Colony cages were introduced as a welfare improvement over battery cages, but they still restrict natural behaviors and cause significant welfare problems.
Colony cage hens have somewhat more space than battery cages but still cannot express key natural behaviors including full wing-spreading, dust bathing, and foraging. High stocking density causes chronic aggression. Nest box access is limited and competitive. Perches are often too few for all birds. While better than battery cages, colony systems still fall far short of the behavioral needs of chickens. Truly cage-free systems with outdoor access provide substantially better welfare.