OpenUCT :: Browsing by Subject "Conservation Biology"

Browsing by Subject "Conservation Biology"

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Open Access
A camera trap assessment of factors influencing leopard (Panthera pardus) habitat use in the Nouabalé-Ndoki National Park, Republic of Congo
(2018) Mavinga, Franck Barrel; O'riain, Justin; Mann, Gareth; Breuer,Thomas
Leopards (Panthera pardus) are faced with increasing levels of anthropogenic pressure resulting in population declines across much of their historical range. While there is relatively limited knowledge of leopards occurring in African rain forests, their abundance and distribution is assumed to be impacted by a combination of several anthropogenic factors, most notably loss of prey and habitat conversion. In this study I used a long-term camera trap array that forms part of the Tropical Ecology, Assessment and Monitoring (TEAM) project - Terrestrial Vertebrate (Camera Trapping) Monitoring Protocol, to estimate the species richness of mammals, the relative abundance of leopard prey species and leopard habitat use in the Nouabalé-Ndoki National Park (NNNP) in the Republic of Congo. I investigated the impact of different environmental and anthropogenic factors on leopard occurrence at two camera trap arrays (a northern and southern cluster) within the NNNP using occupancy modelling. While there were no significant differences in mammalian species richness between the two clusters there was a higher relative abundance of the preferred prey species of leopards in the northern cluster. A total of 106 leopard photographic events were recorded across all camera traps and all survey years. The top occupancy model produced an average probability of site use (ψ) over all sites of 0.52 ± 0.14 (SE). The covariate specific β-coefficient estimate suggests that leopard occurrence and detectability were positively correlated with both the relative abundance of the blue duiker (Philantomba monticola) and the distance to the nearest river (β =0.062 ± SE 0.053 and 6.55 ± SE 10.84, respectively). Therefore there was no support for the prediction that the probability of leopard habitat use increases with a higher relative abundance of all potential prey species, nor was there support for the prediction that leopard habitat use would be higher further away from human settlements (β =3.42 ± SE 2.94). 2 Leopard habitat use was higher in the southern cluster which may be linked to the denser understory that would provide greater cover which is important for improved hunting success in leopards. Together, these results suggest that both the prey species and leopards appear to be thriving within the NNNP with limited evidence of anthropogenic impacts despite an increase in commercial logging and the itinerant bushmeat hunting in the peripheral area. It would be worth expanding the existing camera trap arrays to cover a greater spatial extent within NNNP and hence allow for a more detailed analysis of edge effects and to detect the potential impacts of anthropogenic activities which are predicted to increase in selected villages in the periphery of the park.
Open Access
A genetic perspective on leopard (Panthera pardus) conservation units across southern Africa
(2021) Thacker, Thomas M; Bishop, Jacqueline M; Naude, Vincent N
Conservation units are a tool to guide policy such that conservation goals can be achieved. These units should ideally synthesise a wide array of data – genetic, ecological, demographic – to identify the appropriate scales at which conservation actions can then be directed. Despite being the most widespread of all felids in Africa, and facing numerous threats across its range, it has been proposed that the entirety of southern Africa be considered one conservation unit for leopards (Panthera pardus pardus). This proposal does not take into consideration the likelihood of existing population genetic structure across an increasingly fragmented landscape. Further complicating regional leopard conservation is the variability in conservation policies among the geopolitical leopard-range states. Within this single proposed conservation unit, the patchwork of different legislation does not support a unified policy for leopard conservation. Using a population genetic perspective, this study explores and tests the values and shortcomings of southern Africa as a single conservation unit, and explores the importance of leopard range states within the context of conservation units. Parallel investigations of leopard microsatellite genotype data within the framework of a genetic population study spanning eight countries across southern Africa were carried out. This study presents consilient evidence supporting the finding that southern Africa contains six clusters of unique genetic lineages, and as such does not constitute a single genetic unit. Furthermore, it is shown here that the spatial genetic structure that exists does not correlate with the separate geopolitical range states. Leopard range states within southern Africa instead capture varying levels of unique genetic structure and thus are not of equal value with respect to the conservation of genetic lineages. These findings have several implications for leopard conservation across the region. While the data presented here specifically consider a genetic element of conservation units, they do suggest shortcomings in adopting either the entirety of southern Africa as a single unit or separate geopolitical range states as conservation units. The variability in leopard conservation policy across southern Africa is unlikely to sufficiently protect their existing regional genetic structure. If conservation units are indeed a tool to guide conservation policy, then the southern Africa unit for leopards is potentially less effective than a smaller unit whose spatial scale more accurately captures the discrete variation in population genetic structure. Genetic diversity and population structure is an important component of conservation units and should not be neglected. Currently, however, an appropriate framework allowing for conservation policy to be informed at the necessary scale does not exist; although the establishment of Transfrontier Conservation Areas speaks to the growing acknowledgement that conservation needs to evolve beyond the historical confines of geopolitical range states. The evidence presented here further supports the need for a rethinking of existing policy structures.
Open Access
An investigation into the root of two of the main vulture threats: poisoning and belief-based use of vulture body parts in Southern Kenya
(2023) Sekyanzi, Joseph; Thomson, Robert
Vultures are crucial scavengers, removing carcasses, and maintaining the healthy and clean environments. However, their populations are rapidly declining. Six of eight Kenyan vulture species are currently listed as ‘Endangered' or ‘Critically Endangered' on the IUCN Red List. Poisoning caused by human-wildlife conflicts is a major threat to vultures after belief-based use of their body parts. A total of 1387 interviews were administered within Maasai Mara pastoral community. We used the ‘Unmatched Count Technique' to estimate the prevalence and distribution of poison use, and direct questions to characterize poison types, usage and sources, as well as belief-based use of vulture body parts. We found that 54% of respondents reported Carbofuran poison, whereas nearly half (48%) of respondents pointed to agrovets as a major source of all poisons and popularly (84%) smeared on carcasses. The vast majority (75%) particularly use vulture feathers for arrows. Further, 22% fence off their livestock against predatory wildlife. We further explored how predation protection measures used predict individual poisoning likelihoods. None of the five main predation protection measures significantly influences poison use. Both fencing and the use of lights as predator control measures attenuate the poisoning risk. However, herding indicated weak signals for poison use amongst pastoralists. We proposed that an effective vulture poisoning risk reduction should be multi-faceted and collaborative. Regulating and monitoring of the import, local trading and use of poisonous substances. Building partnerships and engagements for more support for local livelihoods. Lastly, upscaling fencing and expanding the communal conservancies. These strategies would curb retaliatory human-wildlife conflicts and poison use against wildlife and vultures in Southern Kenya.
Open Access
An analysis of vegetation pattern and its relationship to NDVI data in the Namaqualand area, South Africa
(2003) Fox, Sarah-Jane Caroline; Hoffmann, Timm; Hoare, David
The Namaqualand area in the North Western Cape, South Africa is unique in comparison to other similar semi-arid areas of the world. It has a high biodiversity and endemism and is consequently an area of interest for a growing number of conservation initiatives. Climate plays an important role in influencing the phenology and growth of the vegetation in the area. Remote sensing techniques were used to reveal the vegetation patterns in the greater Namaqualand area and to relate them to climatic variables. To do this we used the normalised difference vegetation index (NDVI) to relate biomass to altitude, rainfall and vegetation type. Each vegetation type in the area had a unique temporal signature and the climatic variables influencing the summer rainfall and winter rainfall vegetation types differed significantly from each other. Mean annual NDVI was significantly correlated to precipitation and potential evapotranspiration (PET) (r = 0.60, -0.63 respectively). A multiple regression model explained 52% of the variance when Mean Annual NDVI was related to climatic variables. Mean NDVI in August (the month of maximum NDVI in most of Namaqualand) was significantly related to PET and the current plus two previous months of precipitation (r = -0.72 and 0.74 respectively). A multiple regression model for mean NDVI in August and climatic variables explained almost 58% of the variance. The results suggest that NDVI can be used successfully as a measure of growth and phenology in the Namaqualand area and that NDVI could be used in climate models, drought prediction, desertification predictions and a number of other applications in the future.
Open Access
Are Cape Cormorants (Phalacrocorax capensis) losing the competition? Dietary overlap with commercial fisheries
(2018) Masiko, Oyena B; Makhado, A B; Crawford, R J M; Ryan, P G
Characterisation of the diet of pelagic feeders can be regarded as key to development of ecosystem-based management plans, conservation of predators as well as understanding of ecological and trophic interactions. Therefore, long term studies on dietary changes provide insights into the nature of competition and overlap between seabirds and fisheries. The Cape Cormorant Phalacrocorax capensis breeds in the Benguela upwelling region of southern Africa. Its population has decreased by over 50% in the three most recent generations resulting in the species being listed as Endangered in the IUCN Red Data List. Its decline has previously been postulated to result from reduced prey availability. In this thesis, I examined and reported on the spatio-temporal distribution of Cape cormorant diet obtained from different colonies over two decades (1988 – 1997 and 1998 – 2007). I further investigated the extent of overlap between the diet composition and sizes of fish eaten by Cape Cormorants and those caught by the purse-seine fishery. Epipelagic fish (Anchovy, Sardine, Horse Mackerel and Redeye) dominated the diet of Cape cormorants at all sites. Anchovy was the most important in the diet in all years except in 1992 and 1993, when Sardine dominated the diet, and in 2007 when ‘other’ fish species (mainly Cape Silverside Atherina breviceps and Southern Mullet Chelon richardsonii) became the most frequently eaten fish. There were decadal variations in the relative numerical abundance of different prey species. Over both decades investigated, the diet was largely dominated by Anchovy and Sardine, with Horse Mackerel contributing more in the second than first decade. There was, however, an increase in the contribution of Anchovy relative to Sardine from the first decade to the second. At all colonies, Cape Cormorants mostly preyed on Anchovies of sizes between 5 and 11cm. Sardines eaten were larger than Anchovies (mostly 11 – 23 cm), with a bimodal distribution in the first decade. However, the few Sardine eaten in the second decade were smaller (4 – 7 cm) perhaps reflecting the length of fish available. There was an overlap in the distribution of fish sizes caught by the fishery and those found in the diet of Cape Cormorants especially in the first decade. However, increased sampling of Cape Cormorant diet is required to more fully understand the extent of competition and overlap with fisheries.
Open Access
Assessing conservation of a tropical African estuary : waterbird disturbance, livelihoods, and ecotourism
(2011) England, Kate; Hockey, Phil A R
The aim of this study was to evaluate the potential costs and benefits of increasing conservation in the Sabaki River Mouth Important Bird Area. This was achieved by assessing the vulnerability of waterbirds to disturbance from human activity in the estuary, the current use and importance of the area to local livelihoods, and the value (current and potential) of tourism. Waterbird densities and levels of human activity were quantified from 20 September to 25 November 2010 in the intertidal area of the Sabaki River Mouth Important Bird Area on the central Kenyan coast. Household surveys were conducted in the adjacent Sabaki Village from 15 October to 24 November 2010 (N = 190). The current and potential value of ecotourism was investigated by recording visitation rates and interviewing visitors to ascertain their preferences and willingness to pay an entry fee from 5 October to 4 November 2010. Three types of response variables were collected at six sites to characterize relative responses of waterbirds to simulated human disturbances. These were 1) changes in bird density within a 40 m radius of a stationary disturbance (D40); 2) minimum distance of birds from the source of a stationary disturbance (¡Ü 40 m); and 3) the time for 90% of original bird abundance to recover following a mobile human disturbance which caused all birds to flee the immediate vicinity. Disturbance response metrics were estimated from these variables by calculating normalized mean residuals from regressions of density (D40) and minimum approach distance against expected densities measured in the absence of disturbance, for 14 waterbird species.
Open Access
Assessing sea turtle, seabird and shark bycatch in artisanal, semi-industrial and industrial of fisheries in the Cabo Verde Archipelago
(2020) Montrond, Gilson; Ryan, Peter; Jabado, Rima; Wanless, Ross
Firstly, I am very grateful to Birdlife International for the MSc scholarship. I am also very grateful to Professor Peter Ryan of the FitzPatrick Institute of African Ornithology, University of Cape Town, for agreeing to supervise this project and for his guidance, insights and comments on the write-up. I am grateful to Sarah Saldanha, for all the support during this MSc. Many thanks also to Dr Ross Wanless, Dr Rima Jabado and Ruben Rocha for all support, guidance and advice. I want to thank a lot Andy Angel for their accommodation and all support in South Africa. I am grateful to all the UCT staff and BirdLife Senegal Staff for all the support during this study. Many thanks to my family for all the encouragement and support. I want to thank to all the Cabo Verde fishers for their willingness to share their knowledge and experience. Finally, many thanks to the Conservation Biology class of 2019, for all their support.
Open Access
Assessing the anthropogenic threats to vultures in the communal farmlands of Namibia
(2017) Craig, Christie; Thomson, Robert; Santangeli, Andrea
The use of poison by farmers to control livestock predators is a major threat to vulture populations across Africa. In Namibia, there is now some understanding of poison use on commercial farms, but the situation in the communal farmlands is still poorly understood. Using a series of 36 questions, I interviewed 367 communal farmers to assess the prevalence of poison use across the north-west, north and eastern communal land. I found that 18% (SE 2.8) of farmers had killed a predator in the last year and 1.7% (SE 2.1) used poison to do so. I mapped the probability of poison use across the communal regions surveyed and found that poison use is predicted to be higher (up to 7% of farmers using poison) in some areas of the upper north-west. In contrast to previous research, those living adjacent to protected areas did not experience greater losses to predators and as a result were not more inclined to use poison. I found that those using poison are more likely to own greater numbers of livestock, particularly large livestock. Overall, my study suggests that poison use is approximately 12 times lower in the communal areas than on commercial farms. A number of farmers expressed that it is dangerous to use poison on communal land as the risk of non-target impacts is much higher where the land is not fenced and is communally used. Nonetheless there are communal farmers who are using poison and this poses a risk to already threatened vulture populations. Lastly, I did a survey to look at the farmers' local knowledge about vultures, their attitudes towards them and any cultural value that vultures hold. Overall vultures were viewed positively by farmers. The cultural use of vulture parts appeared fairly uncommon, with 9.5% of farmers reporting that they knew of uses. Many farmers indicated that the cultural use of vulture parts was something practiced by previous generations. Feathers were the most commonly used part, mainly for decorations and making arrows. From my assessment, it appears that anthropogenic threats to vultures in communal areas are fairly low. The cultural use of vulture body parts is rare. In addition, poison is used but this practice is not nearly as common as it is on commercial farms. Since poison can have such devastating impacts on vulture populations, I nonetheless advise that reactive and preventative measures are put in place to reduce poisoning and minimise the impact when poison is used. The identified 'hotspots' of poison use will assist local authorities to focus their poison mitigation efforts.
Open Access
Assessing the climate change vulnerability of reptile and amphibian species found in Table Mountain National Park
(University of Cape Town, 2020) Harper, Jack; Cunningham, Susan; Foden, Wendy; Van Wilgen, Nicola
It is increasingly apparent that climate change and its associated impacts are a major threat to the rich biodiversity of the Cape floristic region. As the knowledge of the associations between biological traits and climate change impacts strengthens it has become clear that the assessment of climate change vulnerability is a key consideration in the management of biodiversity. This study is the first attempt to use a trait-based approach at the scale of a single national park, focusing on the climate change vulnerability of reptile and amphibian species found in Table Mountain National Park (including historically present species). The park and its immediate surrounding areas are home to a rich diversity of herpetofauna including the Critically Endangered Table Mountain ghost frog (Heleophryne rosei), Rose's mountain toadlet (Capensibufo rosei) and micro frog (Microbatrachella capensis), and the Endangered western leopard toad (Sclerophrys pantherina). Amphibian and reptile-specific assessment frameworks of biological and ecological traits were designed to identify the species most sensitive and least able to adapt to climate change pressures. Using a combination of a literature review and expert consultation, 18 species of amphibian and 41 species of reptile were assessed. The assessment highlighted that, in the worst-case scenario, 85% of the park's reptile species and 67% of the park's amphibian species are predicted to be highly vulnerable to climate change. The southern adder (Bitis armata), Cape long-tailed seps (Tetradactylus tetradactylus), Table Mountain ghost frog (Heleophryne rosei) and the Lightfoot's moss frog (Arthroleptella lightfooti) were identified as being the species most vulnerable to climate change within their respective taxa. All three of the Critically Endangered amphibian species were identified as having both high sensitivity and low adaptive capacity to climate change. Among the focal reptile species, climate change vulnerability was independent of current IUCN Red List status, highlighting that species currently not identified to be under threat by other anthropogenic pressures could imminently become threatened by climate change. Spatiallyexplicit presentation of the assessment output will help prioritise the management of areas within Table Mountain National Park that contain a high diversity of climate-vulnerable species. By reducing the threats from other human-associated impacts to these species, and by identifying when direct intervention is appropriate, the park's management can give these species the best opportunity of persistence in an uncertain climate future.
Open Access
An assessment of ecological impacts of community-based restoration on communal grasslands in the Drakensberg foothills
(2011) Marx, Dane Lee; Hoffman, Timm
Okhombe is a ward in the Northern Drakensberg where community based restoration of degraded lands has been conducted for over a decade. In this important water supply region, payment for ecosystem services has been suggested as a means through which to conserve biodiversity, improve veld condition, provide income to local communities, and ensure water security. However, before such alternative market mechanisms can be considered, the effects of community based restoration must be properly quantified. The primary aim of this study was to determine some of the ecological impacts of community based restoration in these communal grasslands.
Open Access
Assessment of pesticide concentrations in environmental and biological parameters from two Kenyan Rift Valley Lakes
(2012) Gudka, Masumi; Simmons, Robert E; Virani, Munir
In the last two decades Kenyan agriculture has developed rapidly. In particular, horticultural and floricultural activities have intensified on the riparian fringe of Lake Naivasha, a RAMSAR site. The lake supports a large variety of wildlife and avifauna in particular. In the 1980s, the African Fish-Eagle (Haliaeetus vocifer) population on the lake was the densest in Africa. As a top predator resident in the Kenyan Rift Valley Lakes the African Fish-Eagle is a good indicator of general ecosystem health but is also highly susceptible to toxic effects of pesticide contamination...Globally, most organochlorine pesticides have been banned, but endosulfan, HCH and methoxychlor are widely used in Kenya, while aldrin, dieldrin and lindane are restricted and DDT, endrin, and heptachlor banned. Studies examining residue levels of these harmful chemicals in African Fish-Eagles are limited to small sample sizes examined in the 1970s and 1980s. This study is the first comprehensive investigation of organochlorine residue contamination in biological and environmental parameters from Lake Naivasha and the control water body at Lake Baringo.
Open Access
An assessment of the distribution and conservation status of endemic and near endemic plant species in Maputaland
(2016) Matimele, Hermenegildo Alfredo; Raimondo, Domitilla; Hoffman, Timm; Timberlake, Jonathan; Lötter, Mervyn; Burrows, John
The Maputaland Centre of Endemism (MCE), an area stretching from northern-east KwaZulu-Natal in South Africa to the Limpopo River in southern Mozambique, holds more than 2,500 native plant species. Of those, over 203 are endemic or near endemic to this area. However, the current high human population density in MCE, coupled with high population growth, has increased the pressure on the natural resources of the region and threatens the natural vegetation and plant diversity. Therefore, there is a pressing need to fully understand the threats faced by the Maputaland endemic and near endemic plants and to carry out appropriate conservation actions. In this context, the main aim of the study was to document the distribution of the MCE endemic plant species, with particular emphasis on southern Mozambique. The study also aimed to document the threats to these species and to assess their global conservation status using the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria. This was done by gathering historical species distribution data from herbarium specimens and by assessing their current distribution in the field. In addition, a land cover data set was used to evaluate the level of habitat transformation over time. As a result, 13 endemics were assessed, 11 of these species for the first time. Of the 13 species assessed, two were assessed as Least Concern, five as Vulnerable, four Endangered, one Critically Endangered, and one possibly Extinct. MaxEnt models were used to model the potential distribution of the species assessed and to identify hotspots and priority areas for conservation. The priority areas represent sites of greatest overlap, where 50% of all modelled species overlap in their suitable potential distributions. With this approach, priority areas were identified that can be used in conservation planning, protected area expansion, or other conservation projects. This analysis showed that the highest number of the study species (>7) is concentrated within the Licuati Forest, located south of Maputo in Matutuine District, southern Mozambique. The main threat to this area is charcoal extraction and although none of the endemic species are targeted for charcoal production, the impact of the associated habitat destruction on the endemic species is expected to cause severe declines. It is recommended that studies on the dynamics of the Licuati Thicket vegetation are needed, particularly in terms of the impact of charcoal extraction on the endemics.
Open Access
Associations between MHC class I variation and blood pathogen prevalence in caracal
(2017) Ly, Alicia; Bishop, Jacqueline M
Adaptive genetic variability is vital to long-term species survival, as it presents the potential for evolutionary adaptive responses to environmental change. Genes of the Major Histocompatibility Complex (MHC) trigger the vertebrate adaptive immune response to pathogens through the recognition and presentation of foreign peptides, and thus provide an informative genetic marker for studying the adaptive potential of species with respect to disease. MHC class I loci mediate the immune system's recognition of intracellular pathogens, including protozoans, viruses and bacteria, and the high levels of genetic diversity reported at these loci is thought to be primarily the result of pathogen-mediated selection. Although variation within a number of MHC genes has been described in many felid species, the relationship between MHC diversity and pathogen prevalence within wild felid populations has rarely been examined previously. Because many wild felids are highly sensitive to the effects of anthropogenic-induced environmental changes, evolutionarily relevant adaptive genetic variation is particularly important for their conservation. This study explored the relationship between MHC class I exon 2 and exon 3 diversity and a number of tick-borne blood pathogens in a population of caracal (Caracal caracal) in the urban landscape of Cape Town, South Africa. The characterization of MHC class I diversity identified 38 and 45 unique, putatively functional alleles in the population, from exon 2 and exon 3 respectively. The influence of MHC allelic diversity and specific alleles, together with sex, age class, home range size and urban cover within home range, on individual pathogen prevalence was assessed using Generalized Linear Models. A positive relationship between Babesia infection and multiple measures of MHC diversity, including nucleotide diversity, average number of nucleotide differences and number of exon 3 alleles, was detected. Additionally, the presence of two specific alleles was significantly correlated with Babesia infection. High levels of infection by a number of tick-borne pathogens were observed in the population, suggesting environmental factors also have an important influence on pathogen prevalence. However, home range and urban cover within home range, as well as sex and age, were not significantly associated with Babesia infection. This study provides the first assessment of the relationship between MHC class I adaptive genetic variation and individual pathogen prevalence in caracal.
Open Access
Baited remote underwater video survey of reef fish in the Stilbaai marine protected area, with an assessment of monitoring requirements
(2012) De Vos, Lauren; Attwood, Colin; Götz, Albrecht
Long-term monitoring of changes in species abundance and community composition within marine protected areas (MPAs) is essential to assess whether conservation goals are being reached. The costs, logistics and sampling biases inherent to traditional monitoring methods limit sustainable monitoring in all MPAs along the South African coastline. Baited remote underwater video (BRUV) technology offers non-extractive monitoring with lower labour and cost requirements, whilst eliminating inter-observer variability and increasing statistical power. Species richness and relative abundance were assessed employing BRUV technology in the Stilbaai MPA in the Western Cape, South Africa. ... [The] result corroborated findings from traditional underwater visual census (UVC) and controlled angling surveys, confirming BRUV technology as a sound monitoring tool.
Open Access
Behavioural and physiological responses of chacma baboons (Papio ursinus) to wildfire in the Cape Peninsula of South Africa
(2018) Dubay, Shannon; O'riain, Justin; Lewis, Matthew; Swedell, Larissa; Foerster, Steffen
In an ecological context, ‘flexibility’ refers to an animal’s ability to respond immediately to environmental stimuli through physiological and behavioural adjustments. Specifically, primates exhibit a high degree of ecological flexibility, which allows them to persist through environmental changes that vary in duration and predictability. To cope with the variability of conditions within their habitats, baboons have evolved flexibility in ranging behaviour, social behaviour, and diet. Natural disasters are predicted to increase across the globe, and many parts of the world are experiencing longer wildfire seasons and higher wildfire frequencies than ever before. The aim of this study is to use an existing data set to assess how baboons responded, behaviourally and physiologically, to an extensive wildfire. I compare home range use, activity budgets, faecal glucocorticoid concentrations, and urinary C-peptide concentrations three months after the fire to the same three months in the previous year for the same 16 adult females. In the months following the fire, the baboons had a larger spatial range compared to the same months in the year prior. The additional area incorporated unburnt areas into their home range, which were preferentially used over burnt areas. Behavioural adjustments included notably less time spent engaging in social behaviours than in the year prior. Perhaps most surprisingly, postfire physiological indicators did not suggest high levels of psychological, energetic, or nutritional stress, as glucocorticoid concentrations were significantly lower post-fire compared to the year prior, while C-peptide concentrations were not significantly different between the two periods. The troop appears to have benefited from a surfeit of exotic pine seeds that were released by pine trees as a result of the fire. This unexpected nutritional windfall, in addition to the inclusion of vineyards within their ranging patterns, may explain why there were no physiological indicators of nutritional stress despite the loss of most above ground biomass. Despite suffering the loss of 12 troop members in the fire and injury to a further 12 individuals, adult females in the Tokai troop were able to adjust to a severe and extensive change to their home range. Although primate ecological flexibility has been widely documented, this is the first study to explore the behavioural and physiological responses of baboons to extensive habitat changes resulting from a wildfire, and the potential implications for the management of wildlife on the urban edge.
Open Access
Biodiversity survey towards conservation of subtidal reef habitats in KwaZulu Natal : biogeography and depth patterns
(2005) Lawrence, Cloverley; Harris, Jean M; Branch, George M
Subtidal reef communities in KwaZulu-Natal (KZN), South Africa are poorly known. This lack of knowledge is problematic as the biodiversity of these reefs may be severely impacted and inadequately conserved. This study documents and describes subtidal benthic communities occurring on reefs at four depth categories along the whole length of the coast. A distinct difference between northern reefs from those in the south and central parts of the province emerged with substantiating evidence of a discrete biogeographic separation at Cape St Lucia. Pairwise ANOSIM tests found no signiﬁcant differences in community composition of reefs along a depth range of 10 m to 30 m at nine localities in KZN. However, differences among localities were significant at both regional (R = 0.607, P = 0.1%) and local (R = (1.792, P = 0.1%) scales. In the north, trends in species assemblages and functional groupings revealed a higher percentage cover of fauna (mainly corals) at shallower depths and a greater coverage of algae on deeper reefs. In the southern localities algae dominated shallower reefs while filter-feeding epifauna were more prevalent at deeper depths. Species richness, evenness and diversity were highest at 10m in the northern coral-dominated region while in the central/south region diversity peaked in the intermediate depth zone (15 - 25 m). Appropriate measures to conserve representative habitats in each biogeographic zone are necessary. Further research to assess biodiversity at a finer scale, as well as the establishment oflong-term monitoring to quantify natural variability and human effects, are required.
Open Access
Biogeochemical niche construction in the forest-fynbos mosaic of Jonkershoek Nature Reserve, South Africa
(2014) Dalwai, Raheem; Khomo, Lesego
The south-western Cape of South Africa is dominated by fynbos vegetation with patches of forest restricted to rock screes and stream banks owing to the more favourable moisture status of these microhabitats. A detailed analysis of soil underlying forest and fynbos vegetation in Jonkershoek Nature Reserve was investigated. A total of nine soil pits were dug in forest and on fynbos slopes with high and low gradients. Pits were analysed by depth examining texture while soil was also sent for x-ray fluorescent analysis and carbon and nitrogen analysis. Evidence for dust deposition varied spatially, although this could be a result of the rapid erosion experienced during winter. Soil properties, mainly texture and nutrient concentration differed distinctly between forest and fynbos. I argue that these differences are caused by topographical diversity and maintained by vegetation which influences nutrient enrichment via dust accumulation and plant litter decomposition. Thus I concluded that soil texture favours nutrient retention in forest soil more than in fynbos soil enhancing the disparity between nutrients in the respective environments. By influencing litter decomposition and aeolian inputs of dust, vegetation is responsible for modifying its niche increasing the difference between fynbos and forest patches.
Open Access
Birds at risk in warming southern African deserts: inferences from behavioural and physiological thermoregulation
(2011) Louw, Gina; Hockey, Phil A R
The study focused on avian species' responses to high ambient temperature. Ambient temperature is a variable to which birds are particularly sensitive and which climate-change models predict will increase disproportionately rapidly in southern Africa's hot deserts, especially the Kalahari.
Open Access
The birds, the bees and Erica: vulnerability of plant-pollinator communities in fragmented fynbos landscapes
(2016) Angoh, Siow Yan Jennifer; Midgley, Jeremy J; Brown, Mark
Habitat fragmentation has been identified as a major cause of pollination mutualism collapse that can eventually impinge on plants' reproductive success (e.g. through pollen-limitation). Agriculture, timber plantations, invasion by alien trees and the urbanisation of the southern Cape lowlands have transformed and fragmented large parts of the former distribution range of many Erica species. Recent evidence suggests that in the Fynbos biome, small remnants of natural and disturbed vegetation are likely to display depauperate plant communities. In the present study, it was found that Erica species richness declined significantly as patch size decreased. Limited nectar resources available on those small 'islands' might not be enough to attract essential bird and insect pollinators. Insect-pollinated species were more impacted by reduced patch size than the bird-pollinated ones. Further investigation using Erica discolor showed that for this widespread ornithophilous species, pollination mutualism still occurred in smaller fynbos patches. These findings stressed the importance of conserving small fragments for maintaining remnant plant populations, which can act as reliable food sources for avian pollinators. In addition, to cope with the effects of pollen limitation, highly resilient plant species have evolved and adopted different compensatory mechanisms. From a short-term perspective, adopting compensatory reproductive strategies (e.g. autonomous self-pollination, vegetative growth, and generalised pollination systems) could reduce dependence on specific pollinators and increase the chances of a species being able to persist through a period of low-pollinator abundance. The prevalence of autogamy and geitonogamy as alternatives to xenogamy was assessed in six different obligate seeder Erica species in the eastern coastal part of the Cape Floristic Region. Despite the long history of plantation-based timber production that fragmented the study area, and the subsequent possible pollinator loss, none of the species analysed in this study have adopted autonomous self-fertilisation as a response mechanism. Erica sessiliflora was the only species that showed a high compatibility for self-pollen. The species under investigation in a breeding system conducted here were also incapable of vegetative propagation and were plants targeting specific animal taxa (e.g. birds or insects) for successful pollination. Having limited compensatory mechanisms, further degradation of their habitat and weakening of their ecological interactions could be extremely detrimental to these Erica species' reproductive success.
Open Access
Breeding and dispersal implications for the conservation of the Southern Ground Hornbill Bucorvus leadbeateri
(2017) Carstens, Kate; Ryan, Peter G; Little, Rob M; Thomson, Robert
Populations of secondary tree-cavity nesting bird species are often limited by a shortage of natural nesting sites. For the Southern Ground Hornbill Bucorvus leadbeateri that typically nests in natural tree cavities, the shortage of nesting sites is one factor potentially limiting population growth. The species is listed as endangered in South Africa, and vulnerable throughout the rest of its range. Nest boxes can improve the conservation status of threatened birds that are limited by nest-site availability. However, nest boxes or other types of artificial nests are not always beneficial to the target species, and their value as a conservation tool needs to be tested for each species. Wooden nest boxes were installed for ground hornbills in a study area in north eastern South Africa with a paucity of natural nest sites. In this thesis, I assess productivity, timing of breeding, and dispersal in the Southern Ground Hornbill in a study area supplemented with nest boxes and discuss the implications for the conservation of this endangered species. Nest boxes are an effective conservation tool to improve productivity in areas lacking natural tree cavity nesting sites. Breeding success (calculated as the proportion of nesting attempts that fledged a chick) and predation levels were similar for groups using nest boxes and natural nests. Natural nests were more buffered against cooling night temperatures, but otherwise nest boxes provided nesting conditions that were no better than natural nests. Timing of breeding for nests in natural tree cavities and nest boxes were similar. However, groups with access to a nest box attempted breeding more often than groups with access to a natural nest only, resulting in an 15 % increase in the number of fledglings per group compared to an adjacent protected area with no artificial nests. The number of breeding groups in the study area increased by 460 % over 12 years. However, there is a limit to the density of breeding groups. Breeding success was highest when breeding density was one breeding group per 90-120 km², so nests should be spaced ~10 km apart. Given that the threats to ground hornbills include persecution and poisoning, increasing the reproductive rate by providing nest boxes should assist in slowing the decline by the increased recruitment of offspring into the population. Timing of breeding varied across years. The first eggs laid each year ranged from 9 September to 14 November, and median lay date was 03 November. Breeding attempts that were initiated early in the season were more likely to fledge a chick than those initiated later in the season. Timing of breeding was delayed during warmer springs, particularly under dry conditions. In savannas, hotter spring temperatures could limit food availability, for example, if higher temperatures cause the vegetation to dry out, resulting in a rapid decline in insect flush, especially in the phytophagous insect groups that form a large part of the ground hornbill diet. Factors to consider when constructing and placing nest boxes include thickness of the cavity walls, entrance height above ground and density of nest boxes placed in the landscape. Breeding attempts in natural nests and nest boxes with thicker nest walls and those positioned with higher entrances above the ground increased breeding success. Therefore, nests should be constructed with cavity walls at least 6 cm thick and placed so that the entrances are situated > 6 m above the ground. With 186 ringed chicks fledging from the study area after the installation of nest boxes, it was possible to observe their dispersal within the study area and farther away into the adjacent Kruger National Park. There was no evidence for sex-biased dispersal. Males and females dispersed at similar ages, and over similar distances, raising interesting questions about inbreeding avoidance mechanisms in this species. If females do not disperse beyond the range of related males, how do related individuals avoid pairing, and what forms of individual recognition exist?