Predator olfactory cues generate a foraging-predation tradeoff through prey apprehension

Most animals are faced with the challenge of securing food under the risk of predation. This frequently generates a trade-off whereby animals respond to predator cues with reduced movement to avoid predation at the direct cost of reduced foraging success. However, predators may also cause prey to be apprehensive in their foraging activities, which would generate an indirect ‘apprehension cost’. Apprehension arises when a forager redirects attention from foraging tasks to predator detection and incurs a cost from such multi-tasking, because the forager ends up making more mistakes in its foraging tasks as a result. Here, we test this apprehension cost hypothesis and show that damselflies miss a greater proportion of their prey during foraging bouts in response to both olfactory cues produced by conspecifics that have only viewed a fish predator and olfactory cues produced directly by fish. This reduced feeding efficiency is in addition to the stereotypical anti-predator response of reduc...多数动物都面临着在掠食（predation）风险下获取食物的挑战。这往往会催生一种权衡取舍：动物会对捕食者的相关线索做出反应，通过减少活动来规避掠食，但直接代价是觅食成功率下降。然而，捕食者还可能使猎物在觅食活动中变得警觉，由此产生间接的“警觉成本（apprehension cost）”。当觅食者将注意力从觅食任务转移到捕食者侦测上时，便会产生警觉，而这种多任务处理会带来成本——因为觅食者最终会在觅食任务中出现更多失误。本研究对该警觉成本假说进行了检验，结果表明，当暴露于仅观察过鱼类捕食者的同种个体（conspecifics）释放的嗅觉线索（olfactory cues），以及鱼类直接释放的嗅觉线索时，豆娘（damselflies）在觅食过程中会错过比例更高的猎物。这种觅食效率的下降，是除了典型反捕食反应（anti-predator response）之外的额外...