Various avian species give mobbing calls that draw conspecific and heterospecific individuals to react against the potential predator. According to the ‘attract the mightier’ hypothesis, when predators appear, prey will produce mobbing calls to attract superior predators to repel or kill the primary predator. To test this hypothesis, we broadcast calls from light-vented bulbuls, Pycnonotus sinensis (the prey) in the vicinity of a taxidermy model of a collared scops owl, Otus lettia (the primary predator). Three call types were used: the typical call (TC, the control treatment), a mobbing call to a collared scops owl (the MtO treatment) and a mobbing call to a crested goshawk, Accipiter trivirgatus (the superior predator; the MtH treatment). Our results showed that crested goshawks appeared and attacked the taxidermy model during the MtO treatment, but not during the control or MtH treatment. The difference between the MtO and other treatments was significant. Our results, therefore, provide strong evidence for the hypothesis that mobbing calls to primary predators can successfully attract superior predators to harm primary predators.

中文翻译：

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鸟类围攻的功能：“吸引更强大”假设的实验检验

各种鸟类发出围攻呼叫，吸引同种和异种个体对潜在的捕食者做出反应。根据“吸引更强大”的假说，当捕食者出现时，猎物会发出群聚叫声，以吸引上等捕食者击退或杀死主要捕食者。为了验证这一假设，我们广播了来自位于有颈鸮 Otus lettia（主要捕食者）的动物标本剥制模型附近的光口鹎（Pycnonotus sinensis）（猎物）的呼叫。使用了三种呼叫类型：典型呼叫（TC，控制处理），对有领角鸮的围攻呼叫（MtO 处理）和对凤头苍鹰的围攻呼叫，Accipiter trivirgatus（高级捕食者；MtH 处理） . 我们的结果表明，在 MtO 处理过程中，凤头苍鹰出现并攻击动物标本剥制模型，但不是在控制或 MtH 治疗期间。MtO 和其他处理之间的差异是显着的。因此，我们的研究结果为以下假设提供了强有力的证据，即对初级捕食者的围攻可以成功吸引高级捕食者来伤害初级捕食者。