Mixed-species groups are usually explained by foraging advantages and reduced predation risk for at least one of the participating species. Given that animals trade-off foraging and vigilance, the optimal level of vigilance of individuals in mixed-species groups depends partly on the vigilance levels of both conspecifics and heterospecifics. However, the benefits and costs of being part of a mixed-species group do not need to be evenly distributed between the species in a group. In this paper, we modeled the evolutionary stable strategy (ESS) for the optimal level of vigilance of an individual in a mixed-species group influenced by the effects of “many eyes,” “dilution” and “attraction,” and unequal costs and benefits between the species. Our model illustrates under what conditions associations with other species may facilitate reduced predation risk for at least one of the participating species. We show that vigilance of individuals in mixed-species groups becomes a social game, and that the ESS of these vigilance games may predict the individual's adaptive level of vigilance. This paper provides the first step in the development of a predictive theory for the numerous empirical studies on mixed-species groups.

中文翻译：

---

对混合物种群体的警惕性建模

混合物种群体通常被解释为觅食优势和至少一个参与物种的捕食风险降低。鉴于动物在觅食和警觉之间进行权衡，混合物种群体中个体的最佳警觉水平部分取决于同种和异种的警觉水平。但是，作为混合物种群体的一部分的收益和成本不需要在群体中的物种之间平均分配。在本文中，我们对受“多眼”、“稀释”和“吸引力”的影响以及不等成本和物种之间的利益。我们的模型说明了在什么条件下与其他物种的关联可能有助于降低至少一个参与物种的捕食风险。我们表明，混合物种群体中个体的警觉成为一种社交游戏，这些警觉游戏的 ESS 可以预测个体的警觉适应水平。本文为针对混合物种群体的众多实证研究提供了预测理论发展的第一步。