1. The mesopredator release hypothesis, defined as the change in distribution, abundance or behaviour of a middle‐ranking predator in response to a decrease in density or distribution of an apex predator, is an increasingly popular topic in ecology. Terrestrial mesopredators have been reported as being released in multiple systems globally, particularly in North America, over the past century.
2. We reviewed 2687 scientific articles, of which we determined that 38 met our criteria for investigating mesopredator release (MR) in terrestrial North American mammalian predators.
3. We observed no support or mixed support for MR in 46% of all relevant studies, including conflicting evidence between measures (mesopredator distribution, abundance or behaviour) within a given study and among studies of the same community in different settings.
4. To advance the study of MR, we provide a conceptual framework that 1) highlights the multiple spatial, temporal and ecological scales at which mesopredator responses can occur; 2) suggests the relative weight of evidence for MR that is provided by measures of mesopredator responses at each scale; and 3) clearly defines the threshold for determining when MR is occurring.
5. In increasingly reshuffled predator communities with declining apex predators, there is a need for future studies to assess in more detail the contexts in which mesopredator behavioural responses scale up to the population‐level processes and species‐level distribution changes needed to identify these responses as MR.

中文翻译：

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识别中捕食者在多捕食者系统中的释放：来自北美的证据回顾

1. 中繁殖者释放假说是生态学中日益流行的话题，该假说被定义为中等数量捕食者响应于尖顶捕食者密度或分布的减少而发生的分布，丰度或行为变化。据报道，在过去的一个世纪中，全球范围内，特别是在北美，陆生中子繁殖体被释放到多个系统中。
2. 我们审查了2687篇科学文章，确定其中38篇符合我们调查北美陆生哺乳动物捕食者中速释放（MR）的标准。
3. 我们在46％的所有相关研究中均未观察到对MR的支持或混合支持，包括在给定研究中的措施（中指分布，丰度或行为）之间以及在不同环境中同一社区的研究之间证据相互矛盾。
4. 为了推进MR的研究，我们提供了一个概念框架，即：1）突出了中指响应可能发生的多个空间，时间和生态尺度；2）提出了由各个等级的中指反应所提供的MR证据的相对权重；3）明确定义了确定MR何时发生的阈值。
5. 在前掠食者数量减少的改组捕食者社区中，有必要进行进一步的研究，以更详细地评估中性捕食者行为反应扩大到种群水平过程和物种水平分布变化的背景，以将这些反应识别为MR 。