Abstract The selective pressure exerted by avian brood parasites forces their hosts to evolve specific defense strategies. When subject to brood parasite attack, avian hosts will often emit alarm calls. To date, few studies have examined whether and how host responses to different alarm calls indicative of different enemies vary with the host’s breeding stage. We carried out alarm call playback experiments during both the egg and nestling stages of the oriental reed warbler Acrocephalus orientalis, a host of the common cuckoo Cuculus canorus. The playback exemplars were selected from recorded alarm calls of the warbler to the presence of common cuckoos, sparrowhawks Accipiter nisus, and oriental turtle doves Streptopelia orientalis, which represented brood parasite, predator, and harmless control, respectively. The results showed that the oriental reed warblers did not discriminate alarm calls issued to different intruder types, but the intensity of the response was significantly higher in the nestling stage than in the egg stage. Attack behavior related to sparrowhawk alarm calls was absent in the egg stage, but aggressive behavior increased dramatically and exceeded the attack frequency in response to the cuckoo alarm call in the nestling stage, implying a shift in the tradeoff between the parents’ own survival and the loss of offspring. Alarm calls attracted a larger number of conspecifics than members of other species. In general, the oriental reed warbler had consistently stronger responses to different alarm calls in the nestling stage than in the egg stage, supporting the offspring value hypothesis.

中文翻译：

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杜鹃宿主根据繁殖阶段对不同警报信号的具体反应：后代价值假设的检验


摘要 禽类寄生虫施加的选择压力迫使其宿主进化出特定的防御策略。当受到巢寄生虫攻击时，鸟类宿主常常会发出警报声。迄今为止，很少有研究探讨宿主对指示不同天敌的不同警报呼叫的反应是否以及如何随着宿主的繁殖阶段而变化。我们在东方芦苇莺 Acrocephalus orientalis（常见杜鹃 Cuculus canorus 的宿主）的卵和雏鸟阶段进行了警报叫声回放实验。回放样本选自记录的莺鸣声、杜鹃、雀鹰 Accipiter nisus 和东方斑鸠 Streptopelia orientalis 的存在，分别代表寄生寄生虫、捕食者和无害控制。结果表明，芦苇莺并不区分对不同类型入侵者发出的警报叫声，但雏鸟阶段的反应强度明显高于卵阶段。与雀鹰警报相关的攻击行为在卵阶段不存在，但攻击行为在雏鸟阶段急剧增加并超过了响应布谷鸟警报呼叫的攻击频率，这意味着父母自身生存和后代之间的权衡发生了转变。失去后代。警报声吸引的同种动物数量多于其他物种的成员。总体而言，东方芦苇莺在雏鸟阶段对不同警报信号的反应始终比卵阶段更强，支持了后代价值假设。