Data from: A predation cost to bold fish in the wild

Studies of predator-mediated selection on behaviour are critical for our understanding of the evolution and maintenance of behavioural diversity in natural populations. Consistent individual differences in prey behaviour, especially in the propensity to take risks (“boldness”), are widespread in the animal kingdom. Theory predicts that individual behavioural types differ in a cost-benefit trade-off where bolder individuals benefit from greater access to resources while paying higher predation-risk costs. However, explicitly linking predation events to individual behaviour under natural conditions is challenging and there is currently little data from the wild. We assayed individual behaviour and electronically tagged hundreds of fish (roach, Rutilus rutilus) before releasing them into their lake of origin, thereby exposing them to predation risk from avian apex predators (cormorants, Phalacrocorax carbo). Scanning for regurgitated tags at the cormorant roosting site provided data on individual predation events. We found that fish with higher boldness have a greater susceptibility to cormorant predation compared to relatively shy, risk-averse individuals. Our findings hereby provide unique and direct evidence of behavioural type-dependent predation vulnerability in the wild, i.e. that there is a predation cost to boldness, which is critical for our understanding of the evolution and maintenance of behavioural diversity in natural populations.针对捕食者介导的行为选择（predator-mediated selection）开展研究，对于我们理解自然种群中行为多样性的演化与维持机制至关重要。猎物行为中存在稳定的个体差异，尤其是在冒险倾向（即"大胆性（boldness）"）方面，该现象广泛分布于动物界。相关理论预测，不同的个体行为类型存在成本-收益权衡：更大胆的个体能够获得更多的资源获取机会，但同时需要承担更高的捕食风险代价。然而，在自然条件下将捕食事件与个体行为直接关联极具挑战，目前野外实测的相关数据仍较为匮乏。我们首先对数百条欧鳊（*Rutilus rutilus*）开展个体行为测定，并为其佩戴电子标记，随后将其放归原生湖泊，使其暴露于鸟类顶级捕食者——普通鸬鹚（*Phalacrocorax carbo*）的捕食风险之下。通过在鸬鹚栖息地上扫描其反刍吐出的标记物，我们获得了个体捕食事件的相关数据。研究结果显示，相较于相对腼腆、规避风险的个体，大胆性更高的欧鳊受鸬鹚捕食的易感性更强。本研究的发现首次为野外环境中行为类型依赖的捕食易感性提供了直接且独特的实证依据，即大胆性存在捕食代价，这一结果对于我们理解自然种群中行为多样性的演化与维持机制具有关键意义。