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 tracked 116 breeding Adélie penguins (Pygoscelis adeliae), corresponding to 43% of active breeders in a colony, across 653 foraging trips and examined their movement decisions. We found that foraging site selection was often predicted by individuals’ own previous space use, but in 21.7% 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 and use, particularly under unfavourable foraging conditions. Our study presents a potential pathway by which sociality reduces uncertainty about the foraging environment, underscoring the costs of population decline for species that rely on social foraging.