The kākāpō is the only living parrot known to nest underground.
This flightless, nocturnal parrot excavates or uses natural cavities beneath tree roots, rocks, or dense vegetation. Females raise chicks in these sheltered spaces, returning repeatedly to feed them. The species evolved in New Zealand without native land mammals that could hunt it, so it developed an unusual combination of flightlessness, ground living, and nocturnal behavior.
The kākāpō is also the world’s heaviest living parrot, although that fact is separate from its underground nesting habit. It has moss-green plumage, a strong smell, and a distinctive booming call used by males during breeding displays.
Introduced predators such as rats, cats, and stoats caused severe declines. Intensive conservation now involves managed islands, tracking, supplementary feeding, and careful monitoring of every known bird. The species remains critically endangered.