Vultures are among the most threatened bird guilds on the planet and have a unique functional role within ecosystems. They are therefore subject to increasing research interest, calling for standardised study approaches and monitoring methods. The use of Unmanned Aircraft Systems (UASs) is rapidly gaining popularity in ecological research due to technological advances, affordability, and accessibility. This study reviews the existing peer-reviewed publications and grey literature on the responses of European vultures and other comparable species to UASs, and summarises the types of UAS use, their potential disturbance effects on vultures, and the resulting inter- and intra-specific interactions. Our goal was to assess the potential effects of UASs and to provide practical recommendations to optimise their safe use in vulture conservation and research. We acknowledge the potential of UASs to increase research efficiency and reduce research effort, time, and financial cost. Owing to the absence of sufficient data on long-term disturbance effects, we advocate the precautionary principle and offer a set of species-tailored practical recommendations to limit the potential negative effects of UASs and maximise their value in conservation management. We urge that the physiological and long-term impacts on vulture reproduction are considered and call for standardised monitoring protocols and controls on UAS use. Our conclusions and recommendations are particularly aimed at researchers working on vulture conservation and restoration projects worldwide.

The Egyptian vulture Neophron percnopterus is categorized as Endangered on the IUCN Red List, as well as on the European and Spanish Red Lists. Spain is home to the most important breeding population of Egyptian vultures in Europe but this population has differing trends at a regional scale. We present data for the Egyptian vulture population in the Cantabrian Mountains, north-west Spain, during the last 3 decades and assess the main threats to the species there. The Egyptian vulture population in the Cantabrian Mountains was estimated to be 175 breeding pairs in 2008, which comprised 13–14% of the Spanish population. This population has been stable, or increasing slightly, since 2000. During 2000–2008 4.3% of the Cantabrian Egyptian vulture population was affected by the use of illegal poison. During the same period the number of sheep and goats reared (which contributes to the maintenance of Egyptian vulture territories) was reduced by 27.4%, which could lead to food shortages for the vultures in the near future. Currently 32 breeding pairs (18.3% of the population) have wind turbines within their foraging areas, with an average of 59 wind turbines per territory (range 1–176). During the next few years this number will increase to 110 turbines per territory within 69 vulture territories (39.4% of the population). Nearly a third (32.6%) of breeding territories are located outside protected areas. Better coordination between administrative areas is needed to guarantee the conservation of the Cantabrian Mountains population of Egyptian vultures through effective surveillance and protection in the numerous existing protected areas.

Identifying threats to declining species and prescribing ways of preventing their extinction are basic challenges for biodiversity conservation. We analysed the causes underlying the loss of territories of the Endangered Egyptian vulture Neophron percnopterus in a key population at the north-western edge of its distribution in Europe by developing multi-scale models that combined factors from nest site to landscape. We used generalized linear models and an information-theoretic approach to identify the optimal combination of scales and resolutions that could explain territorial abandonment. Those models combining nest-site and landscape scales considerably improved prediction ability compared to those considering only one scale. The best combined model had a high predictive ability (96.9% of correctly classified cases). Small cliffs at high altitudes in rugged areas with declining livestock (especially of sheep and goats) increased the likelihood of territory abandonment. Our findings highlight the importance of developing region-specific multi-scale models to determine reliably the factors driving territory loss and of designing effective conservation strategies accordingly. Conservation measures for the studied population should be developed at two spatial scales. At the smaller scale it is necessary to closely control nest sites to avoid direct disturbances. At a larger scale it is essential to implement policies that can support traditional pastoralism.