The critically endangered Kakapo (Strigops habroptilus) is a flightless, nocturnal parrot native to New Zealand. It possesses few defenses against introduced mammalian predators, has a low reproductive rate, and usually lays only a single egg. Apart from being the world’s heaviest parrot, the only flightless parrot, it is the only parrot that provides no parental care to its offspring.
This parrot species is an example of a species that has evolved a nocturnal lifestyle in an otherwise diurnal species. The Kakapo has a unique visual system unlike that of other parrots or any other bird examined to date. This bird possesses traits consistent with nocturnal birds, including owls (retina, eye size and shape and orbit orientation), and kiwi (brain structure), and also diurnal birds (eye size and shape).
The Kakapo generate two types of vocalisation: booming, which is a very low frequency call and chinging, which is a relatively high frequency call. These low frequency signals fall near or below the threshold of human hearing (20 Hz).
The kakapo breeds on average once every 2 – 5 years. Breeding is clearly linked to masting years of fruits of podocarp trees such as rimu (Dacrydium cupressinum), which are the principal food used by females for rearing the young. This strongly suggests that the decision by female Kakapo of whether or not to breed is linked to nutrition.
Although kakapos were once common throughout New Zealand, the population has declined to 125 individuals, confined to three predator-free islands off the coast of New Zealand. This critically endangered New Zealand parrot is subject to intensive management aiming to maintain bird health and boost population size. Newly hatched kakapo chicks are frequently placed in captivity throughout their formative months. Hand rearing greatly reduces mortality among juveniles.