Gorilla nest building is a nightly ritual that reflects sophisticated cognitive and physical capacities, and sleep quality is a key indicator of gorilla welfare.
Gorillas deprived of appropriate nesting materials in captivity cannot express a behavior that occupies nightly time in the wild and appears to have important rest-quality implications. Facilities that provide adequate nesting material observe better sleep quality and reduced nocturnal stress behaviors. Nest-building is not merely a curiosity - it is a fundamental behavioral need that welfare-conscious facilities must accommodate.