The chicken pecking order is a natural social hierarchy, but intensive housing conditions cause pathological feather pecking that causes significant welfare harm.
Feather pecking welfare is a systems problem - the behavior arises from the interaction between natural hen behavior and housing conditions that prevent its expression in appropriate ways. Hens redirect intense pecking motivation to conspecifics when lacking appropriate substrate to peck, while high stocking densities prevent social hierarchy establishment and increase aggression. Beak trimming prevents the worst consequences of feather pecking but does not address its causes and itself causes welfare harm. The welfare solution requires addressing the housing conditions driving feather pecking through enrichment, lower density, and breed selection - addressing cause rather than symptom.