Blue whales track oceanographic variability across spatial and temporal scales

Abstract

Animals' ability to track variable resources in space and time is critical to their survival in dynamic and changing ecosystems. Understanding populations' behavioral flexibility in response to natural and anthropogenic ecosystem variation requires long-term and detailed measurements of both animal behavior and ecosystem properties. In a series of recent studies, we leverage blue whales' widely-propagating songs to understand their capacity to track ecosystem variability across episodic foraging and seasonal-to-interannual migration scales. By integrating individual and population-level study of singing blue whales, we first identify an acoustic signature of their population-level transition from foraging to migration. Applying this acoustic signature to a six-year study period, we find that blue whales flexibly time their transition to migration to track interannual variability in the phenology of their foraging habitat. Within the foraging season, we further track blue whale behavior via a directional acoustic vector sensor. Using this approach, we find that blue whales maximize access to aggregated prey patches by dynamically tracking fine-scale wind-driven upwelling plumes in space and time. Combined, these findings display blue whales' ability to track oceanographic variability across spatial and temporal scales and suggest mechanisms by which these predators individually and collectively sense their dynamic foraging habitat.