Masters Degrees (Zoology)

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The performance and spatial ecology of the critically endangered black rhinoceros, diceros bicornis l., population in iThala game reserve, KwaZulu Natal, South Africa.
(2020) Greaver, Catherine Caroline.; Slotow, Robert Hugh.
Ensuring the persistence of populations of endangered species requires an understanding of, and response to, the causes of population declines. Species occurring in small populations are vulnerable to stochastic problems that are environmental, demographic, or genetic in nature, and can reduce survival as much as the threats of habitat degradation. Critically endangered black rhinoceros, Diceros bicornis, populations have declined throughout Africa since 1960, but, more recently, numbers are increasing at a continental level, but remain lower than three generations ago. The south-central black rhinoceros, Diceros bicornis minor is considered critically endangered and are found primarily in protected areas. To ensure the persistence of the species, management efforts have focussed on live-harvesting and translocation of individuals from certain sub-populations to populate additional reserves, whilst monitoring involved collecting demographic data (births, deaths, density, and sex and age structure) that could be used to improve conservation management of this species. This study was initiated to determine population estimates, growth rate, and fecundity over time, as well as sex and age structure and age-specific probabilities of survival, using 18 years (1990–2008) of long-term sightings data from Ithala Game Reserve, KwaZulu-Natal, South Africa. I also wanted to determine if mortality occurrences were associated with social or environmental factors, or as a result of management interventions. There was no significant difference in the sex ratios at birth, although the proportion of females in the population was 0.58. There was strong evidence for density-dependent regulation, with density in conception year a key driver of population ii performance (birth rate). The population does not appear to be at ecological carrying capacity; however, social effects are delaying conception. The model analyses showed that social interactions carried more weight than environmental factors on mortality, with a strong association between mortality and intensity of use, as well as mortality and management removals from the population. The mechanism of density dependence in Ithala Game Reserve is through mortality that is associated with increased social interactions, rather than from resource limitations. To mitigate density-dependent social effects, my study recommends an adaptive management strategy of pre-selecting individuals with known information on their social behaviour and context, before removal from the reserve, so as to maintain stability in the social organization of the population. In the absence of restoring linkages between populations of black rhinoceros, the translocation of black rhinoceros is a primary tool to mimic how meta-population dynamics would play out across the landscape. However, careful monitoring to enhance understanding of social factors, particularly black rhinoceros male behaviour, should be intensified to allow strategic translocation of individuals in such a way that negative density dependent effects are mitigated.
Taxonomic revision and Red List assessment of the ‘red millipede’ genus Centrobolus (Spirobolida: Pachybolidae) of South Africa.
(2021) Mailula, Raesetsa Portia.; Hamer, Michelle Luane.; Munyai, Thinandavha Caswell.
There are over 500 described species of millipedes in southern Africa, as well as a large number of species that have not been discovered or described. One group of poorly studied millipedes is the genus Centrobolus, for which 39 species were previously described. The species in this genus and specimens are difficult to identify based on the existing literature and identification keys. The genus distribution is also not well known, but it is thought that most species have narrow ranges and may be threatened by habitat loss and degradation. This study revises the taxonomy of Centrobolus, and provides detailed species descriptions, an identification key and illustrations of the main characters. The distribution of each species is updated. An assessment of the threat status of each species according to the IUCN Red List criteria is also carried out. The study used specimens deposited in Iziko and KwaZulu-Natal (Pietermaritzburg) Museums as well other material previously collected through field work. A total of 826 specimens were examined representing 28 Centrobolus species. Male gonopod structure, distribution of tarsal pads in male legs, colour pattern, female vulva structure and body sculpturing including scobinae were examined and illustrated. Where necessary, specimen localities were georeferenced and maps showing species’ distributions were produced. The IUCN Red List categories and criteria were used to assess the threat status of each Centrobolus species. Four possible new species have been identified; three of these are from KwaZulu-Natal, and the fourth is from the Eastern Cape. The two previously described subspecies are considered to be distinct species. The Red List assessment categorised most species as Data Deficient because of the poor knowledge of distribution, or Least Concern because the species are relatively widely distributed, or they are in less accessible and sparsely populated areas. Twelve species are considered threatened and this include nine Vulnerable and three Endangered species. Key areas for future research include additional surveys both to increase knowledge of distribution and habitat preferences, and to provide material for molecular studies.
The present ecological status of the blue wildebeest (Connochaetes taurinus taurinus, Burchell, 1823) in the central district of the Kruger National Park.
(1985) Whyte, Ian John.; Hanks, John.; Joubert, S.C.J.
Abstract available in PDF.
Drivers of bat fly diversity and prevalence of six Rhinolophus bat species in southern Africa.
(2016) Staegemann, Michael William.; Schoeman, Marthinus Cornelius.
Demographic and ecological characteristics render obligate cave roosting bats highly susceptible to infestation by ectoparasites. However, the patterns and factors of ectoparasite loads among bat host species are understudied, particularly in the Old World. I tested predictions of habitat heterogeneity, host sex, body size hypotheses to explain parasitic bat fly (Streblidae and Nycteribiidae) abundance, morphospecies richness and prevalence on six Rhinolophus bat species in southern Africa. I sampled and classified 930 bat flies to six morphospecies (3 streblids and 3 nycteribiids) captured on 333 bats at 20 sites in eight biomes. In support of the habitat heterogeneity hypothesis, there were significantly positive relationships between habitat heterogeneity and bat fly abundance, morphospecies richness and prevalence. In support of the host body size hypothesis, there were significantly positive relationships between host body condition and bat fly abundance, morphospecies richness and prevalence. By contrast, there was little evidence that parasitic flies preferred either male or female bats. Recursive partitioning analysis showed that the most significant predictor of bat fly abundance and morphospecies richness was habitat heterogeneity, specifically the number of land cover classes surrounding bat roosts. My results suggest that land use and biome characteristics at the meso-scale, and to a lesser degree biotic processes at the local scale, mediate bat fly abundance and morphospecies richness on rhinolophid bats. Specifically, structurally heterogeneous and complex habitats increase the number of niches available for bat species as well as their prey, which, in turn, may favour diverse bat fly populations. Thus, factors responsible for driving bat diversity may also drive bat fly diversity. Future studies should focus on other families of cave-roosting bats, as well as endoparasites, to better understand the mechanisms responsible for ectoparasitism in Old World bats.
Genetic diversity of the Rattus complex (Rodentia: Muridae) in KwaZulu-Natal.
(2010) Nair, Deenadayalan.; Lamb, Jennifer Margaret.; Contraffato, Giancarlo.; Taylor, Peter John.
The rodent genus Rattus is considered to be the single largest genus of mammals in the world. One species of Rattus is usually more dominant than another within a specific geographical area; however within the province of KwaZulu-Natal South Africa current observations indicate that Norway rats (R. norvegicus), black rats (R. rattus) and the indistinct Asian house rat (R. tanezumi) exist sympatrically. DNA sequencing of the cytochrome b and D-loop regions of the mitochondrion were used in conjunction with karyotyping of bone marrow and tissue culture cells to analyse the genetic diversity of selected Rattus populations from KwaZulu-Natal. Comparison of sequence data obtained during the study to reference sequences obtained from the NCBI GenBank revealed three well-supported monophyletic groups in maximum parsimony and Bayesian analyses. These three monophyletic groups indicated the existence of three species of the Rattus complex within KwaZulu-Natal, namely Rattus rattus, Rattus norvegicus and Rattus tanezumi. Analysis of cytochrome b sequence data revealed the presence of 6, 3 and 2 haplotypes in 20 R. norvegicus, 8 R. rattus and 5 R. tanezumi specimens, respectively. The R. norvegicus haplotypes were separated from R. rattus and R. tanezumi haplotypes by 60 mutational steps, while R. rattus haplotypes were separated from R. tanezumi haplotypes by 24 mutational steps. Analysis of D-loop sequence data revealed the presence of 6, 2 and 1 haplotypes in 14 R. norvegicus, 4 R. rattus and 3 R. tanezumi specimens, respectively. R. norvegicus haplotypes were separated from R. rattus and R. tanezumi haplotypes by 15 mutational steps, while R. rattus haplotypes were separated from R. tanezumi haplotypes by 11 mutational steps. Karyotype analysis of specimens revealed that: (1) R. rattus specimens sampled presented with a karyotype of either 2n = 38 or 2n = 40; (2) R. tanezumi specimens sampled presented with a karyotype of 2n = 42 and (3) R. norvegicus specimens sampled presented with a karyotype of 2n = 42 which was very distinct from that of R. tanezumi.
Population genetic studies of Fasciola species from cattle and selected wildlife species in Zimbabwe and localities of KwaZulu-Natal and Mpumalanga provinces of South Africa.
(2014) Mucheka, Vimbai Tendai.; Mukaratirwa, Samson.; Lamb, Jennifer Margaret.; Pfukenyi, Davies M.
The objective of the study was to confirm the species and determine the genetic diversity of the confirmed Fasciola species from cattle and selected wildlife hosts from Zimbabwe and KwaZulu-Natal and Mpumalanga provinces of South Africa. This was based on analysis of DNA sequences of the nuclear ribosomal internal transcribed spacer (ITS) and mitochondrial cytochrome oxidase 1 (CO1) regions. Flukes were collected from livers of 57 cattle at four abattoirs in Zimbabwe and 47 cattle at four abattoirs in South Africa. DNA was extracted from each fluke and 3 wildlife, alcohol preserved, duiker, antelope and eland samples from Zimbabwe. The ITS and CO1 regions of individual flukes were amplified by the polymerase chain reaction (PCR) and sequenced. Aligned sequences (ITS 506 base pairs and CO1 381 base pairs) were analyzed by neighbour-joining, maximum parsimony and bayesian inference methods. The phylogenetic trees revealed the presence of Fasciola gigantica in cattle from Zimbabwe and F. gigantica and Fasciola hepatica in the samples from South Africa. Fasciola hepatica was more prevalent (64%) in South Africa than F. gigantica. Fasciola gigantica was the only species found in Zimbabwe save one sample and an antelope and a duiker which were found to be F. hepatica. This is the first molecular confirmation of Fasciola species in Zimbabwe and South Africa. Knowledge on the identity and distribution of these liver flukes at molecular level will allow disease surveillance and control in the studied areas.
Range expansion of the Hadeda Ibis (Bostrychia hagedash) in Pietermaritzburg, KwaZulu-Natal : an urban environment.
(2014) Singh, Preshnee.; Downs, Colleen Thelma.
Many animal species are typically negatively affected by urbanization; however those species which are not negatively affected are those that can use resources available in urban areas to survive. Hadeda Ibis (Bostrychia hagedash) is an indigenous southern African bird that was previously threatened and associated with wetlands but has become an urban exploiter and increased its population size and expanded its range across South Africa with a pattern following urbanization. The aim of this thesis was to investigate the factors that promoted this range expansion in urban areas particularly in Pietermaritzburg, KwaZulu-Natal. To determine the urban ecology of Hadeda Ibis, flying, foraging, calling and perching activities were compared between summer and winter and between areas differing in proportion of green and grey space. We expected there to be differences between seasons and we predicted that Hadeda Ibis, although an urban exploiter, would show a lower urban tolerance for areas with a larger proportion of grey space. Five suburbs of varying degrees of green to grey space were surveyed in summer and winter for Hadeda Ibis activity. Results indicated that calling behaviours differed between seasons with more calling observed in summer. This may be because of individuals communicating with conspecifics that were more dispersed in summer due to nesting habits while there were more individuals at colonial roosts in winter. There was no significant difference in foraging and flying between seasons or between the different areas. This was probably due to adequate foraging resources being available throughout the year with the maintenance of green spaces in terms of grass lawns kept well watered and short. Hadeda Ibis were observed using urban features to perch but not for nesting or roosting which indicated that although they have a high degree of urban tolerance, they still depend on trees in green spaces for nesting and roosting for their urban persistence and were more common in suburbia than the city centre in Pietermaritzburg. To determine Hadeda Ibis nesting and roosting habits in Pietermaritzburg, we measured roost tree height and analyzed roost and nest location to establish possible roost and nest habitat preference. We expected their roosts and nests to be in close proximity to green spaces, for instance wetlands, and that they would use exotic trees more than indigenous trees. We mapped known nests and roosts onto aerial photographs with a habitat land use layer using ArcGIS and roost tree height was measured. The surrounding habitat types within a radius of 10 km from each roost and nest was analyzed and roost tree height compared. As expected Hadeda Ibis used more exotic trees for roosting and nesting because of availability and there were no differences with roost tree height. The 10 km area around nest and roost locations showed a variety of habitats suggesting that Hadeda Ibis need not nest or roost close to natural habitats like wetlands. This pattern can be explained by the fragmented nature of urban environments where green space is scattered between other urban features thereby providing Hadeda Ibis with nesting, roosting and foraging opportunities throughout the urban area of Pietermaritzburg. To determine the home range and habitat use of urban Hadeda Ibis in Pietermaritzburg, we attached GPS/GSM transmitters to four individuals to track their movements. However all transmitters failed and data were recoverable from only one. Those data combined with general observations of colour ringed individuals, suggested that Hadeda Ibis have a relatively small home range for a bird of its size. We also confirmed that Hadeda Ibis show roost site fidelity. In conclusion, urban areas provide Hadeda Ibis with foraging, nesting and roosting resources required for its urban persistence. Short grass lawns that are well watered are ideal for Hadeda Ibis foraging and exotic trees that are abundant in urban areas provide adequate nesting and roosting sites. The species has also been observed using alternative food sources like garbage and dog food and urban features like swimming pools as a substitute for wetland habitat. The combination of these factors has resulted in Hadeda Ibis having increased its population and expanded its range. Provision of resources factored within urban design and planning may help to conserve species threatened by increased urbanization just as Hadeda Ibis has gone from having low population numbers and being associated with wetlands to urban success.
The rock lobsters (Palinuridae) of South-East Africa, with particular reference to the life histories of Panulirus Homarus and Palinurus Delagdae.
(1970) Berry, Patrick Fleetwood.; Heydorn, A. E. F.
Abstract available in PDF file.
Monitoring the brown wattle mirid, Lygidolon Laevigatum (Hemiptera : Miridae)
(1995) Ingham, Deidre Suzanne.; Samways, Michael John.
No abstract available.
The ecology of Black Sparrowhawks (Accipiter melanoleucus) in KwaZulu-Natal, South Africa.
(2014) Wreford, Erin Paula.; Downs, Colleen Thelma.
Black Sparrowhawks (Accipiter melanoleucus) are a medium-sized raptor found across much of sub-Saharan Africa. Within South Africa their distribution has historically been across most of the east with no distribution across the west of the country. Recently, however, the Black Sparrowhawks of South Africa appear to have undergone a range shift with their range expanding into the west, and in particular into the Cape Peninsula. Much of their new range appears to be into urban and peri-urban areas. The aim of this thesis was to analyse reproductive characteristics as well as range changes and dynamics of Black Sparrowhawks along a rural urban gradient in KwaZulu-Natal. In particular what influences range changes, reproductive success, nest site selection and home range of Black Sparrowhawks was determined. Urbanisation is one of the fastest changing and growing land uses worldwide, generally impacting negatively on fauna and flora community composition, species density and species ranges. Despite this the Black Sparrowhawk is one raptor species that appears to be thriving in urban habitats and has seemingly undergone recent range expansion, largely into urban areas. It was investigated whether Black Sparrowhawks have changed their range over recent years in South Africa. This was determined using data from both of the South African Bird Atlas Projects (SABAP1 and 2) and showed a definite shift and increase in the Black Sparrowhawk distribution. Black Sparrowhawk habitat use in terms of indigenous forest, commercial plantations and urban areas in South Africa were compared. Data from the SABAP2 project was analysed together with land cover types using generalized linear models with binomial errors and a logit link function. These results showed a positive relationship between the probability of encountering a Black Sparrowhawk in areas with tree plantations and in urban areas. However, no significant relationship was found between the probabilities of encountering a Black Sparrowhawk in areas of indigenous forest. Black Sparrowhawks appear to be a common urban species, however it seems they are limited to certain land use areas and this could affect their persistence in the future, particularly in urban areas. Black Sparrowhawks appear to be thriving in urban habitats. Typically known as a shy forest species, they are now frequently seen and heard in urban areas in South Africa during the breeding season. The spatial and environmental factors that influence Black Sparrowhawk nesting sites in urban and peri-urban areas were investigated in KwaZulu-Natal. Our data suggest that Black Sparrowhawks appear to be very selective in nest site selection particularly with respect to nest tree species, tree and nest height, area of greenspace’ surrounding the nest, and associations with water sources, roads and buildings. Black Sparrowhawks show a significant preference for a particular tree height class (20 – 29 m) as well as a significant preference for a specific nest height class (10 – 19 m). Similarly the preference of distance classes to the nearest water sources, buildings and roads all showed a significant selection by Black Sparrowhawks. Nest sites appear to be associated with the alien Eucalyptus sp. Due to ever changing urban habitats and human altered landscapes, as well as the removal of alien tree stands within urban areas, the availability of nest sites and foraging habitats may decline. It is therefore important that we understand the specific needs of such a species in order to monitor their success and initiate management programmes where necessary for their persistence. Black Sparrowhawks appear to be increasing in human altered landscapes, however little is known about their breeding success and characteristics. Consequently their reproductive and resource requirements and trends, as well as overall reproductive success along a rural/peri-urban urban gradient in KwaZulu-Natal were investigated. Over the 2011 and 2012 Black Sparrowhawk breeding seasons the majority of successful nests raised two nestlings. In 2011 Black Sparrowhawk nests had a success rate of 74 % while the success in 2012 was only 41 % which yielded a higher number of unsuccessful breeding attempts, these results were determined by nest observations during the breeding seasons. Nest preparation was done predominantly by the male with incubation then predominantly by the female. An increase in fresh leaf material being brought to the nest as the chick aged suggested that this is more likely due to parasite control rather than showing nest occupancy as has been previously speculated. There is little known about the movements and home range of Black Sparrowhawks, particularly in an urban environment. Consequently the home ranges of both an adult breeding female and a juvenile male Black Sparrowhawk were determined during the 2012 breeding season in Durban, KwaZulu-Natal. Transmitters were attached to the individuals recording their locations at regular intervals between 6h00 and 18h00. An adult female was trapped and had the transmitter placed approximately a week prior to the chicks fledging the nest. Her breeding season home range remained within close proximity to the nest. A juvenile male from the same nest was trapped approximately two weeks after fledging at the point of starting to learn to hunt independently. The data produced a minimum convex polygon (MCP) for the adult female of 0.0025 km2 while the young male remained within an MCP of 0.4554 km2. This pilot study has allowed us to determine a viable method which can be used to obtain Black Sparrowhawk home range information. This method can now be applied to numerous pairs within a population to determine home range overlap, territoriality as well as post natal dispersal. Despite the fact that Black Sparrowhawks appear to be increasing in human altered landscapes and expanding their range, further studies should be built on this pilot study in order to identify the degree of threat this species faces. This will allow for long term management plans to be establish which will facilitate their persistence in South Africa.
Eavesdropping : how do vervet monkeys perceive the alarm calls of other species?.
(2013) Khoury, Robyn E.; Shrader, Adrian Morgan.; Payne, Hallam.
Perceived predation risk has a large impact on how prey species utilise landscapes. In an effort to reduce predation risk, individuals tend to utilise safer areas more than unsafe areas. How perceived predation risk affects the utilisation of landscapes by animals is termed a “landscape of fear”. Vervet monkeys (Chlorocebus pygerythrus) have a landscape of fear that operates in both horizontal and vertical planes. Within this landscape, vervets perceive the safest area to be up in a tree, under the canopy. To reduce predation risk, vervets use various predator-specific alarm calls and have been found to eavesdrop on the alarm calls of other species (e.g. birds). In this study, I explored whether vervet monkeys were able to associate eavesdropped alarm calls with specific predator types (i.e. aerial and terrestrial) as they do with their own predator specific alarm calls. To do this, I first quantified the three-dimensional landscape of fear for vervet monkeys by measuring giving up densities in artificial patches. I then used playbacks of the vervets’ aerial and terrestrial predator alarm calls, the alarm call of a red-backed shrike, and a mixed-species flock mobbing call to manipulate perceived predation risk. By comparing changes in foraging intensity within the patches, I quantified the specific reactions of the vervet monkeys to aerial and terrestrial predators. In addition, I found that the monkeys did not eavesdrop on the red-backed shrike call. However, the vervets did eavesdrop on bird mobbing calls, and associated the calls with the location of the potential treat and reacted as if it was a particular predator type. Specifically, the vervets reacted to mobbing calls played from up in a tree the same way as they did if an aerial predator was present, and calls from the ground as if a terrestrial predator was present. Thus, this suggests that they were able to associate a non-functional referential call (i.e. the mobbing call) with specific information, gathered from the location of the calls, and interpreted it in a referential manner. Moreover, intensity of these reactions (as measured by total feeding effort) indicated that vervets saw aerial predators as a greater threat compared to terrestrial predators. Ultimately, my results suggest that vervets can associate eavesdropped calls with specific predators, and this likely provides a fitness benefit in a dangerous and unpredictable world.
The pest status and chemical control of whitegrubs and cutworms in forestry in the Natal Midlands.
(1995) Govender, Pramanathan.; Miller, Raymond Martin.
The limited availability of land to forestry and the ensuing emphasis on intensive silviculture, developed a renewed interest in soil pests in the establishment of plantations. Ten field trials were planted over three seasons to determine the mortality factors influencing the establishment of commercial eucalypt and black wattle plantations in the Natal Midlands, and simultaneously, to investigate the chemical control of the soil pest component. A complex of indigenous soil pests contribute to an average 22,9 % failure of Acacia mearnsii and Eucalyptus grandis seedlings from reaching full establishment. This pest complex, which includes termites, whitegrubs, cutworms, tipulid larvae, wireworms, millipedes and nematodes, was responsible for an average 12,3 % of the failure of the plantings to establish. In the absence of termites, in shallow humic soils, whitegrubs followed by cutworms were the most frequent and economically important pests. Eucalypts are more susceptible than wattle seedlings to whitegrub damage when planted in marginal sites. Seedlings in the summer rainfall region were most susceptible to whitegrub damage from December to April; and to cutworm damage during the first two months after planting. An average of 398 hectares was annually damaged by whitegrubs and cutworms. The total annual loss in planting costs and the additional costs of blanking over the three year study period were 1,22 and 2,65 million rands respectively. Existing non-chemical control applicable to woodlot forestry is reported. Chemical control as one of the options in the management of whitegrubs and cutworms was evaluated. The controlled release formulations of carbosulfan 10% and chlorpyrifos 10% at 1,0 g active ingredient/tree (a.i./tree), gamma BRC 0,6% dust at 0,06 g a.i./tree and the synthetic pyrethroid deltamethrin 5 % SC at 0,025 g a.i./tree were persistent and effective in controlling whitegrubs, even when applied early in the planting season. Deltamethrin 5 % SC at 0,025 g a.i./tree was also successful in controlling cutworms.
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.
The invertebrates of indigenous forests in Limpopo province South Africa : diversity, biogeography and conservation.
(2004) Horn, Johanna Lynn.; Harmer, Michelle.; Lawes, Michael John.
In this study I investigated patterns of invertebrate diversity in Limpopo Province indigenous forests, in order to highlight forests and taxa of special conservation significance. Invertebrates from seven target taxa were sampled in 11 patches of indigenous forest in Limpopo Province from February 2001 to January 2002, including six forests in the Soutpansberg and five forests in the northern Drakensberg. Selected forests comprise three distinct vegetation subtypes and the target taxa selected were millipedes, centipedes, earthworms, terrestrial molluscs, spiders, scorpions and amphipods. Invertebrates were sampled by active searching of quadrats and line transects and pitfall traps. A total of 11 969 indigenous target group individuals were sampled, comprising 14 orders, 50 families, 86 genera and 142 species (including at least nine new). There was a significant difference in the total invertebrate species richness and diversity of forest patches but results varied considerably when different target group figures were analyzed. With the exception of spiders, the factors influencing total and individual target group richness in forests could not be determined. Introduced invertebrates comprised a large proportion of the species and individuals sampled, but were not shown to affect indigenous fauna. Invertebrate species assemblages were most similar between forests sharing the same vegetation subtype and between forests in the same mountain region. However, each forest patch had unique species and some even had unique families. Limpopo Province forests support high numbers of endemic invertebrates. A total of 47 endemic invertebrate species were sampled, including six site endemics, eight local endemics, nine regional endemics and 24 national endemics. The numbers and scales of endemism varied by target group. Invertebrate species’ distributions in Limpopo Province forests generally support the biogeographic theories of Pleistocene forest refugia and the Limpopo River valley as a radiation barrier, although some important contradictions were found. Local endemism in Limpopo Province forests is likely the product of historical processes. Although some significant relationships were found between surrogate and true measures, single taxon biodiversity indicators, the higher taxon method, morphospecies and land classes could not accurately predict patterns of target invertebrate species richness in Limpopo Province forests. Results show that formal species identification should be used if accurate richness estimates are desired; the use of surrogates is not supported by this study. Conservation of Limpopo Province forests is vital for the preservation of valuable invertebrate communities. No forest sampled in this study can be considered unimportant. Effective forest conservation and management is dependent upon the protection of forests of varying patch size, careful evaluation and control of utilization and the establishment and maintenance of corridors linking isolated forest patches.
The ecology of Nile Crocodile (Crocodylus niloticus) in Pongolapoort Dam, Northern KwaZulu-Natal, South Africa.
(2010) Champion, Gareth.; Downs, Colleen Thelma.
In general Nile Crocodile Crocodylus niloticus numbers in South Africa appeared to have recovered after persecution and eradication attempts during the last century. Within the last decade, however, the future of South Africa’s Nile Crocodiles seems ominous yet again, as they are faced with renewed threats including habitat destruction and/or degradation. The primary Nile Crocodile populations in South Africa, Kruger National Park, Lake St Lucia and Ndumo Game Reserve are all currently threatened as a result of anthropogenic actions. The vulnerability of South Africa’s major Nile Crocodile populations has highlighted the need for further studies on and assessment of other populations in the country. This study was conducted from April 2009 to July 2010 on the Nile Crocodile population found in Pongolapoort Dam. The aim of the study was to obtain baseline data on the ecology of this previously unstudied population, which included obtaining an estimate of population size and structure, the reproductive dynamics and success of the population, general distribution of the population in the dam and seasonal changes in their distribution. The impact of the impoundment on this population was also discussed. Initial surveys from 1981 and 1989 described few crocodiles in the system. Currently Pongolapoort Dam contains a significant Nile Crocodile population that was previously not considered as substantial. A conservative estimate of 273 Nile Crocodiles was determined for Pongolapoort Dam in 2009-2010. A combination of survey methods allowed for a population structure to be gauged and identified as having 116 juveniles (< 1.2 m), 75 sub-adults (1.2 - 2.5 m), and 82 adults (> 2.5 m). Currently the population has a high percentage of juveniles (42 %), suggesting a growing population, with the proportion of adults (30 %) able to sustain a viable population into the future. From the construction of the Pongolapoort impoundment in 1972 the water level has fluctuated and the surrounding landscape has been altered. As a result the Nile Crocodiles residing in the area had to adapt to the ever changing environment. Their general distribution changed after dam wall completion, when the dam began to fill. First distributional change was a movement out of the gorge section into the newly flooded areas. After the Domoina floods (1983) the dam level rose by over 70 % and the crocodiles moved into the current inlet section. The majority of the crocodile population is now found in the inlet section of the Pongolapoort Dam, utilizing the Phongola River in summer months and residing in the inlet section as historical basking sites during the winter months. Investigating reproductive ecology is essential in order to access the population dynamics of an unstudied population, as reproductive output can be a measure of population health. Reproduction and nesting of Nile Crocodiles in Pongolapoort Dam, and in particular determining the effects of the impoundment on these were investigated. No previous reproductive effort had been documented prior to this study. Crocodiles congregated at a major basking site, where the Phongola River entered the dam, during August 2009 with a 576 % increase in numbers. This signalled the commencement of the breeding season. Females with transmitters made short trips upstream during this time. In November, with the first rains, the river rose and the majority of crocodiles moved up the inlet, and females established nests. Three major nesting areas were identified, two of which were located in the river inlet to the dam. Approximately 30 nesting females were identified during the 2009/2010 nesting season. All nesting areas identified had been used in prior nesting seasons. Nests were located on a variety of substrate types, from clay formed through culluvial and fluvial deposits to course river sand. Several of the nests were predated by Water Monitor (Varanus niloticus). Although the number of nesting females was greater than expected, during the study period there was a total recruitment failure of nests along the river due to a flash flood of the Phongola River in January 2010, destroying all nests prior to hatching. As several juvenile crocodiles were found during surveys, this preliminary study suggests that the Pongolapoort Dam Nile Crocodile population has a relatively high potential reproductive out-put, although their annual successes may vary greatly because of loss of nesting sites because of water level fluctuations and predation. It appears that the impoundment has generally had a positive impact on this Nile Crocodile population recruitment although suitable nesting sites may become limited. There appear to be no current threats to the Nile Crocodile Pongolapoort Dam population, however illegal gill-netting and poaching on the dam and surrounding reserves is on the rise and if not prohibited can result in future problems. A second concern is the high abundance of alien invasive plants that dominate the area, most notably in the river inlet section, the Nile Crocodiles main nesting area. The water quality entering the system is unknown at present and should be tested in future studies to assess whether there may be any reason for concern. In general the Nile Crocodile population in Pongolapoort Dam appears to be one of the least vulnerable and most reproductively successful in South Africa at present. The population has increased dramatically as a result of successful reproductive output even with the ecosystem changes as a result of the impoundment of the Phongola River. It is unlikely that the population increase was as a result of immigration from surrounding areas as the dam wall is a substantial barrier between the dam and the lower crocodile population of Ndumo Game Reserve some 70 km downstream. The high number of crocodiles found through all size classes, juveniles to large adults, also suggests that this population has been stably increasing for a number of years and has a sustainable breeding population.
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.
The role of Anopheles arabiensis (Diptera: Culicidae) in malaria transmission and control in Gokwe and Binga districts, Zimbabwe..
(1996) Masendu, Hieronymo Takundwa.; Sharp, Brian Leslie.; Appleton, Christopher Charles.
Opportunistic feeding behaviour and partial exophily make An. arabiensis much more difficult to control by indoor residual spraying than any other vector in the Afro-tropical region. The persistent malaria outbreaks in Zimbabwe despite decades of indoor house spraying prompted this investigation into the role of An. arabiensis in malaria transmission and assessment of the possible impact of this control measure. The study was conducted in the malaria endemic districts of Binga and Gokwe. An. gambiae complex mosquitoes were collected from artificial outdoor resting sites, and from human dwellings by i) daytime hut searches, ii) pyrethrum spray catches and iii) exit window traps. Mosquito components were processed to enable: i) the distinction of An. arabiensis from An. quadriannulatus and An. merus on the basis of the pale band at the junction of the hind leg 3/4 tarsomeres; ii) species identification and scoring of inversion polymorphism on the basis of the X chromosome and autosomes respectively; iii) the determination of blood meal sources using the Ouchterlony precipitin test; and iv) identification of An. gambiae s.l. using polymerase chain reaction (PCR) and enzyme electrophoresis techniques. Entomological assessment of residual spraying included determining: the vector resting densities indoors and outdoors, bioassay and insecticides susceptibility tests. Data were also collected on hut profiles, knowledge-attitudes-practices surveys, and household malaria prevalence . surveys. An. arabiensis and An. quadriannulatus were found in sympatry in Binga and Gokwe, and in addition, An. merus was found in Gokwe. Most species identifications were made using PCR; which was found to have 7.5% and 41.6% levels of error for An. arabiensis and An. quadriannulatus respectively, using the cytogenetic technique as benchmark. The pale band technique yielded > 80% correct identification for An. arabiensis but the extent of overlap in the pale band lengths between An. arabiensis and An. quadriannulatus renders the method unsuitable for distinguishing these two species. Inversions 2Rb and 3Ra were found floating in An. arabiensis, with 60% frequency in the former. The Wright's F statistic value of -0.0416 indicated an excess of heterozygotes, and a state of panmixis in the vector population. No significant differences were observed between 2Rb karyotypes in host choice. Human blood indices among indoor (0.82), exit trap (0.98) and outdoor resting (0.30) specimens suggested exophilic behaviour. This was corroborated by the high fed:gravid ratios of 6.8: 1 and 11.6: 1 in sprayed and non-sprayed dwellings respectively. This was worsened by a high feeder-survivor index (FSI) of 93 % among exit trap specimens. The susceptibility to deltamethrin coupled with residual efficacy nine weeks post-spray indicated the suitability of the insecticide. Rural dwellings were suitably built for spraying but had no mosquito proofing. Personal protective measures are hardly known; sleeping outdoors occurs in Siabuwa. While An. arabiensis bites humans indoors the partial exophily it exhibits is a threat to indoor residual insecticide spraying. An integrated malaria control approach is recommended.
Use of space and activity rhythms of spotted-necked otters in the Natal Drakensberg.
(1995) Carranza, Ilaria d'Inzillo.; Perrin, Michael Richard.; Rowe-Rowe, David Treloar.
The study was carried out in Kamberg Nature Reserve (Natal Drakensberg) from June 1994 to August 1995. Seven spotted-necked otters were fitted with an intraperitoneal radio-implant; radio-tracking was performed by both temporally independent locations and 24h continuous tracking sessions. When active, otters were always found in aquatic habitats, mainly dams, the river or oxbow lakes. Dense vegetation cover, as trees, reeds, and tall grass were preferred while resting. Otters were active both during the day and during the night, with peaks of activity at twilight. The amount of time spent in consecutive activity varied seasonally together with the main prey items exploited. Average home range area was 11.3km², including a stretch of river with an average length of 14.8 km. No intersexual nor intrasexual territoriality was detected. Intraspecific relationships varied with the dispersion and availability of food resources.
Habitat use and feeding ecology of the roan antelope at Weenen Nature Reserve.
(1995) Taolo, Cyril Lebogang.; Perrin, Michael Richard.; Bowland, Anthony Ernest.
The roan antelope Hippotragus equinus equinus, is listed as endangered in the South African Red Data Book. A herd of nine roan were introduced to Weenen Nature Reserve (WNR) in 1988. The herd has since increased to sixteen animals. The aim of the study was to determine those habitat characteristics which influenced the preference or avoidance of the habitat types available at WNR. The extent to which the antelope's occurrence was correlated with certain habitat elements was determined. The roan preferred open woodland on gently undulating terrain. Themeda triandra was found to be the most common grass species in the diet of the roan. Cauline grass species such as Hyparrhenia spp. were avoided in the dry season. Dicots assumed greater importance in the diet in the dry season. Several management practices employed at the reserve were assessed to determine their influence on habitat use by the roan. These practices were not found to be incompatible with the goal of conserving roan antelope in the reserve.
Rodent damage control in commercial forestry in the Natal Midlands, South Africa.
(1996) Taylor, Stuart.; Perrin, Michael Richard.
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.

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