Abstract Parental provisioning behavior is a major determinant of offspring growth and survival, but high provisioning rates might come at the cost of increased predation threat. Parents should thus adjust provisioning activity according to current predation threat levels. Moreover, life-history theory predicts that response to predation threat should be correlated with investment in current reproduction. We experimentally manipulated perceived predation threat in free-living great tits (Parus major) by presenting parents with a nest predator model while monitoring different aspects of provisioning behavior and nestling begging. Experiments were conducted in 2 years differing greatly in ecological conditions, including food availability. We further quantified male territorial aggressiveness and male and female exploratory tendency. Parents adjusted provisioning according to current levels of threat in an apparently adaptive way. They delayed nest visits during periods of elevated perceived predation threat and subsequently compensated for lost feeding opportunities by increasing provisioning once the immediate threat had diminished. Nestling begging increased after elevated levels of predation threat, but returned to baseline levels by the end of the experiment, suggesting that parents had fully compensated for lost feeding opportunities. There was no evidence for a link between male exploration behavior or aggressiveness and provisioning behavior. In contrast, fast-exploring females provisioned at higher rates, but only in the year with poor environmental conditions, which might indicate a greater willingness to invest in current reproduction in general. Future work should assess whether these personality-related differences in delivery rates under harsher conditions came at a cost of reduced residual reproductive value.

中文翻译：

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操纵水平的捕食威胁对父母供应和雏鸟乞讨的影响

摘要 父母的供应行为是后代生长和存活的主要决定因素，但高供应率可能以增加捕食威胁为代价。因此，父母应根据当前的捕食威胁级别调整供应活动。此外，生活史理论预测，对捕食威胁的反应应该与对当前繁殖的投资相关联。我们通过向父母展示巢捕食者模型，同时监控供应行为和雏鸟乞讨的不同方面，实验性地操纵了自由生活的大山雀（Parus Major）中感知到的捕食威胁。实验在 2 年内进行，生态条件差异很大，包括食物供应情况。我们进一步量化了男性的领土侵略性和男性和女性的探索倾向。父母以一种明显适应性的方式根据当前的威胁水平调整供应。他们在感知到的捕食威胁升高期间推迟筑巢访问，随后在直接威胁减弱后通过增加供应来弥补失去的觅食机会。在捕食威胁水平升高后，雏鸟的乞食增加，但在实验结束时恢复到基线水平，这表明父母已经完全补偿了失去的觅食机会。没有证据表明男性的探索行为或攻击性与供应行为之间存在联系。相比之下，快速探索的雌性以更高的比率提供，但仅限于环境条件较差的年份，这可能表明总体上更愿意投资于当前的繁殖。