Repeated environmental changes mitigate inter-individual inequality of food gain in a group foraging experiment with large-billed crows

Abstract

Animal group foraging produces inequality of food gain among individuals due to their differences, particularly dominance rank. External environmental factors, such as the spatial distribution of food, may mitigate the influence of social features on individual food acquisition. However, the role of environmental fluctuation in social foraging inequality remains largely unexplored Here, we investigated how repeated environmental changes affect inequality in food acquisition among captive large-billed crows (Corvus macrorhynchos). By repeatedly altering the relationship between feeding sites and food quantity, we examined changes in the inequality of food gains using Gini coefficient. In the short-term, food allocation became unequal immediately after each change but subsequently recovered. Over successive fluctuations, inequality in food acquisition declined in the long-term, while group foraging efficiency increased. We observed a significant influence of sex on food acquisition, while the expected effect of dominance rank was not detected. Our findings provide the first experimental evidence that changing environments can mitigate inequalities in food gains within foraging groups, highlighting the importance of incorporating naturalistic environmental changes into experimental designs for future group-foraging studies.