Orangutans are the most solitary of the great apes and have highly complex cognitive needs. Welfare in zoological collections must address their need for cognitive challenge, complex arboreal environments and semi-solitary social structure.
Orangutan welfare in captivity requires reconciling their cognitive complexity with their semi-solitary social preferences. A great ape confined with an incompatible partner is in a permanently stressful situation; but an orangutan without any social choice and with limited cognitive stimulation is also in poor welfare. The best orangutan facilities provide choice - ability to access or retreat from social contact, complex multi-level arboreal structures, extensive foraging and cognitive challenge, and keeper relationships built on trust and positive reinforcement. Welfare assessment must respect individual personality differences - orangutans show marked individual variation in sociality preferences.