Gyps Fulvus Research Articles

Use of avian GPS tracking to mitigate human fatalities from bird strikes caused by large soaring birds

Abstract Birds striking aircrafts cause substantial economic loss world‐wide and, more worryingly, human and wildlife fatalities. Designing effective measures to mitigate fatal bird strikes requires an in‐depth knowledge of the characteristics of this incident type and the flight behaviours of the bird species involved. The characteristics of bird strikes involving aircraft crashes or loss of human life in Spain were studied and compared to flight patterns of birds monitored by GPS. We tracked 210 individuals of the three species that cause the most crashes and human fatalities in Spain: griffon and cinereous vultures Gyps fulvus and Aegypius monachus and white storks Ciconia ciconia. All the crashes involved general aviation aircrafts, while none were recorded in commercial aviation. Most occurred outside airport boundaries, at midday, and in the warmest months, which all correspond with the maximum flight activity of the studied species. Bird flight altitudes overlapped the legal flight altitude limit set for general aviation. Policy implications. Mitigation of fatal bird strikes should especially address the conflict between general aviation and large soaring birds. Air transportation authorities should consider modifying the flight ceiling for general aviation flights above the studied species' maximum flight altitude. Moreover, policymakers should issue pilots with recommendations regarding the dates and times of peak activity of large soaring bird species to improve flight safety.

Re-introduction of Griffon Vulture (Gyps fulvus) in the Eastern Balkan Mountains, Bulgaria - completion of the establishment phase 2010-2020.

The current study presents and analyses the results from the recently completed 11-year-establishment phase, following the start of the local re-introduction of the Griffon Vulture (Gyps fulvus) in Kotlenska Planina SPA and Sinite Kamani Nature Park in the Eastern Balkan Mountains of Bulgaria in the period 2010-2020. As a result of the re-introduction efforts and release of 153 individuals, the Griffon Vulture has been successfully reproducing again in the Eastern Balkan Mountains since 2016, after more than 40-50 years of absence. At 2020, the local population consists of some 80 local and up to 80-115 birds, together with sojourn individuals. Amongst them, 23-25 breeding pairs, located in five different colonies and two more frequently used roosting sites. The current average productivity remains relatively low: 0.41 fledglings/territorial pair and fledging success of 0.61 fledglings/breeding pair between 2016 and 2020, but shows a trend to increase with time and the growing experience of the young locally re-introduced population. The mortality confirmed between 2010-2021 accounts for 33%, mostly due to electrocution as a post-release effect in the first six months following their release. Our data show that the newly established population in the Eastern Balkan Mountains mostly forages on feeding sites, having a comparatively small 95% home range: 281.88 ± 91 km2 and 50% core area: 6.6 ± 2.28 km2 (range 4.7–8.5 km2). We, therefore, consider the establishment phase of the re-introduction of Griffon Vulture in this particular site as successfully completed, but management should continue. Furthermore, the area of the Eastern Balkan Mountains can currently be regarded as a "source" for the species within the source-sink population regulation concept in the national and Balkan context.

Mining wild animal microbiomes

Microbial Genomics We have only just begun to examine the multitude of bacteria associated with other organisms. Levin et al. sampled the feces of 184 wild animals, including fish, birds, and mammals, from four different continents to survey the diversity of gut bacteria (see the Perspective by Lind and Pollard). They discovered more than 1000 previously undescribed bacterial species and identified factors that correlate with the composition, diversity, and functional content of the microbiota. Supporting the association of specific bacteria with animal lifestyle, they identified proteases, some previously undescribed, from the gut of griffon vultures that can break down toxins that may be present in their carrion diet. Science , this issue p. [eabb5352][1]; see also p. [238][2] [1]: /lookup/doi/10.1126/science.abb5352 [2]: /lookup/doi/10.1126/science.abg9095

Avian scavengers living in anthropized landscapes have shorter telomeres and higher levels of glucocorticoid hormones

Habitat anthropization is a powerful stressor affecting the health and fitness of organisms, ultimately impacting their population dynamics. In vertebrates, stressful living conditions are usually associated with elevated glucocorticoids-based responses (GCs) as well as shorter telomeres, which are in turn associated with decreased overall body condition fitness and life expectancy. However, our understanding of how habitat anthropization per se and population processes synergistically, or independently, may affect GCs and telomere dynamics in natural populations is still very limited. Here, we assessed the physiological footprint of habitat anthropization and conspecific density in 65 GPS-tagged Eurasian griffon vultures (Gyps fulvus) from two populations of the Iberian Peninsula. We examined how extrinsic (human footprint values and conspecifics density within individual activity areas) and intrinsic (sex and home range size) factors determine GCs deposited in feathers (CORTf) and telomere length as proxies of overall individual condition and quality. We found strong differences in both physiological markers between populations, with higher CORTf levels and shorter telomeres in vultures living in the northern, more anthropized area. We also found sex-specific patterns of CORTf, with females having higher levels than males. In both sexes, telomere length decreased as the density of conspecifics increased. Previous studies in these populations have shown lower survival rates in individuals who exploit more anthropized areas, and here we show a potential physiological causal link. We highlight the existence of complex effects of chronic stress associated both with living in anthropized environments and with population-related processes likely associated to the spatial distribution of resources.

An evaluation of machine learning classifiers for next-generation, continuous-ethogram smart trackers

BackgroundOur understanding of movement patterns and behaviours of wildlife has advanced greatly through the use of improved tracking technologies, including application of accelerometry (ACC) across a wide range of taxa. However, most ACC studies either use intermittent sampling that hinders continuity or continuous data logging relying on tracker retrieval for data downloading which is not applicable for long term study. To allow long-term, fine-scale behavioural research, we evaluated a range of machine learning methods for their suitability for continuous on-board classification of ACC data into behaviour categories prior to data transmission.MethodsWe tested six supervised machine learning methods, including linear discriminant analysis (LDA), decision tree (DT), support vector machine (SVM), artificial neural network (ANN), random forest (RF) and extreme gradient boosting (XGBoost) to classify behaviour using ACC data from three bird species (white stork Ciconia ciconia, griffon vulture Gyps fulvus and common crane Grus grus) and two mammals (dairy cow Bos taurus and roe deer Capreolus capreolus).ResultsUsing a range of quality criteria, SVM, ANN, RF and XGBoost performed well in determining behaviour from ACC data and their good performance appeared little affected when greatly reducing the number of input features for model training. On-board runtime and storage-requirement tests showed that notably ANN, RF and XGBoost would make suitable on-board classifiers.ConclusionsOur identification of using feature reduction in combination with ANN, RF and XGBoost as suitable methods for on-board behavioural classification of continuous ACC data has considerable potential to benefit movement ecology and behavioural research, wildlife conservation and livestock husbandry.

Diversity and functional landscapes in the microbiota of animals in the wild.

Animals in the wild are able to subsist on pathogen-infected and poisonous food and show immunity to various diseases. These may be due to their microbiota, yet we have a poor understanding of animal microbial diversity and function. We used metagenomics to analyze the gut microbiota of more than 180 species in the wild, covering diverse classes, feeding behaviors, geographies, and traits. Using de novo metagenome assembly, we constructed and functionally annotated a database of more than 5000 genomes, comprising 1209 bacterial species of which 75% are unknown. The microbial composition, diversity, and functional content exhibit associations with animal taxonomy, diet, activity, social structure, and life span. We identify the gut microbiota of wild animals as a largely untapped resource for the discovery of therapeutics and biotechnology applications.

First substantial evidence for Old World vultures (Aegypiinae, Accipitridae) from the early Palaeolithic and Iberomaurusian of Morocco

Remains of at least three species of large aegypiine vultures from early Palaeolithic and Iberomaurusian of Ifri n’Ammar, Morocco are the first substantial fossil record of these taxa in the Maghreb. They can be tentatively referred to the two extant species Aegypius monachus (Cinereous Vulture) and Gyps fulvus (Griffon Vulture), and to the extinct Gyps melitensis. Few fragments of remarkably large bones may belong to especially large specimens of A. monachus, but it cannot be ruled out that they are indeed remains of the so far only insufficiently known palaeospecies A. prepyrenaicus Hérnandez, 2001, originally described from the Upper Pleistocene of Spain. Two vulture species definitely occurred contemporarily; Gyps fulvus was found in the entire sequence, while A. monachus occurred only between 13,800 and 17,000 calBP. G. melitensis was found only once in an unknown stratigraphic context. All remains were found along with human artefacts in a cave deposit. Few bones show longitudinal scratches, which probably are cut marks, indicating that humans made use of the flesh, feathers and/or bones of these vultures. None of these species were previously recorded for the Upper Pleistocene of the Maghreb, and the fossil specimens provide important evidence for the former distribution of Old-World vultures in this area, which is insufficiently known and which changed dramatically during the twentieth century.

Lead contamination in tissues of large avian scavengers in south-central Europe.

Lead poisoning from spent ammunition is known to affect many avian species. Birds of prey ingest lead when feeding on game shot with lead gunshot or bullets. Raptors with scavenging habits are particularly vulnerable to ingesting lead in areas with intensive hunting and are good indicators of the risk of poisoning from lead ammunition. To assess how much facultative and obligate avian scavengers suffer lead contamination in south-central Europe, between 2005 and 2019 we collected and analysed 595 tissue samples from 252 carcasses of 4 species (golden eagle, bearded vulture, griffon vulture, cinereous vulture). Lead concentrations in organs showed a similar pattern across species with long and small bones revealing the highest median values (5.56 and 6.8mg/kg w.w., respectively), the brain the lowest (0.12), and the liver and kidney the intermediate (0.47 and 0.284). Overall, 111 individuals (44.0%) had lead concentrations above background thresholds in at least one tissue (i.e. >2mg/kg w.w. in soft tissues, >8.33 in bone) and 66 (26.2%) had values indicating clinical poisoning (>6mg/kg w.w. in liver, >4 in kidney, >16.6 in bone). Tissue lead concentrations and incidence of clinical and sub-clinical poisoning were higher in golden eagles and griffon vultures than in bearded and cinereous vultures, likely due to different feeding habits. In all species we found a rapid increase in lead values with age, but differences between age classes were significant only in the golden eagle. Birds with lead fragments in their digestive tract, as detected by X-rays, had higher median lead concentrations, suggesting that hunting ammunition is the main source of lead poisoning. Our results imply that lead impacts the demography of these long-lived species with delayed sexual maturity and low reproduction rate. A rapid transition towards lead-free bullets and gunshot is therefore required across Europe.

Blood Parasites in Sympatric Vultures: Role of Nesting Habits and Effects on Body Condition.

Avian haemosporidians are a common and widespread group of vector-borne parasites capable of infecting most bird species around the world. They can negatively affect host condition and fitness. Vultures are assumed to have a very low prevalence of these blood parasites, likely due to their strong immunity; however, factors contributing to variation in host exposure and susceptibility to haemosporidians are complex, and supporting evidence is still very limited. We analyzed blood samples collected from nestlings of three vulture species in Spain over 18 years, and used updated nested-PCR protocols capable of detecting all haesmosporidian cytochrome b lineages typical for diurnal birds of prey (Accipitriformes). Similarly to previous studies, we found low haemosporidian prevalence in cliff-breeding species, with Leucocytozoon as the only represented blood parasite genus: 3.1% in griffon vultures (Gyps fulvus) (n = 128) and 5.3% in Egyptian vultures (Neophron percnopterus) (n = 114). In contrast, the tree-breeding cinereous vulture (Aegypius monachus) had a substantially higher prevalence: 10.3% (n = 146). By far the most common lineage in Spanish scavenging raptors was the Leucocytozoon lineage CIAE02. No effects of nestling age and sex, or temporal trends in prevalence were found, but an effect of nest habitat (tree-nest vs. cliff-nest) was found in the griffon vulture. These patterns may be explained by a preference of vectors to forage in and around trees rather than on cliffs and wide open spaces. We found an apparent detrimental effect of haemosporidians on body mass of nestling cinereous vultures. Further research is needed to evaluate the pathogenicity of each haemosporidian lineage and their interaction with the immune system of nestlings, especially if compromised due to pollution with pharmaceuticals and infection by bacterial and mycotic pathogens.

Correlation between wing bone microstructure and different flight styles: The case of the griffon vulture (gyps fulvus) and greater flamingo (phoenicopterus roseus).

Flying is the main means of locomotion for most avian species, and it requires a series of adaptations of the skeleton and of feather distribution on the wing. Flight type is directly associated with the mechanical constraints during flight, which condition both the morphology and microscopic structure of the bones. Three primary flight styles are adopted by avian species: flapping, gliding, and soaring, with different loads among the main wing bones. The purpose of this study was to evaluate the cross-sectional microstructure of the most important skeletal wing bones, humerus, radius, ulna, and carpometacarpus, in griffon vultures (Gyps fulvus) and greater flamingos (Phoenicopterus roseus). These two species show a flapping and soaring flight style, respectively. Densitometry, morphology, and laminarity index were assessed from the main bones of the wing of 10 griffon vultures and 10 flamingos. Regarding bone mineral content, griffon vultures generally displayed a higher mineral density than flamingos. Regarding the morphology of the crucial wing bones involved in flight, while a very slightly longer humerus was observed in the radius and ulna of flamingos, the ulna in griffons was clearly longer than other bones. The laminarity index was significantly higher in griffons. The results of the present study highlight how the mechanics of different types of flight may affect the biomechanical properties of the wing bones most engaged during flight.

West Nile and Usutu virus infections in wild birds admitted to rehabilitation centres in Extremadura, western Spain, 2017–2019

West Nile virus (WNV) is an emerging flavivirus transmitted generally by mosquitoes of Culex genus. It is maintained in an enzootic life cycle where birds act as reservoir hosts. Humans and horses are also susceptible to infection, and occasionally, they suffer from neurological complications. However, they do not transmit the virus to other vectors, behaving as dead-end hosts. Sporadic WNV outbreaks observed in horses and wild birds from Extremadura (western Spain) during 2016 and 2017 seasons prompted to carry out this survey in wild birds, focused on specimens coming from two wildlife rehabilitation centres. Between October 2017 and December 2019, samples from 391 wild birds, belonging to 56 different species were collected and analysed in search of evidence of WNV infection. The analysis of serum samples for WNV-specific antibodies by ELISA, whose specificity was subsequently confirmed by virus-neutralisation test (VNT) showed positive results in 18.23 % birds belonging to 18 different species. Pelecaniformes (33.33 %), Accipitriformes (25.77 %) and Strigiformes (22.92 %) orders had the higher seroprevalences. Remarkably, WNV-specific antibodies were found in a black stork for the first time in Europe. Analysis by real time RT-PCR in symptomatic birds confirmed the presence of WNV lineage 1 RNA in griffon vulture and little owls. Specificity analysis of ELISA positive and doubtful sera was performed by differential VNT titration against WNV and two other cross-reacting avian flaviviruses found in Spain: Usutu virus (USUV) and Bagaza virus (BAGV). Only four samples showed USUV-specific antibodies (1.04 %) corresponding to three species: Eurasian eagle-owl, griffon vulture and great bustard (first detection in Europe) whereas no samples were found reactive to BAGV. Differential VNT yielded undetermined flavivirus result in 16 samples (4.17 %). This is the first study carried out on wild birds from Extremadura (western Spain). It highlights the widespread circulation of WNV in the region and its co-circulation with USUV.

Home range size, space use and resource selection of griffon vultures in an insular environment

AbstractThe extent of home ranges of griffon vultures (Gyps fulvus) was studied on Crete (Greece) during 2005–2015 by monitoring 27 individuals with very high frequency radio‐telemetry. Radio‐tagged birds were followed for an average period of 13.1 months (n = 7–22), where a total of 1615 days of fieldwork produced 4420 radiolocations (x = 163.5 radiolocations per tagged bird, n = 142–328). Overall, the mean home range and mean core area of griffon vultures were estimated at 1560 ± 140 km2 (KDE 95%) and 373 ± 36 km2 (KDE 50%) respectively with significant age‐related differences within seasons. Immature griffon vultures ranged on average about double the area ranged by adults in winter and occupied significantly larger core areas. The home range overlap in per cent and utilization distribution between adult and immature birds was also significantly less in winter than in summer. Foraging griffon vultures avoided northern slopes with unfavourable flight conditions and selected sites within rangelands with low diurnal temperature variations where overwintering livestock and suitable nesting cliffs occur. Foraging adults were restricted to the vicinity of the breeding colonies and favoured sites away from urban zones. In contrast, immature griffon vultures selected pastoral zones in marginal areas with mild winters and rugged terrain. The existence of predictable food sources in combination with suitable roosting sites and favourable flight conditions were the main factors differentiating the space‐use pattern between the two age classes. We recommend that apart from the maintenance of traditional farming practices, sites, such as large communal roosts and flight corridors or entire ‘hotspot’ activity zones of immature birds, should be taken into account in conservation planning and sensitivity mapping for the species.

Seasonal dynamics in the exploitation of natural carcasses and supplementary feeding stations by a top avian scavenger

Supplementing vulture populations with carcasses disposed at feeding stations is a common management and conservation practice worldwide. However, there is a lack of knowledge on the dependence of large vultures on the supplementary feeding stations (SFS) in areas with high abundance of natural food. We tagged 11 Griffon Vultures (Gyps fulvus, Hablizl 1783) with GSM/GPS transmitters in the Eastern Rhodopes, Bulgaria and studied the seasonal dynamic of feedings at SFS and at occasional carcasses found in the field. We used combination of remote sensing and field inspections to identify the vulture feeding events. Our results show that most of the feeding events occurred at occasional carcasses found in the wild (77.4%), whereas only 22.6% were at SFS, but high seasonal variation was observed. Vulture’s reliance on feeding stations was lowest in summer (19.82 ± 7.8%) and highest in winter when 56.5 ± 16.1% of the feedings were at the SFS. Griffon Vultures travelled longer daily distances in days feeding in the wild compared to days when they were not feeding or were visiting SFS. Our study indicates that in habitats with high abundance of natural food (free-range livestock and game), vultures tend to actively forage and use feeding stations as supplemental sources of food, mostly during long periods of adverse weather or in winter when foraging conditions are worse and natural food is less abundant.

Environmental factors affecting the wintering raptor community in Armenia, Southern Caucasus

The species–habitat relationships can change during the year because of the seasonality of resources. Therefore, the investigation of habitat use by animals in each season plays a fundamental role in their conservation. The main aim of this research was to investigate the raptor community that spends the winter in Armenia, southern Caucasus, and to explore its relationship with environmental features, such as land use and topography. During January 2012, we collected data by carrying out 15 roadside counts along which we calculated three community parameters: the relative abundance, the species richness, and the species diversity. Then, we carried out a multiple linear regression with the Information-Theoretic Approach, to explain the relationship between the parameters and environmental variables. Besides, we computed a Canonical Correspondence Analysis (CCA) between the species and the environment around their observations. As a general pattern, the community was associated with permanent crops, maybe because of their heterogeneity, which in turn allows them to support higher densities of prey during the winter. The most abundant species was the Black Kite (Milvus migrans), followed by the Common Kestrel (Falco tinnunculus) and the Griffon Vulture (Gyps fulvus). To our knowledge, this is one of the first studies investigating the wintering raptor community in the Caucasus, with raptors generally studied in this area during the breeding season and migration.

First description of movement and ranging behavior of the Griffon vulture (Gyps fulvus) from Serbia using GPS satellite tracking

Understanding the movement pattern and ranging behavior of the Griffon vulture population in Serbia is of great importance for prioritizing conservation action. In 2011, an immature vulture was the first bird to be equipped with a satellite transmitter in Serbia. Our study aims to define the vulture?s foraging areas, home ranges, core and basic areas, and to investigate movement patterns across different years and seasons by analyzing satellite telemetry data. We tracked the movements of the vulture for over three years and obtained satellite tracking data for 34 bird-months (1976 GPS fixes) between October 2011 and July 2014. We determined that the overall foraging area of the vulture across the entire study period was 11654.34 km2. The overall area used by the vulture was larger during spring and summer than during winter periods. Combined ranges across all years identified one basic area and its associated core area around the Uvac colony and nearby feeding site; we identified three core areas in its proximity. This study showed that areas of traditional stock-raising practices are important vulture foraging areas and that supplementary feeding sites have a vital role. Our maps can be used for future planning of vulture conservation measures.

The long-term trend, reproductive performance and colony shifting of the Eurasian Griffon Gyps fulvus in Croatia

The long-term trend, reproductive performance and colony shifting of the Eurasian Griffon Gyps fulvus in Croatia

RECORDING OF THE SPRING MIGRATION OF SOARING BIRDS THROUGH GEBEL EL ZEIT, EASTERN DESERT, EGYPT

Egypt is an important pass for the soaring birds’ migration, as it is situated on the mainland connection between the Eurasian and African landmasses that connects breeding grounds in Eurasia with wintering zones in Africa. In the current study, the spring migration of soaring birds was studied along a narrow corridor “bottleneck site” located within the Red Sea/Rift Valley bird migration flyway, Gulf of Suez, Egypt. Over a period of four weeks from April 19th to 17th of May 2019, 89949 soaring birds of 27 species were counted during an eight-hour daily observation window. In total, 47511 raptors of 24 species were recorded. The most common were the group of Levant sparrowhawk “Accipter brevipes”, European honey buzzard “Pernis apivorus”, and Northern steppe buzzard “Buteo buteo vulpinus” forming 33.16%, 32.08%, and 24.91% of all raptors, respectively; while combined black kite “Milvus migrans”, lesser spotted eagle “Aquila pomarine”, steppe eagle “Aquila nipalensis”, short-toed eagle “Circaetus gallicus”, booted eagle “Aquila pennata”, and Egyptian vulture “Neophron percnopterus” recorded more than 6% of the raptor assemblage. In addition, 15 greater spotted eagle “Aquila clanga”, 6 pallid harrier “Circus macrourus”, and 5 Eurasian griffon vulture “Gyps fulvus” were recorded during the observations. Other soaring birds were recorded during the study-time, the most common were: 36700 white stork “Ciconia Ciconia”, 4230 great white pelican “Pelecanus onocrotalus”, and 1500 black stork “Ciconia nigra”.

RECORDING OF THE SPRING MIGRATION OF SOARING BIRDS THROUGH GEBEL EL ZEIT, EASTERN DESERT, EGYPT

Egypt is an important pass for the soaring birds’ migration, as it is situated on the mainland connection between the Eurasian and African landmasses that connects breeding grounds in Eurasia with wintering zones in Africa. In the current study, the spring migration of soaring birds was studied along a narrow corridor “bottleneck site” located within the Red Sea/Rift Valley bird migration flyway, Gulf of Suez, Egypt. Over a period of four weeks from April 19th to 17th of May 2019, 89949 soaring birds of 27 species were counted during an eight-hour daily observation window. In total, 47511 raptors of 24 species were recorded. The most common were the group of Levant sparrowhawk “Accipter brevipes”, European honey buzzard “Pernis apivorus”, and Northern steppe buzzard “Buteo buteo vulpinus” forming 33.16%, 32.08%, and 24.91% of all raptors, respectively; while combined black kite “Milvus migrans”, lesser spotted eagle “Aquila pomarine”, steppe eagle “Aquila nipalensis”, short-toed eagle “Circaetus gallicus”, booted eagle “Aquila pennata”, and Egyptian vulture “Neophron percnopterus” recorded more than 6% of the raptor assemblage. In addition, 15 greater spotted eagle “Aquila clanga”, 6 pallid harrier “Circus macrourus”, and 5 Eurasian griffon vulture “Gyps fulvus” were recorded during the observations. Other soaring birds were recorded during the study-time, the most common were: 36700 white stork “Ciconia Ciconia”, 4230 great white pelican “Pelecanus onocrotalus”, and 1500 black stork “Ciconia nigra”.

A long-term population study of the Eurasian griffon (Gyps fulvus) in Serbia before and following the establishment of a supplementary feeding program

The Eurasian griffon population in Serbia declined throughout the 20th century from widespread to a rare species, counting a total of 14 detected pairs in two colonies in western Serbia in the 1990s. Although the conservation measures have been implemented since the 1970s, they have had little effect on the further population decline until the supplementary feeding program started in 1989. In this paper, we present the results related to the population trends and reproduction parameters, following the establishment of a supplementary feeding program of the Eurasian griffon in Serbia based on a 34-year survey (1985–2018). By 2018, a total of 2458 tons of supplementary food was provided at three feeding stations. The population increased from 14 detected pairs in two colonies in 1992 to 262 detected pairs in four colonies in 2018. A total of 1807 juveniles were fledged, with breeding success – fledged chicks/laying pairs (i.e., breeding pairs) (0.81 ± 0.07; mean ± SD) and productivity – fledged chicks/detected pairs (0.57 ± 0.10). The amount of supplementary food was in a significant positive correlation with the number of detected and breeding pairs and the number of fledged juveniles. Furthermore, breeding parameters remained high despite the substantial increase in population size, implying that the population is far from saturation level. Our study emphasizes the importance of applied protection measures, especially supplementary feeding. The implementation of appropriate networks of feeding stations and the promotion of free-range livestock farming, as well as returning to the traditional way of disposing of dead cattle, would be a recommendation for future main conservation activities for the Eurasian griffon population in Serbia.

Comparison of orbital asymmetries among some raptor species: “when size does not matter”

Abstract A sample of 73 dry, well-preserved skulls was studied, representing various species of raptors with different foraging strategies. The sample included Accipiter nisus (n = 15), Buteo buteo (n = 13), Gyps fulvus (n = 24) and Neophron percnopterus (n = 5), Bubo bubo (n = 16) and Tyto alba (n = 2). Geometric morphometric methods were used to detect orbital asymmetries. On digital pictures of each skull side, a set of 16 semi-landmarks and two landmarks were located in order to describe the orbital ring. The variables were analysed based on Generalized Procrustes analysis. The morphometric data showed that the orbital asymmetry of raptors differed significatively between species, although directional asymmetry (e.g. left orbita systematically more developed than the right) appeared not to be correlated with orbital size. This indicates that larger orbitas do not lead to greater asymmetry. Differences between species should rather be explained by their foraging strategies and degree of visual obstruction in their natural environment.