In a number of publications serious concern has been expressed about 'the status of lechwe in the Kwando/Linyanti/Chobe system. Concern has also been expressed about the effects of possible water extraction from the Okavango Delta on the habitat of lechwe in the delta. This study was motivated by this concern and was undertaken to provide information that would facilitate the conservation and management of lechwe in Botswana. Continuous field work on the western edge of the Linyanti Swamp began in January 1975 and ended in May 1977. Follow-up visits were made in February/March and September/October 1979. Data were collected on the following: variation in water l6vels, physiognomic and floristic characteristics of lechwe habitat, age determination, food habits, habitat use, distribution,condition growth, reproduction, non-social behaviour, social behaviour and organjsation and population status. From data collected it was concluded that, although there was no indication of a drastic population decline, the prevailing high water levels in the system were causing a downward trend in the population by pushing the animals into poorer quality habitat. The decline in the quality of the habitat available to the population was reflected by high juvenile mortality and reduced fecundity of young females. On the basis of the findings of this study a strategy for the conservation and management of lechwe in the Linyanti Swamp is proposed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1980.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977

Over two hundred and forty strains of limax amoeba including eight potentially pathogenic strains of Naegleria and Acanthamoeba were isolated from a variety of habitats in South Africa. The amoeboid and flagellate stages of all Naegleria strains examined by light microscopy were found to be similar in morphology. Differences were noted in the excystment of Naegleria fowleri, Naegleria gruberi and other limax amoebae. Time-lapse microcinematography has been utilised to study cytokinesis and motility in the amoeboid and flagellate stages of Naegleria fowleri and Naegleria gruberi. A new phenomenon was observed in Naegleria where amoebae attempted cytokinesis after brief exposure to a temperature of 9°C. The amoeboid and flagellate stages of virulent and avirulent Naegleria were found to be similar in surface topology when examined under the scanning electron microscope. Differences were noted in the excystment patterns of various limax amoebae. No structure suggestive of a surface active lysosome was found in any of the cells examined. A comparative transmission electron microscope study of virulent and avirulent Naegleria and other limax amoebae has revealed striking similarities as well as sharply defined ultrastructural differences. Partioles suggestive of a virus were detected in several of the pathogenic Naegleria. Surface-active lysosomes were not found in any of the amoebae examined. Distinct feeding preferences were evident in Naegleria fowleri and Naegleria gruberi when they were tested on a variety of gram-negative and gram-positive bacteria. Differences were noted on the growth of these amoebae at various temperatures. Cell fractions of Pseudomonas aeruginosa affected excystment, encystment, cell division and the amoeba-to-flagellate transformation in Naegleria. Differences were observed in the transformation kinetics of Naegleria fowleri and Naegleria gruberi at 25ºC and 43º C. A variety of inhibitors affected motility and transformation in Naegleria. For the first time, La[3+]ion, a competitive inhibitor of Ca[2+]ion, was shown to inhibit amoeboid motion, transformation and flagellar beating in Naegleria. Electron microscope observation suggested that La[3+]ion acts on the plasmalemma. Material from two suspected cases of primary amoebic meningoencephalitis was examined and cultured but no limax amoebae were isolated. New criteria for the classification of virulent and avirulent Naeglerid. have been advanced. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.

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. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg.

Plovers was compared with particular reference to breeding biology, feeding ecology and habitat preference. Crowned and Blackwinged Plovers coexisted in mixed flocks in grasslands which aided predator detect ion and defence against predators. Lesser Blackwinged Plovers were opportunistic in their use of habitat and were found in habitats ranging from the muddy edges of pans to woodlands. Body size was found to have an important effect on the breeding biology of these birds, affecting incubation behaviour and reproductive pattern. The behaviour of Lesser Blackwinged Plovers differed considerably from that of Crowned and Blackwinged Plovers. Crowned and Blackwinged Plovers appear to constitute a superspecies on account of their behavioural and morphological similarities while the Lesser Blackwinged Plover is possibly closely related to the ancestral stock of the genus Vanellus. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg.

The Bearded Vulture Gypaetus barbatus has experienced a substantial decrease in range in southern Africa during this century. The present population, numbering about 200 pairs, is confined mainly to the highlands of Lesotho and the Natal Drakensberg. In these areas the birds breed successfully (about 0,9 young/pair/year) and non-adult birds about 36% of the total population. constitute The food supply was found not to be responsible for the decline of Bearded Vultures on commercial farming areas in South Africa. The use of poisons by farmers for the control of mammalian predators is considered to be the most important factor leading to the extinction of Bearded Vultures and other scavenging species on farmlands. Adult Bearded Vultures forage over an area of about but were recorded up to 75 km from the nest. They feed exclusively on carrion, at least 75% of which is derived from domestic animals. Present conservation areas are not large enough to contain the entire ranges of any pairs of these birds or to supply sufficient food to support a viable population throughout the year. The birds therefore have to forage over commercial farmlands in South Africa and communal areas in Lesotho. This study, designed to be as broad-based as possible, covers in detail the following aspects of Bearded Vulture biology; age related characteristics, home range and movements, feeding ecology, breeding biology, behaviour away from the nest, energetics, distribution, status and population dynamics and their conservation. In conclusion, recommendations on the management and monitoring of the population are offered. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1988.

The breeding biology and the annual cycle of the Red Bishop Euplectes orix was studied over a two year period in Natal. Some comparative data were also gathered for the related species the Red-shouldered Widow E. axillaris and the Red-collared Widow E. ardens, and additional data from a ringer in Rhodesia have been analysed. The breeding season of these polygynous ploceids coincides with the summer rainy season, and the amount of breeding activity in the Red Bishop appeared to be correlated with the amount of rain during the previous year. Breeding success at the colony studied was low; predation was the major cause of nest failure. In all three species the entire population, including the juveniles, undergoes a complete moult at the end of the breeding season. There is some evidence that the birds may make local movements during the winter dry season. These species are sexually dimorphic, the males being larger than the females. The population sex ratio was Significantly biased in favour of males in the Red Bishop and the Red-shouldered Widow but not in the Red-collared Widow. However, about half the male birds are subadults which do not breed, so that there is an excess of females in the breeding population. Adult males undergo a partial moult at the start of the breeding season and acquire a distinctive nuptial plumage. This is shed again at the post-nuptial moult, and in eclipse plumage they resemble the females. There is a similar pattern of weight change in all three species, with peaks early in the breeding season and again during the moult. The lowest annual weights are recorded during the dry season. The mortality rate of the Red Bishop is not high for a small passerine. The findings of this study are compared with the available information on other members of the genus, and discussed in relation to the evolution of polygyny in the Euplectes species. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.

The biology of bottlenose dolphins from the east coast of southern Africa is investigated. Births occur predominantly in summer, after a one year gestation period. Calves are born at a length of approximately 103 cm and a mass of nearly 14 kg. Neonates are closely attended by the mother, she determines the calf's respiration rate and behaviour as it swims in a negative pressure vortex high on her flank. The initial weeks are marked by the calf's acquisition of swimming skills and its ability to regulate its own respiration rate. Although the calf takes solid food between six months and one year, suckling may continue for as much as three years. Initial growth is rapid but slows with the approach to puberty. Females reach sexual maturity at about ten years of age and may undergo a series of rapid ovulations before fertilisation occurs. Subsequently, the mean ovulation rate indicates a three year calving interval. Males show a mass growth spurt at the onset of puberty, between 10 and 12 years, and reach sexual maturity between 12 and 15 years of age. In both sexes, physical maturity and asymptotic size are reached at about 15 years and maximum life-span is in excess of 40 years. Although a wide variety of fish and cephalopods are taken, the fishes Pomadasys olivaceum, Scomber japonicus, Pagellus bellotti, Trachurus delagoae, and the cephalopods Sepia officinalis and Loligo sp. contribute some 60 % by mass of all prey taken. Different sex and maturity classes of dolphins consume differing sizes and species of prey, implying a partitioning of food resources within the group. Comparisons of stomach volumes with estimates of prey mass and nutritional requirements suggest that calves and lactating females may need to feed more often than other sex and maturity classes. Examination of shark stomachs indicates that shark predation may be an important component of dolphin natural mortality. Four species of shark, the Zambesi (Carcharhinus leucas), the tiger (Galeocerdo cuvien), the great white (Carcharodon carcharias) and the dusky shark (Carcharhinus obscurus) are implicated as dolphin predators. Estimates from the number of these four species caught annually and the frequency of occurrence of dolphin flukes and vertebrae in their stomachs suggest that a minimumof 20 bottle nosed dolphins or 2.2 % of the estimated population in southern Natal coastal waters are killed each year by sharks. Some 32 bottlenose dolphins, about 4 % of the estimated population, are captured in shark nets annually. Calves of two years or less constitute nearly 45 % of the catch, while lactating females make up a further 15 %. An analysis of biological, environmental and physiographic factors associated with each capture, suggest that feeding and probably prey movement and distribution are directly associated with capture. PCB, t-DDT and dieldrin concentrations in the blubber of male bottlenose dolphins increase with age and reach levels that may impair testosterone production. In females, there is an 80 % decline in residue concentrations after the first or second ovulation. Evidence presented suggests that first born calves receive possibly lethal doses of residues within two months of birth. Residue concentrations in dolphins from different geographical areas varied significantly, implying a degree of isolation of sections of the population. Investigation of reproductive parameters indicates that mortality of bottlenose dolphins off Natal probably equals or exceeds the replacement rate. The necessity for and requirements of further research on the natural history of bottlenose dolphins off the east coast of southern Africa are summarised. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.

The phylogeny of the Ammobatini was studied, with regard to the principles of cladistics using parsimony, and the classification is revised. It is concluded that the tribe forms a monophyletic group that comprises six distinct monophyletic genera: Pasite Jurine, Sphecodopsis Bischoff, Ammobates Latreille, Melanempis Saussure, Spinopasites Warncke and Oreopasites Cockerell, of which Pasites, Sphecodopsis, Ammobates and Melanempis occur in the Afrotropical Region. The Afrotropical species of these four genera are revised. Pseudopasites Bischoff and Pseudodichroa Bischoff are synonymized with Sphecodopsis. Pasites includes 17 Afrotropical species, Sphecodopsis 10 species, and Ammobates and Melanempis are each known from a single Afrotropical species. Ten new species are described: Passites nilssoni, P. paulyi, P. humecta, P. gnoma, P. namibiensis, P. somalica, Sphecodopsis vespericena, S. longipygidium, S. namaquensis and Ammobates auster. Thirty-three names are synonymized: they are P. nigerrima (Friese), P. argentata (Baker) (= P. barkeri (Cockerell)); P. chubbi Cockerell, P. nigritula Bischoff, P. peratra Cockerell (= P. atra Friese); P. nigripes (Friese), P. fortis Cockerell, P. subfortis Cockerell, P. stordyi Cockerell, P. voiensis Cockerell, P. altior Cockerell (= P. carnifex (Gerstaecker)); P. natalensis (Cockerell), P. aiboguttatus (Friese), P. ogilviei (Cockerell) (= P. jenseni (Friese)); P. alivalensis (Cockerell), P. rufitarsis (Cockerell) (= P. histrio (Gerstaecker)); P. marshaUi (Cockerell) (= P. jonesi (Cockerell)); P. abessinica (Friese), P. fulviventris (Bischoff), P. rhodesialla (Bischoff), P. apicalis (Bischoff), P. turneri (Cockerell), P.politula (Cockerell), P. indecisa (Cockerell), P. nudicauda (Cockerell), P. bechuanica (Cockerell), P. breviceps (Cockerell) (= P. appletoni (Cockerell); S. rufula (Cockerell) (= S. minutissima (Cockerell)); S. pygmaea (Friese), S. rufescens Bischoff, S. algoensis Bischoff, S. perpunctata Cockerell (= S. aculeata (Friese)); S. leonis (Cockerell) (= S. semirufa (Cockerell)). Keys to the genera and species are provided. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.

A herpetofaunal study was undertaken at the 670 ha Owen Sitole College of Agriculture (OSCA) near Empangeni, Zululand, from 1986 to 1988. Collecting was carried out primarily opportunistically, throughout all seasons. A total of 28 amphibian taxa and 44 reptile taxa, comprising two chelonians, one crocodylid, 13 lizards and 28 snakes, were recorded. A further 11 amphibian and 42 reptile taxa may possibly occur. The majority of amphibians and reptiles display a tropical distribution, often with enormous ranges. Nineteen (68%) amphibian taxa have tropical or quasi-tropical (Poynton 1964) zoogeographical affinities and 33 (75%) reptile taxa have tropical wide ranging or tropical east coast littoral (Bruton and Haacke 1980) zoogeographical affinities. Only one amphibian taxon and four reptile taxa, all snakes, have Cape or temperate affinities. These taxa are marginal in the region, reaching their distributional limits in Maputaland. Niche segregation of amphibians occurs primarily according to water bodies. Vegetation per se does not appear to be important, with the majority of species occurring in a savanna environment; however, three species, Leptopelis natalensis, h. mossambicus and Arthroleptis wahlbergii, appear to be sylvicolous in habits and are restricted to riverine vegetation. The vast majority of taxa are summer breeders, whereas only one, Cacosternum nanum nanum, was recorded breeding in winter too. The syrnpatry of h. natalensis and Hyperolius semidiscus was confirmed in this study, and H. semidiscus and H. argus were shown to behave as good species with specifically distinct calls. Snakes are segregated according to size, mode of life, activity patterns and food. Certain species, such as Naja mossambica, have catholic diets whereas others, such as Duberria lutrix lutrix, Aparallactus capensis and Dasypeltis scabra, are specialists. The lizard fauna is differentiated according to diet, foraging strategies and habitat preferences, including substrate and vegetation. Amphibians are unselective feeders, consuming a variety of insects. Some, namely Xenopus laevis laevis and Pyxicephalus adspersus edulis, have catholic tastes and are even cannibalistic. Snakes and amphibians constitute the main prey items of snakes, whereas most lizards, with the exception of Varanus niloticus niloticus which is a generalist, feed exclusively on arthropods, especially insects. Schismaderma carens, Bufo gutturalis, Hemidactylus mabouia mabouia, Lygodactylus caoensis capensis, Mabuya striata striata, Lamprophis fuliginosus, Causus rhombeatus, Duberria lutrix lutrix and Naja mossambica are attracted to places of human habitation either for feeding or for shelter. Many amphibians benefit from artificial water bodies. No less than 19 taxa were recorded from the fish ponds, the majority of which bred there, possibly because the waters are more stable, permanent and relatively free of predators than natural water bodies. The Leguaan Tick Aponomma exornatum was recorded parasitizing adult Varanus niloticus niloticus, and the Snake Tick A. latum was found on N. mossambica and h. rhombeatus; A. latum, with an extensive subSaharan distribution, shows no predilection for any species of snake. Pentastomids and nematodes were found in a number of snakes (Atractaspis, Telescopus, Psammophis and Causus); the life cycle implications of these organisms are that mammals and snakes are intermediate hosts, though more ecological and experimental evidence is necessary. Python sebae natalens is and Kinixys natalensis, both Red Data Book - Reptile and Amphibian species, are particularly threatened, the first due to slaughter for traditional uses, the second due to agricultural activities and frequent fires. It is recommended that both these reptiles be afforded maximum protection in the 110 ha game park, which is regularly patrolled and which is subjected to infrequent fires. Generally, however, the herpetofauna has fared well at the hands of the local people, testimony to which is the high species diversity. / Thesis (M.Sc.)-University of Natal, 1990.