<b>Using animal tracking for early detection of mass poisoning events</b>

1 Amidst the sixth mass extinction, some animal groups, such as vultures, the only obligate scavengers among vertebrates, are disappearing at an unprecedented rate. Vulture populations worldwide are declining, primarily due to poisoning. As many vulture species are social foragers, they can congregate in large numbers to scavenge at a carcass, potentially increasing their exposure to poisoning risk. Current anti-poisoning prevention and mitigation measures are insufficient to tackle this threat. There is an urgent need for new effective strategies to prevent mass vulture mortality. 2 In this study, we applied agent-based modelling using white-backed vulture (Gyps africanus) data from Namibia to: (1) quantify the impact of different foraging strategies on vulture poisoning risk, and (2) evaluate the cost-effectiveness of using vultures as sentinels for poisoning detection. This approach involves GPS tracking of various numbers of vultures and using the data to quickly detect poisoning incidents and decontaminate carcasses. These actions help mitigate further vulture mortality and prevent mass poisoning. 3 Our findings demonstrate that social foraging significantly increases the risk of poisoning among white-backed vultures. However, GPS tracking of individual vultures enables earlier detection of poisoning events, thereby reducing associated mortalities. Poisoning mitigation effectiveness improves with both the number of tracked individuals and the speed of decontamination response. According to our agent-based model tailored to our study system and species, tracking approximately 5% of the population (25 individuals) offers a good balance between cost and effectiveness, requiring an estimated budget of USD 60,000. Using this strategy and approach, and assuming a response time within two hours, up to 45% of poisoning-related deaths could be prevented. 4 Synthesis and applications: Our results suggest that, in order to reduce mortality incidences from poisoning in our study system and species, it is sufficient to track a small proportion of the vulture population, which would act as sentinels for the rest. By evaluating the costs and ecological benefits of alternative strategies, varying in number of birds tagged or response time, we provide evidence-based solutions that practitioners can use to design conservation plans. These findings are therefore instrumental in supporting vulture and scavenger conservation policy and practice.1 在第六次生物大灭绝的背景下，部分动物类群正以前所未有的速度消失，其中就包括脊椎动物中唯一专性食腐动物（obligate scavengers）秃鹫。全球秃鹫种群数量持续下降，其主要诱因是中毒事件。由于多数秃鹫物种为社群觅食者（social foragers），它们会聚集在一具动物尸体上大规模取食，这会提升其接触有毒物质的风险。当前的中毒预防与缓解措施不足以应对这一威胁，因此亟需开发新型有效策略以遏制秃鹫大规模死亡事件的发生。 2 本研究基于纳米比亚的白背秃鹫（white-backed vulture, Gyps africanus）数据开展基于智能体的建模（agent-based modelling），旨在达成两个目标：(1) 量化不同觅食策略对秃鹫中毒风险的影响；(2) 评估将秃鹫作为中毒检测哨兵（sentinels）的成本效益。该方法通过对不同数量的秃鹫进行GPS跟踪（GPS tracking），并利用获取的监测数据快速识别中毒事件并对受污染尸体进行净化处理，以此减少后续秃鹫的死亡并避免大规模中毒事件的发生。 3 研究结果显示，社群觅食行为会显著提升白背秃鹫的中毒风险。但对单只秃鹫进行GPS跟踪，能够更早地发现中毒事件，从而降低相关死亡数量。中毒缓解的效果会随着跟踪个体数量的增加以及尸体净化响应速度的提升而增强。针对本研究对象与物种定制的基于智能体的模型表明，跟踪种群中约5%的个体（即25只秃鹫）能在成本与效益间实现良好平衡，预估所需预算为60000美元。若采用该策略并将响应时间控制在2小时以内，最多可避免45%的中毒相关死亡事件。 4 综合与应用：研究结果表明，在本研究的对象与物种体系中，只需跟踪少量秃鹫个体作为其余种群的哨兵，即可有效降低中毒引发的死亡事件。本研究通过评估不同标记个体数量与响应时间的替代策略的成本与生态效益，为保护从业者制定保护计划提供了循证解决方案。因此，本研究结果可为秃鹫与食腐动物的保护政策与实践提供有力支撑。