Large-scale movement patterns in a social vulture are influenced by seasonality, sex, and breeding region

Mapping bird and bat assemblage vulnerability for predicting wind energy impact

The drive towards decarbonization has led countries to seek renewable energy sources to mitigate global warming. Wind energy is an attractive option due to its low cost and sustainability, but it poses significant risks to birds and bats through collisions and barotrauma with wind turbines. We examined the main ecological traits linked to wind turbine mortality in 214 bird and 19 bat species in peninsular Spain. We assessed the vulnerability of bird and bat assemblages to help understand the potential impact of wind energy development on the most vulnerable assemblages. Our findings indicate that bird and bat casualties were driven by morphological and ecological traits. For birds, scavenger species, those with partial migratory patterns, and aerial lifestyles were most affected by turbine collisions. We also found that vulnerability was positively correlated with observed mortality rates at the province level, but the effect was weaker for birds. Sensitive areas for birds and bats are located in southern, south-eastern, and central Spain, with birds showing additional vulnerability in western and northern regions, while future wind energy development affects bats more in eastern Spain. Our research highlights the importance of mitigating impacts on vulnerable bird and bat species, as well as abundant species. The study highlights the potential risk of ecosystem function loss for bird and bat assemblages due to wind energy projects. We provide spatial tools to identify high-vulnerability areas, guiding energy development to minimize ecological impacts. This work calls on authorities to implement measures to protect species and preserve essential ecosystem functions.

Differential Flight Responses of Sympatric Raptor Species to Weather Conditions and Extreme Temperature Events

Climate change has increased the frequency, severity, and duration of extreme weather events, for example, heatwaves, underscoring the need to comprehend their impact on animal behavior. Flying organisms, particularly birds, are greatly affected by changes in atmospheric conditions and may modify their speed or direction, adjust their flight strategy, and even make decisions on whether to fly based on weather. In this study, we assessed flight-related parameters in three GPS-tagged raptor species: the golden eagle (Aquila chrysaetos), the Bonelli's eagle (Aquila fasciata), and the Spanish eagle (Aquila adalberti), in relation to weather conditions and heatwaves. The results showed that the three species varied in their flight patterns despite similar environmental conditions, including temperature, precipitation, wind speed, and atmospheric pressure. Each species exhibited unique strategies and responsiveness to heatwaves, reflecting diverse adaptive capacities and behavioral flexibilities. Specifically, Bonelli's eagle displayed comparatively minor adjustments in its flight strategy during periods of extreme temperature, contrasting with the pronounced behavioral variations observed in the golden eagle. These findings suggest that extreme and unpredictable weather events, particularly heatwaves, may impact raptor species differently. An understanding of how extreme weather events may impact individual fitness, through modifications to energy expenditure and foraging practices, is essential for predicting their potential impact on long-term population dynamics.

Demographic effects of sanitary policies on European vulture population dynamics: A retrospective modeling approach

The prediction of population responses to environmental changes, including the effects of different management scenarios, is a useful tool and a necessary contributor to improving conservation decisions. Empirical datasets based on long-term monitoring studies are essential to assess the robustness of retrospective modeling predictions on biodiversity. These allow checks on the performance of modeling projections and enable improvements to be made to future models, based on the errors detected. Here, we assess the performance of our earlier model to assess the impact of vulture food shortages caused by sanitary regulations on the population dynamics of Spanish vultures during the past decade (2009-2019). This model forecasts the population trends of three vulture species (griffon, Egyptian, and bearded vultures) in Spain (home to 90% of the European vulture population) under various food shortage scenarios. We show that it underestimated bearded and griffon vulture population numbers and overestimated Egyptian vultures. The model suggested that the most plausible food shortage scenario involved an approximate 50% reduction of livestock carcass availability in the ecosystem compared with the previous situation without sanitary carcass removal. However, the observed annual population growth for the period 2009-2019 (7.8% for griffon vulture, 2.4% for Egyptian vulture, and 3.5% for bearded vulture) showed that food shortages had little impact on vulture population dynamics. After assessing the robustness of the model, we developed a new model with updated demographic parameters and foraging movements under different hypothetical food shortage scenarios for the period 2019-2029. This model forecasts annual population increases of about 3.6% for the bearded vulture, 3.7% for the Egyptian vulture, and 1.1% for the Griffon vulture. Our findings suggest that food shortages due to the implementation of sanitary policies resulted in only a moderate impact on vulture population growth, probably thanks to the supplementary feeding network which provided alternative food. Also important was the availability of alternative food sources (intensive farms, landfills) that were used more regularly than expected. We discuss the computational performance of our modeling approach and its management consequences to improve future conservation measures for these threatened species, which provide essential ecosystem services.

Pharmaceuticals in avian scavengers and other birds of prey: A toxicological perspective to improve risk assessments

Pharmaceuticals are emerging contaminants given their increasing use worldwide due to intensive food production and population growth. These compounds reach the environment through different pathways with potential negative consequences for wildlife. One dramatic example occurred in Asia, where three native vulture populations collapsed almost to extinction due to acute intoxication with diclofenac, a veterinary use non-steroidal anti-inflammatory drug (NSAID). As seen with diclofenac, avian scavengers are useful sentinels to monitor for the presence of pharmaceuticals in the environment given their position at the top of the trophic chain, and in the case of obligate avian scavengers (vultures), their intimate link to domestic animal carcasses. Unfortunately, little is known about the wider exposure and potential health and population risks of pharmaceuticals to birds of prey. Here we compile literature data regarding relevant toxicological aspects of the most important pharmaceutical groups for birds of prey in terms of toxicity: NSAIDs, antibiotics, external antiparasitics and barbiturates. This work also includes critical information for future risk assessments, including concentrations of drug residues that can remain in animal tissues after treatment, or specific pharmaceutical features that might influence their toxicity in avian scavengers and other birds of prey. We also consider future research needs in this field and provide management recommendations to prevent potential intoxication events with pharmaceuticals in these species. This review highlights the need to consider specific risk assessments regarding exposure to pharmaceuticals, especially those used in veterinary medicine, for birds of prey.

Early life movements and mortality of Egyptian vultures: Implications for transcontinental conservation

Understanding the movements and mortality of individuals across different life stages is crucial for the effective conservation of wild populations. We used data from 32 Egyptian vultures (Neophron percnopterus) tagged with GPS transmitters as nestlings in three Iberian breeding areas to study their dependence period, migration routes, movements in Africa, and mortality at each stage. Our results show no significant differences in the timing of nest departure or the duration of the dependence period between individuals of different sexes or breeding nuclei. Most juveniles migrated to sub-Saharan Africa in their first year, but some (3 of 32, 9.4%) remained in the Iberian Peninsula. Individuals that migrated to Africa did so annually, while those remaining in Iberia never migrated to the Sahel, indicating distinct migratory and non-migratory strategies. Non-migratory individuals consistently moved northward during the breeding season to their natal territories. Siblings did not coordinate their migration strategy or timing. All juveniles showed extensive overlap in the vast areas used in Africa, where females arrived before males, and in the Iberian Peninsula. Our study also revealed that no juveniles died immediately after fledging, but that none of the tagged individuals lived more than 7 years or were recruited as breeders. Although most casualties occurred during the longer stay in the Sahel, the mortality rate was highest during the few days of the first migration. Our results show that despite small variations in movement patterns between breeding nuclei and sexes, Egyptian vultures face similar challenges during the years before recruitment as breeders, mostly determined by their migratory strategy. These findings are relevant for designing conservation strategies, both in breeding areas and, more importantly, in wintering areas and along migration pathways. Such strategies will significantly impact the entire Iberian population of this endangered species.

Age and sex differences in pharmaceutical contamination in a keystone scavenger

Pharmaceutical contaminants have a recognized negative impact on wildlife health. However, there are still many knowledge gaps on the factors influencing exposure and metabolic processing of compound mixtures as a function of season and individual characteristics such as age and sex. We evaluated age and sex differences in a set of seventeen compounds, including eleven antibiotics, five NSAIDs and caffeine, evaluated by HPLC-MS-TOF analysis in griffon vultures (Gyps fulvus) from central Spain. Pharmaceutical cocktails (up to 10 compounds simultaneously) were found in all individuals. Lincomycin was detected in all individuals, and fluoroquinolones were found at high frequencies, while NSAIDs were at low frequencies and concentrations, including flumixin meglumine, which can be lethal to vultures. A higher total number of compounds and sum of concentrations, as well as prevalence and concentration of several of the pharmaceuticals tested was found in females than in males for both nestlings and adults. This is the first study to present evidence of sex differences in the pharmacokinetics of dietary drug contaminants in a vulture species. Chronic exposure to "medications" in entire populations can potentially have sub-lethal health effects that affect fitness differently according to age and sex, with demographic implications for population viability. Specifically, if females have higher mortality after fledging due to high pharmaceutical contamination, this should be considered when modelling the population dynamic of this species for conservation purposes.

High-risk lineages of extended spectrum cephalosporinase producing Escherichia coli from Eurasian griffon vultures (Gyps fulvus) foraging in landfills in north-eastern Spain

Extended-spectrum cephalosporinase producing (ESC) E. coli are regarded as key indicator microorganisms of antimicrobial resistance (AMR), calling for a One Health integrated global surveillance strategy. Wildlife is exposed to antibiotic contaminants and/or resistant bacteria that have been released into the environment, potentially acting as reservoirs and spreaders of resistance genes as well as sentinels of anthropogenic pressure. Monitoring AMR in wildlife has become crucial in determining anthropogenic environmental impacts as well as transmission routes. In this study, we determined the occurrence and potential sources of ESC E. coli in 218 Eurasian griffon vultures (Gyps fulvus) foraging regularly on human waste disposed at a dumpsite in north-eastern Spain. Minimal inhibitory concentration for 14 different antimicrobials was performed to evaluate the phenotype of the isolates, and whole genome sequencing was carried out to investigate lineages and plasmids harbouring ESC genes. Our sequences were compared to previously published Spanish sequences of human, animal, and wildlife origin. We report a high prevalence of CTX-M-15, as well as the presence of other resistance genes such as OXA-10, CTX-M-27, and CTX-M-65 which are rarely described in European livestock, suggesting a human origin. The isolates also carried a diverse range of additional AMR genes for a broad spectrum of drug families, with the majority being multi-drug resistant. The phylogenomic analyses suggests the transmission of high-risk lineages from humans to vultures, with 49 % of our isolates matching the most common extraintestinal pathogenic E. coli (ExPEC) lineages described in humans worldwide, including ST131, ST10 and ST58. We conclude that anthropogenically altered habitats, such as landfills, are hotspots for the acquisition and spread of high-risk ESC E. coli lineages associated with hospital infections. Measures must be implemented to limit their spread into natural environments.

Age-Specific Demographic Response of a Long-Lived Scavenger Species to Reduction of Organic Matter in a Landfill

Food availability shapes demographic parameters and population dynamics. Certain species have adapted to predictable anthropogenic food resources like landfills. However, abrupt shifts in food availability can negatively impact such populations. While changes in survival are expected, the age-related effects remain poorly understood, particularly in long-lived scavenger species. We investigated the age-specific demographic response of a Griffon vulture (Gyps fulvus) population to a reduction in organic matter in a landfill and analyzed apparent survival and the probability of transience after initial capture using a Bayesian Cormack-Jolly-Seber model on data from 2012-2022. The proportion of transients among newly captured immatures and adults increased after the reduction in food. Juvenile apparent survival declined, increased in immature residents, and decreased in adult residents. These results suggest that there was a greater likelihood of permanent emigration due to intensified intraspecific competition following the reduction in food. Interestingly, resident immatures showed the opposite trend, suggesting the persistence of high-quality individuals despite the food scarcity. Although the reasons behind the reduced apparent survival of resident adults in the final four years of the study remain unclear, non-natural mortality potentially plays a part. In Europe landfill closure regulations are being implemented and pose a threat to avian scavenger populations, which underlines the need for research on food scarcity scenarios and proper conservation measures.

Eurasian griffon vulture (Gyps fulvus) as a bone modifying agent and its implications for archaeology

Neo-taphonomic studies have allowed us to detect bone damage patterns linked to carnivore preferences and behavioral traits as well as to improve our understanding of the origin of different alterations on vertebrate fossil faunas. However, taphonomically speaking vultures are among the least studied of all common, obligate scavengers. The research reported here contributes to characterise Eurasian griffon vulture (Gyps fulvus) behavior from a taphonomic perspective describing bone damage on 12 small-sized ungulate carcasses. The combination of observational data from photo/video-trap together with taphonomic analyses allowed us to manage factors like feeding behavior or time of consumption, as well as to accurately record bone modified items. Some bone-modifying effects are described here for the first time as vulture-made bone-damage distinctiveness. Still, some others may pose equifinality problems especially regarding small carnivores. This taphonomic conundrum leaves an interpretation problem particularly in archaeological sites in which those agents are present and consequently, an individualization dilemma about the taphonomic actors involved in bone modified assemblages.

Medicated livestock carcasses and landfill sites: Sources of highly toxic veterinary pharmaceuticals and caffeine for avian scavengers

Veterinary drugs are of concern in terms of potential environmental pollution and their negative impacts on avian scavengers. These pharmaceuticals reach vultures through the consumption of carcasses of previously treated livestock. Here, we analysed samples from livestock carcasses (n = 159), avian scavenger tissues (n = 116) and plasma (n = 312) for 49 compounds commonly used in veterinary medicine in Aragon (NE Spain) and nearby regions. Samples were analysed using liquid chromatography with electrospray ionization mass spectrometry (LC-ESI-MS/MS). We detected pharmaceuticals in 54.1% of livestock carcasses analysed (50.3% with antibiotics, 10.8% with NSAIDs). For veterinary pharmaceuticals in tissues and plasma from avian scavengers, we detected pharmaceuticals in 51.7% and 28.5% of samples, respectively. Antibiotics were detected in 50.9% and 25.3% while NSAIDs were determined in 6.0% and 5.5% of tissues and plasma from avian scavengers, respectively. Moreover, caffeine was detected in plasma in 73.7% of vultures sampled at landfill sites, indicating its usefulness as a biomarker of urban garbage ingestion. We found an association between livestock carcasses, especially pigs and chickens, and the presence of veterinary pharmaceuticals in avian scavengers. We highlight that carcass disposal for feeding avian scavengers must address the potential risks posed by veterinary pharmaceutical residues.

Admission Causes, Morbidity, and Outcomes in Scavenger Birds in the North of Portugal (2005-2022)

Portugal is the habitat of three species of vultures. According to the IUCN Red List of Threatened Species, Neophron percnopterus is an Endangered species, Aegypius monachus is nearly Threatened, and Gyps fulvus is of Least Concern. This study aims to investigate the admission causes, morbidity, and outcomes of vultures admitted to a wildlife rehabilitation centre and necropsy service in Northern Portugal. Over 17 years (2005-2022), 84 animals were admitted: 10 A. monachus, 69 G. fulvus, and 5 N. percnopterus. The main causes of admission to the centre were 80% (n = 63) unknown cause, 13% (n = 10) found debilitated, 6 % (n = 5) vehicle collision, 4% (n = 3) captivity, 1% (n = 1) gunshot, and 1% (n = 1) electrocution. Most animals were admitted during the summer (45.2%) and autumn (36.9%). Analysis of outcome data showed that 73% (n = 58) of the animals that arrived alive at the centre could be rehabilitated and released back into the wild. Thirteen animals died during treatment and five were found dead. This is the first time that such a lengthy study of results and mortality has been carried out for these species in Portugal. Although the data are limited, they can already provide some information about these populations, particularly for the endangered species that are so rare to observe.

Insights on the best release strategy from post-release movements and mortality patterns in an avian scavenger

Conservation translocations involving vultures rely either on soft- or hard-release strategies. To investigate whether these strategies affect home range stability and survival, we compared the spatial behavior and mortality of 38 Griffon vultures (Gyps fulvus) released in Sardinia. Griffons were released after no acclimatization or after 3 (short) or 15 (long acclimatization) months in an aviary. In the two years that followed their release, griffons without acclimatization did not stabilize their home range size, while those subjected to long acclimatization stabilized it in the second year. Short-acclimatized griffons always had a large home range, soon after their release. The number of individuals that reached sexual maturity was higher (71.4%) in long-acclimatized griffons than in short-acclimatized ones (40%) or in griffons that were hard released (28.6%). Soft release with a long acclimatization period seems to be the most successful method to ensure stable home ranges and the survival of griffon vultures.

The Influence of Age, Sex and Season on Andean Condor Ranging Behavior during the Immature Stage

Immature individuals move from their natal area to the area where they settle and reproduce, and this may take several years. This process is essential for long-lived species such as vultures and condors, which spend long periods as immature and move extensively. We studied the movement behavior of 26 GPS-tagged immature Andean condors (Vultur gryphus) from northwestern Patagonia throughout the immature stage, analyzing whether these patterns differed according to age, sex and season. We found that season and age influenced home range size and flight distances, the warm season being when immature condors move most; movement patterns were greater in sub-adults than in juveniles. The age effect was associated with the sex of individuals, with males increasing their home range more than females. Our results provide the first description of how immature Andean condor movement patterns are affected by internal and external factors. This information could be key to understanding condor responses to environmental change and threats at different stages during their immature phase. Until now, condor conservation efforts have not considered the areas used by dispersing individuals. Our results increase our understanding of ranging behavior during the immature stage of this threatened bird, enabling us to improve the conservation policies and management strategies designed to protect them.