Ecology

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Aardvark and people: can a shy species be widely known in a localised area?
(2022) Makwati, Nolutho.; Kraai, Manqhai.; Tsvuura, Zivanai.
The increase in human populations has led to humans sharing space with wild animals even in the natural habitats of the animals. Conflicts may arise when people and wildlife attempt to fulfill their needs which can be detrimental to one or both parties, and this type of conflict is called human-wildlife conflict (HWC). The human needs include people hunting wild animals for consumption of the animal and trading in animal body parts.Hunting is one of the factors that decreases populations of numerous animal species, and it occurs in many parts of the world e.g. in Africa, Asia and South America, where it contributes to extinction of species. The conservation and management of burrowing animals is a major challenge due to their elusive and nocturnal behaviour. The aardvark is an African medium-sized, burrowing mammal whose conservation status has not been updated recently due to the difficulties associated with studying nocturnal animals. Aardvarks may play a significant ecological role in the ecosystems in which they occur, such as by changing the landscape through their digging activities, or through affecting the dispersal of seeds. Therefore, the aim of this study was to explore the influence of humans on population trends and activity patterns of aardvarks outside protected areas, and to determine people’s perceptions about the animal. The study was conducted in Ncunjane village in Msinga Local Municipality, KwaZulu-Natal Province of South Africa. To understand people’s perceptions about aardvark in their community, I used a semistructured questionnaire survey. I asked personal information of the participants (sex, level of education and age), and questions related to people’s perceptions about the aardvark, such as people’s knowledge, myths, and their uses of the animal or its body parts. To determine activity patterns of the animal, I focused on aardvark foraging activities in a semi- arid savanna ecosystem that is also used as a communal rangeland over eight months between 2020 and 2021. I measured and quantified aardvark foraging holes using 53 50 m × 10 m transects where there was evidence of aardvark activity. In addition, I quantified aardvark burrowing of dens in the dry, wet and early dry seasons using walking transects guided by a research assistant who knows the area. I found that people have different perspectives about aardvark with the majority (78%) of respondents having strongly positive perceptions. The positive perceptions arise from aardvark not causing physical harm to people, and fleeing away upon sighting people. I found that aardvarks were mainly hunted for meat while some animal body parts were sold to traditional healers for traditional medicine. All seasons consisted of a greater number (> 51%) of old than new and very old foraging holes.The surface area of new, old, very old holes differed significantly with season (P < 0.0001) and the depth of new, old and very old holes also varied with season (P < 0.0001). In addition, the contents of foraging holes varied with age of the hole and season in that new holes lacked evidence of plant life across seasons. Aardvark dens were used by other animals such as spiders, wild cats, Cape porcupines and snakes. Hence, an increase in aardvark holes can be associated with significant landscape heterogeneity for vegetation and animal life. Aardvarks in Ncunjane fed close to their dens presumablyto mitigate against human predation through hunting threats, which may directly affect the extent of aardvark digging activities. These results show that aardvarks may be categorised as ecosystem engineers as the burrows provide shelter for other animals, also, their effects on other animals are disproportionate to their abundance. These results highlight that aardvarks are threatened by human uses and may decline in abundance in the area. Finally, aardvarks remain poorly studied in landscapes shared with humans. Further studies to assess aardvark numbers in human-dominated landscapes are required which can raise awareness and play a significant role in conservation of aardvarks.
Ant community responses to fertiliser application and disturbance in a mistbelt grassland, KwaZulu-Natal.
(2021) Khoza, Lindiwe Rebecca.; Munyai, Thinandavha Caswell.; Andersen, Alan N.
Abstract available in PDF.
Aspects of common hippopotamus (Hippopotamus amphibius) behavioural ecology and their consequences in managed systems in South Africa.
(2020) Fritsch, Camille Jacques-Armand.; Downs, Colleen Thelma.
Abstract available in PDF.
Aspects of fruit digestion and selection in selected Southern African avain frugivores.
(2014) Zungu, Manqoba Moses.; Downs, Colleen Thelma.
Fruit-frugivore interactions play a central in maintaining the structure and diversity of ecosystems through their effects on seed dispersal. Because fruit selection and thus fruit removal represents the first stage in the seed dispersal process, understanding factors affecting fruit selection can play an important role in the formulation of sound conservation efforts especially light of the on-going habitat change. However, to date, the research is inconclusive as to factors affecting fruit selection as results have revealed inconsistent and controversial with a huge variation in fruit selection patterns between species and within individuals of the same species. The huge inter- and intra-specific variation in fruit selection patterns precludes any generalizations on fruit selection notwithstanding the research effort addressing the issue. One factor that could be attributed to this pattern is that most studies on fruit selection patterns in frugivorous birds have studied fruit attributes or physiological adaptations of frugivores to fruits in isolation. Because fruit profitability is affected by both pre- and post-ingestional factors, studying these factors in isolation deprives us of fresh insights into the fruit-frugivore interaction. Therefore by relating the physiological aspects of frugivores to fruit characteristics, this study aims to provide a link between the physiology of birds and their feeding ecology. Cape white-eyes (Zosterops virens), red-winged starlings (Onychognathus morio) and speckled mousebirds (Colius striatus) were used for this study. In the first part of this thesis, transit times and digestive efficiencies of birds fed equicaloric glucose and sucrose artificial fruit diets of varying concentrations were determined. Three concentrations were used: low (6.6%), medium (12.4%) and high (22%). Digesta transit times of birds increased with an increase in concentration for all diets but were generally higher on glucose diets. This finding has been widely reported in other similar studies. The increase in digesta transit times with an increase in sugar concentration may be due to high nutrient density on high concentration diets which require a longer processing time. Intake rates, on the other hand, decreased with an increase in sugar concentration. The inverse relationship between food intake and nutrient levels has often been attributed to compensatory feeding which posits that birds respond to nutrient dilution by increasing intake to allow a constant flux of assimilated energy. Indeed, speckled mousebirds and Cape white-eyes maintained a constant assimilated energy intake on sucrose diets by modulating food intake rates. The apparent assimilation efficiencies of glucose diets for all species were comparable and typical of those found in other frugivorous birds. However, red-winged starlings displayed low assimilation efficiencies for sucrose diets and lost significant body mass on all sucrose diets. The lack of significant sucrase activity in this species was attributed to this finding. This study showed the importance of digestive physiology in explaining fruit selection patterns in frugivorous birds. The second part of this thesis assessed the deterrence effects of tannins which are ubiquitous secondary compounds in plant material and are known for their ability to bind to protein which reduces nitrogen availability in the diet. In this study, birds were fed artificial fruit diets containing varying levels of tannins (0%, 2.5% and 5%) in paired choice tests. It was predicted that tannins would have no effect at low concentrations but at higher concentrations would act as deterrents although the levels at which they would become deterrents would differ among species. Red-winged starlings preferred the control diet, were indifferent to the medium tannin diet and were deterred by the high tannin diet whereas speckled mousebirds and Cape white-eyes were not deterred at all concentrations. The discrepancy in the results was attributed to differences in taste sensitivity, tolerance levels and detoxification mechanisms of secondary compounds between species. Occasional geophagy and consuming a broad diet were also implicated in producing the results obtained. Plant secondary compounds in fruits are diverse and their effects are similarly diverse and there is a possibility that different groups of secondary compounds generate disparate effects. Similar studies on other types of secondary compounds may thus contribute towards a broader understanding of the role of secondary compounds in mediating fruit-frugivore interactions. Overall, this study showed how diet affects ability to handle secondary compounds in fruits. The third part of this thesis addressed the influence of ethanol concentration on fruit selection in frugivorous birds. Because ethanol is ubiquitous in fruits and its concentration is positively correlated to fruit sugars, it has been suggested that because frugivores could use its odour to locate fruiting plants, they should select fruit with high ethanol concentrations. The aim of this study was to test this hypothesis by determining whether frugivorous birds show a preference for fruit laden with alcohol at levels equivalent to those of over-ripe fruits. Birds were provided with two artificial fruit diets in pairwise choice tests: an experimental diet containing 1% ethanol and an artificial fruit diet with no ethanol. For all species, there were no significant differences in the amount of fruit consumed between the two food types. These findings provided corroborating evidence to the suggestion that birds are unlikely to prefer over-ripe fruits compared to ripe fruits due to the negative impacts associated with ingesting ethanol at high concentrations. However, it could be possible that the lack of preference observed in this study was because the ethanol concentrations used were too low to be detected. Overall, this study suggests that at high concentrations, ethanol in fruits acts as a deterrent rather than an attractant. The last part of this thesis was conducted to determine the use of taste and olfaction by red-winged starlings in making foraging decisions. To determine whether they use taste in fruit selection, they were concurrently offered a control artificial fruit diet with another artificial fruit diet flavoured with different concentrations of ethanol and various fruit essences. To test whether they were able to use olfaction to locate food, they were provided with two choices: artificial fruit suspended over either banana and orange fruit essences and ethanol of varying concentrations or a control artificial fruit (without essence). It was hypothesized that (1) red-winged starlings have tasting ability which helps them in selecting fruits to feed on and that (2) red-winged starlings use olfaction to locate food. Results were consistent with the first hypothesis but inconsistent with the second one. Thus, red-winged starlings use taste when selecting fruits to feed on but do not use olfaction to locate fruit sources. The latter was unexpected because birds with olfactory bulb sizes similar to theirs exhibit advanced olfactory abilities. It was speculated that the lack of olfactory abilities in starlings could be attributed to the fact that this study was conducted outside of this species’ breeding season when olfactory abilities were likely to be lowest and also to that olfactory abilities may not have been important at the scale investigated in this study. Overall, the study showed that the sense of taste in birds plays an important role in making foraging decisions than currently appreciated. Overall, this thesis demonstrated the value of relating physiological attributes of frugivores to fruit attributes in acquiring deeper understanding of fruit-frugivore interactions. One particular advantage of the methodology employed in this study was that it controlled for covariance among fruit characters and also removed the confounding effects of as seed size and secondary compound composition. The shortcoming of this approach is related to the applicability of the results to the field conditions. Therefore an approach combining laboratory and field observations may produce results that may be important in informing us about how to manage our ecosystems.
Aspects of monitoring wild and captive Nile crocodile (Crocodylus niloticus) populations in southern Africa = Izingxenye zokubhekelela uhlobo lwengwenya yasendle nevalelwe yaseNile (Crocodylus niloticus) e-Afrikha eseningizimu.
(2021) Myburgh, Hendrik Albert.; Downs, Colleen Thelma.
As biodiversity across the globe declines because of anthropogenic activities, the need for conservation efforts increases. For conservation efforts to be successful, it is imperative that detailed information about species and their populations; size and status within and outside of protected areas be collected. In freshwater systems, crocodile population demographics can provide an integrated view of ecosystem state, but the habitat and cryptic nature of crocodilians confound the derivation of population demographics for the taxa. Crocodile populations were historically monitored by fixed-wing aircraft, helicopter or limited spotlight surveys in those areas that are navigable by boat. These techniques are costly and labour-intensive; require specialised personnel and equipment, and are subject to observer bias and low accuracy in size class estimations. Furthermore, they produce population demographic data that is not verifiable as they rely on decisions and opinions of observers in the moment of surveying, often fromfast-moving platforms. Lately, unmanned aerial vehicle (UAV) techniques have been shown to accurately and effectively count crocodiles, but they still require costly software and hardware packages. In this study, low-cost, open-source UAV techniques were developed as an alternative method to monitor and survey crocodilians, particularly Nile crocodiles (Crocodylus niloticus), both in captivity and in the wild. In South Africa, Nile crocodiles occur in open bedrock systems with relatively little riparian vegetation, an ideal scenario for the application of UAVs. The possibility of improved population demographic data for wild Nile crocodile populations by converting size data derived from UAVs to age data was explored by radiocarbon dating Nile crocodile claws. Morphometric correction factors applicable to UAV census are derived, and a fixed-wing survey is compared with a commercial-grade UAV survey of wild Nile crocodile populations in the Kruger National Park. The limitations and applicability of these approaches for crocodilian and other ecological studies were assessed. Their future applications in ecology and management are proposed. Iqoqa Njengoba impiliswanomvelo kuwo wonke umhlaba yehla ngenxa yezenzo ezidalwe ngabantu, isidingo sokongiwa kwemvelo siyakhula. Ukuze imizamo yokongiwa kwemvelo ibe impumelelo, kuyaphoqa ukuthi kuqoqwe ulwazi olunzulu mayelana nokuphilayo kanye nezinhlobo zakho, ubungako kanye nesigaba phakathi kanye nangaphandle kwezindawo ezivikelwe. Emanzini aphilayo, uhlobo lwemiphakathi yezingwenya zingasinika iso eliyinhlanganisela lesimo sohlalonhlaliswano yokuphilayo nokungaphili, kodwa isimo sendawo yokuhlala kanye nesingachazeki sididisa ukwehlukanisa ukutholakala komphakathi wezinhlobo zezingwenya. Imiphakathi yezingwenya yayibhekelelwa emandulo ngendizamshini ehlala phezulu emoyeni, indiza enophephela emhlane noma amasaveyi angemaningi agqamile kulezo zindawo okuhambekayo kuzo ngezikebhe. Lawa masu ayabiza futhi adinga amandla okusebenza, adinga abasebenzi abaqondene kanye nemishini yokusebenza, kanti futhi ancike ekuchemeni kobukelayo kanye nezinga eliphansi ngobungako besihlawumbiselo sohlobo. Okunye futhi, akhiqiza imininingo yohlobo lwemiphakathi engathembakali njengoba ethembele ezinqumeni kanye nemibono yababukela ngesikhathi sokwenza amasaveyi, okujwayele ukuthi kube izinhlaka ezihamba ngokushesha. Kamumva nje, amasu esithuthi ezingasetshenziswa muntu ezisemoyeni, i-unmanned aerial vehicle (UAV) asevezwe njengakhombisa ukubalwa kwezingwenya okuqondile nokunemiphumela emihle, kodwa asadinga ubuchwepheshe obubizayo kanye nezindodla zobuxhaxhaxha bobuchwepheshe. Kulolu cwaningo, okungabizi, amasu ezizinda ezivulekile e-UAV kwaqanjwa njengenye yendlela engasetshenziswa ukubhekelela nokusaveya izingwenya, kakhulukazi izingwenya zaseNile (Crocodylus niloticus), zozimbili ezivalelwe kanye nezasendle. ENingizimu Afrikha, izingwenya zaseNile zivela ekusetshenzisweni kwamadwalamsuka avulekile anotshalovikelo olungeluningi, okuyisibonelo esincomekayo sokusebenzisa ama-UAV. Ukuba khona kwemininingo ethuthukile yezinhlobo zemiphakathi yezingwenya zasendle zeNile ngokushintsha ubungako bemininingo etholakale kuma-UAV ukukhulisa imininingo kwaphenywa ngekhabhoni yomoya ukubona izindlawu zengwenya yaseNile. Izimo zokulungisa ukusebenza kokubala kwe-UAV kutholakele, kanti futhi isaveyi yophiko olunganyakazi luqhathaniswa nesaveyi ye-UAV yohlobo lokusebenza lwemiphakathi yohlobo lwengwenya yasendle yaseNile e-Kruger National Park. Imikhawuko kanye nokusebenzeka kwalezi zindlela zokubhekelela izingwenya kanye nezinye izicwaningo zezemvelo kwahlolwa. Ukusebenza kwayo kwesikhathi esizayo emvelweni kanye nokwenganyelwa kuyaphakanyiswa.
Aspects of Nile crocodile (Crocodylus niloticus) population ecology and behaviour in Pongolapoort Dam, KwaZulu-Natal.
(2015) Summers, Mark Kai.; Downs, Colleen Thelma.
Pongolapoort Dam is one of the largest dams in South Africa by volume. It is also home to a breeding population of Nile crocodiles (Crocodylus niloticus). Crocodiles are keystone species which play an important ecological role in their aquatic habitats but are under threat globally. Consequently the aims of this project were to investigate the population number, nesting ecology, and behavioural aspects of gaping in Nile crocodiles at Pongolapoort Dam. Data were captured from July 2014 to August 2015, where there was a marked decrease in water levels in Pongolapoort Dam due to a drought occurring throughout KwaZulu-Natal. An estimated 549 Nile crocodiles occurred in Pongolapoort Dam in 2015, an increase in population from a conservative estimate of 273 individuals in 2010. The majority (80%) of the Nile crocodile population occurred in the inlet section of the dam, and with dropping water levels, the crocodiles congregated in large numbers in the Croc Bay region of the inlet. The population structure changed from 2010 when the majority occurred in the juvenile class to the majority of the crocodiles occurring in the sub-adult and adult size class in 2014/2015. The reproductive output of a population can be an indicator of population health. Consequently nesting ecology of Nile crocodiles was investigated at Pongolapoort Dam for the 2014/2015 nesting season. A total of 38 Nile crocodile nests were found over four nesting sites in the river section of Pongolapoort Dam. Nest effort decreased from 73% in 2009/2010 to 43% in 2014/2015, with a density of 4.9 nests per kilometre in the river section. All nests were found in alluvial deposits where Phragmites australis was the dominant vegetation. Some nests were predated by water monitors (Varanus niloticus); however, two nurseries were found containing hatchlings, while many nests showed signs of being dug up by the nesting females. The N2 Bend and Buffalo Bend floodplain were the most important nesting grounds, and this was attributed to the presence of suitable nesting conditions. Gaping behaviour in Nile crocodiles has received little attention as there are conflicting ideas as to why gaping occurs. The majority of literature suggests that gaping is a thermoregulatory response aimed at cooling the head of the crocodile. We aimed to identify other possible behaviours associated with gaping, at a basking bank in Pongolapoort Dam during winter. Preliminary results suggest that gaping may be a communicative or behavioural posture brought on by the following factors; position of the crocodile relative to the water, total length of the crocodile, time of gape, degree of gape, nearest neighbouring crocodile and number of neighbouring crocodiles. Further research is needed to help understand this behaviour of Nile crocodiles and its importance in their ecology and behaviour. The study showed that the population of Nile crocodiles in Pongolapoort Dam is increasing and remains in a healthy state compared with other population in South Africa. Insights into their behaviour may be applicable to other crocodilian taxa.
Aspects of the ecology and persistence of vervet monkeys in mosaic urban landscapes in KwaZulu-Natal, South Africa = Izingxenyezici zendawomvelompiliswano kanye nokwanda kwezinkawu zohlobo lwe-vervet ezindaweni zasemadolobheni ezihlukahlukene ngokwezimo zempilo KwaZulu-Natali eNingizimu Afrika.
(2022) Pillay, Kerushka Robyn.; Downs, Colleen Thelma.
The geological era in which we live is termed the Anthropocene and is causing the greatest loss of biodiversity and species brought on by a single species: Homo sapiens. The human population places great demands on the environment, altering and modifying it to suit people’s needs. Urbanisation is one of the greatest anthropogenic land-use modifications, predominantly for infrastructure and housing developments. This results in the loss of natural green spaces where wildlife lives, forcing them into smaller fragmented habitats, often having to share the urban mosaic landscape with humans. These increased interactions often lead to humanwildlife conflict. Generally, urbanisation affects species negatively. However, some species exhibit the ability to persist in urban areas, successfully utilising resources for their natural life traits. One such primate species persisting in urban mosaic landscapes is the vervet monkey, Chlorocebus pygerythrus, particularly in the eThekwini Municipality, Durban, KwaZulu-Natal Province, South Africa. Increased human population growth and associated urban transformation have increased contact between humans and troops of vervet monkeys using residential and industrial gardens. This has led to increased human-wildlife conflict, with vervet monkeys often persecuted because of their damage to human property and harassment. Little is known about the ecology of urban vervet monkeys, so to assess and manage this wildlife conflict, a need to determine the behavioural ecology and persistence of vervet monkeys were investigated in this study. This study analysed vervet monkeys' spatial ecology in the mosaic urban-forest landscape and provided insight into their home ranges and habitat use here. Additionally, the effects of anthropogenic activities and human-wildlife conflict on wild vervet monkeys were documented. The results contribute to understanding the foundation of human-vervet conflict resolution programmes and support for further education and coexistence with wildlife in mosaic urban landscapes. The conservation of vervet monkeys should be supported by all who live in these areas, not by some factions. The presence of primates, such as the vervet monkey, that use managed green spaces, such as gardens, in the eThekwini Municipality should provide the public with the ultimate catalyst and insight into protecting and conserving this species and others for future generations. Overall, the results presented in this thesis provide an understanding of the persistence of this Old World primate in mosaic urban landscapes. Iqoqa Isikhathi esiphila kuso mayelana nesimo sendalo yomhlaba esikuwo saziwa ngele-Anthropocene siyimbangela yokushabalala okusezingeni eliphezulu yokusatshalaliswa kwendawomvelompiliswano kanye nohlobo lwezilwane okubangelwa uhlobo olulodwa: oluyi-Homo sapiens. Izidalwa ezingabantu zinomthelela omkhulu emvelweni ngendlela yokuthi ziguquguqula imvelo ukuze kufezeke izidingo zazo. Ukwakhiwa kwezindawo zasemadolobheni kungenye yezinguquko ezidalwa ngabantu lapho besebenzisa umhlaba ikakhulukazi ukwakha izindawo zokuhlala kanye nezingqalasizinda. Lokhu kuholela ekuthini kuntuleke izindawo okuphila kuzo izilwane zasendle okube sekudala ukuthi lezi zilwane zigcine sezihlala ezindaweni ezimpintshekile zaba zincane. Lokhu kube sekuholela ekuthini zigcine sezibanga indawo nabantu basemadolobheni. Lokhu kwanda kokuhlalisana nabantu kuholela ekushayisaneni phakathi kwabantu kanye nezilwane. Nokho-ke, kunohlobo olukhombisa ukuthi luyakwazi ukuqhubeka nokuphila kahle ezindaweni ezingamadolobha ngokuzizamela kulokho okukhona ukuze luziphilise ngendlela efanele. Uhlobo olukhombise ukuthi luyakwazi ukuqhubeka nokuziphilisa ngaphansi kwesimo sasemadolobheni yilolu lwezinkawu ezaziwa nge-vervet, Chlorocebus pygerythrus,ikakhulukazi endaweni kaMasipala weTheku, eThekwini, esifundazweni saKwaZulu-Natali, eNingizimu Afrika. Ukwanda kwesibalo sabantu kanye nokuguquka kwesimo senhlalo yabantu okuhambisana nakho sekwenze ukuthi kwande nokuhlangana kwabantu nemihlambi yezinkawu ezizitika ezingadini zabantu emakhaya kanye nasezingadini zabalimi abakhulu. Lokhu sekuholele ekushayisaneni phakathi kwabantu kanye nezilwane zasendle okwenza ukuthi izinkawu ezingama-vervet zizithole zisenkingeni ngenxa yokucekela kwazo phansi impahla yabantu kanye nokuba yisicefe esingapheli. Aluluningi ulwazi olukhona mayelana nezinkawu zasemadolobheni ezingama-vervet, ngakho-ke lolu cwaningo lwaphenya mayelana nokuziphatha kwalezi zinkawu ngaphansi kwezimo zendawo eseziguqukile kanye nokwanda kwazo ukuze kuhlolwe kuphinde kulawulwe lokhu kushayisana nezilwane zasendle. Lolu cwaningo lwahlaziya izindawo ezingamahlathi asedolobheni okuhlala kuzo lezi zinkawu ezingama-vervet, lwase lunikeza ulwazi olujulile mayelana nezindawo okuhlala kuzo lezi zinkawu kanye nendlela eziziphilisa ngayo kulezi zindawo. Okunye okwaqoshwa phansi yimithelela yezinto ezenziwa ngabantu kanye nokushayisana phakathi kwabantu kanye nezinkawu ezingama-vervet. Imiphumela yocwaningo yathasisela olwazini olumaqondana nezinhlelo okungakhelwa phezu kwazo ukuxazululwa kokushayisana kwabantu nezinkawu ezingama-vervet, iphinde isekele ukufunda okuqhubekayo mayelana nokuhlalisana nezilwane zasendle ezindaweni ezisakhula zasemadolobheni. Kumele kusekelwe ukongiwa kwezinkawu ezingama-vervet yibo bonke abahlala ezindaweni ezisemadolobheni, kungabi ngabathile kuphela. Ukuba khona kwalolu hlobo lwezilwane ezifana nezinkawu ezingama-vervet ezindaweni ezisetshenziswa nezenganyelwe njengezingadi zomphakathi njengezikaMasipala weTheku kumele kuhlomise amalungu omphakathi ngolwazi nanogqozi lokuvikela kanye nokonga lolu hlobo lwezilwane kanye nezinye izinhlobo ukuze nezizukulwane ezizayo zikwazi ukuzibona ziphila. Ekugcineni kwakho konke imiphumela etholakale kulolu cwaningo iveze ulwazi nokuqonda mayelana nokwanda kwalolu hlobo lwezinkawu ezindaweni ezingamadolobha.
Aspects of the ecology of African woolly-necked storks (Ciconia microscelis) in an anthropogenic changing landscape in KwaZulu-Natal, South Africa.
(2018) Thabethe, Vuyisile.; Downs, Colleen Thelma.
Urbanisation is the fastest-growing forms of anthropogenic land use change and a major threat to biodiversity worldwide. However, despite the negative impacts of urbanisation on native species, some species persist in urbanised environments and this thesis aimed to examine one such species, the African woolly-necked stork (Ciconia microscelis). African woolly-necked storks have recently colonised urbanised environments in KwaZulu-Natal, South Africa, and are now common in suburban areas in particular. Despite its proximity to human settlements and recent high abundance in suburban areas, knowledge of the African woolly-necked stork remains poorly documented in South Africa. Therefore, this thesis aimed to investigate the aspects of ecology of African woolly-necked storks within the suburban landscape to determine what factors facilitate their ability to persist in these environments. Firstly, I assessed the long-term trends in occupancy, colonisation and extinction of African woolly-necked storks as a function of change in land cover across KwaZulu-Natal Province, South Africa. This was accomplished by applying dynamic occupancy models to Counts in South Africa. African woolly-necked stork wetland occupancy was relatively stable (ψ = 0.37-0.39) across years. However, they rapidly extended their distribution range to urbanised environments, becoming common in man-made wetlands. Overall, this study found that the increased area of anthropogenic areas led to an increase in the probability of wetland colonisation by African woolly-necked storks. Secondly, I investigated the foraging opportunities that might be responsible for the recent colonisation of urbanised environment by African woolly-necked storks. I found that a significant number of householders (71%) deliberately fed African woolly-necked storks daily throughout the year and the majority provided meat while others fed inappropriate food such as bread. Furthermore, I found that, African woolly-necked storks were relatively habituated in urban areas of KwaZulu-Natal, with some even feeding from hand and others going inside homes to find the supplemental food. These results showed that the African woolly-necked stork is successfully utilising and exploiting anthropogenic food – a novel behaviour for this species. Thirdly, given that the selection of appropriate nest sites has major implications on reproduction success and survival of urban bird species, I was interested to determine if African woolly-necked storks bred in urbanised areas and, if so, which features of the nest site and surrounding habitat influenced their occupancy. I found 30 African woolly-necked stork nests in suburban areas of KwaZulu-Natal. African woolly-necked storks have successfully established breeding sites in suburban areas (mostly in domestic gardens), especially near swimming pools, while exotic pine (Pinus elliottii) and eucalyptus (Eucalyptus spp.) trees were the most preferred trees. Anthropogenic structures were also used as nesting sites suggesting a nesting behaviour shift. Lastly, after acquiring evidence that African woolly-necked storks successfully utilise anthropogenic food and have established a breeding population in urban areas, I was interested to know what food they provisioned to their nestlings. Furthermore, I investigated the breeding behaviour of African woolly-necked storks using direct observations and infrared camera traps during three breeding seasons (2015-2017). Although anthropogenic food was provided to nestlings, African woolly-necked storks provisioned their nestlings predominantly with natural food, primarily amphibians, particularly guttural toads (Amietophrynus gutturalis). African woolly-necked storks consistently reoccupied most nest sites across study years since initial discovery, suggesting that this population was at least stable. For the first time, I documented evidence of cooperative breeding where more than two adults provided care to a single nest. (Amietophrynus gutturalis). African woolly-necked storks consistently reoccupied most nest sites across study years since initial discovery, suggesting that this population was at least stable. For the first time, I documented evidence of cooperative breeding where more than two adults provided care to a single nest.
Aspects of the ecology of Cape porcupines on farmlands, peri-urban and suburban areas in KwaZulu-Natal, South Africa.
(2018) Ngcobo, Samukelisiwe Princess.; Downs, Colleen Thelma.; Wilson, Amy-Leigh.
The unprecedented changes in the environmental and ecological processes of the biosphere have led some to believe that we have transitioned into a new geological era from the Holocene. This current era is known as the Anthropocene epoch, termed as such due to the unprecedented human-induced environmental change. Humans have dominated global changes in the environment and climate through the conversion of natural land-use systems into anthropogenic landscapes dominated by agriculture, urban and industrial development. The conversion and destruction of natural habitats into anthropogenic ones have caused shifts in ecosystem functions, and ultimately this has dire consequences for biological diversity globally. Although many species have gone extinct due to anthropogenic land-use changes, some have persisted and thrive within human-dominated landscapes. These species have adapted well to these landscapes, to the point whereby they have modified their behaviour to exploit anthropogenic resources, and increase in numbers. However, the expansion of human land-use into historically wildlands means that wildlife and humans will increasingly interact with one another. This is cause for concern, particularly with the projection of future anthropogenic land-use expansion and intensification. As a result, there is need to research how wildlife in human-dominated landscapes adapt and how their survival will influence human-wildlife interaction in the future. Cape porcupines, Hystrix africaeaustralis, are one of those species which have benefited from anthropogenic change of the landscape. However, due to their effectiveness in exploiting anthropogenic food and shelter resources, they have been perceived as problematic. This has led to their persecutions in certain areas, particularly within agricultural systems. But they are also becoming increasingly problematic also in suburbia. Therefore, as motivation for this study, we aim to investigate the spatial ecology of Cape porcupines in human-dominated landscapes of farmland and urban areas. This is because there is very little information on their space use and the research on Cape porcupines is outdated. Consequently, due to their potential to become conflict-causing, there is urgency to determine their spatial ecology and contribute knowledge towards their conservation and management in these landscapes. Therefore, Cape porcupine home range and habitat use along a land-use gradient were investigated. A total of fifteen individual Cape porcupines were captured and fitted with Global Positioning System (GPS) collar transmitters in farmlands of Fort Nottingham, a peri-urban estate near Howick, and in a suburban estate in Ballito, in KwaZulu-Natal, South Africa. Data obtained from the GPS transmitters were used to estimate Cape porcupine home ranges using the Kernel Density Estimator (KDE) (Chapter 2). Overall estimated Cape porcupine home ranges were very small (n = 9, mean ± SE: 39.37 ± 6.33 ha) compared with other Hystrix porcupines. Farmland Cape porcupine home ranges (24.57 ha) were the smallest relative to the peri-urban (34.61 ha) and suburban areas (45.18 ha). These results were as expected, since it has been revealed that porcupine home ranges are determined by forage availability. Consequently, these human-dominated habitats have anthropogenic food resources that are constant relative to natural resources. This means that the expansion of human-dominated landscapes will result in the contraction of Cape porcupine home ranges as they benefit from anthropogenic resources. With the aid of the radio-telemetry data, we also determined Cape porcupine habitat use in the farmland, peri-urban and suburban areas, in KwaZulu-Natal, South Africa (Chapter 3). Habitat use of Cape porcupines were investigated at the landscape-scale (2nd order of selection) and the home range-scale (3rd order of selection). Habitat use of Cape porcupines varied at the two-levels of selection, and individual Cape porcupines utilized different habitats, but generally selected the forest with bushland habitat above other habitats. We thought Cape porcupine habitat use would be determined by habitats dominated by anthropogenic food resources (crops and gardens). However, Cape porcupines utilized natural food resources although they lived in human-dominated landscapes. Their habitat use was determined by the presence of forest with bushland habitat, and to a less extent by croplands or residential gardens. This means that at this point, Cape porcupines opportunistically utilized anthropogenic food resources according to their availability. However, these results should be interpreted with caution since the study duration was limited by battery life of the GPS transmitters (~ 5 months). This study revealed that Cape porcupine showed individual variation in ranging patterns and habitat use which were likely influenced by forage availability. In addition, Cape porcupines shifted their spatial behaviour depending on the landscape they inhabited. Therefore, the behavioural flexibility of Cape porcupines enabled them to adapt to anthropogenic changing land-use and successfully persist there.
Aspects of the ecology of feral cats (Felis catus) in urban Pietermaritzburg, KwaZulu-Natal, South Africa.
(2015) Pillay, Kerushka Robyn.; Downs, Colleen Thelma.
With changing land use such as urbanization, certain species thrive and are successful despite changes in the modified landscapes. Therefore, study of the ecology, adaptations and survival of these species in an urban context is warranted. Often these species include alien invasive species. An example is the feral cat (Felis catus). The negative effects caused by feral cats generally include impacts on native species of wildlife because of their highly predatory nature and their ability to spread zoonotic diseases. Furthermore, it often becomes a public nuisance occurring at high densities in urban areas. Consequently the aspects of the ecology of feral cats were studied from March 2014 to June 2015 in an urban mosaic in Pietermaritzburg, KwaZulu-Natal, South Africa. The research was also undertaken to propose and assist with an effective management strategy that was deemed necessary to control high densities of feral cats existing in urban Pietermaritzburg. Feral cats were trapped and fitted with GPS-GSM-UHF tracking collars in order to determine their home and core range sizes within the urban mosaic containing varying degrees of green and urban areas. Additionally, the disease prevalence in feral cats was also documented by collecting blood samples from feral cats occurring in many areas of the greater Pietermaritzburg area. The information gained in this study allowed compilation of feral cat management recommendations and strategies in order to control the increasing feral cat communities already established in Pietermaritzburg. Feral cat telemetry data showed that availability and abundance of food resources were the primary influencing factors affecting feral cat home range size and distribution as core areas contained at least one supplemental feeding site. There was considerable overlap of feral cats within the core areas. Overall home range size of feral cats was small but varied with individual cats. There was considerable overlap between and within the sexes. There were no significant differences in range size between sexes nor between day and night. However, diurnal ranges were generally smaller than nocturnal range sizes. Generally male feral cats had larger home ranges than female feral cats and nocturnal activity was higher across genders. Feral cats used urban areas more than green areas suggesting that the urban environment supports larger numbers of feral cats. The disease prevalence in feral cats tested was generally low. However, some tested positive for Feline Leukaemia Virus (FeLV) (28.6%) and for Feline Immunodeficiency Virus (FIV) (7.1 %). There was no occurrence of Feline Corona Viruses (FCoV) in feral cats tested in Pietermaritzburg. The location of feral cats within the city had a significant effect on prevalence of FeLV infection in feral cats tested. The findings of this study of feral cats in the urban mosaic of Pietermaritzburg showed that feral cats’ habitat use and home range were mainly affected by supplemental food resources. Furthermore, disease prevalence in feral cats tested was generally low. Thus efficient, cost-effective and realistic methods need to be implemented to control high densities of feral cats in this urban area require the use of a low-key supplemental feeding programme with a combined sterilization programme. This proposed strategy should be adopted and sustained with involvement of all concerned stakeholders to ensure that the welfare and population of the cats is well managed and humanely controlled particularly as this is an alien, invasive species. Additionally, all cats that test positive for any disease should be removed from the population to stop the spread of diseases to other feral or domestic cats in urban areas of Pietermaritzburg.
Aspects of the ecology of three mongoose species along a rural–urban landscape gradient of KwaZulu- Natal, South Africa.
(2020) Streicher, Jarryd Peter.; Downs, Colleen Thelma.; Ramesh, Tharmalingam.
Many small carnivore species are of particular concern for conservation because of their elusive behaviour, diminutive size and crepuscular habits. Management and research tend to be challenging and thus is often limited. Several members of the Herpestidae family fall into this research dead zone, including the large grey mongoose (Herpestes ichneumon), slender mongoose (Galerella sanguinea), white-tailed mongoose (Ichneumia albicauda) and marsh or water mongoose (Atilax paludinosus). The distribution range and other aspects of the ecology of these and other such species, has remained vague for much of the sub-tropical regions of southern Africa because of the scarcity of comprehensive data. There is little understanding of the basic ecology of these mongoose species, and limited progress has been made in understanding the tolerance of these species within a changing environment. These species of mongoose appear to persist across KwaZulu-Natal’s (KZN), South Africa, anthropogenically modified habitats (farmlands and urban). Small carnivore species, such as mongooses, can provide models of how medium-sized carnivores tolerate differing degrees of anthropogenic land-use change. A global review of the current knowledge and research effort for urban mammalian mesocarnivores was conducted. In the last decade, there has been a dramatic increase in the number of studies that focus on medium-sized mammalian carnivores. Disproportionate levels of urban studies exist for mesocarnivores. Several species have been comprehensively studied in the United States of America and the United Kingdom. These two developed countries held more than half of all studies on urban mammalian mesocarnivores. Areas of the world that are undergoing rapid urbanisation have the most significant deficiency of research. Across Africa, the spatial ecology of the Herpestidae family remains relatively poorly studied. We investigated how anthropogenic land-use change affects aspects of the ecology of three co-existing mongoose species (large grey, water and white-tailed) in the agricultural setting of the KZN Midlands. Individuals of these three species of mongooses were trapped, collared and tracked using GPS-UHF (ultra-high frequency). The results presented show that the three focal species have different spatial requirements and movements from previous stated in literature. The natural habitat and farmland mosaic of the KZN Midlands are segregating the preferred habitats into small fragments. These niche fragments are intensely used by each species and allow them to co-exist in these anthropogenically modified environments. Besides these species’ generalist nature, their behavioural plasticity may assist them in persisting in anthropogenically modified landscapes. In the absence of apex predatory control, an expansion in the range and population number of Herpestidae species is expected. This study provides crucial information on the spatio-temporal ecology of large grey, water and white-tailed mongoose in the KZN Midlands. The spatial movements of the three co-existing species in this study highlighted the variability that is present at a species and individual level. Further research is required to address the human–wildlife conflict that takes place locally. The urban aspect of the large grey, water and white-tailed mongoose ecology is also understudied, and we recommend further research be targeted. The spatial ecology of water mongoose in the urban green space matrix of the Upper Highway Area of eThekwini, KZN, was subsequently investigated. This was to compare aspects of their ecology between fragmented natural farmland and urban mosaic using similar methods. Water mongooses occurred at a high density in the fragmented green Durban Metropolitan Open Space System (D’MOSS). Insight into the spatial ecology of urban water mongoose (home range, core area utilisation, overlap and habitat use) determined using GPS telemetry data from 14 water mongooses from July 2018 - October 2019. Water mongooses had constricted spatial movements that were highly dependent on natural refugia, and individuals intentionally avoided built-up areas of the urban matrix. The confined nature of these green spaces consequently resulted in home range sizes that were significantly smaller than their farmland conspecifics. However, the species behavioural plasticity and generalist nature has allowed the species to occur at higher population densities in the green spaces of the urban matrix of the Upper Highway Area. Furthermore, the effects of urban sprawl on the dietary ecology of water mongooses using faecal analyses was conducted. Water mongooses scat samples (n = 104) were opportunistically collected and with the aid of members of the Kloof Conservancy during the study. Urban water mongooses consume a diverse array of dietary items (9 categories), which is dominated by three categories (relative frequency of occurrence: crustaceans 35.7%, invertebrates 19.9%, small mammals 19.1% and other 25.2%). Seasonal variation in the diet only occurred for crustaceans and invertebrates with the other dietary categories consumed equally throughout the seasons. Additionally, it was demonstrated that urban water mongooses are supplementing their diets with anthropogenic waste (chicken bones, plastic particulates and cigarette butts). The broad diversity in dietary categories and supplementation of anthropogenic waste demonstrates the generalist opportunistic feeding behaviour and adaptability of the species in an urban matrix. An online questionnaire survey was conducted to investigate socio-ecological attitudes and general perspectives towards mammalian mesocarnivores across a land-use gradient (rural–urban) from the uMgungundlovu to eThekwini Municipalities of KZN. Significant trends were assessed using the frequency of responses. The public held a range of different perspectives. Overall, respondents viewed mesocarnivores as non-threatening and vital for the environment. However, black-backed jackals (Canis mesomelas) were commonly identified as a problematic pest species, that subsequently are targets of predator control pressures by rural participants. The survey also identified that smaller, behaviourally flexible species (mongoose species and cape genet Genetta tigrina) were commonly sighted and are potentially increasing in both land-use types in the absence of competition and predatory control. Vehicle collisions are the primary cause of mesocarnivore fatality reported by participants of the survey. The impact of mesocarnivores was perceived differently along a land–use gradient which links to levels of interaction. The study emphasises the importance of citizen science and community engagement when attempting to understand the drivers of human–wildlife interactions and potential mitigation strategies. The present multifaceted study has improved our understanding of solitary members of the Herpestidae family and how anthropogenic changes affect them across a land-use gradient. Furthermore, the behavioural flexibility and adaptability of mongooses in enabling them to persist at differing degrees of anthropogenic pressure were evident. However, the size class of mammalian mesocarnivores remains understudied in Africa, and this is of concern in a rapidly developing region.
Aspects of the ecology of trumpeter hornbill (bycanistes bucinator) across urban-forest mosaics in KwaZulu-Natal, South Africa.
(2016) Chibesa, Moses.; Downs, Colleen Thelma.
Abstract available in PDF file.
Aspects of the urban ecology of the Spotted Thick-knee (Burhinus capensis)
(2021) Josiah, Kyrone Kent.; Downs, Colleen Thelma.
Abstract available in PDF.
Aspects of the use of vultures in traditional medicine in KwaZulu-Natal, South Africa, and conservation implications.
(2022) Manqele, Nomthandazo Samantha.; Downs, Colleen Thelma.; Selier, Sarah Anne Jeanneta.
Eighty percent of people in developing countries use traditional medicine either as a primary source of healthcare or as supplementary to western medicine. Traditional medicines are mainly derived from wild plants and animals. There has been a marked global increase in the use of animals and their body parts as ingredients in traditional medicine. The harvesting and use of wildlife resources in traditional medicine are largely unregulated and involve many species of conservation concern. This is true for African vultures, as evidence indicates that traditional medicine is responsible for 29% of African vulture mortalities. Currently, six out of seven vulture species in South Africa face a serious threat of extinction. The threatened species are listed under the Threatened or Protected Species regulations, which prohibit hunting and consumption. However, evidence suggests a long-standing use of vultures in traditional medicine in KwaZulu- Natal, South Africa, yet so much remains unknown about this practice. Understanding the belief system and the socio-economic dispositions underpinning the belief-based use of vultures will favour vulture conservation efforts in the province. Research was undertaken with the aim of advancing the knowledge base regarding the use of vultures in traditional medicine in KwaZulu-Natal. Accordingly, the following objectives were established: 1) to assess human-vulture interactions in a dynamic ecosystem, 2) to evaluate the dynamics behind the illegal harvesting and trade of vultures and their body parts, 3) to investigate the ethnomedicinal use of vultures by traditional health practitioners and 4) report on the efficacy of religion as an alternative for traditional medicine use. The study involved local communities surrounding protected areas and specific groups such as hunters, muthi traders, and traditional healers. A mixed-methodology approach was adopted, and data were collected using questionnaire surveys, in-depth interviews, focus group discussions and observations. A total of 728 respondents contributed to this study. Local people’s perceptions towards vultures were predominantly positive. Respondents appreciated vultures for removing carcases, thus keeping the environment clean. Results also demonstrated that hunting and wildlife consumption were common in the study areas, and that the hunting and use of vultures were a part of this. Vultures were harvested from protected areas and sold directly to traditional healers and also to muthi traders. Vultures were reportedly important in traditional medicine, but their harvesting was limited because it was perceived as a criminal activity, and the birds reportedly occurred in smaller numbers than before. In traditional medicine, seven vulture parts were used, but the head treated the majority (62%) of ailments reported. Seventy-one percent of the uses for vulture-based remedies were spiritual in nature. Religious practices such as church attendance, prayer and fasting, coupled with products like holy water, can provide relief from physical and psychological ailments. In this study, the role of religion in contributing positively to human health and well-being was underscored. Overall, results from this study can be instrumental in guiding efforts to improve vulture conservation in KwaZulu-Natal and other parts of South Africa.
Assessing anthropogenic impacts on the persistence of forest mammals within the Indian Ocean coastal belt of southern KwaZulu-Natal province.
(2016) Ehlers Smith, Yvette Cathrine.; Downs, Colleen Thelma.
Abstract available in PDF file.
Assessing the success of red-billed oxpecker translocations as a conservation tool in KwaZulu-Natal, South Africa.
(2016) Jordaan, Maryna.; Downs, Colleen Thelma.; Combrink, Leigh.
There are numerous factors that contribute to a bird species becoming threatened and in need of increased conservation efforts in order to survive. Compared with fossil records, current extinction rates are much higher than expected, which emphasizes the need for conservation. Conservation translocations aim to increase the survival of threatened species by ameliorating their possibility of extinction, and contribute either to educational, scientific or supportive purposes in this. Reintroductions or translocations are a well-established method for increasing a species’ distribution and for restoring their historical range. Translocations are defined as human-mediated movements of organisms from one area and released in another. A translocation is only considered successful when a population is self-sustained through breeding of the released individuals and does not require intervention. Oxpeckers are African passerines from the starling lineage. Historically, red-billed oxpeckers (Buphagus erythrorhynchus) had a distributional range that extended from Eritrea to Somalia, through south-eastern Sudan to Zimbabwe and into the former Transvaal, Natal and Eastern Cape Provinces, South Africa. Oxpecker populations became threatened in South Africa in the early years of the 20th century. In southern Africa, red-billed oxpeckers became Near-Threatened as a result of cattle dips with substances toxic to the birds, and because of a significant decrease in their large game host species. Conservation efforts in the 1980s onwards have attempted to deal with the factors causing their demise. In 2002, The Endangered Wildlife Trust began translocating red-billed oxpeckers to areas where they had gone locally extinct, in an attempt to increase their current distribution and population in South Africa. Consequently, we documented and reviewed the various capture and quarantine methods, conducted since 1988 to the present, in the various translocations of red-billed oxpeckers. We also highlighted lessons learnt from these translocation events. To determine how successful these translocations were, we compared changes in the Southern African Bird Atlas Project (SABAP) reporting rate data and determined the presence or absence of red-billed oxpeckers at all the 24 translocation release sites in KwaZulu-Natal (KZN). In SABAP 1, data on species occurrences were collected at the Quarter Degree Grid Cell (QDGC) level. In SABAP 2, this was refined to pentads, where nine pentads are in one QDGC. Therefore, the reporting rate comparison was done at QDGC level. Prior to these translocations, red-billed oxpeckers were absent from all these sites. Specifically, we conducted transect surveys to determine red-billed oxpecker’s population estimates in Ithala Game Reserve (IGR) and Tembe Elephant Park (TEP). We also netted and ringed red-billed oxpeckers at these sites to obtain morphological and genetic data and to determine their breeding status. Furthermore, we distributed an online questionnaire to determine public perceptions on red-billed oxpecker’s range expansion in South Africa. We analysed the SABAP data using general linear modelling and the survey data using the Distance Programme in R Studio. There was a significant increase in reporting rates of red-billed oxpeckers in southern Africa since the end of SABAP1 in 1991 with several new areas where they had established. This was again confirmed from landowners reporting the first observation made of red-billed oxpeckers on their respective properties. Reporting rates at the specific translocated release sites had also increased. Twenty-four per cent of the QDGCs (n = 170) showed an increase in reporting rates in southern Africa, however, 36% of the QDGCs showed a decrease in reporting rates (n = 258). Fourteen per cent of the QDGCs (n = 100) showed new areas colonized by red-billed oxpeckers. In South Africa, red-billed oxpeckers had colonised several new areas, particularly near areas where reporting rates had increased. Twenty-six per cent of the QDGCs showed areas where red- billed oxpeckers were absent and had gone locally extinct (n = 187); however these areas were mostly in Botswana and Zimbabwe. We determined that habitat, host preference and host herd size were important factors when calculating population densities of red-billed oxpeckers. Detection probabilities for red-billed oxpeckers were highest in open bush habitat and where large herds were present. In IGR, red-billed oxpeckers were seen in 8% (n = 33) of the total of 391 observations made. In TEP, red-billed oxpeckers were observed in 6% (n = 24) of the total 378 observations made. In both IGR and TEP all red-billed oxpeckers we trapped and ringed had not been previously ringed and some had brood patches supporting their successful reproduction there. To date, a total of 24 reintroduction events and 13 population reinforcements have taken place, with a total of 1359 red-billed oxpeckers translocated in South Africa. The increase in reports of red-billed oxpecker sightings, especially at release sites and on nearby land, showed the importance of translocations for the conservation of oxpeckers. In addition, the placement of artificial nest boxes has increased the likelihood of red-billed oxpeckers breeding at their new translocated site. The recent down-grading of red-billed oxpeckers from Near Threatened to Least Concern, and the data collected in our study support the success of translocation as a conservation tool for this species. Translocations of red-billed oxpeckers in South Africa should be considered one of the more successful of such programmes as indicated by its success.
Assessing the trade of reptile species in the South African pet trade.
(2021) Mantintsilili, Asekho.; Downs, Colleen Thelma.; Shivambu, Tinyiko Cavin.; Shivambu, Ndivhuwo.
Despite the negative impacts that the pet trade has on the native and non-native biodiversity, economy and human health, the research suggests that the demand for pets and the extent of trade in live animals as pets has increased dramatically over the years. As a result, many species, including reptiles, have been translocated and introduced into new or non-native environments. Some of these have established feral populations, become invasive and are causing significant environmental and socio-economic impacts on non-native environments. Reptiles are among the most popular groups of animals in the pet trade industry globally. Trade in pet reptiles in South Africa is large and one of the major pathways through which non-native species, including invasive species, are introduced into the country. Despite this, little is known about the dynamics of the wildlife trade in pet reptiles globally. To understand the dynamics of the global trade in pet reptiles, we carried out a comprehensive literature search to gather relevant information from reptile pet trade-based publications. We further compiled a list of traded pet reptiles from all South African physical pet stores and online advertising websites to determine which species are traded, pose an invasion risk and have potential environmental and socio-economic impacts. We found a total of 39 publications based on the reptile pet trade from 1994 – 2021 worldwide. Our analyses revealed that the research effort was not uniform globally, with the majority (63.6%) of all relevant studies originating from three continents (Asia, Europe, and North America). Moreover, the United States of America (North America) and Indonesia (Asia) produced the greatest research outputs (12.1% each) compared with other countries across the world. We found at least 1140 reptile species belonging to 60 families involved in the global pet trade, with invasive red-eared slider Trachemys scripta elegans being the most frequently studied species (number of studies = 23/39). Of the recorded species, at least 79 are invasive, 46 endangered, 29 critically endangered, while only 546 are CITES-listed. In terms of reptile species sold in South Africa, we recorded a total of 2771 individuals representing 88 unique reptiles, 69 from physical pet stores and 18 from online advertising websites. KwaZulu-Natal, Gauteng and Western Cape Provinces had the highest number of pet stores and online advertising websites; therefore, they subsequently recorded the highest number of pet reptiles compared with other provinces. Physical pet stores were found to have the highest number of species compared to online trade. Of the recorded species, 76 are nonnative, and 15 of these are invasive to South Africa. Moreover, only 32 pet reptiles are listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). For current distributions, red-eared slider Trachemys scripta elegans, P. guttatus, and Western diamondback rattlesnake Crotalus atrox had the largest predicted climatic suitability. The future predictions for the latter two species were predicted to increase, while red-eared slider suitability shifted. Some species, such as Burmese pythons Python bivittatus, showed low invasion risk based on climatic suitability. However, given their large body size, history of invasion and their popularity in the pet trade, they are most likely to escape or be released from captivity and become invasive. A total of 76 reptile species were assessed for environmental and socio-economic impacts using the Generic Impact Scoring System (GISS), Environmental Impact Classification for Alien Taxa (EICAT), and Socio-Economic Impact Classification for Alien Taxa (SEICAT). Using GISS, we found that 13 species had environmental impacts (E_GISS), while 11 species had socio-economic impacts (SE_GISS). For EICAT and SEICAT, 13 species had environmental impacts, and eight had socio-economic impacts, respectively. The most popular pet species, red-tailed boa Boa constrictor, green iguana Iguana iguana, P. bivittatus, T. elegans, and central bearded dragon Pogona vitticeps had impacts in all the three scoring schemes. The later species and corn snake (Pantherophis guttatus) scored the highest for all impact schemes. Species sold in high numbers, with large climatically suitability and potential impacts, are more likely to establish feral populations and become invasive should they escape or be released from captivity. We, therefore, recommended that the trade in pet reptiles should be constantly monitored to avoid new introductions and the implications that the pet trade may have to the country.
Assessment of spatial and temporal variation in water quality of the Pienaars River, Limpopo water management area.
(2018) Mlotshwa, Lungile Wendy.; Tsvuura, Zivanai.; Ndhlala, Ashwell Rungano.; Ncube, Bhekumthetho.
Abstract available in pdf.
Assessment of the current ecological integrity of the uMngeni River, KwaZulu-Natal, South Africa, using fish community structures and attributes of the Labeobarbus natalensis (Castelnau, 1861) populations.
(2019) Dlamini, Pumla Vanessa.; Downs, Colleen Thelma.; O'Brien, Gordon Craig.
Rivers are the main source of freshwater water for human communities and provide people with numerous ecosystem services such as water purification, transportation, power generation, food supply, and water for domestic, agricultural and industrial use. Water resources, and the ecosystem services they provide, are particularly important in developing countries, such as South Africa. The uMngeni River, is a strategic resource that provides water to two of the largest cities in KwaZulu-Natal Province (the uMgungundlovu and eThekwini municipalities), with more than four million people, making it socio-economically important. As such, to maintain sustainability the protection of the river is important. However, in South Africa and KwaZulu-Natal, the impact of anthropogenic activities has made riverine ecosystems one of the most threatened types of ecosystems in the world. The use of fish as key indicators of the ecological state of aquatic ecosystems is well established as their vulnerability to environmental change, mobility, longevity and relative ease of species identification make them good indicators. This study evaluated the current ecological integrity of the uMngeni River in KwaZulu-Natal using multiple lines of evidence including fish communities and the state of Labeobarbus natalensis (the KwaZulu-Natal yellowfish) populations, and environmental variables. The research was undertaken in the major man-made lakes (dams) in the uMngeni River (namely Midmar, Albert Falls, Nagle and Inanda Dams) and in the rivers of the uMngeni Catchment. Abiotic lines of evidence investigated included water quality and habitat, while the biotic lines of evidence included fish community structures and attributes of the population of L. natalensis. Fish community structures at eight selected River Eco-status Monitoring Programme (REMP) sites in the uMngeni catchment were considered. This included consideration of how the fish communities responded to changes in a range of environmental variables and alien fishes using the Fish Response Assessment Index (FRAI), we were able to determine that the ecological integrity of the uMngeni River decreases in a downstream gradient from the upper reaches of the catchment to lower reaches, due the synergistic effect of multiple anthropogenic stressors. The multivariate analyses indicated that the anthropogenic impacts responsible for shifts in fish community structures, and the associated ecological integrity of the river were related to changes in instream habitats and water quality stressors primarily. Most of the environmental changes identified can be linked to flow modifications and land use activities throughout the uMngeni catchment. Assessments of attributes of the L. natalensis populations from large instream impoundments in the uMngeni River (namely Midmar, Albert Falls, Nagle and Inanda Dam) resulted in diminishing wellbeing of the populations of this endemic migratory fish progressively both in abundance and structure, down the length of the catchment. The quality and quantity of water diminished down the catchment gradient with this gradient and the effect of the barriers themselves can partially be attributed to the impaired state of the populations. Impoundments are not preferred by juvenile and young L. natalensis that prefer shallow riffle habitats that are lacking in dams, the occurrence of many predatory alien fishes in the dam can also be attributed to the absence of small yellowfish in the dams. The outcomes of this study can contribute to the sustainable management and development of conservation plans for the rivers and dams in the uMngeni catchment. Major stressors that should be mitigated include the barrier effect and operation or flow releases from the large dams and smaller weirs etc. that cause river fragmentation in the catchment. It is recommended that management plans for the conservation of the fishes in the catchment should be developed which is achievable as the current supply of resources in the catchment is balanced with the demand for use. Fish passages should be established in all of the dams in the uMngeni River to allow migratory fish free passage along the river and to re-establish river connectivity processes. Additionally, the removal of redundant weirs or partial man-made barriers is recommended to alleviate the effects of fragmentation particularly on the yellowfish in the catchment. More research is required to understand the migratory requirements of fishes in the catchments and the cost-benefit of mitigating river fragmentation to achieve a sustainable balance between the use and protection of resources in the catchment. Finally, the study has identified water quality and flow stressors that are negatively affecting the wellbeing of the fish communities in the catchment. The water quality stressors derived from land-based activities and associated management of flows in the catchment must be improved to attain a sustainable balance between the use and protection of the resources of the uMngeni Catchment.
Behaviour of bottlenose dolphins : inference for dolphin tourism off Durban, South Africa.
(2008) Mahomed, Maleeha.
During long-term studies of dolphins, the number of individuals in the population being studied are constantly monitored using the technique of photo-identification. This constant monitoring makes use of different researchers over time. Therefore, measurement of photographic quality and individual distinctiveness for photo-identification analyses was incorporated in this dissertation to provide an additional data set for analysis. Researchers with differing levels of experiences did not obtain the same information from the same photograph and were unable to reliably quantify variables of photo quality and individual distinctiveness, but experienced researchers were found to be more adept than inexperienced researchers in counting notches on the dorsal fin of bottlenose dolphins. These results highlight the necessity for researchers to be trained in photo-identification techniques prior to carrying out their study. This study theodolite tracked dolphins off Durban from June 2004 to Feb 2005 to assess habitat utilization of bottlenose dolphins (Tursiops aduncus) in the Durban bay region. Dolphins were seen in all months surveyed and throughout the survey area. Temporal distribution of dolphins was skewed with 91% of dolphins seen before midday and 98% of sightings observed in water depths less than 30m. Six behavioural categories were recorded, including: social, fast travel, slow travel, feeding, resting and milling. The most dominant behaviour exhibited by dolphins was slow travel (46%) followed by feeding (27%). Resting was not observed at all. Of the feeding behaviour 88% occurred in the southern end of the bay whereas other behaviours occurred randomly throughout the survey area. Additional theodolite tracks were conducted during experimental boat approaches (before, during and after boat approaches) to determine potential short-term reactions of dolphins to dolphin watching boats. Two speeds of approach (slow ~ < 5 km/hr and fast ~ > 40 km/hr) and two distances of approach (20m and 80 m) were tested. The bottlenose dolphin groups did not change their behaviour in response to boat approaches during any of the periods of experimentation. Short-term changes in group speed, group size and spread were not statistically significant. Dolphin groups continued with their ‘normal’ behaviour and spent the same amount of time in the bay when compared to their distribution and behaviour in the absence of the experimental boat. These findings indicate that the experimental boat did not affect the behaviour of dolphins at either a slow or fast approach and even at a close distance. This is interpreted as being as a result of habituation of the dolphins due to their residency in a busy port. This work is crucial in developing guidelines for the development of a sustainable dolphin watching industry off Durban.