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

The 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 (lambda = 1.02) and reached 445-565 pairs in 2019. We recorded a gradual increase of Griffon Vulture subpopulations in Serbia (lambda = 1.08 +/- 0.003), Bulgaria (lambda = 1.08 +/- 0.003) and Croatia (lambda = 1.05 +/- 0.005) and steep to a moderate decline of the species subpopulations in Greece (lambda = 0.88 +/- 0.005) and North Macedonia (lambda = 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.