Eurasian Griffon Vulture Gyps Fulvus Research Articles

Nocturnal Feeding in the Eurasian Griffon Vulture Gyps fulvus: A Response to Human Disturbance and the Presence of Mammalian Predators

Nocturnal Feeding in the Eurasian Griffon Vulture Gyps fulvus: A Response to Human Disturbance and the Presence of Mammalian Predators

Reduction of organic waste in a landfill lowers the visitation probability but not the local abundance of a long-lived scavenger species

Summary Globally, vultures are one of the most threatened of all groups of birds. European vulture populations are benefited by several anthropogenic food sources such as landfills. Current European Union directives aim to decrease the amount of organic matter dumped in landfills, reducing this important food source for some vulture species. In this context, we assessed the effect of the reduction of organic waste available and accessible for scavengers in a landfill on the visitation probability and abundance of a local Eurasian Griffon Vulture Gyps fulvus population in Central Catalonia (NE Iberian Peninsula), using a long-term dataset of captured-marked-recaptured individuals in the period 2012–2018. Our results indicated a decrease in the visitation probability due to a significant reduction of organic matter dumped into the landfill after a waste treatment centre was built (0.82 to 0.76) that may cause a permanent emigration of vultures in response to food reduction. However, the estimated annual abundance of vultures tended to grow over time due to the positive trend that regional vulture populations have experienced in recent decades. These results suggest that population processes occurring at regional scales are more relevant to vulture populations than local waste management measures. A reduction in locally available food can make a site less attractive, but species with high dispersal capacity such as vultures may overcome this issue by moving to other suitable sites. Although Griffon Vultures obtain most of the food from domestic and wild ungulates, a regional application of European directives could threaten an important alternative feeding source, especially in food shortage seasons where landfills could be supporting the energetic requirements of the species. Conservation strategies should be planned to counteract the possible negative effects of new European directives on scavenger populations.

Vultures feeding on the dark side: current sanitary regulations may not be enough

SummaryIt is widely acknowledged that the conservation of vultures, a group of birds threatened worldwide, requires the management of safe, high-quality human subsidies, free of potentially harmful toxic compounds. Additionally, in Europe, the supply of livestock carcasses is subject to current sanitary regulations. It is largely unknown how vultures use sources of food of different abundance, predictability, or different legal status and how individual features shape these preferences. To answer these questions, we took advantage of information yielded by 35 GPS-tagged adult Eurasian Griffon Vultures Gyps fulvus living in a region of northern Spain, which hosts one of the most important European populations. Our results indicated that vultures preferably used predictable feeding sites, such as carcass dumping sites, intensive farms and landfills which together account for the 62% of the observed feeding sites. Less than 10% of all observed sites had permission of authorities for the disposal of the carcasses. Interestingly, sites with large accumulations of carcasses were less used that those with intermediate amounts of food probably because of high intraspecific competition. In addition, sex and breeding status also played a role with males and breeding birds being more prone to visit the studied intensively managed feeding places. This vulture population is heavily dependent on food sources which are not under legal control where the birds could be at risk of intoxication and pathogen acquisition. Hence, current legal scenario allowing farmers to abandon carcasses in their exploitations seems insufficient. The future of vultures in highly anthropized regions is uncertain if interdictory regulations on the abandonment of carcasses of intensive livestock are applied. Additionally, conservation scenarios based on food subsidization must consider the effects of environmental and individual variability. We need science-based strategies ensuring the long-term viability of avian scavenger populations within a scenario of anthropized landscapes and livestock farming intensification.

Long-term size and range changes of the Griffon Vulture Gyps fulvus population in the Balkans: a review

SummaryThe Eurasian Griffon Vulture Gyps fulvus is a large Palearctic, Indohimalayan and Afrotropical Old-World vulture. The species’ range is vast, encompassing territories from the Pyrenees to the Himalayas. We reviewed and analysed a long-term data set for Griffon Vulture in the Balkans to estimate the change in its population size and range between 1980 and 2019. After a large historical decline, the Griffon Vulture population slightly increased in the last 39 years (λ = 1.02) and reached 445–565 pairs in 2019. We recorded a gradual increase of Griffon Vulture subpopulations in Serbia (λ = 1.08 ± 0.003), Bulgaria (λ = 1.08 ± 0.003) and Croatia (λ = 1.05 ± 0.005) and steep to a moderate decline of the species subpopulations in Greece (λ = 0.88 ± 0.005) and North Macedonia (λ = 0.94 ± 0.01). However, species range contracted to half of its former range in the same period. It occurred in 42 UTM squares in the 1980–1990 period and only 20 UTM squares between 2011 and 2019 and concentrated into three source subpopulations in Bulgaria, Serbia, and Croatia. Following reintroductions of the Griffon Vulture in Bulgaria, new colonies were formed at three novel localities after 2010. Regular movements of individuals between the different subpopulations exist nowadays. Therefore, preservation of both current and former core areas used for breeding and roosting is essential for species conservation in the region. However, the Griffon Vulture still faces severe threats and risk of local extinction. Various hazards such as poisoning, collision with energy infrastructure, disturbance and habitat alteration are depleting the status of the Balkan population and its full recovery. Further studies should analyse age-specific survival and mortality, recruitment, genetic relatedness, spatial use to inform the viability of this population in the future.

Use and selection of roost sites by Eurasian Griffon Vultures Gyps fulvus in Bulgaria

ABSTRACT Capsule Roosting behaviour during the pre-breeding season is an important part of the Eurasian Griffon Vulture Gyps fulvus life cycle. We demonstrate the importance of roost site selection and its relation to the breeding distribution of the Griffon Vulture. Aims To quantify the distribution, population size, age structure and roosting site selection of the Eurasian Griffon Vulture in the Eastern Rhodopes, Bulgaria during the pre-breeding season. Methods We used correlation analysis and generalized linear mixed models to examine the relationship between the vultures use of roost sites and their distribution in relation to topographic variables. We additionally used GPS telemetry data from 25 birds to study and compare the use of roosting cliffs. Results During the 14-year survey period the number of roosting Eurasian Griffon Vultures gradually increased from 25 birds in 2005 to 201 in 2018. We recorded 16 cliffs used by 124 ± 51 (sd) vultures for roosting. The number of non-adult vultures increased by 25% and reached 41% of all the recorded birds in the last year of the survey. We found that the number of breeding pairs correlated positively with the number of roosting vultures (r  = 0.85) and that roosting cliff selection was determined by cliff length and height, distance to the nearest feeding site, and whether the cliff was used for breeding. Conclusions Cliffs regularly used by vultures in the pre-breeding season, were afterwards used for breeding. Thus, cliffs used in the pre-breeding season for roosting could be used as an index for the breeding distribution of the species, and should be protected to sustain the species in and out of the breeding season.

Using GPS and accelerometry data to study the diet of a top avian scavenger

ABSTRACT Capsule 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. Aims To study the Griffon Vulture diet composition, seasonal variations, and bathing frequency in an area with high natural food availability. Methods 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. Results 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. Conclusions 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.

Spatial ecology of non-breeding Eurasian Griffon Vultures Gyps fulvus in relation to natural and artificial food availability

ABSTRACT Capsule: The movements and spatial ecology of non-breeding Eurasian Griffon Vultures Gyps fulvus in northern Italy, Croatia and Austria do not seem to be affected by feeding station use. Aims: The purpose of this study was to assess how the creation of a feeding station at the Riserva Naturale Regionale del Lago di Cornino (Forgaria nel Friuli, northeast Italy) during the 1980s might have affected the spatial and behavioural ecology of the Eurasian Griffon Vulture. Methods: Using global positioning system (GPS) satellite tracking, we studied movements of nine non-breeding Eurasian Griffon Vultures within the Riserva Naturale Regionale del Lago di Cornino in Italy, the Hohe Tauern in Austria and the Kvarner Gulf in Croatia. Results: Both the average foraging range size and the time spent by the birds in Italy were comparable to those recorded in Croatia and Austria, where the vultures depend on unpredictable food resources. A significant difference in terms of foraging range size was recorded among seasons. In winter it seems to be smaller as a consequence of reduced movements performed by the individuals due to harsh climate conditions. Conclusions: Our results suggest that the creation of a feeding station in Forgaria does not seem to have affected the spatial ecology of the Eurasian Griffon Vulture. However, due to the limited sample size and the young age of the individuals monitored, which have a long dispersal period, the findings presented should be considered as preliminary. Further research needs to be implemented to inform decisions regarding the management of supplementary feeding stations to promote the recovery and conservation of scavenger species, particularly in areas in which they have declined massively.

Spring Migration of Eurasian Griffon Vultures Across the Strait of Gibraltar: Number, Timing and Age Composition

The Eurasian Griffon Vulture Gyps fulvus population has increased significantly over the last four decades in Spain as well as general knowledge about its biology. However it remains unclear if this species performs a true long distance migration or just dispersal movements between Europe and Africa. This is one of the least monitored species during spring migration at the Strait of Gibraltar, which is the most important migratory bottleneck for Eurasian Griffon Vultures in the world. The aim of this work is to provide information about the number, age composition, and the timing of Eurasian Griffon Vultures crossing from Africa to Europe during the 2017 spring migration—Ramirez, J., Zufiaur Gonzalez de Langarica, F.Ma and Guerrero Molina, M. (2019). Spring migration of Eurasian Griffon Vultures across the Strait of Gibraltar: number, timing and age composition. Ardeola, 66: 113-118.

Characterization of plasma cholinesterase activity in the Eurasian Griffon Vulture Gyps fulvus and its in vitro inhibition by carbamate pesticides

The legal and illegal use of organophosphorus and carbamate pesticides represents one of many threats to birds. The activity of the cholinesterase enzyme in plasma is used as a non‐destructive biomarker to diagnose the exposure of birds to these pesticides. Scavengers are one of the most important bird groups threatened by the use of baits poisoned with anticholinesterase pesticides. Knowledge of the characteristics of this enzyme in each bird species is crucial, as several studies indicate that more than one cholinesterase form may be present in the plasma of birds. In this study, cholinesterase activity was characterized in the plasma of the Eurasian Griffon Vulture Gyps fulvus by using several substrates and inhibitors of the enzyme, and its normal activity value was also determined. The in vitro sensitivity of Gyps fulvus plasma cholinesterase to carbamate insecticides (aldicarb, carbaryl and methomyl) was also investigated. The results indicated that propionylthiocholine iodide was the preferred substrate to determine plasma cholinesterase activity, followed by acetylcholine iodide and S‐butyrylcholine iodide, and acetylcholinesterase was the predominant enzymatic activity in Gyps fulvus plasma. Aldicarb was the most potent in vitro inhibitor of plasma cholinesterase activity in this species. However, cholinesterase enzymatic activity was significantly inhibited by all tested carbamates, providing further evidence that this biomarker is a suitable tool to monitor the exposure to these poisons in the field, highlighting its utility in conservation programmes.

Potential threat to Eurasian griffon vultures in Spain from veterinary use of the drug diclofenac

Summary Spain holds > 95% of the European breeding population of the Eurasian griffon vulture Gyps fulvus. Vultures provide important ecosystem services in carcass removal and influence emissions of greenhouse gases. Despite the known toxicity of the non‐steroidal anti‐inflammatory drug diclofenac to this species and other Gyps vultures, in March 2013 the Agencia Española de Medicamentos y Productos Sanitarios (AEMPS) approved the use of two medicines containing diclofenac for veterinary use in horses, pigs and cattle in Spain. To assess the potential impact of medicated ungulate carcasses on Eurasian griffon vulture populations in Spain, we first used information on the metabolism and elimination of diclofenac from medicated cattle and pigs to calculate residue levels in relation to time elapsed between dosing and death. Secondly, probabilities of the death of a vulture per meal were calculated based upon experimental studies of diclofenac toxicity. Finally, annual numbers of vulture deaths expected to be caused by diclofenac were obtained by multiplying the death rates per meal by the estimated numbers of vulture meals taken from expected numbers of medicated carcasses suggested by AEMPS. Assuming that vultures feed on carcasses that were treated with diclofenac 8 h before the animal's death, the annual number of vulture deaths caused by diclofenac was estimated at 715–6389, depending upon the estimate of numbers of medicated carcasses assumed and the version of the dose–response model used. Using a density‐independent simulation model of a vulture population, the expected rate of decline of the Spanish population of Eurasian griffon vultures caused by these deaths is 0·9–7·7% per year. A density‐dependent simulation model also indicated substantial population‐level effects. Formal estimates of precision and sensitivity analyses of effects of unmeasured variables highlight the uncertainty of estimates using currently available data. Synthesis and applications. Due to the possibility of causing an important impact on vulture populations, our findings justify a precautionary ban on the veterinary use of diclofenac in Spain and encourage the use of meloxicam, a vulture‐safe alternative drug. A programme of monitoring of non‐steroidal anti‐inflammatory drug contamination of ungulate carcasses available to vultures and of moribund and dead obligate and facultative avian scavengers would be needed to be confident that a damaging level of contamination is not present.

Optimization of supplementary feeding programs for European vultures depends on environmental and management factors

Despite the consensus among ecologists and conservationists of the importance of maintaining scavenger feeding patterns based primarily on natural prey sources, human‐mediated feeding remains a widely used management tool for threatened wildlife. Thus, it is important to understand the key factors favoring certain species and age‐groups at supplementary feeding sites. Through a detailed videomonitored experiment of carrion inputs at different locations in the Iberian Peninsula (home of >90% of European vultures), we assessed how variables related to weather, time, demography, management and alternative food availability influenced the occurrence patterns of different age‐classes of vultures at feeding sites. The most threatened and less gregarious species (bearded vulture Gypaetus barbatus and Egyptian vulture Neophron percnopterus) attended to earlier inputs, thus reducing interspecific competition with the Eurasian griffon vulture Gyps fulvus. The bearded vulture was favored by a larger biomass supply at the feeding sites during the chick‐rearing period, while the Egyptian vulture preferred frequent and abundant inputs. Non‐adult cinereous vultures Aegypius monachus were favored at times of lower abundance of natural resources and in the densest networks of feeding sites, while adults preferentially attended sites with periodic inputs close to breeding colonies in areas with lower availability of other natural prey. Finally, the Eurasian griffon vulture showed a preference for continued and periodic inputs, and for feeding sites with numerous other feeding sites in the surroundings. Our results help to inform the management of supplementing food provision with the aim of enhancing its value to reverse the unfavorable conservation status of endangered species and to mitigate the negative effects of the current global threats impacting them.

Manipulating size, amount and appearance of food inputs to optimize supplementary feeding programs for European vultures

Supplementary feeding is one of the most common techniques used to alleviate threats to scavengers species related to the quality and availability of food resources. Because supplementary feeding may have undesired effects, the management of supplementary sites should be optimized from an ecological and conservation perspective. We installed high-resolution videocameras at six Spanish feeding stations recording more that 7500h of observations at 105 feeding events. We analyzed food preferences in the four European vulture species (Eurasian griffon vulture Gyps fulvus, Egyptian vulture Neophron percnopterus, bearded vulture Gypaetus barbatus and cinereous vulture Aegypius monachus) as they relate to the characteristics of the food remains and carcasses provided at feeding sites. Our results suggest that carrion features (format, scattering, prey species, biomass and items) influence differential selection between species and age-classes. At a species level, large inputs of unscattered carrion increased the abundance of actively feeding griffon vultures. The ratio of the abundance of bearded vultures, Egyptian vultures and cinereous vultures with respect to griffon vultures was favored when less biomass was supplied and when the food provided was not presented as whole carcasses. Thus, using medium-size ungulates (i.e. sheep and goats) presented as small, abundant and scattered pieces favors the consumption of the resource by the most endangered species. Our findings can be used to optimize the supplementary provisioning of vultures in cases where this conservation tool is considered essential for managing targeted species or population groups.

Age identification of Eurasian Griffon Vultures Gyps fulvus in the field

Griffon Vultures Gyps fulvus are notoriously difficult to age precisely, given their delayed maturity and large inter-individual variation. However assessing the age of young individuals can be important for studies dealing with behaviour, population dynamics and conservation. Using a large sample of individually marked Griffon Vultures of known age in southern France, we studied changes with age of morphological parameters observable at distance on the ground. Combining features of bill colour, eye colour, shape and colour of neck ruff feathers and shape of upperwing greater coverts, it was possible to attribute age classes with a precision of c 2 years. The first characteristics to change were the colour of the bill, with the front of the bill getting clear before the sides of the bill, and the shape of the greater coverts, where pointed juvenile feathers were replaced by paler and more rounded feathers. In the second year, the ruff turned progressively paler and shorter to become adult-like in the seventh year for most individuals. The eye turned lighter only in the fifth year. Males tended to acquire adult plumages more rapidly than females.

Copulatory behaviour in the colonial Eurasian Griffon vulture Gyps fulvus

We examined copulation patterns and associated sexual behaviour in the colonial Eurasian Griffon vulture Gyps fulvus during the pre-laying period. Eurasian Griffon vulture pairs conducted an average of 71.7 copulation attempts per clutch, with an average copulation frequency of 1.2 copulation attempts per day. Low copulation frequencies compared to other raptors and absence of mate-guarding suggest that this species does not possess adaptive behaviour aimed at increasing paternity assurance. However, the gradual increase in copulations during the fertile period is consistent with the sperm competition hypothesis.

Biometrics, Sexual Dimorphism and Gender Determination of Griffon VulturesGyps fulvusfrom Crete

In the present study we describe the morphometrics of 97 live Eurasian Griffon Vultures Gyps fulvus collected on the island of Crete (Greece) and a sex determination model on the basis of various field techniques and multivariate data analysis. We determined the sex of 49 individuals with sex-specific DNA markers and polymerase chain reaction using DNA extracted from blood samples. Adult birds were generally larger than young ones with the wing chord being the only significantly different character. Male Griffons were smaller than females for most body characters and significantly larger (c. 3–5%) for head length, head width, bill length and bill length including the cere. A stepwise discriminant function analysis showed a high predictive power in gender determination by classifying 94.1% of the individuals of known sex that was not reduced by a jackknife cross-validation technique.

Factors influencing the breeding density of Bearded Vultures, Egyptian Vultures and Eurasian Griffon Vultures in Catalonia (NE Spain): management implications

Using multivariate analyses we examined differences in breeding density of the Bearded Vulture Gypaetus barbatus, the Eurasian Griffon Vulture Gyps fulvus and the Egyptian Vulture Neophron percnopterus in NE Spain (Catalonia) in relation to trophic, orographic-landscape and anthropic variables. Sampling units used were regional divisions (comarques). High density of Bearded Vulture was principally linked to areas with scant vegetation and low human population density. In contrast, high densities of both the Egyptian and Eurasian Griffon Vultures were associated with availability of trophic resources (sheep and goats). Positive effects were detected in relation to low density of inhabitants (Egyptian Vulture) and altitudes between 1,000-2,000 m and landscape with low tree cover (Eurasian Griffon Vulture). The Bearded Vulture seemed to be the most selective species in relation to environmental characteristics while the Eurasian Griffon and the Egyptian Vultures displayed a higher degree of ecological plasticity. Future conservation actions should bear these results in mind in order to optimise management. Food resources from extensive livestock farming, in particular, seem fundamental for the conservation of scavenger species. Preference monitoring and conservation efforts are needed in the regions with highest vulture densities (Alta Ribagorça, Pallars Jussà and Alt Urgell), while regions with low vulture populations should be managed in order to favour the geographical expansion and recolonisation of zones currently not occupied by these species. Conservation priorities should be based on favouring extensive livestock practices, and as an alternative to muladares (traditional animal carcass disposal sites) farmers should be encouraged to leave animal carcasses in the field, while ensuring compliance with health regulations.

Estimating the economic value of viewing griffon vultures Gyps fulvus : a Travel Cost Model study at Gamla Nature Reserve, Israel

The proper valuation of non-market environ- mental commodities such as wildlife viewing has signifi- cant policy implications. We implemented the Travel Cost Method (TCM) to estimate the value of viewing threatened Eurasian griffon vulture Gyps fulvus by the public at Gamla Nature Reserve, northern Israel. We used the zonal TCM, where concentric zones were defined around the site such that the cost of travel from all points in a given zone was approximately constant. We generated a visit-distance function and used it, based on 143 questionnaires, to derive the demand function for the site from which a monetary value could be estimated. The potential annual benefit of Gamla was estimated to be NIS 5.5-6.0 million (USD 1.1-1.2 million). The annual