Successful recovery efforts have strengthened populations of kākāpō, a large, green, flightless parrot with an owl-like complexion endemic to New Zealand and once on the brink of extinction.

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Endemic to the island country of New Zealand, the kākāpō is a large, green, flightless parrot with an owl-like complexion. Regarded as a taonga species (treasured, prized) to Ngāi Tahu, the principal Māori iwi (tribe) of the South Island, the kākāpō evolved to be a distinct species approximately 30 million years ago, thus holding historical, cultural and spiritual significance locally. 

Although once widespread across mainland New Zealand, the introduction of hunting practices, invasive predators, and habitat loss caused rapid declines in kākāpō numbers, resulting in the species being deemed “Extinct in the Wild” by 1994. Nevertheless, recovery efforts have been successful in protecting and gradually strengthening remnant groups, with the current population of 236 kākāpō residing within fenced sanctuaries and on predator-free islands across New Zealand. 

Appearance

Kākāpō are incredibly unique, with the species owing its distinctive morphological and behavioral characteristics to the particular evolutionary context and selective pressures present on the Pacific islands prior to European colonization. 

Having evolved without the presence of mammalian predators, the kākāpō developed a large, robust torso physique well adapted to terrestrial life at the expense of flight capabilities. As a result, kākāpō are the heaviest species of parrot, with males weighing up to 4 kilograms and females weighing between 1-2.5 kilograms. Measuring between 58 and 64 centimeters in length, this remarkable bird uses its wings for balance and small falls, with only lighter females managing glides of 3-4 meters.

Easily identifiable by its moss-green coloration, brownish yellow mottling of feathers, and grey hooked beak, the ground-dwelling kākāpō’s plumage evolved to blend in with surrounding forest foliage, diverging from the distinctive bright, vivid pigments that typically adorn parrot species. Historically threatened only by large, diurnal birds of prey, the kākāpō’s camouflaging coloration, coupled with its tendency to freeze in the face of danger, allowed it to evade aerial predators with relative ease. With short, solid legs and large feet, kākāpō are strong hikers and climbers, using their hooked bills, a characteristic feature of parrot species, to climb up 20 meter tall rimu treesand parachute down with their wings.

Also known as the owl parrot, or night parrot in Māori, the kākāpō’s owl-like complexion is a result of morphological adaptations that support a nocturnal lifestyle. As one of only two species in an otherwise entirely diurnal group to evolve nocturnal behavior, the kākāpō has forward-facing eyes, lending a larger binocular visual field for enhanced light capture, and a flat facial disc of textured feathers. These direct sounds towards its ears, enabling this extraordinary species to navigate the forest floor at night. Typically walking with its head low to the ground, the kākāpō also possesses specialized, sensory feathers around its beak that act as vibrissae (whiskers), utilizing them to sense their environment in the dark.

Diet

The kākāpō is a herbivorous species with a diverse diet that varies seasonally, typically consuming leaves, stems, roots, bark, buds, flowers, fruit, nectar, seeds, and bulbs. Opting for new growth in the summer and spring months, and returning to bark and tubers in the autumn, the historic abundance of terrestrial food sources in New Zealand has been deemed a significant factor in the kākāpō’s evolution towards flightlessness.

Feeding almost exclusively on key species when plentiful, the kākāpō’s most crucial food source is the rimu fruit tree, with mass-fruiting events indicating the start of the kākāpō’s breeding season. The vitamin D and calcium found in the rimu fruit are essential to egg production and the growth of chicks, however mass-fruiting only occurs every two to five years. 

Identifiable by crescent-shaped chew marks, kākāpō are browsers, consuming high-fiber food sources rich in vitamins, minerals and protein. Unlike fellow parrot species that rely on a gizzard to digest food, the kākāpō has a finely ridged, concave upper mandible that grinds and compresses foliage as it passes through the bill from bottom to top, extracting nutrients and leaving behind a ball of indigestible fiber hanging from the plant.

Habitat and Behaviour 

Kākāpō have been a distinct species for approximately 30 million years, and were once widespread on mainland New Zealand prior to human colonization, inhabiting a wide range of vegetation types throughout the majority of the North, South and Stewart Islands. A model of kākāpō fossil records suggests that the species occurred in Hall’s tōtara, mountain beech, and broadleaf forests with mild winters and medium to high levels of precipitation. 

Kākāpō disappeared from New Zealand’s North Island by 1930, and from Fiordland towards the late 1980s. A declining population of less than 200 birds was found on Stewart Island in 1977. By 1995, there was a single kākāpō left on the mainland, and a mere 50 birds on Stewart Island. Throughout the 1980s and 1990s, all known kākāpō were transferred to Whenua Hou/Codfish Island, Maud Island, and Hauturu/Little Barrier Island, where protection measures and predator eradication campaigns were carried out. 

Today, kākāpō are only located on the protected offshore islands of Whenua Hou/Codfish Island, Pukenui/Anchor Island, Te Kākahu-o-Tamatea/Chalky Island, and Coal Island/Te Puka-Hereka, as well as in the fenced mainland sanctuary of Sanctuary Mountain Maungatautari, on New Zealand’s North Island.

As nocturnal foragers, kākāpō sleep in ground or tree-top roosts during the day. When disturbed or faced with danger, kākāpō freeze and rely on their coloration for camouflage, which has historically served as an excellent defense mechanism against avian predators that rely on sight. However, the introduction of mammalian, cathemeral predators that utilize their sense of smell to hunt, such as cats and stoats (short-haired weasels), rendered the distinctive-smelling, flightless kākāpō an easy prey source after European colonization. 

Although widely regarded as a solitary species, recent studies indicate that female kākāpō are occasionally found with young birds in groups of two to four individuals, socializing in the same tree or gathered near a food source. The kākāpō is the world’s only lek-breeding species of parrot, with mature males and females meeting solely to mate. Breeding occurs once every two to five years, coinciding with the superabundant seeding or fruiting period of key, high-nutrient food sources, such as rimu and pink pine trees. Each male kākāpō will form a track-and-bowl system, consisting of a network of tracks emanating from shallow, bowl-shaped pits in the ground, with tracks connecting two to three, or up to 10, bowls. The location of these systems remains fixed. From here, the male emits deep, low-frequency ‘boom’ sounds every one to two seconds, interspersed with metallic “ching” sounds to help navigate females towards them. Male mating calls can last roughly eight hours, every night for two or three months between early January and March. 

Once kākāpō mate, males are not involved in incubation or parental care. Females will lay between one and four eggs in a sheltered nest, such as a hollow tree, a shallow depression in the soil, or a cave made from roots and rocks. Females will leave their eggs and chicks unattended each night to forage for food. Chicks typically fledge after 10 weeks, relying on their mothers for a further three to six months until they can forage independently. 

Kākāpō are amongst the longest-living avian species, with an average lifespan of 60 years but able to live up to 90 years in the wild.

Ecological Importance 

The kākāpō is an ancient, incredibly unique species native to the forests of New Zealand, holding significant cultural significance and ecological importance to the ecosystems it inhabits. Regarded as a “super-generalist” herbivore, consuming a wide variety of plants, fruits, and seeds, the kākāpō plays a crucial role in maintaining the health and vitality of forests through seed dispersal, supporting the regeneration of native vegetation and creating a balanced ecosystem. A distinct species for 30 million years and once widespread across New Zealand, the ecological consequences of the kākāpō’s extinction would not be immediately discernible, yet undoubtedly inevitable. 

The evolutionary distinctiveness of the kākāpō, as the world’s only flightless, lek-breeding parrot, further represents a unique, fascinating result of natural history that could help scientists better understand evolutionary biology and conservation genetics. In 2021, a study containing the first genome sequencing and population genomic analyses of 49 kākāpō was published, shedding light on the effect of evolutionary forces on the species over time. The research is hoped to provide insights into the use of genetic tools in the conservation of long-term isolated endangered species. 

As mentioned, the kākāpō is a taonga species for the principal Māori iwi of the South Island, Ngāi Tahu, holding profound cultural, spiritual and historical significance and viewed as an animal to be treasured. Conservation efforts, which commenced 30 years ago and have had incredible results due to the combined work of iwi, rangers, volunteers, scientists and supporters, have become a totem of national identity and environmental conservation in New Zealand, with the kākāpō viewed as a flagship species to advocate the protection of native biodiversity.

Threats

Although once well-adapted to the particular, localized selective pressures of its native island, the kākāpō suffered catastrophic population declines with the human colonization of New Zealand, no longer able to effectively evade predation with the introduction of mammalian, terrestrial predators. Upon arriving in New Zealand roughly 700 years ago, the Māori began hunting kākāpō as a food source, as indicated by sub-fossil remains found in Māori middens (archeological cooking refuse piles), as well as for their feathers in the production of clothes. 

Two terrestrial mammals were also introduced by Māori settlers, the kurī (Polynesian dog) and kiore (Polynesian rat). Whereas kurī mainly served as companions and hunting aids, the kiore were brought as a source of food, rapidly becoming a widespread, invasive species that significantly affected Indigenous fauna. By the early 1800s, kākāpō were mainly confined to the central North Island and within forested areas of the South Island. 

Cats were introduced to New Zealand from 1769, initially intended as a means of vermin control aboard the ships of European colonizers. By 1820, feral cat populations, as well as two new species of rats, had settled on the islands, becoming widespread pests. As land was increasingly cleared for farming and grazing, mammals such as stoats and weasels were introduced as a biological control method against fast-growing rabbit populations that had destroyed pastoral land. It is believed that between 1883 and 1892, approximately 7,800 stoats and weasels were imported to New Zealand, with populations that had been released solely on rabbit-infested pastures quickly spreading across most parts of the North and South Islands. From 1851, several species of deer were introduced to New Zealand for recreational hunting, and in 1858 the first group of common brushtail possums were imported in an attempt to establish a profitable fur trade. With no natural predators, possum and deer populations rapidly increased, damaging native forests and depleting food sources.

Due to the kākāpō’s distinctive smell, which has been described as “like the inside of a clarinet case, musty and kind of like resin and wood,” coupled with the flightless bird’s tendency to freeze when confronted by danger, populations suffered rapid declines with the introduction of scent-driven, invasive predators. With a prolonged period of chick-rearing, resulting in a pungent-smelling nest, and given that kākāpō mothers leave their nests at night to forage for food, kākāpō chicks and eggs were rendered highly vulnerable to predation by rats. In a 1998 study, researchers found that over 50% of monitored adult kākāpō were killed each year by cats on Stewart Island. Once European colonizers became aware of the unique species, thousands of kākāpō were also captured for export to zoos, museums and for scientific study. 

As with many endangered species, reproductive failure is also a significant concern and impediment to population recovery. In addition to having irregular breeding seasons and a specialized lek mating system, kākāpō have exhibited high rates of reproductive failure, with 61% of eggs failing to hatch and 73% of these failed eggs showing no signs of development. Studies conducted on kākāpō bone fragments recovered from Māori middens and museum specimens indicate that the species once had asignificant degree of genetic diversity, yet centuries of population declines and isolation have inevitably resulted in a substantial level of inbreeding. Of 10 genetic lineages identified from bone fragments, only one remains today.

Due to the kākāpō’s small population size and low genetic diversity, disease has also been noted as a significant threat to the species’ recovery. In 2004, three juvenile kākāpō died of septicaemia caused by the bacterial infection erysipelas (Erysipelothrix rhusiopathiae), which had not previously been observed in the species. First identified in 2002, exudative cloacitis has affected at least 15 kākāpō, causing inflammation of the digestive and reproductive tracts, often resulting in infertility. Of most concern, however, was an outbreak of aspergillosis (a respiratory disease) in 2019 during a highly successful nesting season, which affected 21 kākāpō and resulted in nine fatalities among a total population of 147 individuals at the time. 

Conservation Efforts

The kākāpō is currently listed under Appendix I of the Convention on International Trade in Engendered Species (CITES), and is protected under New Zealand’s Wildlife Act of 1953, classified as “Nationally Critical” by the Department of Conservation.

In 1894, the government of New Zealand launched an initial attempt to save remaining kākāpō populations, with pioneer conservationist Richard Henry transferring several hundred kākāpō to a newly established, predator-free nature reserve on Resolution Island in Fiordland. Within six years, however, stoats had successfully reached the island and decimated the relocated population. 

By the mid-1900s, the kākāpō had become a forgotten species, rarely seen. Between 1949 and 1973, the newly established New Zealand Wildlife Service conducted over 60 expeditions to locate surviving kākāpō, focused primarily on Fiordland. However, only six males were caught and all but one died within a few months. In 1974, a further 18 males were captured on Fiordland, and in 1977, researchers made the remarkable discovery of approximately 200 kākāpō on Rakiura/Stewart Island. This population, which included females, had survived due to the absence of stoats, weasels and ferrets, yet predation by feral cats remained a significant threat. Therefore, between 1980 and 1997, these Rakiura kākāpō were transferred to three offshore island sanctuaries: Codfish Island/Whenua Hou, Maud Island, and Te Hauturu-o-Toi/Little Barrier Island. Although these islands were free of cats and stoats, rats prayed heavily upon eggs and chicks, hindering the species’ breeding success. By 1995, of 12 chicks that had successfully hatched across the three islands, only three survived, and the total kākāpō population had plummeted to a mere 51 birds. Recognizing the urgency of the situation, the Department of Conservation (replacing the New Zealand Wildlife Service) established the Kākāpō Recovery Programme in 1995, focusing on the eradication of predators and breeding support. 

In 1996, however, the New Zealand government faced the Ngāi Tahu tribe with regards to the colonial theft of their land, Codfish Island/Whenua Hou, which had been converted into a nature reserve in 1986 and rendered inaccessible to tribe members. As a result, the Ngāi Tahu Deed of Settlement was signed: Ngāi Tahu was given a distinct role in the management of Whenua Hou and in the conservation of the kākāpō, recognizing the tribe’s historic connection with the species as their kaitiaki (guardians). The Kākāpō Recovery Group was thus formed, incorporating representatives from Ngāi Tahu, the Department of Conservation, and the scientific community to develop holistic strategies for kākāpō conservation that unify both Western and Indigenous approaches to revive native, endangered species. 

Rats were eradicated from Codfish Island/Whenua Hou in 1998, and the island now serves as the center for Kākāpō Recovery in New Zealand, providing a similar habitat to that of Rakiura. The Department of Conservation maintains trap networks and employs detection strategies to prevent any future rat invasions on the island. 

In 2005, stoats were eradicated from Pukenui/Anchor Island, and the first kākāpō were transferred in 2005. Although the island is within swimming distance of the mainland for stoats, traps are regularly monitored to prevent disturbances. Te Kākahu-o-Tamatea/Chalky Island was subject to stoat eradication in 1999, and kākāpō were introduced in 2003. In 2020, a small breeding population was established, where scientists trial natural, low intervention population management strategies. Codfish Island, Anchor Island and Chalky Island all have abundant rimu forests that undergo mass-fruiting events every three to five years, supporting kākāpō breeding efforts. Imported items undergo a strict quarantine process prior to entering the islands, whereby clothes, food, gear, and the vehicle on which they arrived are disinfected and thoroughly checked to ensure the absence of any rats, insects, seeds or dirt.

In July 2023, the kākāpō returned to mainland New Zealand as a small, male population was translocated to the protected forest reserve of Sanctuary Mountain Maungatautari in Waikato, North Island. Enclosed by a 47 kilometre pest-proof fence, the sanctuary houses an ecosystem similar to that of a pre-human New Zealand environment, serving as a refuge for many of the country’s endangered species. This small population is under close observation to determine whether a larger group could flourish at the site. In May 2024, a number of male kākāpō were transferred to Coal Island/Te Puka-Hereka, which is home to a low number of stoats. Viewed as a trial site, conservationists hope to better understand whether low stoat densities pose a significant threat to kākāpō, and thus whether the island holds any potential of supporting a breeding population.

The continued and growing need for new, suitable kākāpō habitats is largely reliant on the success of initiatives such as Predator Free Rakiura and Predator Free 2050, with the Kākāpō Recovery Group ultimately aiming to return kākāpō to their historic range across New Zealand without the need for population management. At present, all kākāpō are radio-tagged and monitored throughout the year, and nests are closely observed during breeding seasons. Once a year, the Department of Conservation carries out a health check on each kākāpō, noting their weight, moulting condition, and any signs of injury or illness, later uploading this information onto a national database. Chicks are examined every one to five days while nesting, every two to six weeks for five months once fledged, and every three months until they reach the age of two. Kākāpō also receive supplemental feedings most years to ensure that the birds remain in good reproductive condition, as well as to increase egg production and support chick-rearing. Artificial insemination has additionally proven a successful tool in conservation efforts, boosting fertility by increasing the number of eggs produced, and improving genetic diversity by pairing birds that are likely to be genetically compatible. 

Once a female kākāpō has laid her eggs, some may be removed for artificial incubation, which replicates the temperature and humidity of a nest, and replaced by “smart eggs” to prepare the mother for when the chick is returned once hatched. If the mother has too many chicks, or if a chick falls ill or appears underweight, they are removed from the nest and hand-reared. Hand-reared chicks are kept together, and returned to the wild at the age of four months to avoid negative imprinting, whereby the bird identifies with humans and refuses to mate with its own species. As of early 2024, 69 kākāpō were hand-reared and returned to their natural habitat with a survival rate of 100%. It is hoped that effective nest management strategies and supplementary feedings will reduce the need for hand-rearing further by increasing the health of kākāpō, thereby allowing the chick-rearing process to occur as naturally as possible.

Due to the fact that the kākāpō population plummeted to a mere 51 birds in 1995, creating a genetic bottleneck, most kākāpō today descend from the same isolated island population. As a result, the species suffers from extremely low genetic diversity, having undergone a significant degree of inbreeding. It has been determined that approximately half of the current kākāpō population carry the same set of disease resistance genes; should a disease to which that particular genome type is susceptible spread across remaining kākāpō groups, the entire population could go extinct. Inbreeding has also been noted as a potential cause for the kākāpō’s low fertility rates, with approximately 61% of kākāpō eggs having failed between 1981 and 2019. As a result, genomic studies have been at the forefront of kākāpō conservation in recent years. 

In 2015, the Kākāpō125+ project commenced with the aim of sequencing the genomes of every living kākāpō. As of 2018, the genomes of 169 to 171 kākāpō have been sequenced, providing conservationists with insights into genetic signatures for diseases, genetic bases for fertility, including sperm quality, clutch size, incubation and hatching success, and genetic management, including the viability of offspring resulting from artificial insemination. In 2019, the largest kākāpō breeding season to date occurred, allowing scientists to determine whether the kākāpō’s high rates of hatching failure were due to fertilization failure or embryo mortality, with the differentiation deemed critical to creating effective breeding management strategies. The results of the study, published in 2021, demonstrated that early embryo mortality is the main reason for kākāpō reproductive failure, contradicting previous assumptions that infertility was the primary cause. Early embryo mortality was found to be driven by inbreeding depression on early survival, with the study highlighting the potential importance of artificial insemination as a management tool for wild kākāpō populations. 

On February 14, 2026, the first kākāpō chick of the breeding season hatched on Pukenui/Anchor Island, marking an incredible step in kākāpō conservation. With the last breeding season having occurred four years ago in 2022, there have been 187 eggs laid this season, 74 of which are fertile. Although not all eggs will hatch and not all chicks will survive to fledge, the inspiring efforts of the Kākāpō Recovery Group, through the Kākāpō Recovery Programme, have demonstrated the remarkable results that can stem from cooperation between government bodies, native iwi, rangers, volunteers and the scientific community to protect a species that was once on the very brink of extinction.

Featured image: Jake Osborne/Flickr.

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