Department of Life Sciences, Ben-Gurion University, Beer Sheva 8410501, Israel.
Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
Proc Biol Sci. 2019 Jul 24;286(1907):20190826. doi: 10.1098/rspb.2019.0826. Epub 2019 Jul 17.
Refuges offer prey animals protection from predation, but increased time spent hiding can reduce foraging opportunities. Within social groups, individuals vary in their refuge use and willingness to forage in the presence of a predator. Here, we examine the relative foraging benefits and mortality costs associated with individual refuge use and foraging behaviour within groups of goldfish (Carassius auratus) under predation risk from an avian predator (little egret-Egretta garzetta). We assessed individual order of emergence from the refuge and participation over 15 group foraging outings, and assigned each fish a daily outing index score. The individual fish that emerged from the refuge earlier than the other group members and that participated in more outings received high outing index scores and consumed more food compared with fish that tended to emerge in posterior positions and participate in fewer outings. However, individual fish that attained high outing index scores suffered a higher risk of predation. Furthermore, the amount of time the egret spent at the pool affected group foraging behaviour: as predation risk increased, groups of fish consumed significantly less food. Our results exemplify the trade-off between foraging success and safety from predation that prey species regularly experience.
避难所为被捕食动物提供了免受捕食的保护，但躲藏时间的增加会减少觅食机会。在社会群体中，个体在避难所的使用和在捕食者存在时觅食的意愿上存在差异。在这里，我们研究了在面临来自鸟类捕食者（小白鹭-Egretta garzetta）的捕食风险下，金鱼（Carassius auratus）群体中个体使用避难所和觅食行为的相对觅食收益和死亡率成本。我们评估了个体从避难所中出来的顺序以及在 15 次集体觅食外出中的参与度，并为每条鱼分配了每日外出指数得分。与倾向于处于后位并参与较少外出的鱼相比，那些比其他群体成员更早从避难所中出来并参与更多外出的个体获得了较高的外出指数得分并消耗了更多的食物。然而，获得高外出指数得分的个体鱼面临更高的捕食风险。此外，白鹭在水池停留的时间会影响群体的觅食行为：随着捕食风险的增加，鱼群消耗的食物明显减少。我们的研究结果体现了被捕食动物经常经历的觅食成功和免受捕食风险之间的权衡。
