Rouhbakhsh Aubtin, Wright Amber N, Ferguson Jake M
School of Life Sciences, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA.
Department of Biology, University of Kentucky, Lexington, Kentucky, USA.
Ecol Lett. 2025 Apr;28(4):e70111. doi: 10.1111/ele.70111.
Past work has shown that group formation in foraging animals aids in resource acquisition and reduces the number of interactions with predators. However, group formation can also increase competition for resources among group members. Here, we model how the individual costs and benefits of group formation drive group size. Our model predicts that when competition for resources occurs within and between groups, forager group size will exhibit a one-third power-law relationship with population abundance. However, if groups form due to intragroup competition and predation, we predict either a one-half power-law relationship with population abundance or a constant group size depending on the coupling between predator and prey. Using empirical data on group foraging birds and ungulates, we found a scaling relationship consistent with the one-third power-law, suggesting that hierarchical competition drives the average group size. Our results support work highlighting the importance of density-dependent group formation in maintaining population stability.
过去的研究表明，觅食动物形成群体有助于获取资源，并减少与捕食者的互动次数。然而，群体形成也会增加群体成员之间对资源的竞争。在此，我们建立模型来研究群体形成的个体成本和收益如何驱动群体规模。我们的模型预测，当群体内部和群体之间都存在对资源的竞争时，觅食者群体规模将与种群丰度呈现三分之一次幂律关系。然而，如果群体是由于群体内部竞争和捕食而形成的，根据捕食者与猎物之间的耦合关系，我们预测群体规模与种群丰度要么呈现二分之一次幂律关系，要么保持恒定。利用关于群体觅食鸟类和有蹄类动物的实证数据，我们发现了一种与三分之一次幂律相符的标度关系，这表明层级竞争驱动着平均群体规模。我们的结果支持了强调密度依赖型群体形成在维持种群稳定性方面重要性的研究。
