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Vuyisile Thabethe

Bio: Vuyisile Thabethe is an academic researcher from University of KwaZulu-Natal. The author has contributed to research in topics: Frugivore & Germination. The author has an hindex of 3, co-authored 8 publications receiving 68 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors investigated the extent (if any) to which householders in urban and suburban areas of KwaZulu-Natal provide supplementary food to African woolly-necked storks.
Abstract: African woolly-necked storks (Ciconia microscelis) depend on wetland habitats for foraging and nesting in natural environments. Recently, they have started colonising urban environments in KwaZulu-Natal, South Africa, and are now a common sight in suburban areas in particular. There have been some anecdotal reports on supplementary feeding of this species by households in some urban areas where they are common. However, these reports have never been confirmed and therefore the extent of feeding and lack thereof is unknown. Using a questionnaire survey, we therefore investigated the extent (if any) to which householders in urban and suburban areas of KwaZulu-Natal provide supplementary food to African woolly-necked storks. We also determined the feeders’ provisioning habits, and identified the motivation behind and attitudes toward feeding. We found that a significant number of householders fed African woolly-necked storks on a daily basis throughout the year. The majority of respondents provided meat while others provided inappropriate food such as bread. Respondents were most often motivated to feed for personal pleasure. Our results showed that this species is successfully utilising and exploiting anthropogenic food – a novel behaviour. The observations and narratives from respondents strongly suggest that the African woolly-necked stork is present throughout the year, contrary to the perception that this species is migratory during winter. Based on the results obtained in this study, supplementary feeding of African woolly-necked stork by householders is relatively common, widespread and established in suburban areas of KwaZulu-Natal, South Africa. However, reported inappropriate feeding may create concerns regarding the health status of African woolly-necked storks in urban population. Therefore, to prevent further detrimental effects and potential human-wildlife conflicts we recommend that suitable feeding guidelines be formulated.

29 citations

Journal ArticleDOI
TL;DR: The results suggest that Knysna and purple-crested turacos are legitimate seed dispersers of fleshy-fruited invasive plants, while rose-ringed parakeets are mainly seed predators.
Abstract: Avian frugivores play a key role in seed dispersal of many plant species, including invasive alien plants. We assessed the effect of gut passage on the germination of selected invasive alien plant species in South Africa. Fruits of four fleshly-fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava, and Morus alba, were fed to two species of indigenous turacos, Knysna (Tauraco corythaix) and purple-crested (Gallirex porphyreolophus) turacos, and to invasive rose-ringed parakeets (Psittacula krameri). Seed retention time was determined as this can influence both seed dispersal and germination success. Germination success of ingested seeds was compared with that of manually de-pulped seeds, as well as to seeds in whole fruit. The germination success of seeds of all the invasive plant species increased significantly after ingestion by both turaco species compared with seeds from whole fruits. Germination success of manually de-pulped seeds did not differ significantly from that of turaco ingested seeds. In contrast, seed passage through the digestive tract of rose-ringed parakeets significantly reduced germination success and viability of ingested invasive plant species. Our results suggest that Knysna and purple-crested turacos are legitimate seed dispersers of fleshy-fruited invasive plants, while rose-ringed parakeets are mainly seed predators. Although seed predation by rose-ringed parakeets negatively affects the reproductive success of these plants, it is unlikely that this will suppress the spread of these invasive alien plants in South Africa as they are already well established. Furthermore, they can facilitate dispersal by seed regurgitation and dropping uneaten fruits away from the parent plant. Similar trends could be expected for indigenous seeds that rose-ringed parakeets feed on and therefore these birds remain a negative influence within invaded ecosystems.

28 citations

Journal ArticleDOI
TL;DR: Examination of the effects of seasonal changes in ambient temperatures of captive-bred rose-ringed parakeets suggests that this species is physiologically and behaviorally equipped to cope with a range of climatic situations and this partly explains their global success as an invader species.

19 citations

Journal ArticleDOI
TL;DR: This paper reviewed case studies of vertebrate species' responses to urbanisation in KwaZulu-Natal, South Africa, to determine trends and presented a novel modification to the final of three phases of the framework described by Evans et al. (2010).
Abstract: Urbanisation is rapidly transforming natural landscapes with consequences for biodiversity. Little is documented on the response of African wildlife to urbanisation. We reviewed case studies of vertebrate species' responses to urbanisation in KwaZulu-Natal, South Africa to determine trends. Connected habitat mosaics of natural and anthropogenic green spaces are critical for urban wildlife persistence. We present a novel modification to the final of three phases of the framework described by Evans et al. (2010), which documents this sequence for vertebrate species persistence, based on the perspective of our research. Species in suburbia exhibit an initial phase where behavioural and ecological flexibility, life-history traits and phenotypic plasticity either contribute to their success, or they stay at low numbers. Where successful, the next phase is a rapid increase in populations and distribution; anthropogenic food resources and alternate breeding sites are effectively exploited. The modified third phase either continues to spread, plateau or decline.

12 citations

Journal ArticleDOI
TL;DR: It is concluded that seed germination success in fleshy fruits including those of alien species, varies with seed treatment by different vertebrate dispersal agents, and their net effect on seeds, may have consequences on species invasion success.
Abstract: The fleshy fruits of exotic Opuntia ficus-indica (L.) Mill and Opuntia robusta (Haw.) Haw (Cactaceae family) are consumed and dispersed by many vertebrates, which likely influences their invasion success. We tested whether seed ingestion by Pied Crows (Corvus albus) and other smaller birds (African Pied Starling Lamprotornis bicolor and the Red-eyed Bulbul Pycnonotus nigricans) improve the germination and speed in O. ficus-indica and O. robusta. Controlled germination trials for two Opuntia species were set up using the seeds extracted from faecal material, depulped seeds, and intact fruits. Overall, results show that seed germination for O. robusta was significantly higher than for O. ficus-indica. There were significant differences in seed germination between treatments of two Opuntia species, with the total mean germination of seeds defecated by the Pied Crows being equivalent to that of seeds defecated by the other smaller birds but significantly greater than the other treatments (i.e., depulped seeds and intact fruit). We noted that removal of the fruit pulp from seeds significantly improved germination in both Opuntia species compared to intact fruits. The O. robusta seeds defecated by the smaller birds had significantly greatest and most accelerated germination of all other treatments followed by the seeds defecated by the Pied Crows. Seeds of O. ficus-indica defecated by the Pied Crows had significantly greater germination than the seeds ingested by smaller birds. We conclude that seed germination success in fleshy fruits including those of alien species, varies with seed treatment by different vertebrate dispersal agents, and their net effect on seeds, may have consequences on species invasion success.

8 citations


Cited by
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Journal ArticleDOI
TL;DR: Previous evidence for the importance of hornbills, bulbuls, elephants, gibbons, civets, and fruit bats in seed dispersal is reinforced, and it is suggested that the roles of green pigeons, macaques, rodents, bears, and deer were previously underestimated.

145 citations

01 Jan 2005
TL;DR: In this paper, the authors compared the fruit fates of C. orbiculatus and native American holly (Ilex opaca) and examined the influence of seed treatment and light intensity on seed germination and seed growth.
Abstract: Oriental bittersweet (Celastrus orbiculatus Thunb.) is a non-indigenous, invasive woody vine in North America that proliferates in disturbed open sites. Unlike most invasive species, C. orbiculatus exhibits a ‘sit and wait’ strategy by establishing and persisting indefinitely in undisturbed, closed canopy forest and responding to canopy disturbance with rapid growth, often overtopping trees. We compared fruit fates of C. orbiculatus and native American holly (Ilex opaca). We also explored mechanisms for this ‘sit and wait’ invasion strategy by testing the effect of C. orbiculatus fruit crop density on removal rates and by examining the influence of seed treatment and light intensity on seed germination and seedling growth. More C. orbiculatus than I. opaca fruits became damaged, and damage occurred earlier. More fruit fell from C. orbiculatus than I. opaca, but removal rates by frugivores did not differ (76.0 ± 4.2% vs 87.5 ± 3.7%, respectively). Density (number of fruits in a patch) of C. orbiculatus did not influence removal rates. Scarification (bird-ingestion) of C. orbiculatus seed delayed germination but seeds germinated in similar proportion to manually defleshed seeds (sown either singly or all seeds from a fruit). Germination of seeds within intact fruits was inhibited and delayed compared to other treatments. Seed treatment did not affect seedling growth. The proportion of seeds germinating and time until germination was similar among five light intensity levels, ranging from full sun to closed-canopy. Seedlings in >70% photosynthetically active radiation (PAR) had more leaves, heavier shoots, and longer, heavier roots than seedlings at lower PAR levels. Results show that most (>75%) C. orbiculatus seeds are dispersed, seedlings can establish in dense shade, and plants grow rapidly when exposed to high light conditions. Control strategies for this highly invasive species should likely focus on minimizing seed dispersal by vertebrates.

90 citations

Journal ArticleDOI
22 Feb 2016-PeerJ
TL;DR: Internal dispersal was investigated by searching for seeds in faeces opportunistically collected at communal roosts, foraging sites and nests of eleven parrot species in different habitats and biomes in the Neotropics, suggesting the importance of parrots as endozoochorous dispersers has been largely under-appreciated.
Abstract: Despite the fact that parrots (Psitacifformes) are generalist apex frugivores, they have largely been considered plant antagonists and thus neglected as seed dispersers of their food plants. Internal dispersal was investigated by searching for seeds in faeces opportunistically collected at communal roosts, foraging sites and nests of eleven parrot species in different habitats and biomes in the Neotropics. Multiple intact seeds of seven plant species of five families were found in a variable proportion of faeces from four parrot species. The mean number of seeds of each plant species per dropping ranged between one and about sixty, with a maximum of almost five hundred seeds from the cacti Pilosocereus pachycladus in a single dropping of Lear’s Macaw (Anodorhynchus leari). All seeds retrieved were small (<3 mm) and corresponded to herbs and relatively large, multiple-seeded fleshy berries and infrutescences from shrubs, trees and columnar cacti, often also dispersed by stomatochory. An overview of the potential constraints driving seed dispersal suggest that, despite the obvious size difference between seeds dispersed by endozoochory and stomatochory, there is no clear difference in fruit size depending on the dispersal mode. Regardless of the enhanced or limited germination capability after gut transit, a relatively large proportion of cacti seeds frequently found in the faeces of two parrot species were viable according to the tetrazolium test and germination experiments. The conservative results of our exploratory sampling and a literature review clearly indicate that the importance of parrots as endozoochorous dispersers has been largely under-appreciated due to the lack of research systematically searching for seeds in their faeces. We encourage the evaluation of seed dispersal and other mutualistic interactions mediated by parrots before their generalized population declines contribute to the collapse of key ecosystem processes.

53 citations

Journal ArticleDOI
06 Dec 2018-PeerJ
TL;DR: Current evidence suggests that urban areas dampen the natural cycles at several temporal scales, and a dearth of long-term comparisons of bird composition and studies that simultaneously analyze the relationship between resources and bird composition stabilization at the seasonal and interannual scales is reviewed.
Abstract: Background A scarcely studied consequence of urbanization is the effect of temporal stabilization of the environment on bird communities. This alteration is thought to dampen environmental variations between day and night, seasons and years, promoting a temporal persistence of bird composition in urban areas. The aim of this study was to review current evidence of temporal stabilization of biotic and abiotic factors in urban environments and the potential effects of such stabilization on temporal variation of bird species presence at different temporal scales. Methods I selected the literature by searching published articles and book chapters using Scopus and Google scholar. I only included articles that compared the temporal variation of bird composition or resources between different levels of urbanization. Results In general, there is evidence of temporal stabilization of abiotic and biotic factors at the three time scales considered. At the diurnal scale, the main factor considered was artificial light in the context of light pollution. At the seasonal and interannual scales, several case studies found a smaller temporal variation of primary productivity in urban than in natural and rural areas. Bird species composition showed more stabilization in urban environments at the three temporal scales: (1) several case studies reported bird activity at night, associated with artificial light; (2) studies in urban parks and along urbanization gradients showed smaller seasonal variation of bird composition in the more urbanized areas; and (3) in general, case studies along urbanization gradients showed smaller interannual variation of bird composition in the more urbanized areas, although some studies showed no relationships or opposite trends than expected. Discussion The published evidence suggests that urban areas dampen the natural cycles at several temporal scales. The stabilization of biotic and abiotic factors, such as light, temperature, food and habitat structure, is desynchronized from natural diurnal, seasonal and interannual cycles. However, there is a dearth of long-term comparisons of bird composition and studies that simultaneously analyze the relationship between resources and bird composition stabilization at the seasonal and interannual scales. More research is needed in the Southern hemisphere, where there is a lack of studies dealing with the seasonal and interannual variations of primary productivity along urbanization gradients and nocturnal activity of bird species. A future research agenda should include differentiation of spatial and temporal homogenization of avifaunas.

39 citations