Unsuccessful foragers acquire social information through group departure and travel in penguins

Colonial animals are theoretically expected to use social information to reduce uncertainty regarding food location and quality; however, few empirical studies have investigated how they acquire and when they rely on such information. Here, we simultaneously tracked 96-116 breeding Adélie penguins (Pygoscelis adeliae), corresponding to 35.6-43.0% of active breeders in a colony, across 653 foraging trips, and examined their movement decisions. We found that foraging site selection was most often predicted by individuals' own previous space use, but in 17.1% of trips, it was better predicted by incorporating the prior space use of conspecifics that departed the colony together. Notably, the simulation with random replacement tests indicated that group departure is a prerequisite for the effects of conspecifics on foraging site selection. Furthermore, penguins with unsuccessful prior trips, quantified as a reduced frequency of foraging dives, changed foraging sites more frequently than those with successful prior trips, relying more on the experiences of conspecifics. These findings suggest that group departure and travel facilitate social information acquisition, particularly for individuals that have recently been unsuccessful in foraging trips. Our study highlights the strategic use of social information and its potential benefits for foraging penguins.