Data for "Risk assessment during nest defense against three simulated predators by northern house wrens (Troglodytes aedon aedon)"

Offspring predation is one of the greatest obstacles to an organism’s reproductive success, but parents vary in the strength of their response to potential predators. One explanation for this variable investment is that defending current offspring has the potential to lower future reproductive success if the predator is also capable of injuring or killing the parent. House wrens (Troglodytes aedon aedon) are cavity-nesting songbirds that defend against multiple species of nest predators including small mammals, birds of prey, and snakes. Here, we used three different predator decoys: two nest predators - an eastern chipmunk (Tamias striatus) and an eastern ratsnake (Pantherophis alleghaniensis) - as well as a predator of both offspring and adults - a juvenile Cooper’s hawk (Accipiter cooperi) - to elicit nest defense and test whether females use risk assessment to modulate their antipredator behavior. We found that antipredator behaviors were not significantly different between the two nest predators, which posed a high risk to the nestlings, but lower risk to the parents as neither species frequently captures adult wrens. Females also did not differ significantly in their responses to the snake between years, suggesting that the population-level response might be consistent through time despite substantial individual variation among females. However, female wrens never dove at or attacked the Cooper’s hawk while they frequently attacked both the snake and chipmunk decoys. Neighboring house wrens from adjacent territories were also less likely to respond to the hawk, but more heterospecifics mobbed the hawk than the snake decoy. Collectively, these results show that risk assessment and the strength of the antipredator response varies substantially both within and among species. Female house wrens exhibit plasticity in their nest defense behavior, and they respond to different types of predators in a way that could maximize lifetime fitness while risking the loss of their current offspring. Please see our BioRxiv Preprint (and eventual publication) for more information on the specific details of our protocol and statistical analysis. Note: version 3 now includes an updated R Markdown file (v3) with the revised code that we used to conduct our statistical analyses and create our figures.后代捕食（offspring predation）是制约生物体繁殖成功的核心障碍之一，但不同亲本对潜在捕食者的应对强度存在显著变异。针对这种投资策略的差异，现有解释之一为：若捕食者同时能够伤害或杀死亲本，那么保护当前后代可能会降低其未来的繁殖成功率。家鹪鹩（House wren，*Troglodytes aedon aedon*）是一类洞巢栖息的鸣禽，可防御包括小型哺乳动物、猛禽与蛇类在内的多种巢捕食者。本研究使用三种不同的捕食者诱饵：两种巢捕食者——东部花栗鼠（eastern chipmunk，*Tamias striatus*）与东部锦蛇（eastern ratsnake，*Pantherophis alleghaniensis*），以及一种同时捕食后代与成体的捕食者——幼年库珀鹰（juvenile Cooper’s hawk，*Accipiter cooperi*），以此诱发巢防御行为，检验雌鸟是否会通过风险评估来调节其反捕食行为。 研究结果显示，两种巢捕食者对应的反捕食行为无显著差异：二者均对雏鸟构成高风险，但对亲本的威胁较低，因为两者均极少捕捉成年家鹪鹩。雌鸟对锦蛇的反应在不同年份间也无显著差异，这表明尽管个体雌鸟间存在显著的行为变异，但种群水平的反捕食反应可能在时间维度上保持稳定。然而，家鹪鹩雌鸟从未对库珀鹰发起俯冲或攻击，却频繁攻击锦蛇与花栗鼠诱饵。来自相邻领地的邻近家鹪鹩对库珀鹰的响应概率同样更低，但相较于锦蛇诱饵，有更多异种个体围攻库珀鹰。 综合而言，这些结果表明，风险评估能力与反捕食反应的强度在物种内部及物种间均存在显著变异。家鹪鹩雌鸟的巢防御行为具有可塑性，它们会以能够最大化终身适合度、同时又合理规避当前后代损失风险的方式，对不同类型的捕食者做出针对性响应。 如需了解实验方案与统计分析的具体细节，请参阅我们的BioRxiv预印本（及最终发表版本）。 注：第3版现已更新了R Markdown文件（v3），其中包含了我们用于开展统计分析与绘制图表的修订后代码。