Department of Biology of Organisms and Systems, University of Oviedo, Oviedo, Spain.
Science. 2014 Mar 21;343(6177):1350-2. doi: 10.1126/science.1249008.
Avian brood parasites lay eggs in the nests of other birds, which raise the unrelated chicks and typically suffer partial or complete loss of their own brood. However, carrion crows Corvus corone corone can benefit from parasitism by the great spotted cuckoo Clamator glandarius. Parasitized nests have lower rates of predation-induced failure due to production of a repellent secretion by cuckoo chicks, but among nests that are successful, those with cuckoo chicks fledge fewer crows. The outcome of these counterbalancing effects fluctuates between parasitism and mutualism each season, depending on the intensity of predation pressure.
鸟类的巢寄生现象是指一些鸟将卵产在其他鸟的巢中，由其他鸟代为孵化和育雏，而这些代育的亲鸟通常会损失自己的部分或全部后代。然而，红嘴山鸦可以通过大杜鹃的巢寄生而受益。由于杜鹃雏鸟会分泌一种排斥性分泌物，寄生的鸟巢因捕食者而导致的失败率较低，但在成功孵化的鸟巢中，有杜鹃雏鸟的鸟巢中会有较少的山鸦幼鸟出飞。这些相互制衡的效应的结果在每个季节都会在寄生和互利之间波动，这取决于捕食压力的强度。
