These flightless birds feature finely blotched yellow-green plumage, a facial disc, owl-style forward-facing eyes with discs of specially-textured feathers, a huge grey beak, short legs, massive blue feet, and comparatively short wings and tail. It's the only flightless parrot, the heaviest parrot, nocturnal, herbivorous, sexually dimorphic in body size, has a low basal metabolic rate, and lacks male parental care. It's the only parrot with polygynous leks. It's one of the world's longest-lived birds, surviving up to 100 years.
Its anatomy shows how birds evolve on marine islands with few predators and plentiful food (a generally-robust torso physique at the expense of flight abilities, resulting in reduced shoulder- and wing-muscles along with a diminished keel on the sternum). The kakapo was historically important to Māori, New Zealand's indigenous people. It featured in mythology and folklore. Māori hunted and exploited it as a resource (both for its meat and for its feathers, which were used to make highly-valued pieces of clothing). Kakapo were rare pets.
The kakapo is highly endangered; there are 197 identified and tagged adults on four islands off New Zealand's coast that have been cleared of predators.
During British colonisation, cats, rats, ferrets, and stoats nearly killed off the already-rare kakapo, which had been overhunted by early Māori. Conservation efforts began in the 1890s but were not effective until the Kakapo Recovery Programme in 1995.
Most kakapo are housed on two predator-free tiny islands, Codfish / Whenua Hou and Anchor. Little Barrier / Hauturu Island is being tested as a third habitat for the species.