Wang Longwu, Zhang Yuhan, Liang Wei, Møller Anders Pape
State Forestry Administration of China Key Laboratory for Biodiversity Conservation in Mountainous Areas of Southwest Karst, School of Life Sciences, Guizhou Normal University, Guiyang 550001, People's Republic of China.
Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, People's Republic of China.
R Soc Open Sci. 2021 Jan 13;8(1):201264. doi: 10.1098/rsos.201264. eCollection 2021 Jan.
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 () parasitize their Oriental reed warbler () 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.
鸟类专性巢寄生者通过移除已经光顾过巢穴的杜鹃的卵而获得优势，这可以增加它们后代的存活机会。相反，为了防止它们的卵被下一只寄生杜鹃拿走，它们需要采取一些预防措施。卵拟态和卵隐蔽是防止被寄生的卵被另一只寄生杜鹃拿走的两种替代策略。在这里，我们测试了在普通杜鹃（）寄生它们的东方苇莺（）宿主时，卵隐蔽假说是否具有预防作用。我们设计了两个具有不同隐蔽效果的实验组来诱导普通杜鹃产卵，并观察杜鹃在寄生过程中是否会选择性地拿走隐蔽程度低的实验卵。我们的结果支持卵隐蔽假说；观察到的杜鹃明显更倾向于选择更显眼的白色模型卵。这表明，即使在开放式巢穴中，充分隐藏的卵在寄生过程中也能避免被杜鹃雌鸟拿走，从而增加它们自己寄生卵的存活机会。
