SummaryAlthough the population of Griffon Vulture Gyps fulvus is significantly increasing in Europe, in Italy the species is still on the Red List as ‘Critically Endangered’, with the last natural population persisting on the island of Sardinia. Several episodes of poisoning hampered the success of conservation actions implemented in the years 1987–1995. In 2005 there were estimated to be only 31–32 territorial pairs, with the population occupying the territories of Alghero and Bosa. We used a long-term dataset of reproductive records from the Sardinian Griffon Vulture populations to run a population viability analysis (PVA) to evaluate the extinction risk using the Vortex simulation software. The model estimated the probability of extinction over the next five generations (estimated generation time: 11 years, simulation time used: 55 years) as 96.4% for the Alghero population, and near-zero for the Bosa population. We used sensitivity analyses to understand how uncertainty about parameter values affect model outcomes. Population projections were evaluated under different management scenarios tackling the main threats (poisoning and human disturbance) and implementing conservation actions (supplementary feeding and restocking). Our results showed that population size is a critical factor in affecting the projections of population dynamics of Griffon Vultures. Sensitivity analyses highlighted the importance of poisoning events to population persistence and showed that juvenile and adult mortality rates had a secondary impact on population viability. The only conservation measure effective in significantly increasing stochastic growth rates in the Alghero population, whose initial population was set at five individuals, was the complete removal of poisoning events. When targeting the Bosa population (initial population size 94 individuals), supplementary feeding, mitigation of the risk of poisoning episodes, restocking, and mitigation of human disturbance in the reproductive sites significantly increased stochastic growth rate. A cost-effectiveness analysis should be performed to prioritise interventions.

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评估不同管理方案对小岛秃鹫种群保护的影响

摘要虽然秃鹫的种群黄花菜在欧洲显着增加，在意大利，该物种仍在红色名录中为“极度濒危”，最后的自然种群仍然存在于撒丁岛。几起中毒事件阻碍了 1987-1995 年实施的保护行动的成功。2005 年估计只有 31-32 对领土，人口占据阿尔盖罗和博萨的领土。我们使用来自撒丁岛格里芬秃鹫种群的长期繁殖记录数据集进行种群生存力分析 (PVA)，以使用 Vortex 模拟软件评估灭绝风险。该模型估计阿尔盖罗人口在未来五代（估计世代时间：11 年，使用的模拟时间：55 年）灭绝的概率为 96.4%，博萨人口接近于零。我们使用敏感性分析来了解参数值的不确定性如何影响模型结果。在解决主要威胁（中毒和人为干扰）和实施保护行动（补充喂养和重新放养）的不同管理方案下评估人口预测。我们的研究结果表明，种群规模是影响秃鹫种群动态预测的关键因素。敏感性分析强调了中毒事件对种群持久性的重要性，并表明青少年和成人死亡率对种群生存能力有次要影响。唯一有效地显着提高阿尔盖罗人口随机增长率的保护措施，其初始人口设定为五个人，是彻底消除中毒事件。当针对 Bosa 种群（初始种群规模 94 个人）时，补充喂养、降低中毒事件的风险、补货和减轻生殖部位的人为干扰显着提高了随机增长率。应进行成本效益分析以确定干预措施的优先顺序。