Most companion birds are capable of flight but live in conditions preventing it. The welfare implications of flight restriction are significant and underappreciated.
Flight is fundamental to bird biology. For species that spend hours daily in aerial locomotion in the wild, restriction to a cage or an aviary too small for sustained flight represents a profound welfare deprivation. Wing clipping — the trimming of primary feathers to prevent flight — is practiced routinely in the pet industry without welfare evidence to support it and considerable evidence of harm. Clipped birds cannot escape threatening situations, cannot exercise aerobically, and may develop musculoskeletal problems from reduced activity. Flighted birds in appropriate environments show better physical health, more complex behavior, and lower stress indicators.