The Kakapo is a critically endangered large flightless parrot that is endemic to New Zealand. It has finely blotched yellow-green plumage, a distinct facial disc, a large grey beak, short legs, large feet, and relatively short wings and tail. A combination of traits make it unique among its kind; it is the world's only flightless parrot, the heaviest parrot, nocturnal, and is the only parrot to have a polygynous lek breeding system with no male parental care. It is also possibly one of the world's longest-living birds.
Before the arrival of humans, the kakapo was distributed throughout both main islands of New Zealand. Today they can be found only on islands free of predation; these are Codfish, Anchor, and Little Barrier Islands. Kakapo lived in a variety of habitats, including tussocklands, scrublands, and coastal areas. They also inhabited forests dominated by podocarps, beeches, tawa, and rata. These birds seem to have preferred broadleaf or mountain beech and Hall's tōtara forest with mild winters and high rainfall, but they were not exclusively forest-dwelling. All kakapo that were transferred to predator-free islands have adapted well to any changes in the environment and food plants.
Kakapos are primarily nocturnal; they roost undercover in trees or on the ground during the day and move around their territories at night. Though kakapos cannot fly, they are excellent climbers, ascending to the crowns of the tallest trees. They can also "parachute" - descending by leaping and spreading their wings. In this way, they may travel a few meters at an angle of less than 45 degrees. On the ground, they move with a rapid "jog-like" gait by which they can move several kilometers. Kakapos are curious by nature and have been known to interact with humans; however, they are not social birds. When they feel threatened, kakapos freeze so that they are more effectively camouflaged in the vegetation their plumage resembles. Like many other parrots, kakapos have a variety of calls. As well as the 'booms' and 'chings' of their mating calls, they will often loudly 'skraark'.
Kakapos are polygynous and don't form pairs; males and females meet only to mate. These birds are the only flightless birds that have a lek breeding system. Males loosely gather in an arena and compete with each other to attract females. During the courting season, males leave their home ranges for hilltops and ridges where they establish their own mating courts and remain there throughout the courting season. At the start of the breeding season, males will fight to try to secure the best courts. They confront each other with raised feathers, spread wings, open beaks, raised claws, and loud screeching and growling. Females listen to the males as they display, or "lek". They choose a mate based on the quality of his display; they are not pursued by the males in any overt way. Once a female enters the court of one of the males, the male performs a display in which he rocks from side to side and makes clicking noises with his beak. After mating, the female returns to her home territory to lay eggs and raise the chicks. The male continues booming in the hope of attracting another female. Kakapos do not breed every year, but usually every 2-4 years. Breeding occurs only in years when trees mast (fruit heavily), providing a plentiful food supply. The female lays 1-4 eggs per breeding cycle. She nests on the ground under the cover of plants or in cavities such as hollow tree trunks. The female incubates the eggs faithfully but is forced to leave them every night in search of food. The eggs usually hatch within 30 days, bearing fluffy grey chicks that are quite helpless. After the eggs hatch, the female feeds the chicks for 3 months, and the chicks remain with the female for some months after fledging. Chicks leave the nest at approximately 10 to 12 weeks of age. As they gain greater independence, their mother may feed them sporadically for up to 6 months. Female kakapos usually reach reproductive maturity at 9 years of age.
Kakapos were once New Zealand's third most common bird and they were widespread on all three main islands. The first factor in the decline of the species was the arrival of humans. Maori hunted the kakapo for food and for their skins and feathers. Its eggs and chicks were also preyed upon by the Polynesian rat or kiore, which the Māori brought to New Zealand as a stowaway. Furthermore, the deliberate clearing of vegetation by Māori reduced the habitable range for kakapo. Although these birds were reduced by Māori settlement, they declined much more rapidly after European colonization. Beginning in the 1840s, Pākehā settlers cleared vast tracts of land for farming and grazing, further reducing kakapo habitat. They brought more dogs and other mammalian predators, including domestic cats, black rats, and stoats. Early European explorers and their dogs also ate kakapo. In the late 19th century, these birds became well known as a scientific curiosity, and thousands were captured or killed for zoos, museums, and collectors. From at least the 1870s, collectors knew the kakapo population was declining and their prime concern was to collect as many as possible before the bird became extinct.
According to the IUCN Red List, in 2018 the total Kakapo population size was 149 individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List but its numbers today are increasing.