Long-distance communication can enable collective migration in a dynamic seascape

Social information is predicted to enhance migratory performance, but the relative benefits of social information in the long-range movements of marine megafauna are unknown. In particular, whether and how migrants use nonlocal information gained through social communication at the extreme spatial scale of oceanic ecosystems remains unclear. Here we combine long-term acoustic recordings of foraging and migratory blue whales, oceanographic and prey data, and individual-based modeling to discern the cues underlying timing of blue whales' breeding migration in the Northeast Pacific. We find that individual whales rely on both personal and social sources of information about forage availability in deciding when to depart from their vast and dynamic foraging habitat and initiate breeding migration. Empirical patterns of migratory phenology can only be reproduced by models in which individuals use long-distance social information about conspecifics' behavioral state, which is known to be encoded in the patterning of their widely-propagating songs. Further, social communication improves pre-migration seasonal foraging performance by over 60% relative to asocial movement mechanisms. Our results suggest that long-range communication enhances the perceptual ranges of migrating whales beyond that of any individual, resulting in increased foraging performance. These findings indicate the value of nonlocal social information in an oceanic migrant and highlight the importance of long-distance acoustic communication in the collective migration of wide-ranging marine megafauna. ### Competing Interest Statement The authors have declared no competing interest.