Foraging Behaviour and Flight Characteristics of Eurasian Griffons Gyps fulvus in the Island of Crete, Greece

We studied the foraging behaviour of Eurasian griffons Gyps fulvus on the island of Crete during 1997–2005 by direct observations in four colonies and by monitoring the movements of seven radio‐equipped individuals. The estimated foraging range of griffon colonies, based on direct observations, ranged from 206–851 km 2 by using the Minimum Convex Polygon method, and 195–527 km 2 by using the Adaptive Kernel method, with corresponding means of 472 and 380 km 2 , respectively. Meanwhile, radio‐tracking showed that foraging vultures covered an area ranging from 390–1300 km 2 . The mean foraging radius was calculated at ca 15 km and the mean maximum one at 29.9 km. On windless days, griffons' mean cross‐country speed was 5.1 m/second (maximum = 13.3 m/second), with a mean climbing rate of 0.6 m/second and a mean inter‐thermal gliding speed of 18.8 m/second. Any livestock carrion located up to 9 km from a colony was exploited by its members with minimum competition from individuals of adjacent areas. In total, we recorded 23 feeding incidences which took place at a mean distance of 8.4 km from the colonies. The food types identified were sheep carcasses located near stock‐farms and offal disposed in waste dumps in the vicinity of the colonies. On average, the griffons allocated 7.6 hour/day to food searching. This varied significantly between months and seasons. The shortest foraging time was recorded in December (6.4 hour/day) and the longest in June (9.3 hour/day). A significant difference of one hour after sunrise was detected in the departure time from the colony between seasons revealing that griffons departed earlier during winter trying to maintain their foraging budget within the available daytime limits.