Seasonal and Spatial Dynamics of the Population of the Griffon Vulture Gyps fulvus (Hablizl, 1783) (Ayes: Accipitridae) in Southwestern Bulgaria

Movements and sojourn of the griffon vulture Gyps fulvus in Bulgaria are poorly known. In the light of multiple reintroductions of the species in Bulgaria and by means of introduction of modern technologies, a lot of new data were collected. Here we analyze data of seven birds tracked by GPS/GPRS transmitters in South-western Bulgaria and additional five vultures from other colonies in the country and adjacent areas. Our results indicate that immature griffon vultures travel long distances across Bulgaria and neighbouring countries (maximum daily distance = 234.3 +/- 87.2 km; minimum convex polygon = 28,347 +/- 42,439 km(2); home-range 95% kernel = 7,893 +/- 20,645 km(2) and core area 50% kernel = 772 +/- 1,826 km(2)). However, they almost exclusively roost and feed in already established griffon vulture colonies or join seasonal gathering of conspecifics, which are usually found within a zone of 15 km radius from a complex of feeding site or abundant, easily accessible food in close proximity to suitable roosting places. Strategically placed and permanently supplied vulture restaurants in close proximity of roosting sites, may concentrate large numbers of griffon vultures in a relatively small and possible to control areas. This, in combination with implementation of site based conservation activities (e.g. creation of Vulture Safe Areas), may buffer the impact of any, otherwise, hardly controlled and acting on large scale threats, such as poisoning and electrocution.