Jacopo Cerri, Davide De Rosa, Mauro Aresu, Chiara Costantino, Ilaria Fozzi, Dhyan Anaja Banič, Camilla Brunet, Joel Echeverria, Luce Pavin, Marco Muzzeddu, Dionigi Secci, Fiammetta Berlinguer

Translocations are fundamental for the conservation of large raptors, including Old-World vultures. Different release methods are usually assessed by comparing the movement patterns and survival of released individuals. However, these approaches fail to capture important aspects related to the gregarious behaviour of many vulture species. We compared the effect of long (15 months, n = 7) and short (3 months, n = 16) acclimatisation over the post-release spatial behaviour of 4 cohorts of Griffon Vultures (Gyps fulvus) in Sardinia (Italy). Namely, we studied their occurrence distribution at a biweekly resolution and modelled its temporal trends to assess whether long-acclimatised griffons were faster and more prone i) to overlap their space use with that of other griffons from the same cohort, ii) to restrict their movements around colonies. Although no temporal trend was detected, long-acclimatised griffons had a higher intra-cohort correlation in their occurrence distribution. Long-acclimatised griffons were also faster at moving between the two main colonies than short-acclimatised ones. After 4-5 years, they were also more prone to use both colonies and thus less prone to remain confined into a single colony for 2 weeks, or in moving far away. Long acclimatisation seems to promote group cohesion in released griffons, probably due to the creation of stronger inter-individual bonds at the aviary, which can then facilitate movement at release sites and explain their faster use of a multiple colony system. Long acclimatisation periods (> 12 months) should be preferred for translocations of gregarious birds, such as Griffon Vultures, as they might foster group cohesion and facilitate post-release survival.