Predation is a significant cause of nest failure in passerine birds, and, thus, natural selection is expected to favor behavioral plasticity to allow birds to respond to perceived changes in predation risk. However, behavioral plasticity in response to perceived predation risk, and its potential fitness-related costs, are understudied. In a wild population of breeding house wrens (Troglodytes aedon), we tested the hypotheses that (1) birds show behavioral plasticity in response to perceived nest-predation risk to reduce self-risk or risk to offspring, but (2) this plasticity incurs fitness-related costs. We experimentally increased the perceived risk of nest predation by enlarging the diameter of the nestbox entrance from the standard 3.2 to 5.0 cm once incubation began. Unexpectedly, large-hole females spent significantly less time being vigilant than small-hole (control) females during late incubation. Both males and females also exhibited plasticity in their provisioning behavior. Large-hole males increased and large-hole females decreased provisioning visits with increasing brood size, whereas small-hole males and females behaved similarly and were unaffected by brood size. Females did not show plasticity in their incubation or brooding behavior. Notwithstanding this behavioral plasticity in response to increased perceived predation risk, treatment had no effect on hatching success or early hatchling survival, nor did it affect nestling body condition or fledging success. We conclude, therefore, that house wrens show behavioral plasticity in response to perceived nest-predation risk, but that any short-term fitness-related costs associated with this flexibility appear negligible.

中文翻译：

---

行为可塑性对种in中感知到的捕食风险的反应。

捕食是雀形目鸟筑巢失败的重要原因，因此，自然选择有望促进行为可塑性，从而使鸟类能够应对捕食风险的感知变化。然而，对可感知的捕食风险的行为可塑性及其潜在的适应性相关成本的研究仍不足。在繁殖屋w的野生种群中（Troglodytes aedon），我们测试了以下假设：（1）鸟类表现出行为可塑性，以应对感知到的巢捕食风险，以降低自我风险或后代风险​​，但（2）这种可塑性会产生与健身相关的成本。一旦孵化开始，我们通过将巢箱入口的直径从标准3.2厘米扩大到5.0厘米，实验上增加了感知到的巢巢捕食风险。出乎意料的是，在孵化后期，大孔雌虫的警惕时间比小孔雌虫（对照）少得多。男性和女性的预配行为也都表现出可塑性。大孔雄性增加，而大孔雌性减少繁殖次数，而育雏量增加，而小孔雄性和雌性表现相似，不受育雏量的影响。雌性的孵化或育雏行为没有表现出可塑性。尽管这种行为可塑性响应于增加的感知到的捕食风险，但治疗对孵化成功或早期孵化存活没有影响，也没有影响雏鸟的身体状况或成年成功。因此，我们得出的结论是，家w显示出对感知到的巢穴捕食风险的行为可塑性，但是与这种灵活性相关的任何短期健身相关成本似乎都可以忽略不计。