Data from: Riding the crimson tide: mobile terrestrial consumers track phenological variation in spawning of an anadromous fish

When resources are spatially and temporally variable, consumers can increase their foraging success by moving to track ephemeral feeding opportunities as these shift across the landscape; the best examples derive from herbivore-plant systems where grazers migrate to capitalize on the seasonal waves of vegetation growth. We evaluated whether analogous processes occur in watersheds supporting spawning Pacific salmon, asking whether seasonal activity of predators and scavengers shift spatial distributions to capitalize on asynchronous spawning among populations of salmon. Both glaucous-winged gulls and coastal brown bears showed distinct shifts in their spatial distributions over the course of the summer, reflecting the shifting distribution of spawning sockeye salmon, which was associated with variation in water temperature among spawning sites. By tracking the spatial and temporal variation in the phenology of their principal prey, consumers substantially extended their foraging opportunity on a superabundant, yet locally ephemeral, resource. Ecosystem based fishery management efforts that seek to balance trade-offs between fisheries and ecosystem processes supported by salmon should therefore assess the importance of life-history variation, particularly in phenological traits, for maintaining important ecosystem functions such as providing marine-derived resources for terrestrial predators and scavengers.

当资源在空间与时间维度上均存在异质性时，消费者可通过移动追踪景观中动态分布的短暂觅食机会，以提升自身觅食成功率；其中最典型的案例来自草食动物-植物系统：植食动物通过迁徙利用植被生长的季节性浪潮。本研究评估了在支持产卵太平洋鲑鱼（Pacific salmon）的流域中是否存在类似过程，并探讨捕食者与食腐动物的季节活动是否会调整其空间分布，以利用鲑鱼种群异步产卵带来的资源窗口期。研究发现，灰翅鸥（glaucous-winged gulls）与沿海棕熊的空间分布在夏季均出现显著变化，这一变化与产卵期红大麻哈鱼（sockeye salmon）的分布动态一致，而红大麻哈鱼的产卵分布又与各产卵场的水温差异密切相关。消费者通过追踪其主要猎物的物候学时空动态，大幅延长了在这一整体资源充裕但局部分布短暂的食物资源上的觅食窗口。因此，旨在平衡渔业与鲑鱼支撑的生态系统过程之间权衡的基于生态系统的渔业管理（ecosystem-based fishery management）工作，应当评估生活史变异——尤其是物候性状变异——对于维持关键生态系统功能的重要性，例如为陆生捕食者与食腐动物提供海洋衍生资源。