The social hierarchy in chicken flocks creates welfare challenges through chronic subordination stress that affects the health and psychological wellbeing of low-ranking individuals in large commercial flocks.
Chronic subordination stress in large commercial flocks creates ongoing psychological and physiological harm for lower-ranking hens that cannot escape or establish stable relationships. Unlike small natural flocks where hierarchies stabilize, large commercial flocks have too many individuals for stable recognition, creating perpetual uncertainty and agonistic interactions. Environmental modifications that reduce visibility and provide refuges dramatically reduce aggressive interactions. Breed selection for reduced aggression offers a genetic approach. Both require recognition that behavioral welfare extends beyond physical health into social psychological wellbeing.