Movements of restocked Griffon Vultures in Sardinia

Movements of restocked Griffon Vultures in Sardinia ACTION D2 October 2025 João Guilherme1, Franziska Lörcher1, Ilaria Fozzi2, Dionigi Secci3, Marco Muzzeddu3, Mauro Aresu, Fiammetta Berlinguer2 Recommended citation: Guilherme, J.L., Loercher, F., Fozzi, I., Secci, D., Muzzeddu, M., Aresu, M., & Berlinguer, F. (2025). Movements of restocked Griffon Vultures in Sardinia (Action D.2). LIFE Safe for Vultures. https://doi.org/10.5281/zenodo.17252172 ________ 1 Vulture Conservation Foundation 2 University of Sassari 3 Agenzia Forestas LIFE19/NAT/IT/000732 Life Safe for Vultures First step to the restoration of the vulture guild in Sardinia Coordinating Beneficiary Università degli Studi di Sassari | Via Vienna 2 | 07100, Sassari | mail: lifeforvultur[email protected] | tel: +39 079 229904 Associated BeneficiariesCommunity www.lifesafeforvultures.eu With the contribution of the LIFE financial instrument of the European Community Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna The Griffon Vulture (Gyps fulvus) population in Sardinia has recovered through conservation efforts, including those implemented during the LIFE Safe for Vultures project, which focus on habitat protection, threat mitigation, supplementary feeding, and restocking of the population. Here, we report on the movements of two groups of Griffon Vultures released in 2024 in Villasalto, alongside data from Griffon Vultures previously released in Bosa breeding colony. The birds in the first group were released in Villasalto in April 2024 after a 10-month acclimatization period, while the second release group (n = 22) was released in October 2024 following a 6-month acclimatization. We analysed the movements, utilization distributions, feeding events, and roosting sites used by the groups compared to the older group. Results showed different movement patterns between the groups. The first group exhibited strong fidelity to the release area with limited dispersal, likely influenced by acclimatization and available resources. In contrast, the second group dispersed widely across Sardinia, particularly towards the established Bosa and Punta Cristallo colonies, suggesting the role of social cues and possibly seasonal influencing their movement patterns. Overall, survival rates of the translocated birds were robust and comparable to those reported in similar translocation efforts elsewhere. These findings highlight the importance of adaptive release strategies, considering factors like acclimatization, age, and ecological conditions. Continued monitoring is crucial to refine management approaches and ensure the long-term success of the Griffon Vulture population in Sardinia. Abstract Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna We warmly thank the personnel of Forestas for their dedicated work in managing the animals during the acclimatisation and recovery phases at the Monastir and Bonassai Wildlife Recovery Centres, and in Villasalto aviary. We are also deeply grateful to all those who supported us in the tagging and monitoring of the animals. Our appreciation further goes to the group of volunteers who contributed to monitoring and management activities within the LIFE ‘‘Under Griffon Wings’’ and LIFE “Safe for Vultures” projects. Acknowledgements Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna INTRODUCTION ............................................................................................................ 5 RESULTS ....................................................................................................................... 7 1. Old group and the Bosa Colony .................................................................. 7 2. First release group ....................................................................................... 9 3. Second release group ................................................................................ 11 DISCUSSION ............................................................................................................... 14 METHODS .................................................................................................................. 16 1. Standardization the tracking data ............................................................. 16 2. Utilization distributions and home range estimation ............................... 20 3. Identifying feeding events ......................................................................... 21 4. Identifying roosts ....................................................................................... 21 5. Software ..................................................................................................... 21 REFERENCES ............................................................................................................. 22 Contents Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna The Griffon Vulture (Gyps fulvus) is a key scavenger species whose populations across Europe have undergone dramatic fluctuations over the last two centuries, culminating in the extinction of several populations (BirdLife International, 2025). In recent decades, coordinated conservation initiatives at both European and regional level have enabled a gradual recovery through restocking, reintroduction and rehabilitation programmes, coupled with actions to mitigate the main threats to Griffon Vultures, namely poisoning, electrocution, and food scarcity. Sardinia is home to the last native population of Griffon Vultures in Italy, although recent conservation measures have brought the species back to other parts of Italy (e.g., Monti et al., 2023). In the 1930s, the Sardinian Griffon Vulture population numbered 800-1200 individuals, but direct persecution, poisoning, and increasing food scarcity caused a sharp decline in the population, restricting the Griffon Vultures to a single and vulnerable breeding nucleus in northwestern Sardinia, between Bosa and Alghero. The first conservation efforts began in the 1970s with supplementary feeding sites, followed by legal protection and systematic monitoring of breeding birds (Schenk et al., 2008). This was followed by translocations of birds from Spain and France between 1987 and 1995 (Schenk and Aresu, 1992), which helped to increase the population, although mass poisonings in the late 1990s and 2000s undermined these gains (Schenk et al., 2008). From 2016, intensive efforts have focused on restoring a viable, self-sustaining Griffon Vulture population across the island Sardinia. Conservation actions carried out under LIFE Under Griffon Wings (LIFE14/NAT/IT/000484) and, currently, under LIFE Safe for Vultures (LIFE19NAT/ IT/000732), tackled major threats (including poisoning, electrocution, and disturbance), increased food availability through centralised and farm feeding stations and secured the protection of key habitats. Combined with a carefully planned restocking programme, these actions have created the foundations for population recovery and long-term viability of a sustainable Griffon Vulture population in Sardinia. Recent releases under the LIFE Safe for Vultures project aimed to recolonise the breeding colony in Villasalto (southeastern Sardinia), not only to reconnect vultures with their historical range, but also to support a more balanced distribution of the species across the island (Secci et al., 2024). Monitoring the movements of translocated birds is essential to understand the dynamics of recolonisation in Villasalto, the factors that may lead to their attachment to the release site or their dispersal to other areas, their feeding routines and roosting preferences. This knowledge is esIntroduction 5 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna sential to assess the success of the conservation actions implemented and to adapt management strategies for the future. Here, we report the movements (up to 1st June 2025) of two groups of Griffon vultures restocked in Sardinia in 2024, within the LIFE Safe for Vultures. The ‘first release group’ included 15 Griffon vultures, which were released on 9th April 2024, in Villasalto (SE Sardinia), following an acclimatization period of 10 months. The ‘second release group’, included 22 Griffon vultures, which were released on 9th October 2024, also in Villasalto, following an acclimatization stay of 6 months. We further present the general movements of 29 Griffon vultures that were tagged and monitored previously to the start of the current LIFE project (‘old group’), most of them restocked during the LIFE Under Griffon Wings. For each group, we analysed the (a) overall movements, (b) Utilization Distributions (core range, 50% UD; mid-range, 75% UD; and overall home range, 95% UD), (c) feeding events (based on accelerometer data); and (d) roost utilization. Finally, to provide a comprehensive overview of spatial use across the population, we mapped the aggregated movements and utilization distributions of the three Griffon vulture groups monitored in Sardinia. 6 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna 1. Old group and the Bosa Colony Griffon vultures forming the old group are all those tagged and monitored before the start of the LIFE Safe for Vultures project. This group includes birds from different sources: individuals translocated from Spain (n = 21), birds originating from captive-breeding programmes (n = 7), and Sardina-born birds that were rehabilitated and released after recovery (n = 9) (Table 1). All these individuals were part of the previous efforts started in 2016, to recover the Griffon vulture population and increase their conservation status in Sardinia under the LIFE Under Griffon Wings. The strategy was specifically centred around the Bosa colony in the northwest of the island, the stronghold of the Griffon vulture in Sardinia. Therefore, two birds that were rehabilitated during the LIFE Safe for Vultures and hard released in Bosa in 2024 were included in this group, bringing the total to 39 birds. Overall, these birds exhibited a mean 6-month survival rate of 80.95% and a 1-year post-release survival rate of 74.6% (Berlinguer et al., 2025), both of which fall within the range reported in other Griffon Vulture translocation projects (e.g., Sarrazin et al., 1994; Monti et al., 2023). Analysing the movements and utilization distributions of these old group birds, becomes apparent that their range remained largely confined to the release sites within Bosa colony and nearby smaller Punta Cristallo colony. Only limited dispersal to other parts of the island took place (Figure 1a,b). This restricted spatial pattern is most likely influenced by the presence of conspecifics – including more experienced individuals – and availability of reliable foraging grounds around the main roosting sites and breeding cliffs (Cerri et al., 2023). Moreover, the existing supplementary feeding stations (both centralised feeding stations and farm feeding stations) implemented in these areas since 2016 provide a significant amount of predictable carrion for the vultures (LIFE Under Griffon Wings, 2020). This interpretation is reinforced by the clustering of feeding events around Bosa and Punta Cristallo – although this analysis was based only on six tracked birds, which may be under representative of the overall feeding activity by this group (Figure 1c; Fozzi et al., 2025). Nevertheless, some birds undertook larger movements away from the main colonies (Figure 1a), occasionally roosting in areas well outside their home ranges (Figure 1d). These large-range movements took some of the old group Griffon vultures to different sites scattered across Sardinia (Figure 1d), putting in evidence not only their dispersal aptitude but also the need to warrant food availability across the island. While these large-range movements away from the home ranges may not be entirely intentional, and in some cases driven by the weather conditions (Cerri et al., 2025), they are ecologically significant; for example, the use of these roosts, even if sporadically, may indicate favourable sites used by non-tagged conspecifics. Results 7 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Figure 1 Overall movements and spatial use of 39 Griffon Vultures released in Sardinia before the LIFE Safe for Vultures – old group birds: (a) all tracked movements illustrated by light-grey lines connecting locations recorded every two hours (light-blue dots; night locations not shown) of released vulture; (b) Utilization Distribution (UD), modelled using dynamic Brownian Bridge Movement Models (dBBMMs), with contours representing the core range (50% UD), mid-range (75% UD), and home range (95% UD) within an annual-cycle; (c) feeding events revealed using triaxial accelerometer data (n = 6 birds; n = 2239 feeding events); and (d) roosts used by the vultures, with each location (n = 14 125 nights) showing a single night used by a single vulture. 8 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna 2. First release group The first release group of Griffon vultures (n = 15) was released in the Villasalto region on 9th April 2024 following an acclimatization period of 10 month. This was an important milestone in the expansion of the Sardinian reintroduction programme. The first release group included birds translocated from Spain (n = 10) as well as Sardinia-born birds that were rehabilitated and released (n = 5). The Villasalto area was targeted for releasing Griffon Vultures for its historical significance as breeding site and, thus, its potential to again support a thriving colony. The released birds generally remained within a tightly restricted home range, with most birds exhibiting a strong attachment to their release area. Similarly to the behaviour of the old group, dispersal of the first release group was also relatively limited, with birds’ home ranges well established in Villasalto. For most of the monitoring period, their activity remained concentrated within a few kilometres of the release area and only rarely they ventured far from there (Figure 2a,b; Figure 4). Tracking data also confirmed that their foraging activity was concentrated within their home range around Villasalto (Figure 2c; Fozzi et al., 2025). In addition, GPS tracking showed that of the 15 birds released, 11 (66.7%) survived the first 6 months post-release, and of those, 10 (60%) survived to the end of their first year free ranging in Sardinia (Berlinguer et al., 2025). Only occasional exploratory mid-range flights were observed into nearby areas in the southwestern and central Sardinia, along with just a few long-range movements northward. Notably, however, none of these movements indicated any visit to the other colonies of Bosa and Punta Cristallo. This fidelity to the release area likely reflects the favourable conditions and attractiveness of Villasalto area for Griffon Vultures, including foraging opportunities and availability of safe roosting sites (Figure 2d). It also highlights the effects of long acclimatization in stabilizing home ranges (Fozzi et al., 2023) and synchrony in space use (Cerri et al., 2024) of released birds as they adapt to their new environment. 9 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna 1. Standardizing the Tracking Data Our analysis was based on high-quality GPS tracking data from 77 Griffon Vultures tagged in Sardinia during the LIFE Save for Vultures as well as during the preceding LIFE Under Griffon Wings project. Griffon Vultures were tagged at different times during these projects, with the first bird was tagged in December 2016, and movement data considered up until June 2025. Two different tag manufactures were used, Ecotone for the early-tagged birds, and Ornitela from 2018 (initially for some individuals and later for all vultures tagged under the LIFE Safe for Vulture). Prior to the analysis we standardized the tracking data, so that the tracks from different birds obtained throughout the years with different transmitter models, and working on different settings could be comparable. Tracking data was downloaded from the project LIFE_GriffonVultures_Sardinia (ID 1659758323) in Movebank (www.movebank.org), a global archive for animal movement data (Kays et al., 2022). First, we removed rows with empty or erroneous latitude or longitude. Second, we applied a land mask of Sardinia to remove impossible points falling on the Mediterranean Sea. Third, all tracks were truncated by day of release of each bird to the date of the end of the monitoring (e.g., birds died, tag loss, tag malfunction), and periods during which the birds were in rehabilitation were excluded as well. Fourth, all locations during nighttime were identified and removed from the main dataset and stored in a different file (see identification of roosts). This is standard procedure in vulture studies because only few points were obtained during the night (>1%), and to minimize the influence of the roost sites on home range estimation (Kane et al., 2022). Finally, all tracks were down sampled to an identical frequency of one location every 2 hours. To guarantee data quality to estimate home ranges with dynamic Brownian Bridge Movement Models (see below), for each bird, only months with at least 10 days of data were retained, and birds with fewer than 100 observations were excluded from the analysis. The standardization process resulted in tracks from 77 individual Griffon vultures available for movement analysis. (Figure 6). Methods 16 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Figure 6 Monitoring period of the 77 Griffon Vultures analysed, with birds grouped by release group and ordered by date of release. 17 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Bird name Origin Source Release area Release group Barca Spain Translocated Bosa Old group Bonalva Spain Translocated Bosa Old group Calmedia Spain Translocated Bosa Old group Caniga Spain Translocated Bosa Old group Cannisone Spain Translocated Bosa Old group Corte Spain Translocated Bosa Old group Cristallo Spain Translocated Bosa Old group Cuada Spain Translocated Bosa Old group Doglia Spain Translocated Bosa Old group Fenuggiu Spain Translocated Bosa Old group Idile Spain Translocated Bosa Old group Macomer Spain Translocated Bosa Old group Meilogu Spain Translocated Bosa Old group Monteleone Spain Translocated Bosa Old group Pabelanasa Spain Translocated Bosa Old group Pituabile Spain Translocated Bosa Old group Pozzomaggiore Spain Translocated Bosa Old group Tempestosa Spain Translocated Bosa Old group Timidone Spain Translocated Bosa Old group Tottubella Spain Translocated Bosa Old group Urincule Spain Translocated Bosa Old group Artis1 Netherlands Captive-bred Bosa Old group Artis3 Netherlands Captive-bred Bosa Old group Artis4 Netherlands Captive-bred Bosa Old group Artis5 Netherlands Captive-bred Bosa Old group Artis6 Netherlands Captive-bred Bosa Old group Artis7 Netherlands Captive-bred Bosa Old group Dresda1 Germany Captive-bred Bosa Old group Bonassai Sardinia Wild-born, Bosa Old group rehabilitated Calcassone Sardinia Wild-born, Bosa Old group rehabilitated Ciuffo Sardinia Wild-born, Bosa Old group rehabilitated Table 1 Details of the birds included in the analysis of movements 18 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Cristina Sardinia Wild-born, Bosa Old group rehabilitated Entulzu Sardinia Wild-born, Bosa Old group rehabilitated Hospiton Sardinia Wild-born, Bosa Old group rehabilitated Jana Sardinia Wild-born, Bosa Old group rehabilitated Julio Sardinia Wild-born, Bosa Old group rehabilitated Life Sardinia Wild-born, Bosa Old group rehabilitated Lobo Sardinia Wild-born, Bosa Old group rehabilitated Mina Sardinia Wild-born, Bosa Old group rehabilitated Armungia Spain Translocated Villasalto First release group Burcei Spain Translocated Villasalto First release group Gerrei Spain Translocated Villasalto First release group Quirra Spain Translocated Villasalto First release group SanPriamo Spain Translocated Villasalto First release group Sarrabus Spain Translocated Villasalto First release group Silius Spain Translocated Villasalto First release group Sinnai Spain Translocated Villasalto First release group Villasalto Spain Translocated Villasalto First release group Villasimius Spain Translocated Villasalto First release group Arriceli Sardinia Wild-born, Villasalto First release group rehabilitated Ballao Sardinia Wild-born, Villasalto First release group rehabilitated Cearomana Sardinia Wild-born, Villasalto First release group rehabilitated Sanandrea Sardinia Wild-born, Villasalto First release group rehabilitated Sannicolo Sardinia Wild-born, Villasalto First release group rehabilitated Arcilloni Spain Captive-bred Villasalto Second release group 19 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Brecca Spain Translocated Villasalto Second release group Cardiga Spain Translocated Villasalto Second release group Castiadas Spain Translocated Villasalto Second release group Colostrai Spain Translocated Villasalto Second release group Cordiolu Spain Translocated Villasalto Second release group Enzo Spain Translocated Villasalto Second release group Fraigada Spain Translocated Villasalto Second release group Ghirrau Spain Translocated Villasalto Second release group Gregorio Spain Translocated Villasalto Second release group Grupa Spain Translocated Villasalto Second release group Liuru Spain Translocated Villasalto Second release group Maracalagonis Spain Translocated Villasalto Second release group Marzana Spain Translocated Villasalto Second release group Pedrarba Spain Translocated Villasalto Second release group Perdas Spain Translocated Villasalto Second release group Senni Spain Translocated Villasalto Second release group Troccia Spain Translocated Villasalto Second release group Villaputzu Spain Translocated Villasalto Second release group Zinnicas Spain Translocated Villasalto Second release group Meriagus France Captive-bred Villasalto Second release group Carogna Sardinia Wild-born, Villasalto Second release group rehabilitated Esmeralda Sardinia Wild-born, Villasalto Second release group rehabilitated 2. Estimating utilization distributions and home ranges To estimate the utilization distribution of Griffon Vultures we fitted dynamic Brownian Bridge Movement Models (dBBMM; Kranstauber et al., 2012). dBBMMs handle well the temporal autocorrelation found in high-quality GPS tracking data and have been previously used to estimate the occurrence distributions of Griffon vultures in Sardinia (Cerri et al., 2023). Following Cerri eat al. (2023), we parametrized the dBBMMs as follows: GPS location error of 25 m, window size of 31 m, margin of 11 m, and 250 m resolution. One dBBMM was fitted to each individual-year combination, excluding data gaps longer than 5h. To account for differences in the time each bird was tracked per year, each individual-year dBBMM was weighted by the number of days with tracking data. Finally, to obtain the occurrence distribution of Griffon Vultures in Sardinia, we first summed the individual dBBMMs for each year. 20 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Then, the yearly distributions were combined by keeping the maximum value in each cell across years To visualize the Griffon Vultures’ home ranges, we used the 95% isopleth of the utilization distribution (i.e., 95% UD) to represent the home range (i.e., areas regularly used by the birds), the 75% UD to represent the mid-range (i.e., areas of intermediate use), and the 50% UD to represent the core range (i.e., areas where they spent most of their time). 3. Identifying feeding events To identify feeding events, we used accelerometer data recorded through the GPS tags. Previous behavioural observations of two captive and one wild Griffon Vultures allowed to distinguish and validate different behaviours (e.g., feeding, flapping, and soaring) of the GPS-monitored birds using triaxial accelerometer data (anterior–posterior, dorso–ventral, and lateral). Feeding events were manually annotated and used to train a Random Forest model, using summary statistics derived from the accelerometer data as model predictors (details in Fozzi et al., 2025). 4. Identifying roosts To map the roosts used by Griffon Vultures, we extracted all nighttime locations from all tagged individuals and, for each night, selected the location closest to midnight, ensuring that only one point was mapped per night. 5. Software All tracking data standardization, spatial analysis and mapping were conducted in R (R Core Team, 2025) using the packages move and move2 (Kranstauber et al., 2024a, 2024b), amt (Signer et al., 2019), and sf (Pebesma, 2018). All figures were produced with ggplot2 (Wickham, 2009) using the UTM zone 32N projection. 21 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Acácio, M., Gahm, K., Anglister, N., Vaadia, G., Hatzofe, O., Harel, R., Efrat, R., Nathan, R., Pinter-Wollman, N., & Spiegel, O. (2024). Behavioral plasticity shapes population aging patterns in a long-lived avian scavenger. Proceedings of the National Academy of Sciences, 121(35), e2407298121. https://doi.org/10.1073/pnas.2407298121 Berlinguer, F., Costantino, C., Fozzi, I., De Rosa, Cerri, J., Aresu, M., Secci, D., Chessa, R., Fantini, Manca, M., & Graziano, U. (2025). Feasibility study for the reintroduction of the Cinereous Vulture (Aegypius monachus) and the Bearded Vulture (Gypaetus barbatus) in Sardinia (ACTION E.6). LIFE Safe for Vultures (LIFE19NAT/IT/000732). BirdLife International (2021). Species factsheet: Griffon Vulture Gyps fulvus. [Accessed on 15/09/2025]:https://datazone.birdlife.org/species/factsheet/griffon-vulture-gyps-fulvus Cerri, J., Fozzi, I., Rosa, D. D., Aresu, M., Apollonio, M., & Berlinguer, F. (2023). Griffon Vulture movements are concentrated around roost and supplementary feeding stations: Implications for wind energy development on Mediterranean islands. Global Ecology and Conservation, 47, e02651. https://doi.org/10.1016/j.gecco.2023.e02651 Cerri, J., De Rosa, D., Aresu, M., Costantino, C., Fozzi, I., Banič, D., Brunet, C., Echeverria, J., Pavin, L., Muzzeddu, M., Secci, D., & Berlinguer, F. (2024). Acclimatisation affects synchrony in space use and the frequentation of multiple colonies in translocated Griffon Vultures (Gyps fulvus). https://doi.org/10.32942/X2TP67 Cerri, J., Fozzi, I., De Rosa, D., Costantino, C., Aresu, M., Secci, D., Muzzeddu, M., & Berlinguer, F. (2025). Weather conditions are systematically associated with long-range nonroutine movements in a large scavenger. EcoEvoRxiv Preprint. https://doi.org/10.32942/X20W77 Fozzi, I., Brogi, R., Cavazza, S., Chirichella, R., De Rosa, D., Aresu, M., Cerri, J., Apollonio, M., & Berlinguer, F. (2023). Insights on the best release strategy from post-release movements and mortality patterns in an avian scavenger. iScience, 26(5), 106699. https://doi.org/10.1016/j.isci.2023.106699 Fozzi, I., Cerri, J., Costantino, C., De Rosa, D., Aresu, M., Muzzeddu, M., Secci, D., & Berlinguer, F. (2025). Where do Gyps fulvus (Griffon Vulture) feed? Combining biologging with socioeconomic analysis can guide sustainable ecotourism development. Ornithological Applications, duaf042. https://doi.org/10.1093/ornithapp/duaf042 Kranstauber, B., Kays, R., LaPoint, S. D., Wikelski, M., & Safi, K. (2012). A dynamic Brownian bridge movement model to estimate utilization distributions for heterogeneous animal movement. Journal of Animal Ecology, 81(4), 738–746. https://doi.org/10.1111/j.1365-2656.2012.01955.x Kranstauber, B., Smolla, M., & Scharf, A. (2024a). move: Visualizing and Analyzing Animal Track Data. R package version 4.2.6, https://gitlab.com/bartk/move. References 22 Coordinating Beneficiary Università degli Studi di Sassari Via Vienna 2 | 07100, Sassari mail: lifefor[email protected] | tel: +39 079 229904 www.lifesafeforvultures.eu Associated Beneficiaries Agenzia Regionale Forestas Corpo Forestale e di Vigilanza Ambientale RAS E-distribuzione | Vulture Conservation Foundation With the contribution of the LIFE financialinstrument of the European Community Progetto LIFE19NAT/IT/000732 LIFE SAFE for VULTURES First step to the restoration of the vulture guild in Sardinia Primo passo verso il ripristino della gilda dei vulturidi in Sardegna Kranstauber, B., Safi, K., & Scharf, A. K. (2024b). move2: R package for processing movement data. Methods in Ecology and Evolution, 15(9), 1561–1567. https://doi.org/10.1111/2041-210X.14383 Kane, A., Monadjem, A., Aschenborn, H. K. O., Bildstein, K., Botha, A., Bracebridge, C., Buechley, E. R., Buij, R., Davies, J. P., Diekmann, M., Downs, C. T., Farwig, N., Galligan, T., Kaltenecker, G., Kelly, C., Kemp, R., Kolberg, H., MacKenzie, M. L., Mendelsohn, J., … Kendall, C. J. (2022). Understanding continent-wide variation in vulture ranging behavior to assess feasibility of Vulture Safe Zones in Africa: Challenges and possibilities. Biological Conservation, 268, 109516. https://doi.org/10.1016/j.biocon.2022.109516 Kays, R., Davidson, S. C., Berger, M., Bohrer, G., Fiedler, W., Flack, A., Hirt, J., Hahn, C., Gauggel, D., Russell, B., et al. (2022). The Movebank system for studying global animal movement and demography. Methods in Ecology and Evolution 13(2):419-431. https://doi.org/10.1111/2041-210X.13767 Life Under Griffon Wings (2020). Monitoring the functioning of the feeding stations – Action D.4. Progetto Life Under Griffon Wings (LIFE14/NAT/IT/000484). http://www.lifeundergriffonwings.eu/export/sites/default/.galleries/doc-notizie/Azione-D4_report-2020.pdf Monti, F., Serroni, P., Rotondaro, F., Sangiuliano, A., Sforzi, A., Opramolla, G., Pascazi, A., Spacca, S., La Civita, F., & Posillico, M. (2023). Survival of a small reintroduced griffon vulture population in the Apennines: Insights from Global Positioning System tracking. Avian Biology Research, 16(1), 3–13. https://doi.org/10.1177/17581559221137309 Sarrazin, F., Bagnolini, C., Pinna, J. L., Danchin, E., & Clobert, J. (1994). High Survival Estimates of Griffon Vultures (Gyps Fulvus Fulvus) in a Reintroduced Population. The Auk, 111(4), 853–862. https://doi.org/10.2307/4088817 Secci, D., Ballocco, C., & Tronci, P. P. (Coords.) (2021). Studio di fattibilità per il restocking del Grifone (Gyps fulvus) nel settore sud-orientale della Sardegna – Action A3. LIFE Safe for Vultures. https://www.lifesafeforvultures.eu/report/studio-di-fattibilita-per-il-restocking-del-grifone-gyps-fulvus-nel-settore-sud-orientale-della-sardegna.pdf Schenk, H., Aresu, M., & Naitana, S. (2008). Proposta di un Piano d’Azione per il Grifone (Gyps fulvus) in Sardegna. Legambiente Sardegna. Schenk, H. & Aresu, M. (1992). Il ripopolamento del Grifone (Gyps fulvus) nella Sardegna Nord-Occidentale: risultati, problemi e prospettive. Att. IV Conv. Sic. Ecologia: 159-184. Siracusa. Signer, J., Fieberg, J., & Avgar, T. (2019). Animal movement tools (amt): R package for managing tracking data and conducting habitat selection analyses. Ecology and Evolution, 9(2), 880–890. https://doi.org/10.1002/ece3.4823 23 LIFE19/NAT/IT/000732 Life Safe for Vultures First step to the restoration of the vulture guild in Sardinia Coordinating Beneficiary Università degli Studi di Sassari | Via Vienna 2 | 07100, Sassari | mail: lifeforvultur[email protected] | tel: +39 079 229904 Associated BeneficiariesCommunity www.lifesafeforvultures.eu With the contribution of the LIFE financial instrument of the European Community