Avian obligate brood parasites gain an advantage by removing the eggs of the cuckoos who have already visited the nest, which can increase the chances of survival for their offspring. Conversely, to prevent their eggs from being picked up by the next parasitic cuckoo, they need to take some precautions. Egg mimicry and egg crypsis are two alternative strategies to prevent the parasitized egg from being picked up by another parasitic cuckoo. Here, we tested whether the egg crypsis hypothesis has a preventative effect when common cuckoos (Cuculus canorus) parasitize their Oriental reed warbler (Acrocephalus orientalis) hosts. We designed two experimental groups with different crypsis effects to induce common cuckoos to lay eggs and observed whether the cuckoos selectively picked up the experimental eggs with low crypsis levels in the process of parasitism. Our results supported the egg crypsis hypothesis; the observed cuckoos significantly preferred to select the more obvious white model eggs. This shows that even in an open nest, eggs that are adequately hidden can also be protected from being picked up by cuckoo females during parasitism so as to increase the survival chance of their own parasitic eggs.

禽专性寄生虫通过去除已经探访过巢的杜鹃的卵而获得优势，这可以增加后代存活的机会。相反，为防止卵被下一个寄生杜鹃捡起，他们需要采取一些预防措施。模仿鸡蛋和冷冻卵是防止寄生的鸡蛋被另一种寄生杜鹃捡起的两种替代策略。在这里，我们测试了当普通杜鹃（Cuculus canorus）寄生它们的东方芦苇（Acrocephalus Orientalis）时，卵低温昆虫假说是否具有预防作用。）主机。我们设计了两个具有不同低温效应的实验组，以诱导普通杜鹃产卵，并观察杜鹃是否在寄生过程中选择性地选择了低低温的实验卵。我们的研究结果支持了卵形低温杆菌假说。观察到的布谷鸟更倾向于选择更明显的白色模型蛋。这表明，即使在开放的巢中，也可以保护被充分隐藏的卵在杜鹃花寄生过程中不被杜鹃母捕获，以增加其自身寄生卵的存活机会。