Palaearctic Migrants Research Articles

English

This study was carried out in Lake Hawassa, Tikur wuha riverine habitat and Cheleleka wetland from August 2017 to February 2018. The study aims to investigate species composition, seasonal abundance and distribution of birds. Systematic random sampling techniques at an interval of 3 km were used to select sampling blocks. T-test and one way ANOVA were applied for analysis of the effect of season on the composition and abundance of species. The result showed a total of 103 avian species record belonging to 47 families and 14 orders during the wet and dry seasons. Of the species recorded, (71) bird species (68.93%) were residents, 29 Palaearctic migrants (28.16%) and 3 Intra-African migrants (2.91 %). The overall species composition of birds during the wet and dry seasons was not significantly different, but there was a significant difference within the study sites. There was no significant seasonal difference in the abundance of birds in Lake Hawassa and the riverine habitat.  However, dry season had an effect on the avian abundance in Cheleleka wetland. Distributions of bird species were variable in the study areas. The results imply the need to conserve the avifauna of the whole study sites through the conservation of their habitats.     Key words: Wetland birds, abundance, endemic, migrant, resident.

Forest Availability and Fragmentation Drive Movement Behaviour of Wintering European Honey-Buzzard Pernis apivorus in Africa

Decreases in suitable habitat due to loss and fragmentation on the African non-breeding grounds are believed to be a driver of the declines in Palaearctic migrants. However, the effects of habitat loss and fragmentation on individual migrants have rarely been investigated. The European Honey-buzzard Pernis apivorus, a migratory forest specialist, displays the characteristics of a species that would be sensitive to declines in suitable habitat. We assessed site fidelity, habitat selection and home range characteristics of 32 tracked European Honey-buzzards in Africa to understand how habitat transformation on the non-breeding grounds affects the movement behaviour (particularly habitat use and home range characteristics) of the species. Adults had greater site fidelity than juveniles, indicating that young birds were exploring to locate suitable habitat for future non-breeding territories. Besides site fidelity, there were few significant differences between the movements of adult and juvenile Honey-buzzards. Birds of all age classes strongly selected treed habitat, as expected. Treed largest patch index and edge density had a negative effect on home range size, demonstrating that Honey-buzzards rely on large tracts of continuous forest, but can tolerate some level of fragmentation. Individuals with larger home ranges due to greater levels of forest fragmentation moved greater daily distances. In addition, Honey-buzzards spent more time in home ranges with larger treed largest patch indices and lower edge density. This reveals that birds that do not have access to a large patch of unfragmented forest are both flying greater distances on a daily basis and moving to new home ranges more often. This likely results in greater energy expenditure over their non-breeding period, which may have adverse effects on their long-term survival. Furthermore, our analyses support the hypothesis that continuing forest loss in Africa will have a negative effect on the European Honey-buzzard population.

Avifaunal Biodiversity in Peril: Pre- and Post-Vegetation Clearance Survey of Avifauna in a Fragmented Thicket in an Urban Landscape, Dar Es Salaam City, Tanzania

In contrast to the bird faunas of most protected areas in Tanzania, those found in urban areas have poorly been studied. In December 2009 and May 2010, using mist netting and audiovisual observations, we undertook surveys of birds at Kituo cha Biomazingira Dar es Salaam (KIBIDA), a privately owned 6 ha area, as an initial attempt to ascertain which bird species are found there. In 2012 and 2017 this 6 ha area (dominated by thickets) was cleared by unknown people further reducing it to about one-third and one-sixth of the original area, respectively. This led us to further assess whether the birds were negatively affected by habitat reduction after one-third and one-sixth of the study area remained. In both cases we continued to use mist nets augmented by audio-visual observations of birds. We detected a total of 98 species of which 62, 48, 53 and 42 were recorded before wood vegetation in the original 6 ha area was cleared, during clearing, two years and six years after it was cleared, respectively. Some of the species detected were forest-dependent and Palaearctic migrants suggesting that remnant thickets and forest patches in urban landscapes are important for conservation of forest dependent and migrant birds. Twenty-two species that were detected before the wood vegetation in the area was cleared were neither found during the time of clearance nor after clearance suggesting possible emigration or local extinction. Similarly, 44 species that were not found in the study area prior to clearance were either observed or mist netted afterwards as a result of turnover in species composition during the sampling period. The results suggest that there is a need to continue to protect KIBIDA and other similar habitats in urban landscapes in order to preserve their avifauna. The results further imply that should such habitats continue to be cleared for provision of settlement, some of the bird species found in them will be lost leading to local extinction. As such, the study recommends conserving thickets and forest patches in urban landscapes as habitats for birds and other fauna.

The effectiveness of point counts and mist-netting in surveying Afrotemperate forest bird community structure in South Africa

ABSTRACT Point counts and mist-netting are two frequently employed survey techniques used in assessing forest avian communities, although the reliability of these methods varies according to species composition and habitat. This study investigates how effectively these two methods survey forest bird community structures within South African Afrotemperate forests. Seven forests within the Eastern Cape were surveyed from 140 duplicate point count and 63 mist-netting stations. Both methods were compared for assessing species richness, as determined from bird atlas data. Generalised linear mixed-effect modelling was used to determine functional traits which most impacted species detection, and to identify detection biases for both methods. Both methods compared consistently across the seven forests, which shared similar community structure. Point counts detected 79.2% of the total diversity versus 41.0% using mist-netting, and mixed-effects modelling corroborated that species detection is more effective using point counts. All functional traits tested (body size, primary foraging stratum, feeding guild, habitat specialisation, and dispersal behaviour) affected detection outcome. Point counts better represented all aspects forest bird community structure, including mid- and understorey birds which are presumed to be better detected by mist-netting. Use of mist-netting only slightly enhanced diversity assessments, and combined survey efforts under-represented forest-edge foragers, woodland and grassland habitat generalists (~63.6% total diversity), large birds, Palaearctic migrants, and carnivores.

Bird Diversity and Community Composition in Kafta Sheraro National Park, Tigray, Northern Ethiopia

Birds are one of the most important components of biodiversity that has huge ecological, economical, and esthetic values. The main objective of this study was to assess diversity and species composition of bird community in Kafta Sheraro National Park, Northern Ethiopia. Data were collected from August 2017 to March 2018 in the national park. Point count method was employed to collect data on bird species diversity and species composition. Direct observations of birds and discussion with local people and scouts to assess potential threats of avifauna in the park were made. Shannon diversity index was used to calculate the species diversity. A total of 158 bird species belonging to 52 different families and 20 orders were identified. Of the recorded species, there were 76.6% residents, 15.8% Palaearctic migrants (PM), 5.7% Intra-African migrants (IM), and 1.9% partial migrants. Accipitiridae (11.4%) had the highest species followed by Columbidae, Estrilidae, and Ploceidae with 7%, 5.7%, and 4.4% species, respectively. The highest Shannon–Weiner diversity index (H′ = 4.50) was recorded during February while the lowest (H′ = 2.18) was recorded during March. Species richness of the park showed no significance difference among the study months (χ2 = 10.046, df = 5, P>0.05). Agricultural expansions, fire, livestock grazing, mining, and poaching were the major threats of the park bird species. Kafta Sheraro National Park is one of the areas with high avian composition in Ethiopia. In the park, wildlife watching in general and ornithological tourism in particular should be developed. Anthropogenic disturbances should also be minimized to conserve avian diversity of the park.

Evidence of large‐scale range shift in the distribution of a Palaearctic migrant in Africa

AbstractAimLong‐distance Palaearctic migrant birds are declining at a faster rate than short‐distance migrant or resident species. This is often attributed to changes on their non‐breeding grounds and along their migratory routes. The European honey buzzard (Pernis apivorus) is a scarce migrant in southern Africa that is declining globally. This study assessed the distribution and abundance of honey buzzards in southern Africa over the past four decades and compared it to trends in the East African population to examine possible drivers of population expansion in southern Africa.LocationSouthern and East Africa.MethodsEuropean honey buzzard reporting data were collected from a variety of sources including citizen science databases (1983–2017). In addition, records of all other southern African vagrants (including ten other regularly occurring species) were gathered to account for changes in birdwatching effort in the subregion. To assess the effect of forest loss on honey buzzard abundance, rolling correlations were performed using forest cover in East Africa and number of honey buzzard records in both subregions.ResultsEuropean honey buzzard records in southern Africa have increased over five times more than other regularly occurring vagrant species and almost 40 times more than honey buzzard in Tanzania, where the population has remained stable. Loss of forested area in East Africa was correlated with an increase in European honey buzzard records in southern Africa.Main conclusionsWe suggest that the European honey buzzard shift in wintering range may be driven by a decline in suitable habitat further north in Africa amongst other possible reasons. This effect may have been amplified by an increase in appropriate habitat across southern Africa brought about by anthropogenic changes to vegetation such as increased tree cover in urban areas. This study further highlights the importance of using African distributional data banks to understand the effects of global change on Palaearctic migrant bird species.

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.

Importance of Lake Ashenge, a Small Important Bird Area in Northern Ethiopia, to Palaearctic and Other Migratory Birds

Tropical inland lakes harbour a variety of waterbirds and provide a wintering habitat for Palaearctic and other migratory birds. However, the importance of the lakes as a temporary site for migrant bird populations has not been adequately studied. The point count method was used to study waterbird species diversity and abundance in Lake Ashenge, in the semi-arid region of northern Ethiopia, with the main aim to underscore the lake's importance as a stop-over site for Palaearctic and other migratory birds. A total of 36 species belonging to 14 waterbird families were encountered. Fifteen of the species were resident birds, including the endemic Wattled Ibis (Bostrychia carunculata), and 14 of the species were Palaearctic migrants, including the globally Near-Threatened Ferruginous Duck (Ayithya nyroca) and Maccoa Duck (Oxyura maccoa). Significant temporal variation in diversity and abundance was observed during the study period; diversity was highest (Shannon-Wiener H′ = 1.98) in the dry season (December/J...

The birds (Aves) of Oromia, Ethiopia – an annotated checklist

Oromia is the largest National Regional State of Ethiopia. Here we present the first comprehensive checklist of its birds. A total of 804 bird species has been recorded, 601 of them confirmed (443) or assumed (158) to be breeding birds. At least 561 are all-year residents (and 31 more potentially so), at least 73 are Afrotropical migrants and visitors (and 44 more potentially so), and 184 are Palaearctic migrants and visitors (and eight more potentially so). Three species are endemic to Oromia, 18 to Ethiopia and 43 to the Horn of Africa. 170 Oromia bird species are biome restricted: 57 to the Afrotropical Highlands biome, 95 to the Somali-Masai biome, and 18 to the Sudan-Guinea Savanna biome. 26 species of birds of Oromia are Threatened (three Critically Endangered, nine Endangered, and 14 Vulnerable), and an additional 20 species are classified as Near Threatened. International regulations affect 225 Ethiopian bird species. Of the polytypic species, a total of 620 subspecies can be taxonomically assigned to Oromia. 11 of them are endemic to Oromia, 71 to Ethiopia and 150 to the Horn of Africa. This very high diversity underlines the high responsibility of the Oromia National Regional State for bird conservation.

Community composition, relative abundance and habitat association of avian species in Apini and Dikuma forest patches, Awi Administrative Zone, Ethiopia

Study on community composition, relative abundance and habitat association of avifauna in Apini and Dikuma forest patches, Awi Administrative Zone, Ethiopia, was carried out from September 2013 to April 2014. The main objective of this study was to investigate diversity, relative abundance, and habitat association of avian species in the study area. Data were collected using point count method, and analyzed using Shannon Weiner index, Simpson´s diversity index and Sorensen´s coefficient. A total of 95 avian species belonging to 44 families and 11orders were identified. Among 95 bird species, 93 are residents, one is intra-African migrant and one is Palaearctic migrant, and of the 93 resident birds, seven are endemic to Ethiopia, and ten shared between Ethiopia and Eritrea. In the present study, 79 and 83 bird species were recorded during the wet and dry seasons, respectively. Dikuma forest patch had the highest avian diversity during the dry season (H´=3.84) and Apini had the lowest (H´=3.59) in the same season. Habitat association of birds among the vegetation strata showed the highest species similarity occurred between forest interior and forest edge (CC=0.65), followed by forest edge and shrub (CC=0.62), and the least was between forest interior and shrub (CC=0.3). Species richness and composition are important parameters to maintain stability and functioning of an ecosystem. To conserve the rich avian diversity of Apini and Dikuma forest patches, the anthropogenic disturbances in the area should be minimized. Keywords: Diversity index, point count, relative abundance, resident birds, species similarity

Time budget patterns and complementary use of a Mediterranean wetland (Tonga, North-east Algeria) by migrant and resident waterbirds

We carried out a quantitative description of the use of a Mediterranean wetland (Tonga, North-east Algeria) by 22 waterbirds species (11 residents and 11 Palaearctic migrants) during late summer-wintering period, also analyzing their species-specific diurnal time budgets and the main related features of the landscape. The analyses of similarity in time budgets across birds (Hierarchal Cluster Analysis) showed four clusters of species associated with four major activities: day time mostly feeding (11 species), sleeping (6), swimming (3) and resting (2). Residents (Herons and Rails) showed a higher feeding time when compared to migrants (diving ducks, Gulls and Cormorants). From late summer to winter the time budget activity change in migrants; in contrast residents behave uniformly among daytime and at the course of the season. The use of this natural wetland in a complementary way by a high number of waterbirds (residents and migrants), is principally promoted by the existing of numerous habitat types. We found that 3 main ecological units, open water body, mudflats, and flooded meadows were the most utilized as foraging habitats among grebes, rails, ducks, gulls, and herons. In contrast, floating-leafed vegetation, and tall emergent vegetation were the commonest habitat categories used in resting activities especially by cormorants and herons. Data on behaviour requirements of these waterbirds can be used for conservation and correct management of this and other Mediterranean coastal wetlands.

Temperate migrants and resident bird species in Afro‐tropical savannahs show similar levels of ecological generalism

The specificity of an animal's habitat requirements will determine its ability to deal with anthropogenic climate and habitat change. Migratory birds are thought to be particularly vulnerable to such change, but theory predicts that they should be largely generalists. This prediction was tested with the aim of assessing whether migratory Palaearctic‐breeding birds wintering in the savannah biome of Africa are more or less generalist in their habitat use compared with taxonomically and ecologically similar Afro‐tropical resident species. The degree of specialization of these species groups to certain habitat characteristics was assessed and compared by calculating the relative occurrence of the species along habitat gradients, where wide occurrence indicates generalism and narrow occurrence indicates specialism. Palaearctic migrants as a group could not clearly be distinguished as generalists relative to Afro‐tropical residents with respect to habitat attributes. The only indication of greater flexibility in Palaearctic migrants was a significant tendency to use habitats over a wider latitudinal range. The results suggest that migrants are generalists, but not necessarily more generalist than taxonomically similar resident species that also occur over a wide range of habitat types within the savannah biome. The availability of specific habitat requirements on the wintering grounds in Africa is therefore unlikely to be a primary limiting factor for many Afro‐Palaearctic migratory bird species.

Density‐dependent survival and recruitment in a long‐distance Palaearctic migrant, the Sand Martin Riparia riparia

Long‐term studies can provide powerful insights into the relative importance of different demographic and environmental factors determining avian population dynamics. Here we use 23 years of capture–mark–recapture data (1981–2003) to estimate recruitment and survival rates for a Sand Martin Riparia riparia population in Cheshire, NW England. Inter‐annual variation in recruitment and adult survival was positively related to rainfall in the sub‐Saharan wintering grounds, but unrelated to weather conditions on the breeding grounds. After allowing for the effects of African rainfall, both demographic rates were negatively density‐dependent: adult survival was related to the size of the western European Sand Martin population (probably reflecting competition for resources in the shared wintering grounds) while recruitment was related to the size of the local study population in Cheshire (potentially reflecting competition for nesting sites or food). Local population size was more sensitive to variation in adult survival than to variation in recruitment, and an increase in population size after 1995 was driven mainly by the impact of more favourable conditions in the African wintering grounds on survival rates of adults. Overwinter survival in this long‐distance Palaearctic migrant is determined partly by the amount of suitable wetland foraging habitat in the sub‐Saharan wintering grounds (which is limited by the extent of summer rainfall) and partly by the number of birds exploiting that habitat.

Conservation through connectivity: can isotopic gradients in Africa reveal winter quarters of a migratory bird?

Conservation of migratory wildlife requires knowledge of migratory connectivity between breeding and non-breeding locations. Stable isotopes in combination with geographical isotopic patterns (isoscapes) can provide inferences about migratory connectivity. This study examines whether such an approach can be used to infer wintering areas in sub-Saharan Africa, where we lack such knowledge for many species, but where this method has not been used widely. We measured δ (2)H, δ (13)C and δ (15)N in winter-grown feathers of a breeding Swiss and Spanish population of European hoopoe Upupa epops--a typical Palaearctic-Afrotropical migrant. δ (2)H values predicted that ~70 % of the hoopoes spent the non-breeding season in the western portion of their potential winter range. This was corroborated by a shallow east-west gradient in feather-δ (2)H values of museum specimens from known African origin across the potential winter range and by the recovery of Swiss hoopoes marked with geolocators. Hoopoes categorized as from eastern versus western regions of the wintering range were further delineated spatially using feather δ (13)C and δ (15)N. δ (15)N showed no trend, whereas adults were more enriched in (13)C in the western portion of the range, with eastern adults being in addition more depleted in (13)C than eastern juveniles. This suggests that eastern juveniles may have occupied more xeric habitats than sympatric adults. We demonstrated that stable isotopes, especially δ (2)H, could only very roughly delineate the winter distribution of a trans-Saharan Palaearctic migrant restricted primarily to the Sahelian and savanna belt south of the Sahara. Further refinements of precipitation isoscapes for Africa as well the development of isoscapes for δ (13)C and δ (15)N may improve assignment of this and other migrants.

Species composition, relative abundance and habitat association of the bird fauna of the montane forest of Zegie Peninsula and nearby islands, Lake Tana, Ethiopia

The present study was carried out in Zegie Peninsula and Kibran Gebriel and Entos Iyesus Islands of Lake Tana from August 2006 to March 2007. Sampling sites were stratified based on the vegetation type and area cover. Point count technique and chi-square test were employed to see the association of birds with the different vegetation strata. A total of 101 bird species were recorded, out of which 91 were residents (three endemics) and 10 were Palaearctic migrants. The Zegie Peninsula had high species diversity and evenness (0.96 and 0.86, respectively). The relative abundance of birds during the wet and dry seasons was variable. A total of 54 and 68 species were recorded during the wet and dry seasons in the Zegie Peninsula, respectively. The islands possessed 24 species each season. Habitat association of birds within the vegetation strata of Zegie Peninsula during the wet season was: highest at the shore (4.50), followed by gardens (4.00), bushes and shrubs (3.33) and trees (2.17). During the dry season, the highest mean number of birds occurred in the garden vegetation (4.86), followed by trees (3.23), fringe type of vegetation (3.22), and bush and shrub vegetation (2.60). During the wet season, the association of birds with the vegetation stratum was not statistically significant (p > 0.05, chi-square =13, df =7, n = 32). However, this was significant during the dry season (p < 0.05, chi-square = 66.238, df =9, n = 84). Conservation action to minimize the anthropogenic effect at Zegie should be the order of the day.

High variation reduces the value of feather stable isotope ratios in identifying new wintering areas for aquatic warblers Acrocephalus paludicola in West Africa

Stable isotope analysis of feathers can be useful in the study of seasonal interactions and migratory connectivity in birds. For the PalaearcticAfrican migration system, however, the lack of isotope data from feathers of known origin in Africa renders the geographic assignment of birds captured on European breeding grounds to potential wintering areas problematic. Rectrices of the threatened aquatic warbler Acrocephalus paludicola grown in Africa were sampled across six European countries to assess whether birds in different breeding populations shared similar isotopic signatures and so were likely to have wintered in the same region in Africa. Freshly grown feathers of aquatic warblers collected at the only known wintering site in Senegal showed high variation in carbon, nitrogen, and hydrogen isotope ratios. Due to similarly high variation in isotope ratios of African-grown feathers within all breeding populations, it was not possible to determine whether different populations wintered in different regions. However, isotope signatures of 20% of birds captured on European breeding grounds fell outside the range of those captured in Senegal, suggesting a wider wintering distribution than is currently known. We therefore assessed whether the origin of these feathers could be estimated by trying to establish isotopic gradients across sub-Saharan West Africa. Feathers of three ecologically similar surrogate species were sampled from wetlands across a 3000 km east-west and a 2000 km northsouth transect. Within-site variation in feather isotope ratios was frequently larger than the difference predicted by gradients across West Africa. Thus, predicting the origin of individual feathers using single-isotope gradients was not reliable. The large within-site variability of feather isotope ratios of a habitat specialist species like the aquatic warbler indicates that using feather isotope ratios will require large sample sizes from many locations, and may thus not be an efficient tool in identifying wintering areas of Palaearctic African migrants.

‘Flying barnacles’: implications for the spread of non-indigenous species

The presence of adult barnacles of Fistulobalanus pallidus (Darwin) and Fistulobalanus albicostatus (Pilsbry) attached to field-readable plastic leg rings on the Lesser Black-backed Gull Larus fuscus in Northern Europe is reported. L. fuscus is a long-distance palaearctic migrant, breeding in temperate areas spreading widely over inland and marine habitats outside the breeding season. The species is known to perform long-distance migration to Africa and the Middle East. Combining present knowledge on the birds' migratory pattern and the home range of the barnacle species, it is concluded that the cypris larvae of F. pallidus must have settled in African waters, whereas the area where F. albicostatus settled on the bird leg rings is less certain. The barnacles were of adult size and must thus have been attached for a period of no less than 2 months. More than 30 individual barnacles could occur together on a single field-readable plastic leg ring. The barnacles could therefore, if ported alive to a new area, reproduce successfully and thus either introduce the species or genetically affect other native populations. This may pose a new and wholly unexpected transportation pathway for barnacles as invasive species.

Understanding changes in bird populations – the role of bird marking

Studies of marked birds play a central role in research on avian population dynamics and life histories because they are the main means of estimating survival, recruitment and dispersal. Integrated Population Monitoring aims to combine such information from ringing with data on abundance, productivity and the environment in order to develop population models that address applied questions. Diagnosing the demographic and environmental causes of population declines provides a basis for developing management prescriptions for population recovery. We discuss examples of how such studies are contributing to the conservation of European farmland birds and to understanding declines in Afro–Palaearctic migrants. Adaptive harvest management of North American duck populations demonstrates that similar principles apply to the management of quarry species. Over the next two decades we expect significant advances in our understanding of seasonal variation in demographic rates, of density dependence and of the ways in which continental‐scale population dynamics are built up from processes operating at much smaller spatial scales. This will be achieved through analyses of large‐scale data sets, the combination of conventional and new technologies and the widespread application of fully integrated modelling methods. Large‐scale data gathering through national ringing centres will play a key part in this process.

Waterbirds at Paarl Waste Water Treatment Works, South Africa, 1994–2004: seasonality, trends and conservation importance

Numbers of waterbirds were counted monthly from May 1994 to April 2004 at Paarl Waste Water Treatment Works, South Africa. Seventy-two waterbird species were recorded, of which 33 species (46%) were recorded breeding. Mean summer and winter counts were 2822 ± 504 and 1651 ± 251 birds, respectively. Summer peaks were driven primarily by large numbers of White-winged Terns (mean summer count = 858 or 34% of total count). Resident species dominated from December to April, whereas Palaearctic migrants peaked from December to March. Ducks and geese had greatest numbers from December to April and resident waders and grebes peaked from April to July. Flamingos peaked in October and November with another small peak in June. Gulls and terns had two peaks, one in November–March, driven by migrant White-winged Terns, the other in July and August, driven by abundance of resident Benguelan (Hartlaub's) Gulls. White-winged Terns showed the greatest decline (82%) of all species. Influx of Little Grebe and Red-billed Teal during winter showed a positive correlation with rainfall, while Egyptian Goose, Yellow-billed Duck and Cape Shoveler numbers declined as winter and spring rainfall increased. Paarl Waste Water Treatment Works ranked as the second-most important wastewater treatment works for waterbirds in the Cape Town metropole. It supported globally and regionally important numbers of 11 species and qualifies as a global and/or subregional Important Bird Area and Ramsar Site.

Seasonal patterns of occurrence of Palaearctic migrants in southern Africa using atlas data

Seasonal patterns of occurrence of Palaearctic migrants in southern Africa using atlas data