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This chapter describes the taxonomic nomenclature, distribution, morphology, diet, reproduction, behaviour, habitats, pathways of invasion, environmental impact, control and relevance to humans of the greylag goose (Anser anser).
This chapter describes the taxonomic nomenclature, distribution, morphology, reproduction, behaviour, diet, habitats, pathways of invasion, environmental impact, control and relevance to humans of the red-whiskered bulbul (Pycnonotus... more
This chapter describes the taxonomic nomenclature, distribution, morphology, reproduction, behaviour, diet, habitats, pathways of invasion, environmental impact, control and relevance to humans of the red-whiskered bulbul (Pycnonotus jocosus).
This 381-paged book covers the biology, ecology, impact and management of 34 common alien invasive species, with reviews on the history and context of avian introductions and invasions in five major regions (Oceania, Africa, Europe... more
This 381-paged book covers the biology, ecology, impact and management of 34 common alien invasive species, with reviews on the history and context of avian introductions and invasions in five major regions (Oceania, Africa, Europe (including the Middle East, Asia and South America)), as well as management challenges and the potential of citizen science for monitoring alien birds. The book pitches at the introductory level and is ideal for readers to gain a quick and comprehensive view of the current status of global avian invasions. It has brought the records and research of avian invasion one step ahead of other alien invasive animal taxa. Many chapters contain distribution maps and data tables on the diet and morphology of the species, providing a good reference for the species and its management issues. Each chapter also contains a rich list of references that could help readers dive further into the topic.
Common white terns Gygis alba lay a single egg balanced on rocks or branches and consequently are at risk of low nesting success. A novel technique of hollowing out coconut husks and providing artificial nest sites was developed on... more
Common white terns Gygis alba lay a single egg balanced on rocks or branches and consequently are at risk of low nesting success. A novel technique of hollowing out coconut husks and providing artificial nest sites was developed on Cousine Island, Seychelles. Our study aimed to critically assess whether common white tern nesting success differed between artificial and natural nest sites. For natural nest sites, nesting success and the stage of nest failure were also compared between seasons, nest heights, and tree species. Finally, we compared results from our study to those of a study conducted 10 years ago on the same island. Nesting success differed significantly between artificial nests and natural nests, with the success of artificial nests nearly double that of natural nests. Hatching success was similar for artificial and natural nests (65% and 52% respectively), suggesting coconut husks do not reduce egg losses, but rather provide secure perches for young chicks. Most natural nest failures occurred during the egg phase (70%), followed by the youngest chick phase (21%). Of the eggs that hatched in natural nests, 61% fledged successfully. Tree species and season significantly influenced nesting success for natural nests and nest height varied significantly between tree species. Higher nesting success was observed during the mixed seasonal period (50%) followed by the cooler, windier and drier South-East Monsoon season (33%). The hotter and more humid North-West Monsoon period had the lowest nesting success (20%). Comparisons of nesting success at natural and artificial nest sites with the earlier study did not differ significantly, despite a smaller population of common white terns being present on the island at that stage. Our results support the use of artificial nest sites to improve nesting success for this species and serve as a model for similar species currently under threat.
Abstract While fleshy-fruited invasive alien plants are recognized as some of the worst invaders on a global scale, until recently, little consideration has been given to the frugivores that feed on these fruits and, more specifically,... more
Abstract While fleshy-fruited invasive alien plants are recognized as some of the worst invaders on a global scale, until recently, little consideration has been given to the frugivores that feed on these fruits and, more specifically, the fruit traits, which may influence this. We investigated a series of morphological and nutritive fruit traits for ca 30 species of fleshy-fruited invasive alien and exotic species in South Africa. Invasive alien fruit traits were compared with comparable traits of a similar sample size of indigenous fleshy fruits, which ...
Abstract The spread of invasive alien plants into natural habitats is of growing global concern. Several studies have investigated the role that avian frugivores play in the dispersal of these seeds and their effects on germination... more
Abstract The spread of invasive alien plants into natural habitats is of growing global concern. Several studies have investigated the role that avian frugivores play in the dispersal of these seeds and their effects on germination success. Fruit bats have however received little attention as important dispersal agents of invasive alien plants, despite their recognized role as long distance dispersal agents of various native flora. We investigated whether Wahlberg's epauletted fruit bats, Epomophorus wahlbergi, would positively ...
Many highly invasive plants are fleshy-fruited and owe their invasiveness largely to mutualisms formed with local dispersers. The energetic benefits gained by frugivores from ingestion of fruits of invasive alien plants remain poorly... more
Many highly invasive plants are fleshy-fruited and owe their invasiveness largely to mutualisms formed with local dispersers. The energetic benefits gained by frugivores from ingestion of fruits of invasive alien plants remain poorly documented. We assess whether avian frugivores process fruits of invasive alien plants effectively to meet their daily energetic requirements. Four fleshy-fruited plant species that are invasive in southern Africa were considered-Solanum mauritianum, Cinnamomum camphora, Lantana camara and Psidium guajava. Their fruits were fed to three common generalist frugivores-Red-winged Starling Onychognathus morio, Speckled Mousebird Colius striatus and Dark-capped Bulbul Pycnonotus tricolor-to determine the efficiency of digestion. Energetic parameters calculated for all fruit diets varied significantly between frugivore species. Speckled Mousebirds and Dark-capped Bulbuls maintained body mass and efficiently processed all four fruit types, whereas Red-winged Starlings only did so on C. camphora and S. mauritianum diets. These results explain why these fruits are attractive to local avian frugivores. Furthermore, these avian frugivores processed large quantities of invasive fruits, thereby serving as potentially efficient dispersers.
Many highly invasive plant species have fleshy fruits which are eaten by native frugivorous animals. These frugivores play an important role in long-distance seed dispersal, and may also affect germination success. The aim of this study... more
Many highly invasive plant species have fleshy fruits which are eaten by native frugivorous animals. These frugivores play an important role in long-distance seed dispersal, and may also affect germination success. The aim of this study was to determine whether generalist frugivores enhance or decrease seed germination of invasive alien species through pulp removal or seed coat abrasion, besides serving as dispersal agents. Fruits of four fleshyfruited invasive alien plant species, namely Solanum mauritianum, Cinnamomum camphora, Lantana camara and Psidium guajava, were fed to three generalist avian frugivorous species, which have been observed feeding on these fruits in the wild. Seed retention time was recorded as this affects dispersal distance and the duration that seeds are exposed to the effects of the gut. Seeds removed from excreta, seeds from manually de-pulped fruit, and whole fruit were planted in soil trays housed in a greenhouse. Daily germination counts were done. Seed retention times differed significantly between bird species for all fruits, except those of C. camphora. However, all frugivores had a similar effect on the germination success of seeds of S. mauritianum, L. camara and P. guajava, showing that gut retention time was not important. Germination of seeds from manually de-pulped fruits did not differ from that of ingested seeds of all plant species, suggesting that seed coat abrasion was also not important. Pulp removal resulted in significantly higher germination rates, both in the two species with larger, multi-seeded fruit (S. mauritianum and P. guajava), and in the two species having single-seeded fruit with waxy exocarps (C. camphora and L. camara). Pulp removal also resulted in significantly earlier germination of L. camara and P. guajava seeds. Therefore, frugivores not only accelerate dispersal, but also greatly enhance seed germination of all fleshy-fruited invasive alien species in this study.
There is a global threat of invasive alien plants to biodiversity and ecosystem services. Of these, fleshy-fruited species are credited as some of the worst invaders and this is largely due to their mutualisms with local dispersers.... more
There is a global threat of invasive alien plants to biodiversity and ecosystem services. Of these, fleshy-fruited species are credited as some of the worst invaders and this is largely due to their mutualisms with local dispersers. Comparative studies between invasive and indigenous species can shed new insights into the traits which promote invasive plants success over their indigenous counterparts. This study compared the germination success of indigenous Solanum giganteum and invasive Solanum mauritianum, following ingestion by Red-winged Starlings (Onychognathus morio, Sturnidae) and Speckled Mousebirds (Colius striatus, Coliidae) and compared these with de-pulped seed and whole fruit controls. Nutritive and morphological fruit traits were also considered. Seed retention times were only obtained for Red-winged Starlings on both diets, and these did not differ. For both plant species, ingested and de-pulped seeds had similar germination success and mean daily germination, irrespective of frugivore type. However, pulp removal was important for S. giganteum. The type of avian frugivore affected the onset of germination, with the comparatively larger Red-winged Starlings promoting earlier germination of both S. mauritianum and S. giganteum seeds when compared to their controls, except for de-pulped S. mauritianum. These germinated at the same time as ingested S. mauritianum, but significantly earlier than de-pulped S. giganteum. Speckled Mousebirds consumed more S. mauritianum than S. giganteum, while Red-winged Starlings showed the opposite. While S. mauritianum had larger yellow fruits, their seeds were smaller, lighter and more numerous than those in the red fruits of S. giganteum. Furthermore, S. mauritianum fruits contained considerably more sugar content than S. giganteum fruits. In summary, offering greater nutritional rewards and generating greater reproductive outputs than indigenous species, can explain why fleshy-fruited exotics become highly invasive.
While fleshy-fruited invasive alien plants are recognized as some of the worst invaders on a global scale, until recently, little consideration has been given to the frugivores that feed on these fruits and, more specifically, the fruit... more
While fleshy-fruited invasive alien plants are recognized as some of the worst invaders on a global scale, until recently, little consideration has been given to the frugivores that feed on these fruits and, more specifically, the fruit traits, which may influence this. We investigated a series of morphological and nutritive fruit traits for ca 30 species of fleshy-fruited invasive alien and exotic species in South Africa. Invasive alien fruit traits were compared with comparable traits of a similar sample size of indigenous fleshy fruits, which occur in the same area. Finally, the similarity of traits for the same invasive alien species was compared with those fruits in Australia. Invasive alien fleshy fruits were similar in morphology, but greater in some nutritive aspects when compared with indigenous fruits. Furthermore, they were very similar in all aspects to their counterparts in Australia. Most seeds of invasive fleshy fruits were small and light, which may explain some of their invasive success, as benefits associated with small seededness may promote invasive potential. Nutritionally, most invasive alien fleshy-fruits were hexose-dominant, containing low lipid and nitrogen content. While frugivore preference trends remain to be formally investigated, this study provides insights into fruit traits, which may tentatively outline why invasive fruits are universally fed on and thus successfully spread.
Common white terns Gygis alba lay a single egg balanced on rocks or branches and consequently are at risk of low nesting success. A novel technique of hollowing out coconut husks and providing artificial nest sites was developed on... more
Common white terns Gygis alba lay a single egg balanced on rocks or branches and consequently are at risk of low nesting success. A novel technique of hollowing out coconut husks and providing artificial nest sites was developed on Cousine Island, Seychelles. Our study aimed to critically assess whether common white tern nesting success differed between artificial and natural nest sites. For natural nest sites, nesting success and the stage of nest failure were also compared between seasons, nest heights, and tree species. Finally, we compared results from our study to those of a study conducted 10 years ago on the same island. Nesting success differed significantly between artificial nests and natural nests, with the success of artificial nests nearly double that of natural nests. Hatching success was similar for artificial and natural nests (65% and 52% respectively), suggesting coconut husks do not reduce egg losses, but rather provide secure perches for young chicks. Most natural nest failures occurred during the egg phase (70%), followed by the youngest chick phase (21%). Of the eggs that hatched in natural nests, 61% fledged successfully. Tree species and season significantly influenced nesting success for natural nests and nest height varied significantly between tree species. Higher nesting success was observed during the mixed seasonal period (50%) followed by the cooler, windier and drier SouthEast Monsoon season (33%). The hotter and more humid NorthWest Monsoon period had the lowest nesting success (20%). Comparisons of nesting success at natural and artificial nest sites with the earlier study did not differ significantly, despite a smaller population of common white terns being present on the island at that stage. Our results support the use of artificial nest sites to improve nesting success for this species and serve as a model for similar species currently under threat.
The significance of sleep and factors that affect it have been well documented, however, in light of global climate change the effect of temperature on sleep patterns has only recently gained attention. Unlike many mammals, bats (order:... more
The significance of sleep and factors that affect it have been well documented, however, in light of global climate change the effect of temperature on sleep patterns has only recently gained attention. Unlike many mammals, bats (order: Chiroptera) are nocturnal and little is known about their sleep and the effects of ambient temperature (Ta) on their sleep. Conse-quently we investigated seasonal temperature effects on sleep behaviour and surface body temperature of free-ranging Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi, at a tree roost. Sleep behaviours of E.wahlbergi were recorded, including: sleep duration and sleep incidences (i.e. one eye open and both eyes closed). Sleep differed significantly across all the individuals in terms of sleep duration and sleep incidences. Individuals gener-ally spent more time awake than sleeping. The percentage of each day bats spent asleep was significantly higher during winter (27.6%), compared with summer (15.6%). In summer, 20.7 ...
Maputaland–Pondoland–Albany, South Africa has been identified as a biodiversity hotspot and centre for endemism. Odonata make good indicators of freshwater ecosystem health. Consequently we compiled a list of Odonata species recorded to... more
Maputaland–Pondoland–Albany, South Africa has been identified as a biodiversity hotspot and centre for endemism. Odonata make good indicators of freshwater ecosystem health. Consequently we compiled a list of Odonata species recorded to date in the iSimangaliso Wetland Park. We then detailed important species in terms of endemism, conservation status, and potential as indicator species. Finally, we compared Odonata assemblages of different sites sampled within the park to illustrate habitat importance. Species identified during two formal surveys and incidental observations made during the study period were combined with an existing database to compile an accurate and up to date species list for the iSimangaliso Wetland Park. Data from this study were then analyzed to determine which water bodies had the most similar species composition. The Dragonfly Biotic Index (DBI) value of each study area was also determined. We recorded 68 odonate species in the iSimangaliso Wetland Park, add...
Invasion biology has become an important area of biological research, especially in the light of global climate change. The invasion of alien species is recognised as one of the leading causes of extinction of indigenous animal species,... more
Invasion biology has become an important area of biological research, especially in the light of global climate change. The invasion of alien species is recognised as one of the leading causes of extinction of indigenous animal species, particularly birds. The negative impacts of alien birds could include damage to property and crops, noise and nuisance, and the spread of disease to humans and native species. One example is feral pigeons found in cities. They nest and roost on buildings in large flocks and spread harmful bacteria in their faeces and in some cases parasites from their feathers. Some people also develop an allergy to their feather and scale dust.
Fragmented forests are under threat worldwide. Understanding fruiting phenology of these is important in terms of food supply to frugivores, particularly avifauna, which can move varying distances between forest fragments. Fragmentation... more
Fragmented forests are under threat worldwide. Understanding fruiting phenology of these is important in terms of food supply to frugivores, particularly avifauna, which can move varying distances between forest fragments. Fragmentation can affect tree species' diversity, which in turn determines fruit availability and quality. Many forest types have predictable, synchronous fruiting which is often linked to climatic cues. However, some forest types show no seasonality in fruiting and have varying fruit outputs between years. We investigated the fruiting phenology of four forest fragments in the Ngele Mistbelt Forest complex, which forms part of the Eastern Mistbelt Forests in KwaZulu-Natal, using fruit-fall traps. We hypothesized that fruit availability would vary with forest fragment size and with season. Fruiting in three of the forest fragments did not show seasonal fruiting trends and had increased fruiting in late summer and autumn months. Middlebrook showed trends. Fruiting varied significantly between months for all fragments, and where annual variation was observed trends were insignificant. The number of fruiting species per fragment varied significantly and numbers of fruiting species per fragment per month were generally low. Tree species varied in their fruiting patterns between fragments and fruiting of Afrocarpus/Podocarpus trees and the implications for endemic, endangered Cape Parrots are discussed as an example. In summary, these forests have variable and unpredictable fruiting between fragments. These results highlight the need to conserve forest fragments of varying sizes as a network to provide a year round supply of fruits to frugivores.
Historically, Cousine Island was used for agriculture and harvesting various seabird eggs, but following restoration efforts initiated in the 1990s, it has become an important nesting area for Seychelles seabirds. White-tailed tropicbird... more
Historically, Cousine Island was used for agriculture and harvesting various seabird eggs, but following restoration efforts initiated in the 1990s, it has become an important nesting area for Seychelles seabirds. White-tailed tropicbird (Phaethon lepturus), white tern (Gygis alba), and lesser (Anous tenuirostris) and brown noddy (Anous stolidus) populations were monitored on Cousine Island between 1997 and 2017 to determine the long-term population responses to various environmental variables during the winter breeding season. White tern, brown noddy, and white-tailed tropicbird populations are increasing, indicating that island conditions for breeding have improved for these species in the last 20 years. Lesser noddy populations are in decline, but not significantly, with winter air temperature significantly adding to this trend. Lesser noddies are true colonial nesters and are therefore potentially more affected by climatic conditions that result in nest failures and nearshore prey shortages. The relationship between numbers of seasonally breeding species (lesser and brown noddies) and those of year-round breeders (white-tailed tropicbirds and white terns) was also examined. Brown noddy population trends significantly predicted white-tailed tropicbird and white tern winter breeding population trends, suggesting that these species populations respond similarly to local conditions. Data from this study establish a baseline for future population trend investigations and assessments of island conservation and management success.
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... more
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.
The flight speeds of hunting falconry birds were determined using global positioning system data loggers. Until now, the hunting flight speed of African raptors has not been directly measured. We predicted that hunting flight speeds would... more
The flight speeds of hunting falconry birds were determined using global positioning system data loggers. Until now, the hunting flight speed of African raptors has not been directly measured. We predicted that hunting flight speeds would differ between species and that flight dynamics, such as altitude, and bird morphology, particularly wing surface area, would influence maximum and mean flight speeds. This study considered five African raptor species, which included two long-wing species, Lanner Falcon Falco biarmicus and Peregrine Falcon F. peregrinus, one short-wing species, Black Sparrowhawk Accipiter melanoleucus, and two broad-wing species, African Hawk-eagle Aquila spilogaster and Jackal Buzzard Buteo rufofuscus. Maximum and mean hunt speeds differed significantly between the long- and short-wing species. There was no difference in acceleration or deceleration rates between these species, but this could be due to small sample sizes. There was a significant positive correlation between maximum hunt speed and maximum flight height for the long-wing species. Maximum and mean flight speeds were significantly negatively correlated with wing area for all five species in this study. However, following phylogenetic correction, no significant relationship between wing area and maximum hunt speeds was found. This study presents baseline data of hunting speeds in African raptors and further highlights the importance of inter-species variation, which can provide accuracy to flight speed models and the understanding of hunting strategies.
Evolution is driven by natural selection acting on variable phenotypic traits. Understanding the molecular basis of those traits is crucial for elucidating the mechanisms of natural selection. The southern African jackal buzzard (Buteo... more
Evolution is driven by natural selection acting on variable phenotypic traits. Understanding the molecular basis of those traits is crucial for elucidating the mechanisms of natural selection. The southern African jackal buzzard (Buteo rufofuscus) displays extreme plumage colour polymorphism, with colouration on the chest varying from dark black to pale white. In a number of birds and other vertebrates, genetic variation at the melanocortin-1 receptor (Mc1r) gene is associated with melanin-based colour variation. Here, the Mc1r gene was sequenced from 12 jackal buzzard individuals displaying three distinct colour morphs (dark, intermediate and pale). A single nucleotide change was found, which although it resulted in an amino acid change, was shared by all jackal buzzards irrespective of colour morph. Although the Mc1r has played an important role in colour polymorphism in other species, in this study no association between Mc1r genotype and plumage polymorphism in jackal buzzards was found.
Black Sparrowhawk Accipiter melanoleucus breeding behaviour and nest success was determined using camera traps and field observations in KwaZulu-Natal, South Africa. Nest preparation was done predominantly by the male with incubation and... more
Black Sparrowhawk Accipiter melanoleucus breeding behaviour and nest success was determined using camera traps and field observations in KwaZulu-Natal, South Africa. Nest preparation was done predominantly by the male with incubation and brooding largely performed by the female. Brooding duration decreased with chick age, while feeding frequency and duration increased. Similarly, delivery of fresh leaf material to the nest site increased with chick age. Over the 2011 and 2012 breeding seasons respectively 74% and 41% of nests successfully fledged chicks, with the majority of these producing two offspring.
Many highly invasive plant species produce fleshy fruit that are consumed and dispersed by frugivorous birds. However, little is known about assimilation efficiency of invasive fruit by indigenous and invasive avian species. We... more
Many highly invasive plant species produce fleshy fruit that are consumed and dispersed by frugivorous birds. However, little is known about assimilation efficiency of invasive fruit by indigenous and invasive avian species. We investigated whether indigenous Knysna (Tauraco corythaix) and Purple-crested (Gallirex porphyreolophus) Turacos and invasive alien Rose-ringed Parakeets (Psittacula krameri) met their energy demands when fed fruits of four fleshy- fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava and Morus alba. Birds were fed single-fruit diets for two consecutive days and energetic parameters were calculated for all fruit diets. Our results showed that generally both invasive and indigenous avian species managed to gain their daily energy requirements from fruits of the four respective invasive plants, suggesting that they can meet their energetic demands by feeding on them only. The exception was P. krameri, which did not feed on S. mauritianum fruit. These findings may explain why fruits of invasive alien plants are attractive to most avian frugivores and highlight the role of avian frugivores in their dispersal.
The thermoregulatory capacity of a species can determine which climatic niche it occupies. Its development in avian chicks is influenced by numerous factors. Furthermore, it is suggested that altricial chicks develop their... more
The thermoregulatory capacity of a species can determine which climatic niche it occupies. Its development in avian chicks is influenced by numerous factors. Furthermore, it is suggested that altricial chicks develop their thermoregulatory capacity post-hatching, while precocial chicks develop aspects of this in the egg. We investigated the development of thermoregulation of four co-occurring seabird species in the Seychelles; namely white, ground-nesting white-tailed tropicbirds (Phaethon lepturus) and tree-nesting fairy terns (Gygis alba); and dark plumaged, tree-nesting lesser noddies (Anous tenuirostris) and ground- and tree-nesting brown noddies (A. stolidus). White-tailed tropicbirds have semi-altricial chicks, while the remaining species have semi-precocial chicks. Cloacal temperatures (Tb) were measured at five day intervals from newly hatched chicks and compared over time, and with adult Tbs. Initial Tbs of all chicks, except fairy terns, were lower than those taken when chicks were older. Brooding cessation generally coincided with feather development, as did an increase in Tb. Mean chick Tb was significantly lower than mean adult Tb for all species, but only white-tailed tropicbird and brown noddy chicks in tree nests differed significantly from mean adult Tb when chick Tb at five day intervals were considered. There was a significant interactive effect of nest site and age on brown noddy chick Tb, but chick colour did not have a significant effect on Tb. However, brown noddy chicks on dune crests maintained a constant Tb sooner than chicks in tree nests. Our results demonstrate that tropical seabird species have a more delayed onset of thermoregulatory capabilities when compared with those in temperate environments, perhaps as nest sites are less thermally challenging. Nest microhabitats and behavioural thermoregulation, are likely more important during early chick development for these species.
During incubation parent birds are committed to a nest site and endure a range of ambient conditions while regulating egg temperatures. Using artificial eggs containing temperature loggers alongside ambient temperature (Ta) controls,... more
During incubation parent birds are committed to a nest site and endure a range of ambient conditions while regulating egg temperatures. Using artificial eggs containing temperature loggers alongside ambient temperature (Ta) controls, incubation profiles were determined for four tropical seabird species at different nest site locations. Camera traps were used for ad-hoc behavioural incubation observations. Eggs experienced a range of temperatures during incubation and varied significantly between species and in some cases between different microhabitats within a species. Such variation has important consequences in the phenotypic expression of both physical and physiological traits of chicks, and ultimately species fitness. Exposed nest sites were more strongly correlated to Tas. Camera traps highlighted different incubation strategies employed by these species that could be related to trade-offs in predator defence, feeding habits, and temperature regulation of eggs. This study prov...
Birds generally incubate eggs by transferring body heat from an exposed abdominal area known as a brood patch. However, there are exceptions to this where some species use foot-mediated incubation. It was previously thought that, although... more
Birds generally incubate eggs by transferring body heat from an exposed abdominal area known as a brood patch. However, there are exceptions to this where some species use foot-mediated incubation. It was previously thought that, although White-tailed Tropicbirds, Phaethon lepturus, lack a brood patch, the heat generated by their feet was too low to incubate their eggs. Using modern thermal imaging techniques, our results indicate the opposite, revealing that tropicbird feet are an important heat source when incubating their eggs.
Worldwide, there is concern about the increased prevalence of infectious diseases and their effects on biodiversity. Increasing changes in the environment, particularly changes in climatic conditions as a consequence of... more
Worldwide, there is concern about the increased prevalence of infectious diseases and their effects on biodiversity. Increasing changes in the environment, particularly changes in climatic conditions as a consequence of anthropogenic-induced climate change, are some of the factors driving this increased disease prevalence. Vertebrate taxa that appear to be most affected by these diseases are amphibians and birds, though this may be a consequence of research effort. Beak and feather disease virus (BFDV) affecting psittacine bird species is the disease of concern here. Data on BFDV incidence in wild, endangered Cape parrots (Poicephalus robustus) were collected opportunistically from 1992 to 2014. Data show that the disease is prevalent naturally in the wild during extreme climatic events, including drought. This stresses the birds, which may result in the expression of pathological symptoms. Juveniles in particular appear to succumb during times of drought. This has conservation implications with the impacts of extreme climatic events associated with anthropogenic-induced climate change.
The Cape Parrot Poicephalus robustus is endemic to South Africa and numbers have reportedly declined since the early 1900s. It is a forest specialist and food nomadic, moving between patches depending on fruit availability. This makes it... more
The Cape Parrot Poicephalus robustus is endemic to South Africa and numbers have reportedly declined since the early 1900s. It is a forest specialist and food nomadic, moving between patches depending on fruit availability. This makes it difficult to estimate numbers accurately and to determine its distribution. The annual Cape Parrot Big Birding Day was initiated in 1998 as a national census to determine a population estimate. Volunteers assist in monitoring and counting the Cape Parrot in the Eastern Cape, KwaZulu-Natal and Limpopo provinces in indigenous forests as well as sites where the parrots are known to feed outside of forests. Here, a summary of 15 years of census data is presented. In all years, with the exception of 2009, less than 1 600 Cape Parrots were recorded in the wild. The census data showed a slight increase in Cape Parrots, although this may be largely explained by an increase in coverage of suitable habitat and stabilisation in the population since 2005. A current distribution map for the Cape Parrot, based on census data, is presented. The distribution remains largely unchanged from that presented in the 1970s. This study highlights the value of public participation in monitoring an Endangered species and the need to conserve the forests where these parrots occur, due to their nomadic feeding behaviour.
ABSTRACT Invasive species are a major threat to global biodiversity. Rose-ringed parakeets Psittacula krameri are widely established outside their native range and are successful invaders in many countries, including South Africa.... more
ABSTRACT Invasive species are a major threat to global biodiversity. Rose-ringed parakeets Psittacula krameri are widely established outside their native range and are successful invaders in many countries, including South Africa. Physiological and behavioral responses to environmental conditions are considered to be major factors that influence the abundance and distribution of birds. As rose-ringed parakeets are able to tolerate wide varieties of climatic conditions as invaders, it is important to understand their physiological responses to these. This study examined the effects of seasonal changes in ambient temperatures (Ta) on metabolic rate and body temperature (Tb) of captive-bred rose-ringed parakeets. Resting metabolic rate at various Ta and basal metabolic rate were significantly lower in winter compared to summer, and the thermo-neutral zone was broader in winter than in summer. There was no significant difference in body mass (Mb) between seasons. These parakeets showed seasonal thermoregulatory responses that represented energy conservation as expected, rather than cold tolerance. They were relatively tolerant of low Ta and showed no hypothermia at 5 °C. Our results suggest 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.
Globally, the rose-ringed parakeet, Psittacula krameri, is the most invasive parrot species and became established in South Africa in the 1970s. The aim of this survey was to determine the current occurrence and distribution of... more
Globally, the rose-ringed parakeet, Psittacula krameri, is the most invasive parrot species and became established in South Africa in the 1970s. The aim of this survey was to determine the current occurrence and distribution of rose-ringed parakeets in the greater Durban Metropolitan area of eThekwini, by engaging the public. Within the study area, rose-ringed parakeets currently occupy c. 730 km2. They occur along the coast from Umhlanga in the north to Merebank in the south, extending inland to Mt Edgecombe and Pinetown in the west. Four roosts were located in the study area, with one becoming inactive during the study period. Roosts varied in size from c. 20-100 parakeets each. Comparison of SABAP1 and SABAP2 data indicate that populations are also established in Pietermaritzburg, Cape Town, and Steytlerville in the Eastern Cape. Trends from this study indicate that rose-ringed parakeets are expanding their distribution particularly in the Durban Metropolitan area.
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... more
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.
This chapter describes the common terminologies, taxonomy, morphology, geographical distribution, physiology, diet, behaviour, reproduction, habitats, ecology, invasion pathways, environmental impact, control and human use of the... more
This chapter describes the common terminologies, taxonomy, morphology, geographical distribution, physiology, diet, behaviour, reproduction, habitats, ecology, invasion pathways, environmental impact, control and human use of the red-billed leiothrix (Leiothrix lutea).
This chapter describes the common terminologies, taxonomy, morphology, geographical distribution, physiology, diet, behaviour, reproduction, habitats, ecology, invasion pathways, environmental impact, control and human use of the common... more
This chapter describes the common terminologies, taxonomy, morphology, geographical distribution, physiology, diet, behaviour, reproduction, habitats, ecology, invasion pathways, environmental impact, control and human use of the common myna (Acridotheres tristis).
This chapter describes the terminology, nomenclature, morphology, geographical distribution, diet, physiology, reproduction, behaviour, ecology, habitats, invasion patterns, environmental impact, control and human use of the jungle myna... more
This chapter describes the terminology, nomenclature, morphology, geographical distribution, diet, physiology, reproduction, behaviour, ecology, habitats, invasion patterns, environmental impact, control and human use of the jungle myna (Acridotheres fuscus).
This chapter describes the geographical and climatic characteristics and the distribution and status of invasive wild birds in continental Africa.