Knysna Turacos (Tauraco corythaix) do not improve seed germination of ingested fruit of some indigenous South African tree species

AbstractSeed dispersal plays an important role in the persistence, regeneration and maintenance of plant communities. It is therefore not surprising that much attention has been paid to the germination potential of seeds ingested by frugivorous animals. Consequently the aim of this study was to determine what effect ingestion of seeds by Knysna Turacos (Tauraco corythaix) has on the germination rate and germination percentage of indigenous South African tree species. Fruits from twelve tree species were fed to the Turacos in separate trials and seed retention times were determined as it has been suggested that a longer seed retention time may increase germination rates. At the end of each trial, seeds were extracted from excreta of individual birds and planted in trays containing potting soil. Germination was recorded daily until 14days of no germination. Knysna Turacos seed retention times were in the range of those obtained by other studies, with Ficus sur seeds having the fastest retention times (12.4±0.8min) and Celtis africana the slowest (34.6±5.6min). Seed ingestion by Knysna Turacos did not influence the rate at which seeds germinated in 83% of the tree species, but ingested Ficus lutea and Ficus natalensis seeds germinated significantly sooner than whole fruit seeds. Future studies relating the composition of indigenous forest fruits to food preferences of Knysna Turacos may give insight into their role as potential seed dispersers of indigenous fruiting tree species

Implementation of a science-action partnership to manage a threatened ecosystem in an urban context

Abstract: The gap between scientific knowledge and implementation of such knowledge in the fields of biodiversity conservation, environmental management and climate change adaptation, is widely recognized. The state of knowledge of urban ecosystems is generally quite poor, and there is a shortage of human capacity to implement scientifically-sound management practices at the local level, especially within institutions having the mandate of regulating land use planning. The need to bridge the science-action gap to improve decision-making for local land use planning and management, and thereby reduce the impacts of urbanization on ecosystems, has been recognized by eThekwini Municipality in the city of Durban, South Africa..

The effect of frugivorous birds on seed dispersal and germination of the invasive Brazilian pepper tree (Schinus terebinthifolius) and Indian laurel (Litsea glutinosa)

Biological invasions are a major threat to biodiversity in most parts of the world. The success of invasive fleshy fruiting plants is linked to the role of native avian frugivores. By ingesting and excreting/regurgitating viable seeds, avian frugivores are able to promote germination and disperse the seeds of these invasive fleshy fruiting plants. The Brazilian pepper tree (Schinus terebinthifolius) and the Indian laurel (Litsea glutinosa) are both invasive species in South Africa, particularly in KwaZulu-Natal. We examined the effect of native birds (Cape white-eyes (Zosterops virens), red-winged starlings (Onychognathus morio), speckled mousebirds (Colius striatus) and dark-capped bulbuls (Pycnonotus tricolor) on germination and dispersal of S. terebinthifolius and L. glutinosa seeds by comparing themto those of whole and manually de-pulped S. terebinthifolius and L. glutinosa fruit. By comparing the seed retention times and fruit consumed by the various avian species,we examined which avian species were likely to have the most effect on germination and dispersal of S. terebinthifolius and L. glutinosa. We found that all avian species readily consumed the fruit of S. terebinthifolius and that (through pulp removal by gut passage) these avian species played a vital role in the germination time and success of S. terebinthifolius. Most of the avian species consumed L. glutinosa fruit (though not as much as S. terebinthifolius), with speckled mousebirds being the only exception. However, ingestion of L. glutinosa fruit had no positive effect on germination as none of the seeds germinated (including the control seeds). Variances in body mass and bill size could potentially mean that larger birds play a greater role in seed dispersal as they ingested a greater number of seeds. Further studies need to be conducted on L. glutinosa in order to determine the conditions in which it germinates in the field and how these may be replicated for germination experiments in the laboratory

Non-native small mammal species in the South African pet trade

Non-native small mammals are amongst the most popular species traded as pets around the world. Some of these mammals have become invasive through various pet trade releases and escapees in most countries. In South Africa, several nonnative small mammals have been introduced for pet trade purposes. We assessed the sale of non-native small mammals in South Africa from September 2018 to 2019 to determine their abundance and degree of trade online and in pet shops. A total of seven websites were recorded selling 2,681 individuals representing 24 species belonging to seven taxonomic orders. For physical pet shops, 19,391 individuals representing 16 species and seven orders were recorded from 122 pet shops. Rodents and primates were the most dominant groups in both online and pet shops. The most common small mammal species traded were the Norwegian rat Rattus norvegicus, the guinea pig Cavia porcellus, the European rabbit Oryctolagus cuniculus and the house mouse Mus musculus. Prices ranged from ZAR9.00 to ZAR12,000.00, with rodents offered at relatively low prices. The most abundant species traded were relatively cheap when compared with the least abundant species and CITES species were more expensive than non-CITES species. Species with high abundances traded at low prices and have a history of invasion through pet trade releases and escapes pose an invasion risk in South Africa. Therefore, their trade should be strictly regulated

Home range and habitat use of feral cats in an urban mosaic in Pietermaritzburg, KwaZulu-Natal, South Africa

The relationship between levels of dominance and species richness is highly contentious, especially in ant communities. The dominance-impoverishment rule states that high levels of dominance only occur in species-poor communities, but there appear to be many cases of high levels of dominance in highly diverse communities. The extent to which dominant species limit local richness through competitive exclusion remains unclear, but such exclusion appears more apparent for non-native rather than native dominant species. Here we perform the first global analysis of the relationship between behavioral dominance and species richness. We used data from 1,293 local assemblages of ground-dwelling ants distributed across five continents to document the generality of the dominance-impoverishment rule, and to identify the biotic and abiotic conditions under which it does and does not apply. We found that the behavioral dominance–diversity relationship varies greatly, and depends on whether dominant species are native or non-native, whether dominance is considered as occurrence or relative abundance, and on variation in mean annual temperature. There were declines in diversity with increasing dominance in invaded communities, but diversity increased with increasing dominance in native communities. These patterns occur along the global temperature gradient. However, positive and negative relationships are strongest in the hottest sites. We also found that climate regulates the degree of behavioral dominance, but differently from how it shapes species richness. Our findings imply that, despite strong competitive interactions among ants, competitive exclusion is not a major driver of local richness in native ant communities. Although the dominance-impoverishment rule applies to invaded communities, we propose an alternative dominance-diversification rule for native communities

Aspects of the feeding ecology of introduced Rose-ringed Parakeets Psittacula krameri in the urban landscape mosaic of Durban, KwaZulu-Natal Province, South Africa

The Rose-ringed Parakeet Psittacula krameri is one of the world’s commonest invasive bird species and has established in the South African urban landscapes. However, relatively little is known about the feeding biology of parakeets here. We surveyed areas in eThekwini Municipality, Durban, South Africa, to determine their feeding sites and the related land-use types. Patterns of the association were explored using Correspondence Analysis to determine parakeets’ diet across seasons and interaction between different tree species fed on by parakeets and other bird species. Dietary items were determined visually using binoculars. We identified a total of 63 feeding sites with many in the urban built land-use cover type. The parakeets’ diet differed significantly across the seasons with spring accounting for 33% of annual food items. We identified 31 fruiting/flowering tree species fed on by the parakeets, with fleshy fruits and flowers accounting for 58% and 19%, respectively. Native tree species (63%) were mostly relied on when compared with non-native (27%). They also fed on carpenter ants Camponotus cinctellus which contributed 3% of their diet. The forest fever-berry Croton sylvaticus (fleshy fruits) and African star-chestnut Sterculia africana (flowers) were the most preferred tree species in autumn and summer. The observed number of bird species that communally fed with parakeets were significantly different across the sampled seasons. The diets for the Common Myna Acridotheres tristis and the Speckled Mousebird Colius striatus overlapped with parakeets for most tree species. Parakeets were observed actively feeding in the early mornings and late afternoons before roosting. Our study supports that parakeets are generalist-opportunistic feeders. The assessment of Rose-ringed Parakeets feeding ecology may help understand their potential impact on native tree and bird species within an urban landscape

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

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 roseringed 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

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

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 roseringed 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

Seed dispersal effectiveness: A comparison of four bird species feeding on seeds of invasive Acacia Cyclops in South Africa

Seed dispersal effectiveness (SDE) for vertebrates is determined as a product of quantity (numbers of seeds dispersed) and quality (probability that a dispersed seed becomes a new adult plant) components. There is a limited understanding of seed dispersal effectiveness for different avian vectors in South Africa, yet birds are important for long-distance dispersal for native species, and are implicated in the dispersal of many invasive plant species such as Acacia cyclops. Consequently, SDE was investigated in four bird species that are common seed dispersers in South Africa, of which two are frugivorous species (the Knysna turaco Tauraco corythaix and the red-winged starling Onychognathus morio), and two are granivorous species (the red-eyed dove Streptopelia semitorquata and the laughing dove Streptopelia senegalensis). Individuals of these species were caged and fed mature seeds of A. cyclops to determine quality of seed treatment in the gut. SDE was computed as a product of germination rates of gut-passed seeds of A. cyclops (i.e. quality) and the average bird body mass (i.e. proxy for seed load as quantity component) for the four bird species. Results show that frugivorous birds had significantly greater SDE than the granivorous bird species. SDEs for respective bird species also showed notable differences: the Knysna turaco had highest SDE followed by the non-significantly different red-eyed dove and red-winged starling, while the laughing dove had the lowest SDE of all bird species. However, it is likely that the two ubiquitous dove species, and both the colonial and nomadic red-winged starling, might have higher SDEs associated with large home ranges than the Knysna turaco with its more restricted geographic range. The results highlight the previously overlooked importance of doves and the other birds inmediating the invasion of A. cyclops, and the dispersal processes for the seeds of other plants included in their diet

Seasonal and daily activity patterns of leopard tortoises (Stigmochelys pardalis Bell, 1828) on farmland in the Nama-Karoo, South Africa

The leopard tortoise (Stigmochelys pardalis) is the largest of southern Africa’s 13 tortoise species, and occurs in a variety of habitats from arid and semi-arid areas to mesic grassveld, savanna and bushveld. Seasonal activity patterns of S. pardalis  were investigated as a function of rainfall, sex, time of day, temperature and time after sunrise on farmland in the semi-arid  Nama-Karoo, South Africa. We predicted that because of seasonal rainfall, and subsequent increase in the food available, activity patterns of leopard tortoises would vary greatly among seasons, but that the primary constraint on activity levels within a season would be ambient temperature. Type of activity, time of day that the activity was performed, and the frequency that each activity was performed, differed among seasons. There was no overall seasonal difference in the level of activity with sex, but in certain seasons and with regard to specific activities, there were significant differences between the sexes. Diel activity was primarily bimodal in summer and autumn, and unimodal in winter and spring, with nonthermoregulatory activities being performed primarily in the afternoon. There was a positive correlation between number of tortoises caught and rainfall per season, but activity levels and number of tortoises walking and feeding was not correlated with seasonal rainfall. Leopard tortoise activity behaviours   responded to ambient temperature, but results indicate that activity is also initiated by the time since sunrise.Key words: Stigmochelys pardalis, leopard tortoise, activity patterns, activity  behaviour, Nama-Karoo Biome, time of day, season