New insight into spatial ecology of Griffon Vulture (Gyps fulvus) on the Balkans provides opportunity for focusing conservation actions for a threatened social scavenger

Abstract

The knowledge in the behaviour and movement of endangered species is of key importance for the precise targeting and assessing the efficiency of nature conservation actions, especially considering vultures, which explore vast areas to locate ephemeral and unpredictable food resources. Therefore, a total of 51 Griffon Vultures (Gyps fulvus) from both the re-introduced population and the autochthonous Balkan Peninsula (Balkans) colonies have been tagged with GPS/GSM transmitters in recent years, in order to study their seasonal and spatial distribution. The current study presents the analysis of the high-resolution GPS location data, acquired between January 2016 and March 2021. A total of 1,138,383 locations (an average number of 23,716 ± 18,886 positions per bird, ranged between 2,515 and 76,431 of total fixes per bird; n=48) were used to estimate the home range size and identify the traditional foraging areas and roosting sites of the birds during the wintering, migration/roaming and summering periods. Our results reveal that Griffon Vultures movement activity and home range size varied considerably throughout the annual cycle, especially between their wintering and summering grounds, while exhibiting significant overlapping amongst the tracked individuals. Specifically, immature Griffon Vultures travel long distances across all Balkan Peninsula countries, but always gather with conspecifics, showing strong fidelity to active breeding/roosting sites. The total home range 95% area of the Griffon Vulture population on the Balkans was estimated at 39,986.4 km² and the 50% core area at 1,545.42 km² (n = 48). All tracked birds were found to either visit or frequently use (> 95% of the time) the same seven vulture key zones on the Balkan Peninsula – one in Serbia, one shared between North Macedonia and Bulgaria, one shared between Bulgaria and Greece, two entirely lying in Bulgaria, one in western Greece and one shared between Kvarner Archipelago islands in Croatia and the Julian Alps - Italy, Austria and Slovenia. Several smaller sub-zones were also defined within these general ones. The seven key zones form a coherent network and are used as stepping stones for Griffon Vultures during their migration movements and roaming, but also wintering and summering. The observed concentration tendency of Griffon Vultures on the Balkans and the predictability of their temporal and spatial presence should be used to precisely target, address and substantially increase the efficiency of the conservation measures in this marginal and, thus, still vulnerable meta-population.

Hidden effects of high numbers of tourists in protected areas: displacement of foraging top scavengers

“…Individual Griffon Vultures forage over huge home‐ranges (Peshev et al . 2021 and references therein), which in our study case are close to 10 000 km 2 (Arrondo et al . 2020).…”

Sex ratio and relatedness in the Griffon vulture (Gyps fulvus) population of Serbia

“…Breeding parameters in the Serbian Griffon vulture population are relatively high despite the substantial increase in population size, implying that the population is far from its saturation level ( Marinkovic et al, 2021 ) further strengthening this population prospect as a reintroduction resource in the Balkan Peninsula ( Davidovic et al, 2020 , 2022 ). The latest research on the spatial ecology of Griffon vultures in the Balkans identified seven key vulture zones (one in Serbia, one shared between North Macedonia and Bulgaria, one shared between Bulgaria and Greece, two in Bulgaria, one in western Greece and one shared between Kvarner Archipelago islands in Croatia and the Julian Alps—Italy, Austria and Slovenia) ( Peshev et al, 2021 ). This research also identified that the young birds tend to migrate but always return to their nesting ground after migration due to the strong natal philopatry specific for this species and so far no or little exchange of migrant birds between these vulture zones in the Balkans was detected ( Peshev et al, 2021 ).…”

abmAnimalMovement: An R package for simulating animal movement using an agent-based model

“…Again similar to badgers we would expect seasonal shifts in the form of an increase and decrease in activity depending on the time of year. [95][96][97]101 We can broadly summarise the vulture ecology we want to parametrise as follows:…”

“…Movement speed approximated by summary statistics from previous studies, [95][96][97][98] with minimal landscape derived resistance 3. A 8-12 hour activity cycle, 100 that shifts over the year 95,96,101 Figure 11. The three resulting landscape layers to be fed into the simulation for the vulture example: shelter quality, foraging resources, movement ease.…”