The mere presence of cuckoos in breeding area alters egg-ejection decisions in Daurian redstarts

Brood parasitic cuckoos and their hosts serve as model systems for studying host-parasite coevolution. Egg-rejection behavior constitutes an effective defense against brood parasitism, but some host species show phenotypic plasticity in egg-rejection behavior. Direct exposure to a cuckoo near the nest can increase egg-rejection likelihood, and long-term studies have shown that increased the egg-rejection rates generally correlate with higher parasite prevalence. However, it remains unclear whether such increases result from interactions between parasites and hosts, as these can be surprisingly common, or whether the mere presence of cuckoos in the breeding area is sufficient. Daurian redstarts Phoenicurus auroreus are a common host of the common cuckoo Cuculus canorus that defend against cuckoo parasitism mainly by ejecting the parasitic egg from the nest. This species is unique, as its first breeding attempt of the year takes place before the arrival of cuckoos, excluding the possibili...

巢寄生杜鹃（brood parasitic cuckoos）与其宿主是研究宿主-寄生协同进化的经典模型系统。弃卵行为是抵御巢寄生的有效防御策略，但部分宿主物种的弃卵行为存在表型可塑性。直接接触巢区附近的杜鹃可提升宿主的弃卵概率，长期研究表明，弃卵率的提升通常与更高的寄生率呈正相关。然而，目前仍不清楚这类弃卵率的提升是源于宿主与寄生生物之间的互作（此类互作实则颇为常见），还是仅依靠繁殖区域内杜鹃的存在即可触发。北红尾鸲（Phoenicurus auroreus）是大杜鹃（Cuculus canorus）的常见宿主，其抵御杜鹃巢寄生的主要方式为将寄生卵逐出巢外。该物种的独特之处在于，其年度首次繁殖发生在杜鹃抵达之前，从而排除了...