Reinvasion of pest animals after incomplete control is a major challenge for invasive species management, yet little is known about the behavioural and demographic categories of reinvaders or the mechanisms that drive population‐level responses to control. To understand the fine‐scale mechanisms of reinvasion, we examined changes in demography, movements and activity patterns of reinvading alien black rats Rattus rattus in the short (4 weeks) and longer term (3 months) following localised experimental pest removal. Using recovery and invasion theory, we tested three hypothesised mechanisms of reinvasion: the ‘in situ effect’, the ‘trickle effect’ and the ‘vacuum effect’. We created space for reinvasion by removing black rats from the core of replicate 1‐ha plots (short‐term experiment) and later by removing animals from the entire plot (longer‐term experiment). Reinvaders were characterised as dispersing juveniles, floaters or neighbours. Radio‐tracking quantified home range changes for adjacent resident animals (short‐term experiment only). In the short term, there was no net influx of rats after targeted removal. Radio‐tracked residents’ movements were highly variable and displayed no directional changes after nearby conspecifics were removed. However, in the longer term, removal led to slow population recovery through a mix of reinvading floaters, dispersing juveniles and shifting residents. These responses best support a hypothesis of reinvasion through a trickle effect, with rats being extremely mobile and having a high degree of population turnover, even in untreated sites. Our findings provide the first test of reinvasion theory at a small scale, demonstrating the importance of understanding the differing categories of reinvaders and mechanisms of reinvasion after population control. These mechanisms drive the rate of population recovery and, in turn, should help determine which strategy of pest control should be used, and the frequency with which they are implemented, in order to slow the recovery of pest populations.

中文翻译：

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外来黑鼠的种群恢复 大鼠 : 再入侵理论的检验

不完全控制后有害动物的重新入侵是入侵物种管理的主要挑战，但对重新入侵者的行为和人口类别或推动种群水平响应控制的机制知之甚少。为了了解重新入侵的精细尺度机制，我们检查了在局部实验性害虫清除后短期（4 周）和长期（3 个月）重新入侵外来黑鼠 Rattus rattus 的人口统计学、运动和活动模式的变化。使用恢复和入侵理论，我们测试了三种假设的再入侵机制：“原位效应”、“涓流效应”和“真空效应”。我们通过从重复的 1 公顷地块（短期实验）的核心中移除黑鼠，然后从整个地块中移除动物（长期实验），为再次入侵创造了空间。Reinvaders 的特点是驱散幼鱼、漂浮物或邻居。无线电跟踪量化了邻近动物的家庭范围变化（仅限短期实验）。短期内，靶向清除后无大鼠净流入。无线电跟踪居民的运动变化很大，并且在附近的同种被移除后没有显示出方向变化。然而，从长远来看，迁移导致漂浮物重新入侵、幼鱼驱散和居民迁移，导致种群恢复缓慢。这些反应最好地支持了通过涓流效应重新入侵的假设，即使在未经处理的地方，老鼠也具有极强的移动性和高度的人口流动性。我们的研究结果提供了小规模再入侵理论的首次检验，证明了理解不同类别的再入侵者和人口控制后再入侵机制的重要性。这些机制推动了种群恢复的速度，反过来，应该有助于确定应使用哪种害虫控制策略，以及它们实施的频率，以减缓害虫种群的恢复。