Vultures are among the most threatened avian taxa in the world. When vultures aggregate in large numbers to feed, poisoned carcasses can extirpate entire populations at once. In the light of shrinking numbers worldwide, restocking and reintroduction projects, where wild or captive-bred vultures are released back into nature, constitute a crucial management tool, successfully implemented in many countries. However, reestablishment of sustainable vulture populations to their historical ranges remains a serious challenge, especially if the threat of poisoning persists, which is usually the case. In this study, we model the outcome of a restocking project where an initial colony is subject to repeated poisoning events. We use as an example the isolated population of the griffon vulture (Gyps fulvus) in Cyprus. Mathematical considerations and model simulations show that the probability of colony persistence depends on the initial population size and the intensity and frequency of the poisoning incidents. This type of scenario creates an Allee effect that requires a colony to exceed a minimum size in order to survive. Also in this scenario, a sequence of small but frequent poisoning episodes is worse on average than a few large and rare ones of the same cumulative mortality. Future population reinforcement efforts for vultures should focus on the release of adult birds in adequate numbers for the successful establishment of sustainable colonies and should involve a reduction in small but persistent sources of mortality such as the poison baiting of small canids that until now has been neglected by conservation scientists.

中文翻译：

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对秃鹰种群的中毒影响模型表明，小而频繁的事件比大而罕见的事件具有更大的影响

秃鹫是世界上受威胁最严重的鸟类类群之一。当秃鹫大量聚集觅食时，中毒的尸体可以立即消灭整个种群。鉴于世界范围内的数量不断减少，重新放养和重新引入野生或人工饲养的秃鹫项目，成为一种重要的管理工具，并在许多国家成功实施。然而，将可持续的秃鹰种群重新建立到其历史范围仍然是一个严峻的挑战，尤其是在中毒威胁持续存在的情况下，这通常是这种情况。在这项研究中，我们模拟了一个重新放养项目的结果，在该项目中，最初的殖民地会受到反复中毒事件的影响。我们以狮鹫（Gyps fulvus）的孤立种群为例) 在塞浦路斯。数学考虑和模型模拟表明，菌落持续存在的概率取决于初始种群规模以及中毒事件的强度和频率。这种类型的场景会产生 Allee 效应，需要殖民地超过最小规模才能生存。同样在这种情况下，一系列小而频繁的中毒事件平均比具有相同累积死亡率的少数大而罕见的中毒事件更糟。未来的秃鹫种群强化工作应侧重于释放足够数量的成年鸟类以成功建立可持续的群体，并应包括减少小而持久的死亡来源，例如迄今为止一直被忽视的小型犬科动物的毒饵保护科学家。