When resources are spatially and temporally variable, consumers can increasetheir foraging success by moving to track ephemeral feeding opportunitiesas these shift across the landscape; the best examples derive from herbivore–plant systems, where grazers migrate to capitalize on the seasonal waves ofvegetation growth. We evaluated whether analogous processes occur in watershedssupporting spawning sockeye salmon (Oncorhynchus nerka), askingwhether seasonal activities ofpredators and scavengers shift spatial distributionsto capitalize on asynchronous spawning among populations of salmon. Bothglaucous-winged gulls and coastal brown bears showed distinct shifts in theirspatial distributions over the course of the summer, reflecting the shifting distributionof spawning sockeye salmon, which was associated with variation inwater temperature among spawning sites. By tracking the spatial and temporalvariation in the phenology of their principal prey, consumers substantiallyextended their foraging opportunity on a superabundant, yet locally ephemeral,resource. Ecosystem-based fishery management efforts that seek to balancetrade-offs between fisheries and ecosystem processes supported by salmonshould, therefore, assess the importance of life-history variation, particularly inphenological traits, for maintaining important ecosystem functions, such asproviding marine-derived resources for terrestrial predators and scavengers.
