Data_Sheet_1_Multi-Species Feeding Association Dynamics Driven by a Large Generalist Predator.docx

Multi-species feeding associations (MSFAs) are temporary communities of animals exploiting the same or co-occurrent resources. Their dynamics are species dependent, often creating competitive interactions, but they can also increase foraging efficiency and ultimately individual fitness. The foraging behaviors of some species can enhance prey capture by others, with different roles depending on the species present. Here, we use the Hauraki Gulf, New Zealand, as a model system to quantitatively characterize the principal types of MSFAs between 2011 and 2020. We determine the foraging associations of a large generalist predator, the Bryde’s whale, and how shifts in its prey preference change the dynamics between seabird competitors. Hierarchical clustering from influential predator groups identified three types of MSFAs. Two of mainly fish-feeding predators, one including and one lacking Bryde’s whales, and one involving (although not limited to) plankton-feeders associated with Bryde’s whales. Cluster frequencies featured significant temporal trends, whereas MSFA diversity and whale association rate showed no significant changes. Bryde’s whales’ increasing reliance on zooplankton highlights their foraging plasticity, with changes in cluster frequencies and resource competition related to this shift from fish to zooplankton. The role of Bryde’s whales varies from joiners and terminators in fish-feeding aggregations to initiators with plankton-feeding seabird associations, thereby changing the MSFA dynamics. MSFAs tend toward a diversity equilibrium, i.e., a maximum number of species involved before competitive effects exceed the benefits of interaction. Functional MSFAs where heterospecific interactions are important to foraging success can be affected by changing composition. Future work should focus on the behavioral interactions between key predators, prey availability and their effect on MSFAs.

多物种觅食联合群（Multi-species feeding associations, MSFAs）是一类利用相同或同期出现资源的临时性动物群落。其动态变化因物种而异，常引发竞争互动，但也可提升觅食效率，最终提升个体适合度。部分物种的觅食行为可增强其他物种的猎物捕获能力，其具体作用取决于群落内的物种组成。本研究以新西兰豪拉基湾（Hauraki Gulf）为模式系统，对2011至2020年间的主要MSFA类型进行定量表征。我们明确了大型广食性捕食者——布氏鲸（Bryde’s whale）的觅食联合关系，以及其猎物偏好的转变如何改变海鸟竞争者间的种群动态。基于关键捕食类群的层级聚类分析，本研究共识别出三类MSFA：两类以鱼类为食的捕食者类群，一类包含布氏鲸，另一类则无布氏鲸；还有一类（虽不限于）与布氏鲸相关的浮游生物捕食者类群。聚类频率呈现显著的时间趋势，而MSFA多样性与鲸鱼关联率则无显著变化。布氏鲸对浮游动物的依赖度不断提升，凸显了其觅食可塑性，而群落频率的变化与资源竞争均与这种从鱼类向浮游动物的食性转变密切相关。布氏鲸的角色从鱼类觅食集群中的参与者与终止者，转变为与浮游生物食性海鸟形成联合群的发起者，从而改变了MSFA的动态。MSFA往往趋向于多样性平衡，即当竞争效应超过互动收益时，所涉及的物种数量达到最大值。异种互动对觅食成功至关重要的功能性MSFA，可能会因群落组成的变化而受到影响。未来研究应聚焦于关键捕食者间的行为互动、猎物可获得性及其对MSFA的影响。