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上存在异质性时，消费者可通过移动追踪景观中随空间动态变化的短暂觅食机会，以此提升觅食成功率；此类过程的典型案例见于草食动物-植物系统，其中植食动物会通过迁徙借助植被生长的季节性波动获取食物。本研究针对支撑产卵太平洋鲑（Pacific salmon）的流域，评估是否存在类似过程，旨在探究捕食者与食腐动物的季节活动是否会调整其空间分布，以利用不同鲑鱼种群异步产卵产生的觅食契机。夏季期间，灰翅鸥（glaucous-winged gulls）与沿海棕熊的空间分布均出现显著变化，这与产卵红大马哈鱼（sockeye salmon）的空间分布动态相呼应，而红大马哈鱼的分布差异与各产卵场的水温变异密切相关。通过追踪主要猎物的物候学（phenology）时空变异，消费者大幅延长了对这一总量丰富但局部短暂的资源的觅食窗口。因此，旨在平衡渔业与鲑鱼支撑的生态系统过程之间权衡取舍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——尤其是物候性状的变异——对维持关键生态系统功能的重要性，例如为陆地捕食者与食腐动物提供海洋源性营养物质（marine-derived resources）。