Supplementary feeding stations are widely used in vulture conservation to support breeding success and reduce mortality [1]. However, most evaluations of supplementary feeding have focused on survival rates, productivity, or population size, whereas explicit quantification of nest-site occupancy responses remains comparatively limited, particularly in arid ecosystems of the Arabian Peninsula. Although Griffon Vulture Gyps fulvus is globally classified as Least Concern, its regional status varies considerably, and the species remains of conservation concern in parts of the Arabian Peninsula. In Saudi Arabia, the Griffon Vulture has been described as threatened by poisoning, electrocution, disturbance, and changes in access to food resources [2][3]. Breeding has been documented across several regions of Saudi Arabia, including the south-western mountains and northern rocky landscapes [3]-[7]. Within the Hibran area in north-western Hail, part of the King Salman Bin Abdulaziz Royal Natural Reserve (KSRNR), a breeding colony with 22 suspected active nests has recently been documented [8].

In arid landscapes, food limitation for vultures may not necessarily reflect a shortage of carrion alone. Access to safe and predictable carrion may also be reduced by carcass-disposal practices, including burial, disposal in pits, removal from open areas, or exposure to poisoned or contaminated carcasses. In Saudi Arabia, poisoning and inappropriate carcass disposal have been identified as important threats to vultures [3][9]. Therefore, feeding stations using veterinary-screened carcasses may provide a practical conservation tool for improving access to safe carrion. Despite these recent observations, published assessments of temporal changes in Griffon Vulture nest occupancy following targeted management interventions remain limited in Saudi Arabia.

This study aimed to evaluate nest occupancy responses of Griffon Vultures to a supplementary feeding programme implemented during the breeding period in northern Saudi Arabia. Using repeated surveys of fixed nesting sites conducted before and after feeding activation, temporal changes in occupancy were quantified, and spatial differences among zones with differing levels of exposure to supplementary feeding were assessed. This appears to be the first published assessment of temporal changes in Griffon Vulture nest occupancy in Saudi Arabia using a repeated-site before-and-after framework. Higher occupancy and increased use of nesting cliffs were expected following feeding activation, particularly in areas closer to feeding stations.

All occupancy analyses were based on the 57 fixed cliff sites surveyed in both 2024 and 2025. Within these fixed cliff sites, 32 active Griffon Vulture nests were recorded in 2024, and 43 active nests were recorded in 2025. In addition, 39 active nests were documented at additional cliffs outside the fixed-site occupancy analysis in 2025, bringing the total number of active nests recorded across the wider survey area to 82. These additional nest records are reported descriptively and were not included in the statistical occupancy analyses.

In 2024, before feeding-station activation, 32 of the 57 fixed cliff sites were occupied, corresponding to an occupancy rate of 56.1%. Occupancy varied among zones: five of 15 sites were occupied in Zone 1 (Alnafs), ten of 19 in Zone 2 (Hibran), and 17 of 23 in Zone 3 (Arnan). Thus, Zone 3 had the highest baseline occupancy before supplementary feeding began. Cliff sites in Zone 3 were more likely to be occupied than those in Zones 1 and 2 combined (OR = 3.59, 95% CI: 1.14 - 11.31; Fisher’s exact test, p = 0.032).

In 2025, after feeding-station activation, 43 of the same 57 fixed cliff sites were occupied, corresponding to an occupancy rate of 75.4%. Between 2024 and 2025, 14 previously unoccupied sites became occupied, whereas three previously occupied sites became inactive. This represented a significant increase in cliff-site occupancy between years (McNemar’s test, χ² = 7.12, p = 0.008). In 2025, occupancy remained highest in Zone 3, where cliff sites were more likely to be occupied than those in Zones 1 and 2 combined (OR = 13.62, 95% CI: 3.33 - 55.90; Fisher’s exact test, p = 0.002).

The present study documented an increase in cliff-site occupancy of Griffon Vultures following the activation of supplementary feeding stations within KSRNR. Occupancy at fixed cliff sites increased from 56.1% in 2024 to 75.4% in 2025, with colonization of previously unoccupied sites exceeding losses. The increase was also spatially uneven, with the highest occupancy recorded in Zone 3, where feeding-station use was greatest. This zone-level contrast was used to quantify the magnitude of spatial variation in occupancy between Zone 3 and Zones 1 - 2 combined. It should not be interpreted as a pre-defined experimental treatment effect. However, Zone 3 also had the highest baseline occupancy before supplementary feeding began, indicating that spatial differences may reflect feeding-station exposure as well as underlying differences in habitat suitability, historical breeding density or other local factors. The repeated-site before-and-after framework provides evidence of temporal change at the same cliff sites, but the absence of an independent unfed control area means that the observed increase cannot be attributed solely to supplementary feeding. These results represent apparent cliff-site occupancy rather than detection-corrected occupancy, because each cliff site was surveyed during a single seasonal visit each year. Although comparable timing, fixed vantage points, repeated scanning, and selective drone confirmation were used to reduce false absences, some risk of imperfect detection remains. Similar associations between supplementary feeding and improved breeding parameters have been reported in several European populations of Gyps vultures [16]-[19]. However, quantitative assessments of nest-site occupancy remain limited, particularly in arid ecosystems [15][20].

The recording of 82 active Griffon Vulture nests within the study area in 2025 highlights the importance of KSRNR as a breeding area for the species in northern Saudi Arabia. This total included 39 active nests documented at additional cliffs that were not included in the fixed-site occupancy analysis. Although these additional nest records may reflect improved knowledge of the study area, interannual variation, or redistribution of birds within the local population, they also indicate substantial breeding activity beyond the original fixed-site sample. Comparable changes in breeding distribution have been documented in regions where food availability increased through management interventions or changes in livestock practices [21][22]. Continued multi-year monitoring will be required to determine whether the pattern recorded in 2025 reflects sustained demographic growth or short-term redistribution. Nevertheless, the 2025 nest total indicates that the KSRNR colony has national conservation relevance.

The findings should be interpreted in the context of access to safe carrion rather than food availability alone. In arid landscapes, vultures may occur in areas where livestock and potential carrion resources are present, but carcass-disposal practices, burial, removal from open areas, or exposure to poisoned or contaminated carcasses may reduce the availability of safe and predictable food [3][9]. The use of veterinary-screened carcasses at feeding stations may therefore have provided a safer and more predictable resource during the study period, consistent with the role of feeding stations in reducing exposure to unsafe carcasses [12][23]. This interpretation is consistent with the potential value of supplementary feeding as a targeted management tool, provided that feeding stations are carefully regulated, monitored, and integrated with wider measures to reduce poisoning and inappropriate carcass disposal [9][24].

Camera-trap records of marked Griffon Vultures bearing leg rings and wing tags indicate that some individuals using the feeding station originated from outside the immediate study area. This suggests possible connectivity among breeding or foraging areas in the region, although movement was not directly quantified. Supplementary feeding can influence spatial aggregation and movement patterns in wide-ranging scavengers [14][25].

The incidental records of Cinereous Vulture, Lappet-faced Vulture, and Egyptian Vulture at the Arnan feeding station show that supplementary feeding stations can attract additional scavenger species of conservation concern in KSRNR. These observations are consistent with the broader role of feeding stations in supporting scavenger assemblages when they are carefully managed and monitored [24]. However, because these records were incidental and species-specific responses were not quantified, they should not be interpreted as evidence of population-level benefits for other scavenger species. Based on available published literature, the Egyptian Vulture breeding records also appear to represent the first documented nesting evidence for the Hail region, highlighting the value of targeted follow-up surveys for this species in northern Saudi Arabia [4][7][9].

The main limitation of this study is that it covered one pre-feeding and one post-feeding breeding season. Although the repeated-site before-and-after framework allowed temporal changes in cliff-site occupancy to be assessed at the same sites, reproductive success, survival, and individual movements were not directly measured. Future monitoring should therefore include breeding success, chick survival, adult survival, and movements of marked or GPS-tagged individuals. Such monitoring will be necessary to determine whether the observed increase in occupancy reflects sustained demographic growth, improved settlement within KSRNR or short-term redistribution within the regional population.

From a management perspective, the findings support the careful and adaptive use of regulated supplementary feeding in KSRNR, provided that provisioning remains linked to veterinary screening, carcass safety, and long-term monitoring.

This study documented an increase in apparent cliff-site occupancy of Griffon Vultures within KSRNR following the activation of supplementary feeding stations during the breeding period. Occupancy at the same 57 fixed cliff sites increased from 56.1% to 75.4%, with colonization of previously unoccupied sites exceeding local losses. The highest post-activation occupancy was recorded in Zone 3, where feeding-station use was greatest, although this zone also had the highest baseline occupancy before feeding began.

Across the wider survey area, 82 active nests were recorded in 2025, highlighting the importance of KSRNR as a breeding area for Griffon Vultures in northern Saudi Arabia. Records of additional vulture species at feeding stations and Egyptian Vulture breeding evidence also indicate the wider ecological relevance of the reserve for scavenger conservation. Because the study used a before-and-after design without an independent unfed control area, the observed patterns should be interpreted cautiously. Continued multi-year monitoring will be needed to determine whether the observed increase reflects sustained population growth, improved settlement within KSRNR, or short-term redistribution.

Field surveys and research activities were approved by the King Salman Bin Abdulaziz Royal Natural Reserve Development Authority under ethical approval number 02144707110422. The authors thank Dr Mohammed Shobrak for his valuable comments and insights relevant to this study. We also thank Abdullah Alsubhi for kindly providing the Egyptian Vulture nest photograph used in this manuscript.