Birds Of South Africa Research Articles

Returning to the Wilderness: Potential Habitat Suitability of Non-Native Pet Birds in South Africa.

The global trade of non-native pet birds has increased in recent decades, and this has accelerated the introduction of invasive birds in the wild. This study employed ensemble species distribution modelling (eSDM) to assess potential habitat suitability and environmental predictor variables influencing the potential distribution of non-native pet bird species reported lost and sighted in South Africa. We used data and information on lost and found pet birds from previous studies to establish and describe scenarios of how pet birds may transition from captivity to the wild. Our study revealed that models fitted and performed well in predicting the suitability for African grey (Psittacus erithacus), Budgerigar (Melopsittacus undulatus), Cockatiel (Nymphicus hollandicus), Green-cheeked conure (Pyrrhura molinae), Monk parakeet (Myiopsitta monachus), and Rose-ringed parakeet (Psittacula krameri), with the mean weighted AUC and TSS values greater than 0.765. The predicted habitat suitability differed among species, with the suitability threshold indicating that between 61% and 87% of areas were predicted as suitable. Species with greater suitability included the African grey, Cockatiel, and Rose-ringed parakeet, which demonstrated significant overlap between their habitat suitability and reported lost cases. Human footprint, bioclimatic variables, and vegetation indices largely influenced predictive habitat suitability. The pathway scenario showed the key mechanisms driving the transition of pet birds from captivity to the wild, including the role of pet owners, animal rescues, adoption practices, and environmental suitability. Our study found that urban landscapes, which are heavily populated, are at high risk of potential invasion by pet birds. Thus, implementing a thorough surveillance survey is crucial for monitoring and evaluating the establishment potential of pet species not yet reported in the wild.

Cultural functional groups associated with birds relate closely to avian ecological functions and services

The global rapid decline of ecological systems has highlighted the potential of ecosystem functions to drive conservation discourse. Ecosystem functions underpin important ecosystem services, and have been described for birds in South Africa based on measurable ecological traits (physiological, structural, behavioural, or phenological characteristics), as well as cultural functions (human preferences for morphological and behavioural traits). Understanding the spatial relationships between ecological and cultural functions can provide insight into the extent to which cultural services of birds are correlated with different ecological functions, and identify potential synergies in the distribution of cultural and ecological services. Here we show that when correcting for the effect of species richness and spatial autocorrelation on functional group richness, there is a clear correlation between avian cultural and ecological functional groups in South Africa (r = 0.6, t = 32.20, df = 1936, p < 0.05), suggesting that cultural functions are strongly correlated with ecologically relevant traits, despite their production being primarily mediated through human perception. This relationship was highly correlated in National Parks (r = 0.75, t = 14.95, df = 182, p < 0.05). For conservation initiatives that aim to maximise both ecosystem function and ecosystem service production, it is critical to identify and support synergies in the distribution of different functional groups to promote the production of multiple ecosystem services.

Identifying the origin of lead poisoning in white-backed vulture (Gyps africanus) chicks at an important South African breeding colony: a stable lead isotope approach.

Elevated lead levels in scavenging raptors can originate from a variety of environmental and anthropogenic sources, including soil, water, mining activities and legacy lead from leaded fuel, but has mostly been attributed to fragments of lead-based ammunition embedded in the tissues of carcasses. To identify the origins of lead in the tissues of white-backed vulture (Gyps africanus) chicks at Dronfield Nature Reserve, South Africa, we used MC-ICP-MS to compare the isotopic composition of lead in blood samples to those of soil in the chicks' immediate environment, different mining activities in South Africa and lead ammunition commonly used in hunting and game management practices. The isotopic ratios in vulture blood samples ranged widely (207Pb/206Pb: 0.827-0.911), but fell within those measured for ammunition (0.761-0.938). Dronfield water can be excluded as a significant source, as the lead concentration for water was below detection limits. Uranium, coal, atmospheric Pb, legacy Pb from fuel and Pb mining can also be excluded as significant sources, based on the limited overlap with Pb isotopic ratios measured in vulture blood. Whereas 55% of chicks we sampled displayed isotopic ratios consistent with Dronfield soil, the low local Pb concentration and the low extractable Pb levels in South African soil in general, imply that soil Pb is unlikely the major source of Pb in WBV chicks, especially in birds with elevated blood Pb levels, i.e. > 20µg/dL. Our results, when considered in the context of vulture feeding ecology and low Pb levels in non-scavenging birds in South Africa, imply the major source of elevated Pb levels in WBV chicks to be fragments of lead-based ammunition embedded in the carrion fed to them by their parents.

Disease surveillance in England and Wales, June 2022.

Disease surveillance in England and Wales, June 2022.

Impact assessment of seven alien invasive bird species already introduced to South Africa

Globally, various avian species have been introduced accidentally and deliberately by humans through different pathways. Some of these species were able to establish, multiply, and become invasive. In this study, we identified areas that are climatically suitable for seven introduced invasive bird species and assessed the environmental and socio-economic impacts associated with the selected bird species in South Africa. We used present distribution records to predict potential climatic suitability distributions and used the Generic Impact Scoring Scheme to assess the impacts associated with seven invasive bird species in South Africa. We found that all the seven species were climatically suitable to South Africa and Passer domesticus, Sturnus vulgaris, and Anas platyrhynchos each had relatively large climatic suitability distributions. The climatic suitability for all the species was within their occurrence ranges in and outside South Africa. For impact assessments, we found that all seven selected species had impacts, with A. platyrhynchos, Acridotheres tristis, Columba livia, and Psittacula krameri having the highest overall impacts respectively. The socio-economic impact ranked higher than environmental impact for all species. The socio-economic impacts were frequently through agricultural production and human infrastructure, while the environmental impact was mostly through impacts of birds on other animals and competition. These need to be incorporated in decision-making and eradication plans for these alien invasive birds in South Africa.

Bagaza Virus in Himalayan Monal Pheasants, South Africa, 2016-2017.

Bagaza virus (BAGV) has not been reported in birds in South Africa since 1978. We used phylogenetic analysis and electron microscopy to identify BAGV as the likely etiology in neurologic disease and death in Himalayan monal pheasants in Pretoria, South Africa. Our results suggest circulation of BAGV in South Africa.

Zulu bird names: A progression over the decades (II) [Part two: The second hundred years, with Roberts, and Doke and Vilakazi

Part One of this two-part series on the history of the recording of Zulu bird names covered the period of the first explorers in KwaZulu-Natal in the 1830s and went up to Samuelson’s 1923 dictionary. This second part begins with the rise of interest in bird-watching as a hobby and the subsequent publication of the first successful bird guide: Austin Roberts’ 1940 Birds of South Africa. Subsequent revised editions, under different authors, were published in 1957, 1970, 1978, 1985, 1993, and 2005: all with the title Roberts Birds of Southern Africa (or minor variations thereof). The changing face of the Zulu names in these editions is examined in detail. As with Part One, the role of dictionaries in developing Zulu bird names is discussed, with Doke and Vilakazi’s 1948 Zulu-English Dictionary playing a major role. The article ends with thoughts on the unequal dynamics between the Zulu people whose oral tradition has provided the Zulu bird names, and the almost entirely white missionaries, ornithologists and lexicographers who have recorded these names. In the last ten years or so, an interest in both bird-watching and in oral traditions relating to birds has seen these dynamics change, with Zulu-speaking people becoming directly involved not only in the recording of Zulu bird names, but also in creating them for educational and tourism purposes.

Zulu bird names: A progression over the decades (I)

For nearly 250 years, beginning with Linnaeus in 1758 and continuing through the nineteenth and twentieth centuries, birds have been given scientific and vernacular names created by deliberate, conscious, and methodological taxonomical naming processes. On the other hand, Zulu names for birds, for centuries only residing in oral tradition, have only found their way into print through being recorded in writing. In this process, oral knowledge is recast as written knowledge. This article looks at the first hundred years of such recording of Zulu names, beginning with the first settlers and explorers in what is now KwaZulu-Natal and continuing through to the publication of Samuelson’s dictionary in 1923. The article, and its planned follow-up article, looks at the contribution of various lexicographers, including Bishop Colenso, the Reverend AT Bryant, and CM Doke and BW Vilakazi, and then interfaces their dictionaries with various works on southern African birds, beginning with Layard’s 1867 Birds of South Africa, looking closely at Woodward and Woodward’s 1899 Natal Birds, and ending with the seventh edition of Roberts Birds of Southern Africa, published in 2005. The primary focus is on how the Zulu oral tradition of bird knowledge has increasingly been revealed to the Western world through the efforts of naturalists and lexicographers. The article concludes with a brief look at recent developments in Zulu bird names between 2013 and 2017.

Genetic characterization of low-pathogenic avian influenza viruses isolated on the Izumi plain in Japan: possible association of dynamic movements of wild birds with AIV evolution.

The Izumi plain in Kagoshima Prefecture, Japan, is an overwintering site of endangered cranes (hooded cranes and white-naped cranes) and of many other migratory birds (including wild ducks) that are considered carriers of avian influenza viruses (AIVs). To assess the risks of a highly pathogenic avian influenza outbreak in the crane populations, we tested various environmental samples for AIVs in this area. In the 2014-2015 winter season, we isolated one AIV of the H6N2 subtype from the cranes' roost water and two AIVs of the H11N9 subtype from a crane fecal sample and a cloacal swab of a dead spot-billed duck. Genetic analysis of these AIV isolates indicated that our H6N2 isolate is genetically close to AIVs isolated from wild birds in Southeast Asian countries, except that the PB1 and NS genes belong to the North American virus lineage. All genes of the two H11N9 isolates are related to AIVs belonging to the Eurasian virus lineage. Notably, in our phylogenetic trees, H11 HA and N9 NA genes showing high sequence similarity to the corresponding genes of isolates from wild birds in South Africa and Spain, respectively, did not cluster in the major groups with recent wild-bird isolates from East Asia. These results suggest that AIVs with viral gene segments derived from various locations and bird species have been brought to the Izumi plain. These findings imply a possible association of dynamic movements of wild birds with AIV evolution.

Identifying ecological and life-history drivers of population dynamics of wetland birds in South Africa

Identifying species most vulnerable to environmental change requires reliable estimates of population trends and identification of traits that tend to be associated with these trends. Using state-space models that explicitly describe how the population size changes over time, we estimated population trends of 25 non-migratory African, 13 intra-African migrants, and 16 Palaearctic migratory waterbird species during 1995–2009 in South Africa. Using the average of the slope of the last five years (2005–2009), we used phylogenetic generalized least squares analyses to identify relationships with life-history (parental care, extent of polygamy, chick development, body size, average brood size) and ecological traits (migratory status, breeding latitude, foraging guild, wintering habitat type). The significant predictors of population trend were migratory status, average brood size, type of chick development (altricial, semiprecocial, precocial), and extent of male polygamy (0%, = <20%, >20%). Long-distance Palaearctic migrants and African non-migratory species on average suffered the greatest magnitude of decline, intra-African migrants showed population increase. There was a negative relationship between population trend and average brood size with an increase in brood size resulting in negative trends. Altricial species and species with some extent of polygamy (=<20%) had the greatest population increase. Our results provide evidence that these recent population trends were non-random with respect to life-history traits.

Do Indigenous Street Trees Promote More Biodiversity than Alien Ones? Evidence Using Mistletoes and Birds in South Africa

Trees in urban landscapes provide a range of ecosystem services, including habitat, refugia, food, and corridors for other fauna and flora. However, there is some debate whether the richness and abundance of other biodiversity supported is influenced by the provenance of trees, i.e., native or non-native. This study assessed the presence of mistletoes and birds (and nests) in 1261 street trees. There were marked differences between native and non-native street trees, with the former having a significantly higher prevalence of birds (and nests) and supporting more species and in greater densities, whilst the latter supported a higher prevalence of mistletoes. Additionally, for birds, the proximity to green space, tree size and species were also important, whilst for mistletoes, the proximity to green space, slope aspect, and tree species were significant. Preference ratios indicated that some tree species had a higher than random occurrence of birds or mistletoes, whilst others had a low abundance. The indigenous tree species, Acacia karroo Hayne was the only reasonably abundant street tree species that was important for birds, nests, and mistletoes. At the street scale, there was a positive relationship between street tree species richness and bird species richness. These results emphasise the importance of selecting appropriate tree species if biodiversity conservation is a core outcome.

Seasonal Variation in the Regulation of Redox State and Some Biotransformation Enzyme Activities in the Barn Swallow (Hirundo rusticaL.)

Little is known of the normal seasonal variation in redox state and biotransformation activities in birds. In long-distance migratory birds, in particular, seasonal changes could be expected to occur because of the demands of migration and reproduction. In this study, we measured several redox parameters in the barn swallow (Hirundo rustica L.) during the annual cycle. We captured the wintering barn swallows before spring migration in South Africa, and we captured the barn swallows that arrived in spring, bred in summer, and migrated in autumn in Finland. The redox status and biotransformation activities of barn swallows varied seasonally. Wintering birds in South Africa had high biotransformation activities and appeared to experience oxidative stress, whereas in spring and summer, they showed relatively low redox (superoxide dismutase [SOD], catalase [CAT], and glutathione reductase [GR]) and biotransformation enzyme activities. Autumn birds had very low biotransformation enzyme activities and low indication of oxidative stress but high activity of some redox enzymes (GR and glucose 6-phosphate dehydrogenase [G6PDH]). High activities of some redox enzymes (SOD, GR, and G6PDH) seem to be related to migration, whereas low activities of some redox enzymes (SOD, CAT, and GR) may be associated with breeding. Barn swallows in South Africa may experience pollution-related oxidative stress, which may hamper interpretation of normal seasonal variation in redox parameters.

Do the European Great Reed Warblers (Acrocephalus arundinaceus) reach South Africa during wintering?

Former studies have shown that the Great Reed Warbler (Acrocephalus arundinaceus) has two genetically distinguishable haplogroups (a ‘‘western’’ and an ‘‘eastern’’ clade). The species occurs in South Africa from January to late March, yet, in the whole database of EURING, there are no recoveries to the south of the Congo. There are at least three hypotheses concerning which birds are seen wintering in South Africa: (1) the European breeders reach South Africa, but there are no ringing recoveries; (2) a mixed population of birds originating from Turkey, Iran and Kazakhstan (Near and Middle East) winters in South Africa; and (3) birds from Europe and the Near and Middle Eastern populations both reach South Africa. We have sequenced a 492-bp part of the mtDNA control region II in 146 samples from five European breeding and one South African wintering population of Great Reed Warblers. The results show that over 60% of the wintering birds in South Africa carry European haplotypes, belonging to both ‘‘eastern’’ and ‘‘western’’ clades. Since the exact haplotypic constitution of the Near and Middle Eastern populations are not known to us, we cannot exclude that a mixed wintering population is formed from birds originating from these regions, but it seems more likely that the European breeders reach South Africa. (Less)

Characterization of influenza A viruses isolated from wild waterfowl in Zambia

Although the quest to clarify the role of wild birds in the spread of the highly pathogenic H5N1 avian influenza virus (AIV) has yielded considerable data on AIVs in wild birds worldwide, information regarding the ecology and epidemiology of AIVs in African wild birds is still very limited. During AIV surveillance in Zambia (2008-2009), 12 viruses of distinct subtypes (H3N8, H4N6, H6N2, H9N1 and H11N9) were isolated from wild waterfowl. Phylogenetic analyses demonstrated that all the isolates were of the Eurasian lineage. Whilst some genes were closely related to those of AIVs isolated from wild and domestic birds in South Africa, intimating possible AIV exchange between wild birds and poultry in southern Africa, some gene segments were closely related to those of AIVs isolated in Europe and Asia, thus confirming the inter-regional AIV gene flow among these continents. Analysis of the deduced amino acid sequences of internal proteins revealed that several isolates harboured particular residues predominantly observed in human influenza viruses. Interestingly, the isolates with human-associated residues exhibited higher levels of virus replication in the lungs of infected mice and caused more morbidity as measured by weight loss than an isolate lacking such residues. This study stresses the need for continued monitoring of AIVs in wild and domestic birds in southern Africa to gain a better understanding of the emergence of strains with the potential to infect mammals.

Alien and native birds in South Africa: patterns, processes and conservation

The spatial distribution of alien species richness often correlates positively with native species richness, and reflects the role of human density and activity, and primary productivity and habitat heterogeneity, in facilitating the establishment and spread of alien species. Here, we investigate the relationship between the spatial distribution of alien bird species, human density, and anthropogenic and natural environmental conditions. Next, we examined the relationship between the spatial distribution of alien bird species and native bird species richness. We examined alien species richness as a response variable, using correlative analyses that take spatial autocorrelation into account. Further, each alien bird species was examined as a response variable, using logistic regression procedures based on binary presence–absence data. A combination of human density and natural habitat heterogeneity best explained the spatial distribution of alien species richness. This contrasts with the results for individual alien species and with previous studies on other non-native taxa showing the importance of primary productivity and anthropogenic habitat modification as explanatory variables. In general, native species richness is an important correlate of the spatial distribution of alien species richness and individual alien species, with alien species being more similar to common species than to rare species.

ENERGY, SPECIES RICHNESS, AND HUMAN POPULATION SIZE: CONSERVATION IMPLICATIONS AT A NATIONAL SCALE

The maintenance of biodiversity rests on understanding and resolving conflict between patterns of species occurrence and human activity. Recent debate has centered on the relationship between species richness and human population density. However, conclusions have been limited by the lack of investigations of these relationships for individual countries, at which level most practical conservation actions are determined, and for a spatial resolution at which practical conservation planning takes place. Here, we report the results of the first such analysis, for birds in South Africa. Species richness and human density are positively correlated, apparently because both respond positively to increasing levels of primary productivity. High species richness is maintained by currently designated reserves, but the areas surrounding these have higher human population densities than expected by chance, placing the reserves under increasing external pressure. Not all species lie within protected areas, but the options are limited for building on the present network to generate a more comprehensive one, which protects all species and significantly reduces the conflict with human activities by designating new reserves in areas with lower human populations. Ultimately, the only solution to the conflict between biodiversity and people is likely to be individual‐based regulation of human population size.

Complementary representation and zones of ecological transition

Minimum complementary sets of sites that represent each species at least once have been argued to provide a nominal core reserve network and the starting point for regional conservation programs. However, this approach may be inadequate if there is a tendency to represent several species at marginal areas within their ranges, which may occur if high efficiency results from preferential selection of sites in areas of ecological transition. Here we use data on the distributions of birds in South Africa and Lesotho to explore this idea. We found that for five measures that are expected to reflect the location of areas of ecological transition, complementary sets tend to select higher values of these measures than expected by chance. We recommend that methods for the identification of priority areas for conservation that incorporate viability concerns be preferred to minimum representation sets, even if this results in more costly reserve networks.

Roberts' Birds of South Africa

Roberts' Birds of South Africa

Further bird records from the Bontebokand Mountain Zebra National Parks

The avifauna of this Park is well-known. Shortly after the Park was relocated to Swellendam in 1960, a preliminary list of the birds of the Park was published (Winterbottom 1962a). This was soon followed by a comprehensive check list (Winterbottom 1967a) and a report on bird densities in the Coastal Renosterbosveld of the Park (Winterbottom 1968a). Six further bird species, five of which have been reported in The Ostrich, are documented here, increasing to 150 the total number of species recorded in the Park. The numbers denote those used in Roberts birds of South Africa (McLachlan and Liversidge 1970) and the nomenclature follows the Check list of the birds of South Africa (S.A.O.S. List Committee 1969).

Rare and vulnerable birds in South Africa

The paper summaries information obtained through an initial survey undertaken to identify those avian populations which qualify for inclusion in a South African Red Data Book, and whose conservation status is in need of special attention. One hundred and one species' populations are included in the preliminary list. Nine of the 101 species are endemic to South Africa. There is a predominance of forest and wetland species, of birds of prey, and of mainly tropical species occurring as intrusions in the north east of South Africa. Many of the species listed are peripheral to South Africa and are widespread and abundant extra-limitally. Twenty species' populations which require urgent conservation attention are listed. As far as is known, no avian species has become extinct during historical times in South Africa, but two are at present endangered, i.e. threatened with immediate extinction.