They nest in burrows under rocks or among tree roots. Keas have a clutch of two to four eggs, and incubate the eggs for three to four weeks. The altricial hatchlings fledge after 13 weeks. These parrots are highly social, and they live in family groups until they reach sexual maturity. Males are sexually mature after four or five years, while females can become sexually mature as early as three years of age.
Female keas remain in their natal area, while young males have been observed dispersing.
The mating system is polygynous. It has been proposed that life in an extreme alpine environment has encouraged keas to explore their surroundings. They commonly investigate human belongings, and are known to destroy car accessories and ski lodge equipment. Experiments on cooperation in keas suggest that dominant individuals can force subordinants to cooperate in tasks that benefit only the dominant birds. In summer, kea parrots inhabit upper scrub and grassland areas, and in autumn, move to higher elevations to forage for berries.