Data from: Cuckoo parasitism in a cavity nesting host: near absent egg-rejection in a northern redstart population under heavy apparent (but low effective) brood parasitism

Brood parasite - host systems continue to offer insights into species coevolution. A notable system is the redstart Phoenicurus phoenicurus parasitized by the “redstart-cuckoo” Cuculus canorus gens. Redstarts are the only regular cuckoo hosts that breed in cavities, which challenges adult cuckoos in egg laying and cuckoo chicks in host eviction. We investigated parasitism in this system and found high overall parasitism rates (31.1% of 360 redstart nests), but also that only 33.1% of parasitism events (49 of 148 eggs) were successful in laying eggs into redstart nest cups. The majority of cuckoo eggs were mislaid and found on the rim of the nest; outside the nest cup. All available evidence suggests these eggs were not ejected by hosts. The effective parasitism rate was therefore only 12.8% of redstart nests. Redstarts responded to natural parasitism by deserting their nests in 13.0% of cases, compared to desertion rates of 2.8% for non-parasitized nests. Our egg parasitism experiments found low rates (12.2%) of rejection of artificial non-mimetic cuckoo eggs. Artificial mimetic and real cuckoo eggs added to nests were rejected at even lower rates, and were always rejected via desertion. Under natural conditions, only 21 cuckoo chicks fledged of 150 cuckoo eggs laid. Adding to this low success, is that cuckoo chicks are sometimes unable to evict all host young, and were more likely to die as a result compared to cuckoo chicks reared alone. This low success seems to be mainly due to the cavity nesting strategy of the redstart which is a challenging obstacle for the cuckoo. The redstart-cuckoo system appears to be a fruitful model system and we suggest much more emphasis should be placed on frontline defences such as nest site selection strategies when investigating brood parasite-host coevolution.育雏寄生（brood parasite）-宿主系统持续为物种协同进化研究提供关键认知。其中一个典型研究系统为欧亚红尾鸲（Phoenicurus phoenicurus）被大杜鹃（Cuculus canorus）红尾鸲专化种群寄生的体系。红尾鸲是唯一一种营洞巢繁殖的常规杜鹃宿主，这一特性对成年杜鹃的产卵行为以及杜鹃雏鸟的宿主驱逐行为均构成挑战。我们针对该系统的寄生现象展开调查，结果显示整体寄生率较高：在360个红尾鸲巢中，寄生率达31.1%；但仅有33.1%的寄生事件（148枚杜鹃卵中的49枚）成功将卵产于红尾鸲的巢杯内。绝大多数杜鹃卵被误置于巢杯外侧的巢缘处，且所有现有证据均表明这些卵并非被宿主主动抛出。因此，实际有效寄生率仅为红尾鸲巢的12.8%。红尾鸲对自然寄生事件的响应表现为：13.0%的寄生巢会被弃巢，而非寄生巢的弃巢率仅为2.8%。我们开展的卵寄生实验显示，对人工非拟态杜鹃卵的拒斥率仅为12.2%；而添加至巢中的人工拟态杜鹃卵与天然杜鹃卵的拒斥率更低，且所有拒斥行为均通过弃巢完成。自然条件下，150枚被产下的杜鹃卵中仅有21枚成功育出雏鸟。进一步加剧这一低成功率的是，杜鹃雏鸟有时无法驱逐全部宿主幼鸟，相较于独自被抚育的杜鹃雏鸟，这类个体的死亡率更高。这一低成功率主要源于红尾鸲的洞巢繁殖策略，这对杜鹃而言是极具挑战性的生存障碍。红尾鸲-大杜鹃系统堪称极具研究价值的模式体系，我们建议在探究育雏寄生-宿主协同进化机制时，应更多关注宿主的前沿防御策略，例如巢址选择策略。

搜集汇总

背景与挑战

背景概述

该数据集研究了红尾鸲作为洞穴巢宿主被杜鹃寄生的系统，发现高表观寄生率（31.1%）但低有效寄生率（12.8%），主要因杜鹃在洞穴巢中产卵困难导致多数卵被误产在巢杯外。红尾鸲对杜鹃卵的拒绝率极低（仅12.2%），且主要通过弃巢方式拒绝，同时杜鹃雏鸟成功率低下（150个卵中仅21只离巢），突出了洞穴巢策略在宿主-寄生虫协同进化中的关键防御作用。