The SABAP2 legacy: A review of the history and use of data generated by a long-running citizen science project

Significance:• The Second Southern African Bird Atlas Project (SABAP2) – initiated in 2007 – is one of the region’s longest-running citizen science programmes and collects spatial and temporal data on birds. • Data from the project are publicly available and used extensively by environmental impact assessment practitioners, conservationists, authors, protected area managers, scientists and the general public.• The project is the template for other established projects that now operate across the continent, collectively now falling under the ‘African Bird Atlas Project’ umbrella.• We show that since the initiation of SABAP2, there has been a three-fold increase in publications, with over 150 papers that can be attributed to SABAP2. • The contribution of citizen scientists to the published scientific domain has been enormous

Bird atlas in action: using citizen science data to generate population trend alerts in Hessequa, South Africa

Citizen science data are rapidly transforming the conservation landscape. Targeted participatory citizen science initiatives generate nuanced data capable of monitoring trends in populations and generating early warnings for species and habitats experiencing significant declines. In the Hessequa Atlasing Area, Western Cape, South Africa, citizen science 'atlasers' involved with the Second Southern African Bird Atlas Project (SABAP2) have worked with scientific leadership since 2014 to improve the quality of bird atlas data in their region for species monitoring. In this study, we used reporting rates from SABAP2 checklists in the Hessequa Atlasing Area to calculate changes in range size and relative abundance for the 165 most commonly reported species in the region. We used a seven-tier alert system and broad habitat categories to sort species by priority for conservation action. Our results showed that wetland and marine associated species are experiencing the greatest declines in range and relative abundance in the Hessequa Atlasing Area, whilst urban and grassland associated species are largely increasing. We discuss how observed changes in populations may be used to guide conservation action and provide recommendations for scientists and non-scientific community members on engaging with and responding to the changes highlighted in each of the seven alert levels provided

Ranging Behaviour of Verreaux's Eagles during the Pre-Breeding Period Determined through the Use of High Temporal Resolution Tracking

Information on movement ecology is key in understanding the drivers and limitations of life history traits and has a potential role in indicating environmental change. Currently we have a limited understanding of the parameters of movement of territory-bound raptors, which are sensitive to environmental change. In this study we used GPS tracking technology to obtain spatially (within 3 m) and temporally ( c . 3 mins) high-resolution movement data on a small sample of Verreaux's eagle Aquila verreauxii during the pre-laying period ( n = 4) with one additional example during the chick rearing period. We present GPS-derived home range estimates for this species and we examine temporal (timing, duration, frequency and speed) and spatial (total path length and maximum distance from nest) patterns of trips away from the nest. For eagles tagged in the agriculturally developed Sandveld region ( n = 3), which is made up of a mosaic of land use types, we also undertook a habitat selection analysis. Home ranges were small and largely mutually exclusive. Trip activity was centred around midday, which is likely to be related to lift availability. Our habitat selection analysis found that eagles selected for near-natural and degraded habitat over natural or completely modified areas, suggesting that these eagles may have benefitted from some of the agricultural development in this region. Although our sample sizes are small, the resolution of our tracking data was essential in deriving this data over a relatively short time period and paves the way for future research

Large-Scale Climatic Patterns Have Stronger Carry-Over Effects than Local Temperatures on Spring Phenology of Long-Distance Passerine Migrants between Europe and Africa

Earlier springs in temperate regions since the 1980s, attributed to climate change, are thought to influence the earlier arrival of long-distance migrant passerines. However, this migration was initiated weeks earlier in Africa, where the Southern Oscillation, Indian Ocean Dipole, North Atlantic Oscillation drive climatic variability, and may additionally influence the migrants. Multiple regressions investigated whether 15 indices of climate in Africa and Europe explained the variability in timing of arrival for seven trans-Saharan migrants. Our response variable was Annual Anomaly (AA), derived from standardized mistnetting from 1982–2021 at Bukowo, Polish Baltic Sea. For each species, the best models explained a considerable part of the annual variation in the timing of spring’s arrival by two to seven climate variables. For five species, the models included variables related to temperature or precipitation in the Sahel. Similarly, the models included variables related to the North Atlantic Oscillation (for four species), Indian Ocean Dipole (three), and Southern Oscillation (three). All included the Scandinavian Pattern in the previous summer. Our conclusion is that climate variables operating on long-distance migrants in the areas where they are present in the preceding year drive the phenological variation of spring migration. These results have implications for our understanding of carry-over effects

Drivers of bird species richness within moist high-altitude grasslands in eastern South Africa

Moist high-altitude grasslands in South Africa are renowned for high avifaunal diversity and are priority areas for conservation. Conservation management of these areas conflicts with management for other uses, such as intensive livestock agriculture, which requires annual burning and leads to heavy grazing. Recently the area has become target for water storage schemes and renewable electricity energy projects. There is therefore an urgent need to investigate environmental factors and habitat factors that affect bird species richness in order to optimise management of those areas set aside for conservation. A particularly good opportunity to study these issues arose at Ingula in the eastern South African high-altitude grasslands. An area that had been subject to intense grazing was bought by the national power utility that constructed a pumped storage scheme on part of the land and set aside the rest for bird conservation. Since the new management took over in 2005 the area has been mostly annually burned with relatively little grazing. The new management seeks scientific advice on how to maintain avian species richness of the study area. We collected bird occurrence and vegetation data along random transects between 2006 and 2010 to monitor the impact of the new management, and to study the effect of the habitat changes on bird species richness. To achieve these, we convert bird transect data to presence only data to investigate how bird species richness were related to key transect vegetation attributes under this new grassland management. First we used generalised linear mixed models, to examine changes in vegetation grass height and cover and between burned and unburned habitats. Secondly, we examined how total bird species richness varied across seasons and years. And finally we investigated which habitat vegetation attributes were correlated with species richness of a group of grassland depended bird species only. Transects that were burned showed a larger decrease in vegetation cover compared to transects that were not burned. Grass height increased over time. Bird species richness was highest in summer compared to other seasons and increased over time. Overall bird species richness increased over the three summer surveys but species richness of birds that prefer heavily grazed habitat showed little change over the three years. Changes in bird species richness were best explained by the model with grass height for combined species richness of grassland depended birds but also for birds that prefer heavy grazing when treated alone. On one hand birds that prefer moderate grazing were best explained by a null model. However, overall bird species richness was better positively correlated to grass height than grass cover or dead grass. We conclude that frequent burning alone with relatively reduced grazing led to higher but less dense grass, which benefited some species and disadvantaged others. We suggest that management of this grassland use combination of fire and grazing and leave some areas unburned to accommodates birds of various habitat needs

Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis

Background The sex of an individual organism plays such an important role in its life cycle that researchers must know a bird’s sex to interpret key aspects of its biology. The sexes of dimorphic species can be easily distinguished, but sexing monomorphic bird species often requires expensive and time-consuming molecular methods. The Little Stint (Calidris minuta) is a numerous species, monomorphic in plumage but showing a small degree of reversed sexual size dimorphism. Females are larger than males but the ranges of their measurements overlap, making Little Stints difficult to sex in the field. Our aim was to develop reliable sexing criteria for Little Stints in different stages of primary moult during their stay on the non-breeding grounds in South Africa using DNA-sexed individuals and discriminant function analysis. Methods We caught 348 adult Little Stints in 2008–2016 on their non-breeding grounds at Barberspan Bird Sanctuary. To molecularly identify the birds’ sex we used P2/P8 primers and DNA isolated from blood samples collected in the field. We used Storer’s dimorphism index to assess the degree of sexual size dimorphism. Then we divided our sample into two groups: before or during and after primary moult. For each group we developed two functions: one using wing length only and the other a combination of morphometric features including wing, tarsus and total head length. Then we used a stepwise procedure to check which combination of measurements best discriminated sexes. To validate our result we used a jack-knife cross-validation procedure and Cohen-kappa statistics. Results All the morphometric features we measured were bigger in DNA-sexed females than in males. Birds with fresh primaries had on average 2.3 mm longer wings than those with worn primaries. A discriminant function using wing length (D1) correctly sexed 78.8% of individuals before moult, and a stepwise analysis showed that a combination of wing length and tarsus (D2) correctly identified the sex of 82.7% of these birds. For birds with freshly moulted primaries a function using wing length (D3) correctly classified 83.4% of the individuals, and a stepwise analysis revealed that wing and total head length (D4) classified 84.7%. Discussion Sexual size differences in Little Stints might be linked to their phylogenetics and breeding biology. Females are bigger, which increases their fecundity; males are smaller, which increases their manoeuverability during display flights and hence their mating success. Little Stints show an extreme lack of breeding site fidelity so we did not expect a geographical cline in their biometrics. Sexing criteria available for Little Stints in the literature were developed using museum specimens, which often shrink, leading to misclassification of live birds. The sexing criteria we developed can be used for studies on Little Stints at their non-breeding grounds and on past data, but should be applied cautiously because of the overlapping ranges

Hand-rearing, release and survival of african penguin chicks abandoned before independence by moulting parents

The African penguin Spheniscus demersus has an ‘Endangered’ conservation status and a decreasing population. Following abandonment, 841 African penguin chicks in 2006 and 481 in 2007 were admitted to SANCCOB (Southern African Foundation for the Conservation of Coastal Birds) for hand-rearing from colonies in the Western Cape, South Africa, after large numbers of breeding adults commenced moult with chicks still in the nest. Of those admitted, 91% and 73% respectively were released into the wild. There were veterinary concerns about avian malaria, airsacculitis and pneumonia, feather-loss and pododermatitis (bumblefoot). Post-release juvenile (0.32, s.e. = 0.08) and adult (0.76, s.e. = 0.10) survival rates were similar to African penguin chicks reared after oil spills and to recent survival rates recorded for naturally-reared birds. By December 2012, 12 birds had bred, six at their colony of origin, and the apparent recruitment rate was 0.11 (s.e. = 0.03). Hand-rearing of abandoned penguin chicks is recommended as a conservation tool to limit mortality and to bolster the population at specific colonies. The feasibility of conservation translocations for the creation of new colonies for this species using hand-reared chicks warrants investigation. Any such programme would be predicated on adequate disease surveillance programmes established to minimise the risk of disease introduction to wild birds

Energy Expenditure of Free-Ranging Chicks of the Cape Gannet Morus capensis

The Cape gannet Morus capensis, a large fish-eating seabird, is endemic to southern Africa. To study the energetics of nestling growth, we used the doubly labeled water technique to measure field metabolic rate (FMR) of nestlings, from hatchings to large partly feathered chicks (n =17) at Malgas Island, Saldanha Bay, South Africa. At the same time, the growth rate of a large sample of chicks was measured (n = 338). These data, together with literature values on resting metabolic rate and body composition, were used to construct and partition the nestling energy budget. Nestling FMR (kJ d(-1)) increased with body mass according to FMR = 1.23m(0.923), r(2) = 0.944. Mass-specific FMR (FMRratio; kJ d(-1) g(-3/4)) was independent of chick age (r(2) = 0.20, P > 0.05); mean mass-specific FMR was 4.11 +/- 1.28, n = 17. Peak daily-metabolized energy (DME), which represents the maximum rate at which parents must supply their nestlings, occurred at age 71 d and was 2,141 kJ d(-1). Between the ages 51 and 92 d (43% of the fledging period), the DME of Cape gannet chicks was equal to or surpassed 90% of adult FMR at the nest. Energy demand during this period of peak DME represented 58% of the total metabolized energy, which was estimated at 150.1 MJ for an average chick during a 97-d period, from hatching to fledging. Sensitivity analysis of the energy budget indicated that the model was robust; the biggest source of error (+15%) was for the mass-FMR equation used in the model

Overlap in utilization of juvenile Cape Horse Mackerel by Cape Fur Seals and the purse-seine fishery in Namibia

The Cape horse mackerel Trachurus trachurus capensisis one of Namibia's most valuable fish stocks, and an important component to the diet of Cape fur seals, Arctocephalus pusillus pusillus, off northern Namibia. The level of overlap in the utilization of this resource between seals and the purse-seine fishery was investigated using two overlap indices. For high overlap measures, seals and the purse-seine fishery utilized age-2 horse mackerel. For low overlap measures, seals mainly consumed age-0 fish whereas the fishery caught age-2 fish. Both indices were adjusted by the proportion of horse mackerel in the seal diet, with the assumption that the proportion consumed by the seals reflects the abundance of horse mackerel in the coastal waters of Cape Cross, Namibia. Both unadjusted and adjusted overlap indices showed that overlap between seals and the fishery in their utilization of juvenile horse mackerel was high only at times when horse mackerel abundance was high, and low when abundance was small. Confidence intervals and significance testing were included. Overall, there was little overlap between seals and the purse-seine fishery. This study provides important information that should be taken into account in the management of the horse mackerel resource

The efficacy of culling seals seen preying on seabirds as a means of reducing seabird mortality

In the 2006/2007 breeding season of Cape gannets Morus capensis at Malgas Island, the removal of 61 Cape fur seals Arctocephalus pusillus pusillus that preyed on gannet fledglings when they left to sea significantly reduced the mortality rate of these fledglings. However, because seals learned to avoid the boat used for their removal, it was not possible to remove all the seals that killed gannet fledglings and some mortality continued. The seals inflicting the mortality were all sub-adult males, with an average age of <5 years. Sustained removal of these animals may reduce this feeding behaviour, which is at present having an adverse impact on several threatened seabirds in the Benguela ecosystem