The Eurasian Griffon Vulture Gyps fulvus is an obligate scavenger relying on spatially and temporally unpredictable food resources. We demonstrate how high-frequency telemetry data can be efficiently ...used to identify vultures' feeding locations in the wild and study their diet.
To study the Griffon Vulture diet composition, seasonal variations, and bathing frequency in an area with high natural food availability.
We used a remote-sensing technique based on GPS and accelerometry data to identify the feeding locations, and ground-truthing to identify the carcass species and investigate the causes of mortality.
We identified 13 taxa in the diet of Griffon Vultures. Cattle comprised 48.5% of the diet, followed by sheep (24.3%), while wild animals were 13.1%. We observed seasonal variation in the proportion of small stock and game species in the diet. Predation was reported as the main cause of mortality (60.2%) for prey species, while natural causes accounted for 37.6%. Vultures were mainly feeding in areas south of their breeding colonies in Bulgaria and Greece. Natural springs and fountains were regularly used by the Griffon Vultures for bathing and drinking, especially in the summer.
Free-ranging livestock creates favourable feeding conditions for vultures, especially in areas with rugged terrain and a high density of predators. An increase in the number of wild ungulates can potentially buffer the fluctuations in livestock numbers and be beneficial for vultures, especially in the autumn and winter months. Lead ammunition must be substituted with non-toxic alternatives to reduce the exposure of vultures and other scavengers to lead poisoning.
The spatial ecology of the Eurasian Griffon Vulture
has been a subject of scientific interest for long due to its conservation status, critical ecosystem role, gregarious lifestyle and complex ...foraging behavior. The trans-border Eastern Rhodope Mountain in Bulgaria and Greece holds an increasing population of the species and one of the largest on the Balkan Peninsula. We used high-frequency GPS data from 13 Griffon Vultures from this population to study their movements, home range size and its seasonal or age specific dynamics. The overall foraging home range (95% kernel) was 3,204 km
and the core area of activity (50% kernel) was 256.5 km
. We found high seasonal variation of the home range size. Vultures were foraging over larger areas in the summer and spring but their activity was limited to four times smaller areas in winter. We found no age specific variation in the home range sizes but the non-adult vultures showed tendency to conduct exploratory movements far from the breeding colony. Our results can be used for planning conservation efforts in the areas of high importance for the species.
Long‐distance migrations are among the most physically demanding feats animals perform. Understanding the potential costs and benefits of such behaviour is a fundamental question in ecology and ...evolution. A hypothetical cost of migration should be outweighed by higher productivity and/or higher annual survival, but few studies on migratory species have been able to directly quantify patterns of survival throughout the full annual cycle and across the majority of a species’ range.
Here, we use telemetry data from 220 migratory Egyptian vultures Neophron percnopterus, tracked for 3,186 bird months and across approximately 70% of the species’ global distribution, to test for differences in survival throughout the annual cycle.
We estimated monthly survival probability relative to migration and latitude using a multi‐event capture–recapture model in a Bayesian framework that accounted for age, origin, subpopulation and the uncertainty of classifying fates from tracking data.
We found lower survival during migration compared to stationary periods (β = −0.816; 95% credible interval: −1.290 to −0.318) and higher survival on non‐breeding grounds at southern latitudes (<25°N; β = 0.664; 0.076–1.319) compared to on breeding grounds. Survival was also higher for individuals originating from Western Europe (β = 0.664; 0.110–1.330) as compared to further east in Europe and Asia, and improved with age (β = 0.030; 0.020–0.042). Anthropogenic mortalities accounted for half of the mortalities with a known cause and occurred mainly in northern latitudes. Many juveniles drowned in the Mediterranean Sea on their first autumn migration while there were few confirmed mortalities in the Sahara Desert, indicating that migration barriers are likely species‐specific.
Our study advances the understanding of important fitness trade‐offs associated with long‐distance migration. We conclude that there is lower survival associated with migration, but that this may be offset by higher non‐breeding survival at lower latitudes. We found more human‐caused mortality farther north, and suggest that increasing anthropogenic mortality could disrupt the delicate migration trade‐off balance. Research to investigate further potential benefits of migration (e.g. differential productivity across latitudes) could clarify how migration evolved and how migrants may persist in a rapidly changing world.
In a large tracking study of an endangered migratory bird, the authors found lower survival during migration compared to stationary periods and higher survival on non‐breeding as compared to on breeding grounds. They conclude that the cost associated with migration could be offset by higher non‐breeding survival at lower latitudes. The photo is by Kayahan Ağırkaya, KuzeyDoğa.
Across Africa, the illegal use of poison is triggering a continent-wide scavenger crisis, with vultures suffering the most severe negative consequences. Vultures may die as indirect victims of the ...conflict between livestock farmers and predators, or they may be directly targeted by poachers with the aim to reduce the role of vultures as sentinels that alert authorities of poaching events. In this study, we provide novel information on vulture mortalities across the commercial farmlands of Namibia. We show that estimated mortalities of vultures due to anthropogenic causes amount to over 800 individuals over the period 2000-2015, which underscores the magnitude of the problem. The highest numbers of vulture deaths were reported from the southern half of the country, with the exception of the areas just south of Etosha National Park, and poisoning was the greatest cause of reported deaths. Aldicarb or carbofuran were the most commonly used poisons, but strychnine is still used by about one farmer out of 10. Poison is typically used by means of distributing poisoned baits in the landscape. Furthermore, willingness to use poison in the future was highest for farmers who own large properties with high livestock numbers, particularly sheep and goats, farmers who purportedly suffered high livestock losses to predators and who have a negative perception towards predators. We discuss the implications of these results and the possible urgent actions that should be implemented in order to address this devastating practice before it will impact vulture populations to irreversible levels.
Assessing the effectiveness of conservation measures to reverse population declines is essential to evaluate management strategies. Management solutions such as direct protection or supplementary ...feeding typically aim at reducing mortality or increasing productivity, but demonstrating such demographic consequences of adopted management is often difficult. Here we assess the effectiveness of large-scale management actions aimed at the conservation of an endangered vulture on the Balkan Peninsula by extending a novel analysis to estimate seasonal adult survival from observations of unmarked individuals. We monitored Egyptian Vulture Neophron percnopterus breeding success and territory occupancy over 11years in three countries during which both nest guarding and supplementary feeding were carried out. We found little evidence that nest guarding and supplementary feeding increased breeding propensity (mean=0.88±0.32 standard deviation, n=463), breeding success (0.82±0.39), or the number of fledglings raised by successful pairs (1.3±0.74). We estimated adult survival during the 23-week breeding season (mean=0.936, 95% credible interval 0.889–0.968) and found no significant increase due to management. In the last 13years 43 dead adult birds have been found during the breeding season, and 77% of confirmed mortalities were due to poisoning. Overall, the current management measures may have so far failed to halt ongoing population declines because the beneficial effects are insufficient to offset the loss of adult birds for example due to poisoning. We suggest that additional measures to slow the decline of Egyptian Vultures in the Balkans are required. In the short term, we urge governments to enforce anti-poison regulations that already exist. In the medium term, alternative approaches need to be developed that reduce the use of poisons and the associated accidental mortality of vultures and other wildlife species.
The Convention of Migratory Species aims to protect migratory animals throughout their range, but efficient mitigation of threats facing migratory birds is hindered by poor knowledge about the ...magnitude and geographic range of threats. We used an expert assessment to prioritise which threats to mitigate in 13 countries along the eastern Mediterranean flyway to protect globally threatened Egyptian Vultures Neophron percnopterus. We informed this assessment by satellite tracking 71 birds to quantify where and how mortalities occurred, surveying 4216 km of powerlines to detect carcasses, conducting 910 interviews to quantify poison use, and by surveying markets and hunters to assess direct persecution. Mortality of 50 birds occurred in Europe and the Mediterranean Sea (44%), the Middle East (18%), and Africa (38%), and mortality causes varied geographically. Inadvertent poisoning resulting from rural stakeholders targeting predators occurred along most of the flyway. On the breeding grounds in eastern Europe and in Saudi-Arabia, poisoning and collision and electrocution are the priority threats to mitigate. Electrocution on small and poorly designed electricity pylons was the priority threat in Turkey, Jordan, Egypt and Ethiopia. Direct persecution for belief-based use of vulture products was the priority threat in Nigeria and Niger, while other illegal killing was the priority threat in Lebanon and Syria. Our work cannot quantify which threat has the greatest demographic impact on Egyptian Vultures. Nonetheless, because all threats we assessed are relevant for many other migratory birds, our assessment highlights the priority threats that range states need to address to protect migratory birds.
Wind turbines and power lines can cause bird mortality due to collision or electrocution. The biodiversity impacts of energy infrastructure (EI) can be minimised through effective landscape‐scale ...planning and mitigation. The identification of high‐vulnerability areas is urgently needed to assess potential cumulative impacts of EI while supporting the transition to zero carbon energy.
We collected GPS location data from 1,454 birds from 27 species susceptible to collision within Europe and North Africa and identified areas where tracked birds are most at risk of colliding with existing EI. Sensitivity to EI development was estimated for wind turbines and power lines by calculating the proportion of GPS flight locations at heights where birds were at risk of collision and accounting for species' specific susceptibility to collision. We mapped the maximum collision sensitivity value obtained across all species, in each 5 × 5 km grid cell, across Europe and North Africa. Vulnerability to collision was obtained by overlaying the sensitivity surfaces with density of wind turbines and transmission power lines.
Results: Exposure to risk varied across the 27 species, with some species flying consistently at heights where they risk collision. For areas with sufficient tracking data within Europe and North Africa, 13.6% of the area was classified as high sensitivity to wind turbines and 9.4% was classified as high sensitivity to transmission power lines. Sensitive areas were concentrated within important migratory corridors and along coastlines. Hotspots of vulnerability to collision with wind turbines and transmission power lines (2018 data) were scattered across the study region with highest concentrations occurring in central Europe, near the strait of Gibraltar and the Bosporus in Turkey.
Synthesis and applications. We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird‐EI conflicts.
Resumo
As turbinas eólicas de geração de energia e as linhas eléctricas podem causar mortalidade de aves devido a electrocução e colisão. Estes efeitos negativos das infrastruturas de energia na biodiversidade podem ser minimizados com a implementação de medidas de planeamento e minimização de impactos. Deste modo, é urgente identificar as áreas de alta risco de colisão e electrocusão para permitir minimizar os impactos negativos das infrastruturas de energia e, simultaneamente, apoiar a transição para uso de energia com baixas emissões carbónicas.
Obtiveram‐se localizações de GPS de 1454 aves de 27 espécies susceptíveis a colisão e identificaram‐se as áreas de maior risco de colisão com a infrastrutura de energia para que as aves monitorizadas. A vulnerabilidade das aves às turbinas eólicas e às linhas de transmissão de energia foi determinada tendo em conta a proporção das localizações de GPS obtidas a altitudes que expõem as aves risco de colisão e susceptibilidade a colisões específica de cada espécie. Mapeou‐se a vulnerabilidade máxima de colisã,o para todas as espécies, na Europa e no Norte de África a uma escala de 5 × 5 km. O risco de colisão foi obtido sobrepondo a vulnerabilidade de cada espécie com a densidade de turbinas eólicas e de linhas de transmissão de energia.
Resultados: A exposição ao risco de colisão variou para as 27 espécies estudadas. Verificou‐se que a altitude de vôo de algumas espécies colocava‐as em alto risco de colisão. Nas áreas da Europa e do Norte de África com bons dados de seguimentos de aves, identificou‐se que 13.6% têm alta vulnerabilidade a turbinas eólicas e 9.4% têm alta vulnerabilidade a linhas de transmissão de energia. As áreas mais vulneráveis concentram‐se em corredores migratórios importantes e ao longo de áreas costeiras. Os “hotspots” de risco de colisão com turbinas eólicas e linhas de transmissão de energia (dados de 2018) apesar de espalhados por toda a área de estudo têm concentrações elevadas na Europa Central, no estreito de Gibraltar e no Bósforo na Turquia.
Síntese e aplicações. Com base em dados de seguimento de aves com tecnologia de GPS identificou‐se as áreas da Europa e do Norte de África em que as populações de aves estão mais vulneráveis a colisões com a infrastrutura eléctrica. Mapearam‐se as áreas com maior risco de colisão com actuais infrastruturas de energia de forma a identificar prioridades para implementação de medidas de mitigação. À medida que aumenta a disponibilidade de dados de seguimento de aves com precisão GPS, será possível identificar e reduzir conflitos com as infrastruturas de energia para mais espécies e em novas áreas.
We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird‐EI conflicts.
Human-induced direct mortality affects huge numbers of birds each year, threatening hundreds of species worldwide. Tracking technologies can be an important tool to investigate temporal and spatial ...patterns of bird mortality as well as their drivers. We compiled 1704 mortality records from tracking studies across the African-Eurasian flyway for 45 species, including raptors, storks, and cranes, covering the period from 2003 to 2021. Our results show a higher frequency of human-induced causes of mortality than natural causes across taxonomic groups, geographical areas, and age classes. Moreover, we found that the frequency of human-induced mortality remained stable over the study period. From the human-induced mortality events with a known cause (n = 637), three main causes were identified: electrocution (40.5 %), illegal killing (21.7 %), and poisoning (16.3 %). Additionally, combined energy infrastructure-related mortality (i.e., electrocution, power line collision, and wind-farm collision) represented 49 % of all human-induced mortality events. Using a random forest model, the main predictors of human-induced mortality were found to be taxonomic group, geographic location (latitude and longitude), and human footprint index value at the location of mortality. Despite conservation efforts, human drivers of bird mortality in the African-Eurasian flyway do not appear to have declined over the last 15 years for the studied group of species. Results suggest that stronger conservation actions to address these threats across the flyway can reduce their impacts on species. In particular, projected future development of energy infrastructure is a representative example where application of planning, operation, and mitigation measures can enhance bird conservation.
The Egyptian Vulture (Neophron percnopterus) has been classified as ‘Endangered’ due to rapid population declines across its range. Thus, exhaustive studies on its demography may serve as an ...important stepping stones for successful conservation programs. Breeding performance is one of the main components of the demography of a raptor population. Evaluating reproductive rates is easier than other demographic parameters, while remaining a very useful metric to identify factors driving raptor population trends. Here we present the breeding performance of the species’ population in Bulgaria as a result of a long-term monitoring (2005–2016). The studied population shows high breeding performance, based on a breeding success (1.11 ± 0.13 fledglings / laying pairs), productivity (0.88 ± 0.1 fledglings / occupied territories) and fledgling success (1.2 ± 0.1 fledglings / successful pairs), all among the highest recorded in Europe. Pairs breeding in territories with high occupancy rate produced 88% of the fledglings.
The European Griffon Vulture
is a large-sized scavenger exploiting carcasses of livestock and wild ungulates and thus having a paramount importance in the natural ecosystems. In this study, we report ...on an adult Griffon Vulture detected with lead levels in the bones over the threshold. After two years of tracking, the bird died. The corpse’s clinical examination and radiography detected the presence of two embedded lead pellets from a healed gunshot wound in its right wing. Quantitative laboratory analysis of lead in bone and liver samples evidencing subclinical/chronic lead intoxication of the Griffon Vulture could potentially be a result of the long-term exposure to the lead originating from the pellets in its wing.
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