Lions, tigers, leopards, and other big cats require vast territories in the wild that cannot be replicated in zoos.
Big cat welfare in captivity is constrained by the fundamental impossibility of providing adequate territory. Lions evolved for life in open savannah with complex social structures; captive housing in small enclosures with limited social opportunity cannot replicate this. Pacing in captive big cats is among the most well-documented stereotypic behaviours in zoo animals and indicates chronic frustration. Enrichment programs can partially address this but the ceiling for welfare improvement in captivity for wide-ranging carnivores is low.