the only tropical island over 20 ha with no alien invasive mammals. Such mammals, especially rodents, can impact substantially on arthropod faunas. This study focuses on the arthropods of the island that live in fallen logs and litter. The dominant log species are Pisonia grandis (Summerhayes, 1932), Ficus spp. and Cocos nucifera (Linnaeus, 1952). Stage of decomposition and forest type in which the logs occurred significantly influenced the composition and structure of the assemblages. Young logs were significantly richer in species than older logs, possibly due to the greater resources and more varied microhabitats in the younger logs. Log type was also important for arthropod species richness and abundance. Although P. grandis and Ficus spp. logs did not differ significantly, these two log types did differ greatly from C. nucifera which had a higher arthropod species richness, composition and abundance. However, these differences were only significant for recently fallen logs. As the logs decayed, their arthropod assemblages converged. Nevertheless, each log type had some arthropod species not present in another log type. This is important in terms of conservation, especially in the case of C. nucifera, which, according to one school of thought, should be removed from some Seychelles islands as it is considered an alien invasive. Arthropod assemblages in woody litter differed in composition depending on forest type in which they occurred. These woody litter assemblages were generally dissimilar to those in logs in the same forest type. Leaf litter was extremely poor in arthropod species. Species richness, both in logs and litter, was comparable to figures from temperate lands, possibly because the rich, topical fauna was ameliorated by small island size. As the logs are home to several Seychelles endemic species, their conservation is essential. Furthermore, as they are also the food base of certain threatened Seychelles vertebrates, their conservation is about conservation of a food chain on this unique tropical island.
Aspects of digestion and physiology in Wahlberg's epauletted fruit bat (Epomophorus wahlbergi)
(2012) Mqokeli, Babalwa R.; Downs, Colleen Thelma.
Degradation of forest environments in South Africa have greatly affected both the plants and animals that interact with these plants. It is therefore important to understand plant-animal interactions in forest ecosystems in an effort to develop strategies for forest conservation. Animal dispersal can assist in the restoration of forest plant diversity and consequently animal diversity. Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) occurs in the eastern part of South Africa and is known to feed on fruit, nectar, pollen and flowers. It is an important disperser of various indigenous and alien invasive forest fruit species. Little is known about the benefits these bats get from feeding on fruit. Furthermore, the buccal cavity and lingual adaptations of fruit bats in Southern Africa are unknown. This study investigated morphological and physiological adaptations for frugivory in E. wahlbergi. In particular, the palatal and lingual morphological structures of E. wahlbergi were examined by light microscopy and scanning electron microscopy. The results of this study showed that the morphological structures of tongue papillae in E. wahlbergi were similar to that of other fruit and nectar feeding bats. The structural arrangement of tongue papillae in E. wahlbergi probably allows food to move from the anterior part of the tongue and collect at the median line of the posterior part of the tongue, and thereafter move down to the pharynx. These bats had an elongated tongue, wide, flattened molar teeth, and a hard papillae structure observed on the upper palate at the posterior end of the buccal cavity. This papillae structure has not been described previously; and it appears that it is with this structure, together with the palatal ridges, and teeth that E. wahlbergi crushes fleshy fruit to extract the juices when feeding. Consequently palatal and lingual structures of E. wahlbergi showed morphological adaptations for efficiently feeding on fleshy fruit and nectar. South African indigenous and exotic fleshy fruits available to E. wahlbergi are found to be generally hexose dominant. These bats are suggested to have high glucose intake irrespective of sugar concentration to power their high energy demands due to flight. High glucose intake could result in increased blood plasma glucose levels which are detrimental to mammals of small body size. This study investigated the diel variations in blood plasma glucose concentrations of E. wahlbergi. Epomophorus wahlbergi’s blood plasma glucose concentration was lower (5.24 ± 0.38 mm ol/l) at 18h00 before feeding and increased during/after feeding (8.19 ± 1.24 mm ol/l), however bats appeared to regulate it within limits. Their range in concentrations was higher than the normal mammalian blood plasma glucose concentrations range. Consequently these bats appear to regulate their blood plasma glucose concentration although at a range higher than normal mammalian levels and thus reduce the negative consequences associated with hyperglycemia. The data obtained provide a baseline for comparison with free-ranging E. wahlbergi. Proteins are important in a diet to provide the required nitrogen and amino acids necessary for maintaining body tissues. Fruits, however, appear to have energy-rich but protein-limited foods. Frugivores that feed exclusively on fruit may therefore have difficulties in maintaining their protein requirements since fruits are generally high in sugar content but low in protein content. The importance of protein in the diet of E. wahlbergi was determined by measuring diet intake at varying levels of protein in the laboratory. Epomophorus wahlbergi were offered equicaloric 15 % glucose solutions with varying protein concentrations (2.58, 5.68, 7.23 g soy protein/kg H2O) and a solution with no protein. This was repeated using 15 % sucrose instead of glucose solutions. Epomophorus wahlbergi’s volumetric intake of the respective glucose and sucrose solutions varied among individual bats, with total volumetric intake highest for the solution with no protein (control) and lowest at 2.58 g/kg soy protein concentration solution for glucose and 5.68 and 7.23 g/kg soy protein concentration for sucrose. These bats appeared to prefer sugar solutions without or low protein, and their daily protein intake was relatively low. This suggests they have low-protein requirements, and this relates to their characteristic low-protein fruit available in the wild. Feeding and digestive efficiency has been widely studied in frugivorous and/or nectarivorous birds but relatively few studies have been done on bats, particularly African bats. Feeding on a liquid nectar diet and fruit juices could cause physiological challenges for nectarivores and/or frugivores as they have to balance water and energy intake from this liquid diet. Mammalian kidneys have to eliminate salts and nitrogenous wastes, conserve water during water restriction as well as excrete it when ingested in excess. Morphological renal characters are known to be reliable indicators of urinary concentrating abilities in mammals. Short digesta residence time is a digestive trait that is known to be associated with frugivory and this may be a problem since digestive efficiency is a function of the length of digesta retention time. Histological sections of E. wahlbergi kidneys and small intestines were examined under microscopy to determine water regulation and specialization for sugar absorption respectively. Cortex and medulla length measurements were taken to calculate the medulla: cortex ratio (M/C) and the percent medullary thickness (PMT). The observed M/C ratio and PMT of E. wahlbergi is typical of a mesic species. Epomophorus wahlbergi feeds on a watery diet and does not need to concentrate urine; therefore the medulla and cortex were more or less the same size. Analysis of the histological sections showed that the kidney structure of these bats allows efficient water regulation in a mesic environment. The microvilli of E. wahlbergi intestine were relatively long with a large surface area thus serves the purpose for efficient digestion and absorption of sugars in these bats. Future studies need to be done to determine the mechanisms by which these bats regulate their blood plasma glucose levels, and also determine intake on a selection of fruit in order to broaden research to adaptation of these bats on low-protein diets. This study contributes to a greater understanding of the physiological and morphological mechanisms that may affect fruit intake and consequently dispersal. It will contribute to a greater understanding of plant-animal interactions in southern Africa.
Aspects of nocturnal physiology and behaviour in malachite sunbirds (Nectarina famosa).
(2007) Wellmann, Andrea Erika.; Downs, Colleen Thelma.; Brown, Mark.
Although sleep forms an important part of an animal’s life, there is a paucity of knowledge about sleep behaviour. The function of sleep in birds is poorly understood, even though birds spend a large part of their lives sleeping. Sleep behaviour in passerine birds has not been looked at as extensively as that of non-passerine birds. I looked at the sleep behaviour of three relatively common passerine birds occurring in southern Africa, namely the Malachite Sunbird (Nectarinia famosa), the Cape White-eye (Zosterops pallidus) and the Fan-tailed Widowbird (Euplectes axillaris). By using an infra-red sensitive camera I described basic sleep behaviours at various ambient temperatures, of all three species, such as sleep position and eye closure, and also investigated the incidence of unihemispheric sleep. Individuals of all three species spent most of the night asleep and kept on waking up intermittently throughout the night, with no significant differences between temperatures. Cape White-eyes and Malachite Sunbirds showed an increase in back sleep and a decrease in front sleep at 5oC. Little evidence of unihemispheric sleep was found, suggesting that it is more likely to occur in non-passerines, especially ground dwelling birds. Diurnal birds generally sleep during the hours of darkness. Most male southern African sunbirds have pectoral tufts, although the function of these is not always understood. In male Malachite Sunbirds it has recently been found that they display their pectoral tufts almost continuously throughout the night, whilst asleep. I explored the possible function of this behaviour and suggest that these tufts might be a deterrent to predators, as they look like ‘eyes’ in the dark. A review of the use and occurrence of pectoral tufts in southern African sunbird species is also presented. Blood glucose concentrations of most birds are much higher than those found in mammals and it is still not known how they evade the complications of such high levels. I investigated the change in blood glucose concentrations of Malachite Sunbirds at two different ambient temperatures and at different times of the night and day and explored the possibility that gluconeogenesis might be used by birds to ‘warm up’ during arousal of torpor in the early morning, before daylight. Generally blood glucose levels were fairly high, between 13.6 and 21.4 mmol/L, which was expected. Blood glucose levels were higher at 5oC than at 25oC and generally lower in the early hours of the morning. Therefore I reject the assumption that Malachite Sunbirds use gluconeogenesis as an additional form of heat generation during torpor. It is thought that the difference in the levels of blood glucose might be a function of the cold temperature and the consumption of their nectarivorous diet. This research clearly highlights the need for further studies to be undertaken in the sleeping behaviours and patterns of birds, especially in southern African species. It also shows that more studies need to be done on the use of pectoral tufts in sunbird species and furthermore it is suggested that more research is needed to elucidate the mechanism by which Malachite Sunbirds are able to rapidly ‘warm up’ during arousal, when in torpor.
Aspects of the biology of the caracal (Felis caracal Schreber, 1776) in the Cape Province, South Africa.
(1982) Stuart, Christopher Trevor.; Hickman, G.
Felis caracal, despite heavy hunting pressure, is common and widespread throughout the Cape Province. Caracal are considered to be the principal wild predator of domestic livestock (goats and sheep) by most farmers and hunt clubs. Scat and stomach content analysis, as well as observations, indicate that F. caracal prey primarily on small to medium-sized mammals. The feeding habits of caracal-in different areas varied, according to abundance and occurrence of prey species. Captive animals required an average of 586g of meat each day. Killing techniques varied for different sized prey items. Physical and behavioural ontogeny are described for captive born animals. A technique for determining age of F. caracal was developed from study of known-age captive caracal. Examination of females killed in the wild, captive births, and births which were back-dated indicated that although young were born throughout the year, there was a definite birth peak between October and February with the lowest point being in May/June. Caracal were distinctly sexually dimorphic in size. Six F. caracal (four females and two males) were trapped, fitted with radio-transmitters, and released at the capture sites. Animals were cumulatively tracked for a total of 164 weeks. The mean range was 24,16km². A young adult male covered approximately 138km before settling in a 48km² area. Recommendations are presented for reducing losses of domestic stock by the caracal, based on the principal of removing the problem individual rather than blanket control.
Aspects of the conservation of oribi (Ourebia ourebi) in KwaZulu-Natal.
(2006) Grey, Rebecca Victoria.; Downs, Colleen Thelma.; Kirkman, Kevin Peter.
The oribi Ourebia ourebi is probably South Africa's most endangered antelope. As a specialist grazer, it is extremely susceptible to habitat loss and the transformation of habitat by development. Another major threat to this species is illegal hunting. Although protected and listed as an endangered species in South Africa, illegal poaching is widespread and a major contributor to decreasing oribi populations. This study investigated methods of increasing oribi populations by using translocations and reintroductions to boost oribi numbers and by addressing overhunting. Captive breeding has been used as a conservation tool as a useful way of keeping individuals of a species in captivity as a backup for declining wild populations. In addition, most captive breeding programmes are aimed at eventually being able to reintroduce certain captive-bred individuals back into the wild to supplement wild populations. This can be a very costly exercise and often results in failure. However, captive breeding is a good way to educate the public and create awareness for the species and its threats. Captive breeding of oribi has only been attempted a few times in South Africa, with varied results. A private breeding programme in Wartburg, KwaZulu-Natal was quite successful with the breeding of oribi. A reintroduction programme for these captive-bred oribi was monitored using radio telemetry to assess the efficacy of such a programme for the oribi. As with many reintroductions of other species, this one was not successful and resulted in many mortalities. However, many variables have been identified that contributed to the failure of this programme and they can be adapted to increase the chances that captive breeding and reintroduction be a viable conservation tool for oribi. Besides captive breeding and reintroductions, the translocation of wild animals can also be effective in sustaining wild populations. Translocations usually appreciate a higher rate of success than reintroductions. A translocation of wild oribi was attempted in this study. This involved the translocation of four males and eleven females and a year-long monitoring programme. This translocation proved to be extremely successful in establishing a sustainable wild population of oribi with few mortalities and several births. However, such translocations can only be attempted when there is suitable habitat and high security from poaching. One source of oribi for the translocation part of the study was from a housing estate that had a high density population of oribi. The existence of such a thriving population of animals on what is often a controversial type of development led to a case study investigation. Housing developments are increasing in size and in numbers in South Africa, and are rarely held accountable for the destruction caused to local habitat or wildlife. This case study used this housing estate as an example of development and conservation cooperating and enjoying the success of a thriving population of endangered oribi. Many variables have been identified that contribute to the success of this venture and that could be used as a requisite for planned housing developments in the future. In particular, clustering of houses to leave open wild areas that are managed ecologically. Finally, the issue of illegal hunting was identified as a very serious threat to oribi conservation. Using surveys, residents of rural settlements and landowners were probed about this issue so that a demographic profile of hunters could be created. This profile could then be used to make recommendations on ways to slow the spread of illegal hunting as well as educate hunters and conservation laws. The results showed that many rural people hunt on a regular basis and most hunt with dogs. It also III showed that there is a high level of ignorance amongst these people on the laws concerning conservation and wildlife species. It was concluded from this study that captive breeding and reintroduction of oribi might be a way to enhance wild populations, but might be more useful in creating public awareness. Translocation, on the other hand, was extremely successful as a way of saving doomed populations and augmenting stable ones. However, it requires suitable and protected habitat. Using housing estates as havens for endangered species is an option but only if the right legislation is passed and cooperation demanded with large portions of land remaining undeveloped. Addressing illegal hunting is the most important, and possibly the most difficult hurdle for oribi conservation besides habitat destruction. Finally, recommendations for oribi conservation and management were made based on the results from this study.
Avian fruit selection and sugar preferences.
(2010) Ally, Ebrahim.; Downs, Colleen Thelma.
It has been suggested that fruit features such as nutrient content, size and colour have co-evolved with dispersal agent behaviour, physiology and morphology. Avian nectarivore feeding ecology is relatively well studied; however, less is known about fruit selection in avian frugivores. Previous work highlights the importance of individual factors that contribute towards fruit preferences, but few studies bring these factors together. Consequently the aim of this dissertation was to attempt this in terms of frugivory by investigating behavioural, physiological and morphological aspects of fruit selection in generalist avian dispersers. This was achieved by manipulating the nutritional content, size and colour of fruits (artificial fruits) under controlled conditions. The first part of the dissertation addresses physiological aspects of fruit selection in Red-winged Starling Onychognathus morio, Speckled Mousebird Colius striatus and Dark-Capped Bulbul Pycnonotus tricolor. Assimilation efficiency of birds fed glucose and sucrose diet treatments of varying concentration was observed. All study species showed high apparent assimilation efficiency irrespective of artificial fruit sugar concentration and type (with the exception of Red-winged Starlings on an all sucrose diet). The second part of the dissertation addresses behavioural aspects of fruit selection in the same three species by observing selective preferences between glucose and sucrose fruits of varying concentration and molarity. While Mousebirds displayed no preference for any of the diet treatments, Bulbuls occasionally favoured glucose diets over sucrose diets and Starlings always favoured glucose diets over sucrose diets. Another behavioural aspect of fruit selection was addressed in the third part of the dissertation. Colour preferences of Red-winged Starling and Speckled Mousebird were observed. Although study species did not conform to trends by favouring black and red fruits, they did show avoidance of green fruits and (Starlings) presented evidence of learning. A morphological aspect of fruit selection is presented in the fourth part of the dissertation. Starlings, Bulbuls and Mousebird beak morphology was measured to investigate if this has an effect on fruit size preferences. Starlings with the largest beak dimensions were more selective of fruit size classes than Bulbuls and Mousebirds which displayed the importance of feeding method (thrashing/swallowing/mashing) to compensate for larger fruit sizes. The final section of this dissertation is a synthesis of the observed behavioural, physiological and morphological aspects of fruit selection in Red-winged Starlings, Dark-capped Bulbuls and Speckled-Mousebirds.
Biodiversity of spiders (Araneae) in a savanna ecosystem and the processes that influence their distribution.
(2000) Whitmore, Cheryl.; Slotow, Robert Hugh.; Crouch, Tanza.
I describe the spider biodiversity for a savanna ecosystem, assess sampling techniques, investigate surrogate measures of species richness and measure the biotic and abiotic processes affecting spider diversity. Spiders were sampled at Makalali Game Reserve, Northern Province, South Africa from February to December 1999 using pitfall traps, sweep netting, beating and active searching. A total of 4832 individuals from 268 species (14 potentially new), 147 genera (8 endemic and 2 new records for South Africa) and 37 families (1 new record for South Africa) were recorded. There was no overall significant difference in spider diversity among different physiognomic habitat types. However, analysing the results at a functional group level revealed that the web builders were significantly affected by the habitat type. Mopane woodland habitat type had the greatest number of web builders and general bushveld the least. Sweeping and active searching sampled the greatest number of individuals and species respectively. I recommend a combination of at least beating and active searching, which together sampled the highest number of unique species, for efficient and cost effective surveys. There was a significant relationship between the spider species richness and other invertebrate richness. However, the relationship is not significant when functional groups are considered separately. There was also a significant relationship between the number of species and families and species and genera. However, species level identifications remain ideal for conservation purposes. Inexperienced participants significantly overestimate the number of species. The use of surrogates is not supported by the work conducted in this study. It is still unclear what biotic and abiotic processes or combination of processes influence spider diversity patterns at the local scale. Different spider functional groups are significantly influenced by different factors. However, habitat diversity (branches and vegetation density) was the most common factor influencing spider diversity . Predicted diversity (modelled using GIS and beta-coefficients from multiple regression analyses) was higher than measured diversity values. While further research into the role of other environmental variables is clearly required, current reserve management should aim to maximise microhabitat structural diversity.
The biogeography of forest birds in the Limpopo Province, South Africa.
(2003) Forbes, Dale.; Lawes, Michael John.
Forest assemblage composition is determined by local ecological (e.g. patch area, species interactions), landscape (e.g. patch connectivity) and regional (e.g. historical change in forest distribution) processes. I investigated the relative effect of these processes on bird and frog assemblage composition in two isolated archipelagos of Afrotemperate forest in the Limpopo Province. The linear relationship between local and regional species diversity suggests that forest bird assemblages in the Limpopo Province are unsaturated. In addition, 66% of bird species and 42% of frog species in southern African forests are generalist species (i.e., forest associated as opposed to forest dependent), suggesting that matrix species have invaded forest assemblages. I thus argue that forest bird and frog assemblage composition is primarily determined by regional (historical) processes and that local ecological processes play a relatively minor role. Forests in the Limpopo Province were eliminated by major climatic changes during the Quaternary with major forest expansion only in the last 6000 years. Limpopo Province forest assemblages have thus established fairly recently. No forest dependent frogs and one forest dependent bird have established in the Limpopo Province forests from the relatively proximate forests in eastern Zimbabwe. This suggests that the Limpopo River catchment has acted as a significant barrier to the dispersal of forest vertebrate faunas. Cluster analyses showed that the forest bird and frog assemblages are essentially Afrotemperate and South African in origin with all forest dependent frogs and 97% of forest dependent birds occurring in the KwaZulu-Natal scarp forests. In addition the most important environmental gradient of change in the southern African forest bird faunas was the geographical distance from northern KwaZulu-Natal. This gradient is congruent with a major northward radiation of faunas from the KwaZulu-Natal scarp into the Limpopo Province. As a result the Limpopo Province forests have low biodiversity values compared to the KwaZulu-Natal scarp because forest frog and bird faunas are largely derived from the latter region. However, the importance of the Limpopo Province forests lies in their protection of threatened vertebrates as well as in providing landscape heterogeneity and ecological services to the surrounding matrix. Soutpansberg forest bird assemblages appear to be more robust and resilient and comprise a significantly greater proportion of forest associated species than those of the Limpopo Province Drakensberg. This is likely to be a consequence of more severe climatic extinction filtering of these faunas caused primarily by the proximity of the Soutpansberg forests to the arid Limpopo valley during the development of these forests. Consequently, regional and historical processes have played a relatively greater role in determining forest bird assemblages in the Soutpansberg than in the Limpopo Province Drakensberg and species richness in the former region was not significantly affected by local ecological processes (including forest area, isolation and habitat heterogeneity). Forest area and habitat heterogeneity did, however, affect forest bird species richness and abundance in the Limpopo Province Drakensberg where the relatively lower importance of regional processes (compared to the Soutpansberg) has combined with anthropogenic disturbance of smaller forests to increase the influence of local ecological processes. However, the role of local processes in determining local species richness is likely to increase in both archipelagos if the current rates of anthropogenic change and disturbance to forests are sustained. Forests greater than 138 ha (minimum critical patch size) are needed to avoid an island effect on bird species richness in the Limpopo Province Drakensberg. However, the long-term conservation of vertebrate assemblages in Limpopo province forests depends upon the successful conservation of evolutionary and landscape processes. This can best be achieved by maximising forest connectivity and landscape heterogeneity through the protection of both riparian corridors and forests of all sizes. The maintenance of historical dispersal routes, in particular connectivity along the escarpment with the scarp forests of KwaZulu-Natal, is important. This would require the protection of forests on the KwaZulu-Natal scarp and along the entire northern Drakensberg escarpment.
Biology of the Grey-headed gull Larus cirrocephalus in South Africa.
(2006) McInnes, Alistair McIntyre.; Piper, Steven Edward.; Allan, David G.; Underhill, Leslie Gordon.
The biology of the Grey-headed Gull was studied between 2004 and 2005 in South Africa's Gauteng, KwaZulu-Natal and Northern Cape provinces. Grey-headed Gulls have a widespread but patchy distribution in South Africa, occurring both inland and at the coast. Their largest population is centred on Gauteng, where the species appears to be a relatively recent colonizer and where the current breeding population is estimated at 2185 breeding pairs (the largest in South Africa). There is evidence that the species has also increased in other parts of South Africa, especially at Port Elizabeth in the Eastern Cape. The majority of coastal birds are found in KwaZulu-Natal and there is strong evidence for regular movements of adult birds between Durban and Lake St Lucia. By contrast, little evidence was found for a putative large-scale, regular movement between Gauteng and KwaZulu-Natal. The breeding biology of the Grey-headed Gull was studied at four sites in Gauteng and at Lake St Lucia's Lane Island during 2004 and 2005. The distance between the Gauteng sites ranges from 1.7 km, between Lakefield Pan and Korsman's Bird Sanctuary, to 25.3 km, between Bonaero Park and Modderfontein Pan. The approximate distance between Gauteng and Lake St Lucia is 460 km. The mean clutch size at all sites was 2.42 eggs and the mean incubation period was 24.9 days. Parental investment in incubation was approximately equal between the sexes while males spent more time in attendance and participated in more aggressive encounters. Empirical growth curves are given for mass, wing, culmen, head and foot morphometrics of Grey-headed Gull chicks. Intraspecific variation in breeding parameters reveal significant differences between sites, including: highly synchronous laying at Lake St Lucia; the largest eggs and fastest growing chicks at Gauteng's Modderfontein Pan (a small, peripheral colony); and the smallest eggs and slowest growing chicks at Gauteng's Lakefield Pan (a large, 'core' colony). Possible reasons for these differences include the relative localities of each site in terms of feeding opportunities, high levels of predation by African Fish Eagle's at Lane Island, and density dependent factors operating on the large colonies within the core population on Gauteng's East Rand. Overall daily egg survival was comparatively high for all sites in Gauteng and low for Lane Island nests. Morphometric, plumage and bare-parts data from a sample of trapped and resighted birds are used to age, sex and determine the timing and duration of moult in the Greyheaded Gull. Six age classes were identified and, for all measurements, males were significantly larger than females. The mean duration of primary moult was 136 days between October and January and there were two waves of secondary moult.
Biology of the greyheaded parrot Poicephalus fuscicollis suahelicus Reichnow.
(2001) Symes, Craig Thomas.; Perrin, Michael Richard.; Downs, Colleen Thelma.
This study was conducted to investigate the biology of the Greyheaded Parrot Poicephalus fuscicollis suahelicus in the wild. Field work was conducted in north-east South Africa in the southern limit of the range of the Greyheaded Parrot during two field seasons. Observations from August to December 1999 in the Levubu region, south of the Soutpansberg mountain range, included months of the non-breeding season when Greyheaded Parrots occur seasonally in the area. Observations in the Luvhuvhu-Mutale river confluence area from March to August 2000 included months of the breeding season. No field work was conducted from January to March 2000 due to exceptionally high rains in the southern African sub-region, that prevented access to sites. The Greyheaded Parrot has a widespread distribution, through southern, south Central and East Africa, that has possible changed little in recent years. However, local populations are likely to have suffered extinctions due to habitat destruction and capture for the illegal trade. Populations in protected areas (Makuya Park and Kruger National Park) are less vulnerable to capture than unprotected areas. The conservation of the Greyheaded Parrot outside of protected areas is highlighted. In various parts of the range of the Greyheaded Parrot seasonal movements occur in response to food and nest site availability. Nest sites are possibly limiting in certain parts of its range due to habitat destruction. During post-breeding flocking, the occurrence of larger flocks, possibly family units (mean ± S.E = 4.7 ± 0.2), is common, when birds wander in search for seasonally available food sources. During this period density of Greyheaded Parrots is 0.28 birds/100 ha. Monogamous pairs are more conspicuous during the breeding season (mean ± S.E = 2.1 ± 0.1) and density estimates are 0.14 birds/100 ha. Egg laying is synchronous between pairs with the timed appearance and flocking of juvenile flocks in spring (August/September). Breeding during the dry season reduces competition with other large cavity nesting bird species. Observations suggest that a skewed sex ratio exists in the population (males:females = 2:1). Daily movements are characterised by a bimodal activity pattern. Early morning movements involve flights to activity centres where the accumulation of numerous smaller flocks occur. Here preening, allo-preening and socializing occur with drinking and/or feeding occurring if food and/or water are available. Thereafter, birds move to regular feeding sites, to feed. Activity is decreased during the heat of the day with birds sleeping, resting and/or preening in the canopies of trees. Late afternoon activities involve increased levels of activity and late afternoon return flights to roosts. Greyheaded Parrots are specialist feeders, accessing the kernel of predominantly unripe fruit. This feeding strategy reduces competition with other frugivore competitors. During any one time few tree species are fed on by the Greyheaded Parrot. Greyheaded Parrots were also observed feeding on bark in the breeding season. Two, almost fully fledged, chicks were found dead in a nest and the causes of death undetermined. Their crops contained numerous pieces of masticated bark and insect parts. Behaviours and vocalizations of the Greyheaded Parrot were similar to that recorded in the Cape Parrot. Recognition of the Greyheaded Parrot as a separate species based on species specific calls and DNA warrants further investigation.
Bird community ecology and composition in afrotemperate forests of the Drakensberg Mountains, South Africa.
(2009) Brocklehurst, Zoë Ann.
Recent research has emphasized the importance of understanding the consequences of species loss, not just for biodiversity per se, but also for ecosystem resilience and functioning. Firstly, a baseline analysis of the effects of a naturally patchy landscape on avian community composition and resilience in a high altitude Afrotemperate forest landscape in South Africa is presented. Bird data from a point count survey of 706 counts at 31 forest sites was used to test whether taxonomic species diversity, functional species richness and density of birds provide insight into community resilience in this historically patchy ecosystem. Bird species richness of forest patches ranged from 17 to 38, with a total species richness of 50. Density was slightly but negatively related to both area and species richness. That density compensation is occurring in these Afrotemperate forests suggests a level of resilience in this system. Following on from this, cumulative species-area and function-area graphs were derived to quantify the loss of forest area or taxonomic bird species richness that this landscape may potentially sustain before ecosystem functioning is negatively affected. The concept that species’ patterns of distribution, abundance and coexistence are the result of local ecological processes has recently been challenged by evidence that regionalscale processes are equally instrumental in shaping local community composition. The historically and naturally fragmented Afrotemperate forests of the uKhahlamba– Drakensberg Park, South Africa, offer an interesting test case. In this study the relative effects of local and regional-scale processes on species assemblages in a naturally patchy forest system were investigated. By employing species-area and species-isolation relationships, and nested subset analyses, we showed that isolation (regional-scale process) had a greater effect on bird species richness and composition than area (local-scale process), though the species-area relationship was significant. Using generalized linear models and an information-theoretic approach to model selection, patch area, the size of the regional species pool as well as the distance to the nearest Eastern Mistbelt forest were all influential in determining local bird species richness in these montane forests. Thus, localities are regionally enriched within the constraints on species occupancy provided by the available habitat.
Bird community structure and convergence in Afromontane forest patches of the Karkloof/Balgowan range, KwaZulu-Natal.
(2001) Wethered, Robyn.; Lawes, Michael John.
Forest fragmentation is caused by the clearing of patches of indigenous vegetation for agriculture, urban development, and other human land uses. Such action results in patches of remnant natural vegetation being surrounded by altered vegetation. I investigate the effects of forest fragmentation and matrix type on avian diversity and assemblage structure in forest patches of the historically fragmented Karkloof / Balgowan forest range, KwaZulu-Natal, South Africa. This study compares the bird assemblage diversity and composition of indigenous forest patches surrounded by commercial forestry (Gilboa complex) with that surrounded by natural grassland matrix (Balgowan complex). Insularisation of Afromontane Mistbelt forest in KwaZulu-Natal has led to loss of species where forest fragments support fewer bird species than comparably sized patches of mainland forest. Small fragments within natural grassland have fewer bird species per unit area than larger fragments. Forest patch area-dependent density compensation is evident and bird assemblages appear saturated. Bird assemblages are characterised by a non-random species distribution pattern where area-dependent processes are dominant, and the loss of species from fragments follows a deterministic sequence. In forests in the plantation-dominated matrix no island-effect is detectable and it appears that forest patches are converging on the same bird species richness, regardless of forest size. No density compensation is evident and bird assemblages are not saturated. The sequence of species loss from forest patches is not as predictable, where a random yet prominent colonisation process exists. As commercial plantations provide suitable habitat cover for movement of forest birds, colonisation of both distant and small indigenous forest patches has been possible, reducing the effects of area-dependent extinction in the forest patches but also resulting in lower species richness in larger patches. Bird species of the Karkloof / Balgowan forest range appear to be fragmentation adapted, and most species are resilient to further landscape change. Certain species are however more prone to local extinction than others. The major predictors of extinction risk are body size, abundance status, and feeding guild. Patch area is the dominant force governing traits in the natural Balgowan complex where larger species with low natural abundance and an insectivorous diet are most prone to local extinction. In the Gilboa complex the nature of the plantation matrix appears to be masking the species natural responses to fragmentation making it difficult to predict which species are most at risk. In order to preserve maximum bird diversity, including high-risk species, the largest intact forest units (≥302ha) must be conserved. Evidently, the nature of the matrix affects avifaunal diversity and distribution in forest patches, and plantations have the capacity to significantly alter bird assemblage structure and composition in indigenous forest patches. Forest fragments must be considered as integrated parts of a complex landscape mosaic, and this study emphasises the importance of understanding landscape-scale processes. Knowledge of ecological and life history traits proves valuable for predicting community level response to landscape change.
The breeding and reproductive biology of the vlei rat Otomys irroratus.
(1990) Pillay, Neville.; Willan, Kenneth Brian Ronald.; Meester, Jurgens Anthonie Jansen.
The breeding and reproductive biology of the vlei rat Otomys irroratus representing three allopatric populations (Committee's Drift, Hogsback and Karkloof) have been studied in the laboratory. The study attempted to establish whether the three populations differed in respect of selected reproductive parameters, and whether the populations are reproductively isolated from one another. The breeding biology of the Hogsback and Karkloof populations was similar while the Committee's Drift population differed from the other two in respect of its smaller litter size and increased interval between pairing and the production of the first litter. Pre-copulatory behaviour differed among populations, with a gradation of increasing intersexual aggression from Hogsback to Karkloof to Committee's Drift pairs. Postnatal growth and development patterns, as well as male reproductive morphology, were indistinguishable among the populations. Attempts at interpopulation breeding were successful. However, some hybrids died before weaning, while those that survived beyond weaning were sterile, particularly those resulting from cross-matings of Hogsback animals with individuals representing the other populations. Interpopulation pairs displayed higher levels of agonistic interaction than did the pure pairings. Growth and development and the reproductive morphology of male hybrids were indistinguishable from those of the parental populations. Interpopulation reproductive variation in o. irroratus appears to be due to a combination of environmental and phylogenetic constraints. 80th pre- and post-zygotic isolating mechanisms would impede gene flow between the populations should they meet in nature. All populations appear to be undergoing active speciation.
Bushbuck ecology and management at Shongweni Dam and Game Reserve.
(2003) Coates, Gregory David.; Downs, Colleen Thelma.; Perrin, Michael Richard.
Msinsi Holdings (Pty) Ltd are considering the introduction of nyala to Shongweni Dam and Game Reserve in KZN. This reserve has a naturally resident population of bushbuck and is located beyond the natural distribution of nyala. Concerns for competition between these two species causing declines in bushbuck numbers elsewhere prompted the present study. The main aim of the present study was to determine some aspects of the ecology of bushbuck within the reserve to assist with decision-making regarding the introduction of nyala and species specific-management of bushbuck at the study site. Bushbuck home range and habitat utilisation was investigated with the aid of radio telemetry and Geographical Information Systems. Estimates of total home range size for males using minimum convex polygons (MCPs) and fixed kernels (FKs) were 33.9 ha and 32.1 ha respectively. Estimates of total home range size for females using MCPs and FKs were 12.0 ha and 13.5 ha respectively. A significant difference between total home range size for gender (male and female) was found but there was no significant difference for age (adult and subadult). Bushbuck typically utilised one core area within their home ranges in which 50 % of their time was spent in approximately 17 % and 11.7 % of their total home range for males and females respectively. A substantial overlap in total home range and core areas between animals was found. Bushbuck showed preference for short thickets and avoidance of low closed grasslands. High reedbeds were utilised in proportion to their availability and tallwoodlands were not utilised by the study animals, but were observed to be utilised by other non radio-collared bushbuck. Habitat preference was a consequence of favourable cover being provided by the structure of the vegetation and the occurrence of favourable foraging species. Bushbuck utilisation of topographical aspect was largely determined by the vegetation type that occurred on the respective slopes. Estimations of bushbuck density and abundance were made using sighting efforts, drive counts, and mark-resightings. Sighting efforts using distance sampling during spring were found to be the most effective in terms of accuracy and man-hour costs, however, these were still not considered to be precise estimations of the total bushbuck population at SDGR, but would be useful for monitoring population trends as a result of the high repeatability and simplicity of the method. Sex, age ratios and nocturnal activity were determined using field classification. The field classification method of age and sex ratio determination used during the present study was found to be very subjective and was therefore suggested to have produced ratios which may be largely biased towards the female component of the population. This in turn also effected the determination of social organization and was evident when compared to previous studies. Bushbuck activity determined from radio telemetry and sighting efforts produced results that corresponded with all previous studies, showing bushbuck to be largely nocturnal, moving much larger distances at night than during the day, and spending most of their time walking and feeding at night. The status and management of synoptic bushbuck and nyala in KwaZulu-Natal was also investigated by means of a questionnaire survey. From the opinions of landowners and reserve managers, the status of bushbuck sharing a sympatric relationship with nyala in KwaZulu-Natal (KZN) appeared to be stable to declining, whereas nyala status was increasing. This trend was suggested to be a result of competition for resources between the two species. Northern KZN recorded a higher frequency of this trend (57.7%, n = 26) compared to the Midlands (35.7%, n = 14), as did Ezemvelo KZN Wildlife Reserves (85.7%, n = 7) compared to privately owned properties (42.4%, n = 33). Very little species-specific management for nyala and bushbuck occurred in reserves that participated in the present survey.
Characterising microsatellite loci in the blue crane (Grus paradisea)
(2007) Meares, Kathleen Frances.; Perrin, Michael Richard.; Burke, Terry A.; Taylor, Tiawanna A.
The blue crane (Grus paradisea) is endemic to southern Africa and has the smallest geographical range of the 15 crane species occurring world-wide. Although this species is still found throughout most of its historic range, it has experienced a significant and rapid decline in numbers over the last 20 years. One factor causing this decline is the illegal removal of chicks from the wild. Permits are required to keep, trade in and breed cranes in captivity. However, birds must be captive bred in order to obtain a permit. Therefore, chicks taken illegally from the wild are fraudulently incorporated into an existing captive population under the pretence that they offspring of a legal captive pair. This study describes the development of a set of microsatellite markers to assist the identification of illegal trade in the blue crane. These markers can ultimately be used to verify the relationship between the offspring and its claimed parents by performing parentage analyses. Forty microsatellite loci were obtained from genomic libraries previously developed in two other crane species and tested for cross-species utility in the blue crane. In addition, 42 loci were developed for this study from a blue crane species-specific genomic microsatellite library, of which 19 were tested for polymorphism in this species. The microsatellite markers characterised here were also tested for their utility in two other crane species: wattled crane (G. carunculatus) and grey-crowned crane (Balearica regulorum). One locus, Gamu007, was found to be sex-linked and therefore excluded from the set of markers. A total of 28 polymorphic loci were tested for the suitability in parentage analysis in the blue crane. Of these, a set of 16 loci were determined to be as suitable for this purpose. These loci were shown to be inherited in a Mendelian fashion in a single blue crane family. In addition, statistical analysis of the loci were identified as exhibiting linkage equilibrium, this was supported by their distant association on a predicted Grus microsatellite map based on the chicken genome. The selected loci were also identified as having a low frequency of null alleles as well as a total first and second parent exclusion power of 0.9999 and 1.0000, respectively. These loci provide a valuable tool for parentage testing in blue crane, and may also be valuable in population genetic studies to assist conservation strategies. In addition, this set may be used to assist legal cases involving the illegal trade in blue cranes upon completion of additional microsatellite marker validation procedures. Twenty-seven loci were polymorphic in the wattled and grey-crowned crane. These could provide a valuable source of micro satellite loci in these species, and could potentially eliminate the need for the development of a species-specific microsatellite library.
Comparative aspects of the thermal biology of African and Australian parrots.
(2006) Burton, Stephen Leslie.; Perrin, Michael Richard.; Downs, Colleen Thelma.
Deserticolous birds inhabit an environment characterised by high ambient temperatures and low rainfall that has low primary productivity. The combination of these factors may lead to the evolution of adaptations that minimise food and water requirements. One physiological adaptation that has been found in many deserticolous birds is the reduction of basal metabolic rate (BMR). I measured metabolic rate in the laboratory using four species of African lovebirds (Agapornis) , and four species of Australian grass parakeets (one Neopsephotus and three Neophema), all similar in body mass. Tests for differences between groups were carried out using both conventional and phylogenetically independent methods. The BMRs of the lovebird and grass parakeet species were not statistically correlated with habitat type. These results confirm the findings of previous studies on the effect of desert conditions on the BMR of parrots. I also found no significant differences in BMR between the species assemblages from different continents. The lack of significant differences in BMR between deserticolous and nondeserticolous parrots supports the idea that birds are "ex-adapted" to living in desert environments. I suggest that the results may have been affected by phenotypic plasticity in BMR, as recent evidence has shown that the scaling exponent of BMR differs between captive-raised and wild-caught birds. To elucidate the effect of origin (captive-raised vs. wild-caught) on the BMR of birds used in this study a large scale analysis of bird BMR data was undertaken. BMR and body mass data for 242 species of birds were obtained from the literature, this study, and unpublished data from various sources. A phylogeny was constructed using molecular and morphological phylogenies from the literature, and analysed using conventional and phylogenetically independent methods. The conventional analysis found significant differences in the scaling exponents of BMR of captive-raised and wild-caught birds. However the phylogenetically independent method showed non-significant differences between these two groups. Conventional analysis of differences between parrots and all other birds yielded significant differences between these two groups, with parrots having significantly higher BMRs than other birds. Again the phylogenetically independent analysis found non-significant differences between these VII two groups. A test of homogeneity of variance between these two groups found significant differences between the variances ofthe two groups, probably due to disparity in sample size and range of body sizes. The conventional and phylogenetically independent tests for differences between captive-raised and wild-caught parrots yielded non-significant results, suggesting that the parrots are not subject to the phenotypic adjustments postulated for all other birds. The lack of significant differences between captive-raised and wild-caught parrots suggests that the analyses of differing habitat type for African and Australian parrots is indeed valid.
A comparative study of agonistic behaviour in hairy-footed gerbils of the genus Gerbillurus (Shortridge, 1942)
(1987) Dempster, Edith Roslyn.; Perrin, Michael Richard.
Agonistic behaviour was investigated by means of staged encounters in three species and two subspecies of deserticolous rodents of the genus Gerbillurus Indiviuals of the species G.paeba paeba, G.paeba exilis, G. tytonis, G. setzeri, and G. vallinus were used in intraspecific and interspecific encounters. Intraspecific territoriality was tested in animals of the same sex G.paeba paeba, G. tytonis, and G. setzeri Analysis of agonistic behaviour permitted identification of four groups of behaviours in most classes of intraspecific encounters. These were "exploratory and solitary", "aggressive", "submissive", and "sexual" behaviours. Males of four species were less aggressive than females in same-sex encounters, and were dominated by females in different-sex encounters; the reverse was observed in G. setzeri. Male G. tytonis and G. setzeri were more tolerant of conspecifics in the territoriality apparatus than females were. In G. tytonis-G.p. paeba encounters a hierarchy emerged: female G.. tytonis were most aggressive, followed by female G.p. paeba, male G. tytonis, and finally male G.p. paeba. In areas of syntopy, G. tytonis displace G.p. paeba through aggressive interactions. A reduction in the level of aggression was exihibited in G.p. paeba-G. setzeri and G. tytonis-G. interactions. This result may reflect the phylogenetic divergence and selection of a different habitat by G. setzeri. G. vallinus dominated G.p. paeba, a result which may have been influenced by past experience and body size, since these two species are syntopic and G. vallinus is larger than G.p. paeba. Cluster analysis of behaviour profiles of different species and sexes revealed two groups, which agree partially with the karyology of the genus. G.p. paeba and G. tytonis formed one cluster, while G. setzeri and female G.p. exilis formed a second group. Male G.p. exilis and G. vallinus were less closely related to both groups. It is suggested that several stages in the process of speciation are represented in species of this genus . A range of social types is exhibited from solitary (G.p. paeba and G. tytonis) through semi-tolerant (G. setzeri and G. tytonis) through semi-tolerant (G. setzeri and female G.p. exilis) to tolerant (male G.p. exilis and G. vallinus). Habitat has a strong influence on social type.
Complementarity between two metrics which use invertebrates to assess riparian conditions of rivers.
(2005) Smith, Jenny.; Samways, Michael John.; Taylor, Stuart.
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.
Conservation of the great white pelican (Pelecanus onocrotalus) and the pink-backed pelican (P. rufescens) in south eastern Africa.
(2006) Bowker, Meyrick Brabbin.; Downs, Colleen Thelma.
Of the seven pelican species found world wide, only the Great White Pelican (Pelecanus onocrotalus) and the Pink-backed Pelican (P. rufescens) are found in Africa. The KwaZulu-Natal province of South Africa supports only one breeding site for each of these species, and both sites represent the southern most breeding colonies for the two species in the eastern region of Africa. These nesting sites fall within the Greater St Lucia Wetland Park, and are afforded a degree of protection, but the same is not true for their foraging and dispersal ranges, and this is a cause for concern. Considerable amounts of data have been collected relating to the status, distribution and breeding efforts of these two species in north eastern KwaZulu-Natal. These data have been collected in a variety of ways by a large number of people. Part of this work represents an attempt to collate and summarise these data to produce an estimation of the status, distribution and breeding success of these species, and to evaluate any trends in their demography. For this south eastern region of Africa I estimated the population for the Great White Pelican to range between 6000 and 9000 individuals, and the Pink-backed Pelican to range between 600 and 900 individuals. Pelicans are highly mobile birds, and this allows them to move considerable distances when they forage, disperse or migrate. They are also long-lived birds with few natural predators. The two pelican species in south eastern Africa have been poorly studied and little is known about their movements, population dynamics and causes of mortality. Habitat change poses a potential threat to pelicans in north eastern KwaZulu-Natal, and habitat loss could drive these species out this region to areas north of South Africa. Much of this north eastern region of KwaZulu-Natal is under threat, mainly through the actions of man. Many areas are naturally unsuitable for pelican foraging, while others are vital to the survival of both species. This study includes an attempt to assess the movements of these two species in south eastern Africa, and to assess the relative importance and condition of the potential pelican habitat in the north eastern KwaZulu-Natal region, focusing particularly on Lake St Lucia and the Pongolo River floodplain. All this is necessary to produce a baseline from which long term predictions of potential pelican species survival can be made. In the absence of documented life tables and environmental variability data, a range of parameters was modelled to generate population viability analyses to simulate possible scenarios. These extinction models show the outcomes of both the deterministic and the stochastic processes. An attempt was also made to identify the factors that impact most severely on the persistence of these two species. The models were most sensitive to variation in survivorship in the first year of life and to the frequency of catastrophes. Changes in these parameters had the greatest effect on extinction risk. In January 2004 Lake St Lucia was reduced to a fraction of its normal capacity as a result of a severe drought in this region of KwaZulu-Natal. After rains in the area the lake level rose and then fluctuated considerably over the next 24 months. During this time the mouth of the estuary into the sea was closed. Great White Pelican numbers and lake levels were monitored throughout this period. This part of the study relates the changes in population numbers to the lake conditions, and highlights the importance of the lake to this avian species. It uses lake levels as a proxy for the conditions of wetlands in the Lake St Lucia region. It also addresses the implications of these relationships to the management strategy of the lake and the conservation of some avifauna. To identify conservation concerns for the Great White and Pink-backed Pelicans it was necessary to generate these baseline estimations. Although much of this information is uncertain for these two species, an attempt has been made here to predict the persistence of these species in north eastern KwaZulu-Natal and to highlight the conservation issues related to their future.

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