Horizontal-vertical movement relationships: Adélie penguins forage continuously throughout provisioning trips

Abstract Background Diving marine predators forage in a three-dimensional environment, adjusting their horizontal and vertical movement behaviour response to environmental conditions the spatial distribution of prey. Expectations regarding horizontal-vertical movements are derived from optimal foraging theories, however, inconsistent empirical findings across range taxa suggests these behavioural assumptions not universally applicable. Methods Here, we examined how changes trajectories corresponded with diving for ubiquitous Southern Ocean predator, Adélie penguin. Integrating extensive telemetry-based datasets chick-rearing penguins at Béchervaise Island, tested relationships between move persistence (continuous scale indicating low [‘resident’] high [‘directed’] autocorrelation), dive effort variables. Results Penguins dived continuously over course trips lower less intense activity, likely indicative resting behaviour. This challenges traditional interpretation based on models, which assumes increased residency within an area translates activity. Movement was also influenced by different during two stages chick-rearing: guard crèche. These differences highlight strong seasonality habitat Island. Conclusions Our advance our understanding this predator demonstrates importance integrating location data before inferring use.