Abstract Nest predation is a common cause of reproductive failure for many bird species, and various antipredator defense behaviors have evolved to reduce the risk of nest predation. However, trade-offs between current reproductive duties and future reproduction often limit the parent’s ability to respond to nest predation risk. Individual responses to experimentally increased nest predation risk can give insights into these trade-offs. Here, we investigate whether social and ecological factors affect individual responses to predation risk by experimentally manipulating the risk of nest predation using taxidermic mounts in the cooperative breeding Seychelles warbler (Acrocephalus sechellensis). Our results show that dominant females, but not males, alarm called more often when they confront a nest predator model alone than when they do so with a partner, and that individuals that confront a predator together attacked more than those that did so alone. Dominant males increased their antipredator defense by spending more time nest guarding after a presentation with a nest predator, compared with a nonpredator control, but no such effect was found for females, who did not increase the time spent incubating. In contrast to incubation by females, nest guarding responses by dominant males depended on the presence of other group members and food availability. These results suggest that while female investment in incubation is always high and not dependent on social and ecological conditions, males have a lower initial investment, which allows them to respond to sudden changes in nest predation risk.

中文翻译：

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实验诱导的反捕食者反应是由社会和环境因素介导的

摘要 巢穴捕食是许多鸟类繁殖失败的常见原因，为了降低巢穴捕食的风险，已经进化出各种反捕食者防御行为。然而，当前繁殖职责和未来繁殖之间的权衡通常会限制父母应对巢穴捕食风险的能力。个体对实验性增加的巢穴捕食风险的反应可以深入了解这些权衡。在这里，我们通过在合作繁殖的塞舌尔莺（Acrocephalus sechellensis）中使用动物标本剥制支架实验性地操纵巢捕食风险，研究社会和生态因素是否影响个体对捕食风险的反应。我们的结果表明，占主导地位的女性，而不是男性，当他们单独面对巢穴捕食者模型时，警报会比与伴侣一起面对时更频繁，而且与捕食者一起面对的个体比单独面对捕食者的个体受到的攻击更多。与非捕食者对照相比，优势雄性通过在遇到巢穴捕食者后花更多的时间保护巢穴来增加它们的抗捕食者防御，但雌性没有发现这种效果，雌性没有增加孵化时间。与雌性孵化相反，优势雄性的筑巢反应取决于其他群体成员的存在和食物供应。这些结果表明，虽然女性在孵化方面的投资总是很高并且不依赖于社会和生态条件，但男性的初始投资较低，