Commuting in crosswinds and foraging in fast winds: the foraging ecology of a flying fish specialist

Understanding how the behaviour of volant species is influenced by winds is important at a time when global airflow patterns and intensities are shifting. We investigated how wind speeds and directions influenced the flight and feeding events of a flap-gliding seabird during central place trips searching for aerial prey like Exocoetidae flying fish. We deployed GPS accelerometers on red-footed boobies (Sula sula rubripes) in the Chagos Archipelago (Indian Ocean) for 45 foraging trips. By comparing foraging commutes to simulated alternative routes, we demonstrate that birds preferentially selected tailwinds and crosswinds, with stronger selection during the outbound compared with the inbound leg. By selecting favourable winds, birds reached higher ground speeds without having to increase flapping flight. Selecting favourable wind conditions may be an adaptation to tropical pelagic habitats and ephemeral prey. Hidden Markov models, used to characterize behavioural states, revealed that birds were more likely to forage during windier conditions, perhaps aided by increased accessibility of flying fish—which a small sub-sample of bird-borne video cameras revealed were largely caught on the wing. We therefore show how wind has divergent consequences for foraging journeys and feeding events, with implications for understanding the ecological effects of climate change-driven wind alterations.