Orangutans are the most arboreal of the great apes, spending most of their lives in tree canopies. Providing adequate vertical complexity and cognitive enrichment in captivity is essential to their welfare.
Orangutan welfare in captivity requires extraordinary investment in three-dimensional space and cognitive complexity. Their arboreal nature means that ground-level enclosures, however large, fail to meet fundamental behavioral needs. Their high intelligence means that unstimulating environments rapidly produce psychological deterioration visible as stereotype and abnormal behavior. The best welfare outcomes come from sky-high climbing structures, frequent novel enrichment, and respect for their natural semi-solitary social preference.