Kakapo are critically endangered; only 91 living individuals are known, all of which have been given names. The ancestral Kakapo migrated to the islands of New Zealand in prehistory; in the absence of mammalian predators, it lost the ability to fly. Because of Polynesian and European colonisation and the introduction of predators such as cats, rats, and stoats, most of the Kakapo were wiped out. Conservation efforts began in the 1890s, but they were not very successful until the implementation of the Kakapo Recovery Plan in the 1980s. As of November 2005, surviving Kakapo are kept on four predator-free islands, Maud, Chalky (Te Kakahu), Codfish (Whenua Hou) and Anchor islands, where they are closely monitored. Two large Fiordland islands, Resolution and Secretary, have been the subject of large-scale ecological restoration activities to prepare self-sustaining ecosystems with suitable habitat for the Kakapo.
The conservation of the Kakapo has made the species well known. Many books and documentaries detailing the plight of the Kakapo have been produced in recent years, one of the earliest being Two in the Bush, made by Gerald Durrell for the BBC in 1962. Two of the most significant documentaries, both made by NHNZ, are Kakapo - Night Parrot (1982) and To Save the Kakapo (1997). The BBC's Natural History Unit also featured the Kakapo, including a sequence with Sir David Attenborough in The Life of Birds. It was also one of the endangered animals that Douglas Adams and Mark Carwardine set out to find for the radio series and book Last Chance to See.
The Kakapo, like many other bird species, has historically been important to the Māori, the indigenous people of New Zealand, appearing in many of the traditional legends and folklore.
Kakapo are large, rotund parrots; males measure up to 60 centimetres (24 in) and weigh between 2 and 4 kilograms (4.5–9 lb) at maturity. Kakapo are unable to fly, having short wings for their size and lacking the pronounced keel bone (sternum) that anchors the flight muscles of other birds. They use their wings for balance, support, and to break their falls when leaping from trees. Unlike other land birds, Kakapo can accumulate large amounts of body fat to store energy making them the heaviest parrot.
The upper parts of the Kakapo have yellowish moss-green feathers barred or mottled with black or dark brownish grey, blending well with native vegetation. Individuals may have strongly varying degrees of mottling and colour tone and intensity — museum specimens have shown that some birds had completely yellow colouring. The breast and flanks are yellowish-green streaked with yellow. Their bellies, undertail, necks and faces are predominantly yellowish, streaked with pale green and weakly mottled with brownish-grey. Because the feathers do not need the strength and stiffness required for flight, they are exceptionally soft, giving rise to the specific epithet habroptilus. Kakapo have a conspicuous facial disc of fine feathers, resembling the face of an owl; thus, early European settlers called it the "owl parrot". Their beaks are surrounded by delicate vibrissa or "whiskers", which they use to sense the ground for navigation as they walk with their heads lowered. The mandible is mostly ivory-colored, with part of the upper mandible being bluish-grey. The eyes are dark brown. Kakapo feet are large, scaly, and, as in all parrots, zygodactyl (two toes face forward and two backward). They have pronounced claws particularly useful for climbing. The ends of their tail feathers often become worn from being continually dragged on the ground.
Females are easily distinguished from males due to some notable differences: they have a more narrow and less domed head, their beaks are narrower and proportionally longer, their ceres and nostrils smaller, their legs and feet more slender and pinkish grey, and their tails are proportionally longer. While their plumage color is not very different to that of males, the toning is more subtle, with less yellow and mottling. They tend to be more resistant and aggressive than males when handled. Nesting females are also distinguished by a brood patch on the bare skin of the belly.
Like many parrots, Kakapo have a variety of calls. In addition to the booms (see below for a recording) and chings of their mating calls, they often skraark to announce their location to other birds.
Kakapo have a well-developed sense of smell, which complements their nocturnal lifestyle. They can discriminate among odours while foraging; a behaviour reported for only one other parrot species. One of the most striking characteristics of Kakapo is their pleasant and powerful odour, which has been variously described as musky, honey-like or fruity. Given the Kakapo's well-developed sense of smell, this scent may be a social chemosignal. The smell often alerts predators to the largely defenseless Kakapo.
Earlier ornithologists felt the Kakapo may be related to the Ground Parrot and Night Parrot of Australia; others pointed to the Nestorini tribe. A 2005 sex chromosome spindlin DNA sequence study confirmed affinities with the genus Nestor, which contains the Kākā and the Kea. The molecular data further suggests that the two Nestor species, and the Kakapo in its own genus, comprise an ancient group that split off from all other Psittacidae before their radiation, but fossil evidence seems to contradict this; given the violent geological history of New Zealand (see, for example, Taupo Volcanic Zone), other explanations such as episodes of genetic drift seem better supported by evidence.
The only mammals native to New Zealand are three species of small bats (one extinct). It seems that the Kakapo — like many of New Zealand's bird species — has evolved to occupy an ecological niche normally filled by various species of mammal. Before the arrival of humans, Kakapo were largely distributed throughout the three main islands of New Zealand. They lived in a variety of habitats, including tussocklands, scrublands and coastal areas. They also inhabited forests, including those dominated by podocarps (rimu, matai, kahikatea, totara), beeches, tawa, and rata. They particularly favored forest margins and areas of regenerating forest for the wider variety of vegetation in a compact area . In Fiordland, areas of avalanche and slip debris with regenerating and heavily fruiting vegetation — such as five finger, wineberry, bush lawyer, tutu, hebes, and coprosmas — became known as "Kakapo gardens .
Kakapo are primarily nocturnal; they roost under cover in trees or on the ground during the day and rove their territories at night.
Though the Kakapo 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.
Having lost the ability to fly, they have developed strong legs. Movement is often by way of a rapid "jog-like" gait by which they can move many kilometres. Females make two return trips each night during nesting from their nest to the food source up to 1 km (0.5 miles) away and males walk from their home ranges to the mating arena up to 5 km (3 miles) away during the mating season (October–January).
Kakapo are a curious species and have been known to interact with humans. Conservation staff and volunteers have engaged extensively with some Kakapo, and they are known to have distinct personalities.
The Kakapo were a very successful species in pre-human New Zealand and one of the reasons for this was their set of adaptations to effectively avoid predation from native birds of prey - which were their only predators in the past. However, these same behaviours have been of no use to them when faced with the mammalian predators which have been introduced to New Zealand following human settlement, as these hunt in different ways. As hunters, birds behave very differently to mammals, relying on their incredible powers of vision to find prey and thus,they usually, (with the exception of Owls) hunt by day. We know that apart from the 2 surviving NZ raptors, the New Zealand Falcon and Australasian Harrier, there were two additional birds of prey in New Zealand in pre-human times; Haast's Eagle and Eyles' Harrier. All 4 species soared overhead searching for prey in daylight and to avoid these avian predators, the kakapo's ancestors adopted camouflaged plumage and became nocturnal. In addition, when Kakapo feel threatened, they freeze, so that they are more effectively camouflaged in the forest vegetation which their plumage resembles. It was not entirely safe at night however as the Laughing Owl was active at this time and it is apparent from their nest deposits on Canterbury limestone cliffs that Kakapo were among their victims.
Mammalian predators, in contrast to birds, rely on their sense of smell and hearing to find prey and often hunt by night. The Kakapo's adaptations to avoid avian predation have thus been quite useless against their new enemies - this is one of the reasons for their massive decline since the introduction of dogs, cats and mustelids following human settlement - see Conservation: Human impact. A typical way for humans to hunt down Kakapo is by releasing trained dogs.
Kakapo diet changes seasonally. The plants eaten most frequently during the year include some species of Lycopodium ramulosum, Lycopodium fastigium, Schizaea fistulosa, Blechnum minus, Blechnum procerum, Cyathodes juniperina, Dracophyllum longifolium, Olearia colensoi and Thelymitra venosa. Individual plants of the same species are often treated differently. Kakapo leave conspicuous evidence of their feeding activities, from 10×10 m to 50×100 m feeding ground areas. Manuka and yellow silver pine scrubs are obvious signs of their center of feeding activities.
The Kakapo is the only species of parrot in the world, the only bird in New Zealand, and the only flightless bird anywhere that has a lek breeding system. Males loosely gather in an arena and compete with each other to attract females. Females watch the males 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. No pair bond is formed; males and females meet only to mate.
During the courting season, males leave their home ranges for hilltops and ridges where they establish their own mating courts. These leks can be up to 7 kilometres (4 mi) from a Kakapo's usual territory and are an average of 50 metres (160 ft) apart within the lek arena. Males remain in the region of their court 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. Fighting may leave birds with injuries.
Each court consists of one or more saucer-shaped depressions or "bowls" dug in the ground by the male, up to 10 centimetres (4 in) deep and long enough to fit the half-metre length of the bird. Kakapo are one of only a handful of birds in the world which actually construct their leks. Bowls are often created next to rock faces, banks, or tree trunks to help reflect sound - the bowls themselves function as amplifiers to enhance the projection of the males booming mating calls. Each male’s bowls are connected by a network of trails or tracks which may extend 50 metres (160 ft) along a ridge or 20 metres (60 ft) in diameter around a hilltop. Males meticulously clear their bowls and tracks of debris. One way researchers check whether bowls are visited at night is to place a few twigs in the bowl; if the male visits overnight, he will pick them up in his beak and toss them away.
To attract females, males make loud, low-frequency (below 100 Hz) booming calls from their bowls by inflating a thoracic sac. They start with low grunts, which increase in volume as the sac inflates. After a sequence of about 20 loud booms, the volume drops off. The male Kakapo then stands up for a short while before again lowering his head, inflating his chest and starting another sequence of booms. The booms can be heard at least one kilometre (0.6 mi) away on a still night; wind can carry the sound at least five kilometres (3 mi). Males boom for an average of eight hours a night; each male may produce thousands of booms in this time. This may continue every night for three or four months during which time the male may lose half his body weight. Each male moves around the bowls in his court so that the booms are sent out in different directions. These booms are also notorious for attracting predators, due to the long range at which they can be heard. The large number of Kakapo concentrated in a lek, combined with the inability to readily escape from mammalian predators, means that a single assailant, such as a feral cat, can easily kill many of the birds.
Females are attracted by the booms of the competing males; they too may need to walk several kilometres from their territories to the arena. 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. He turns his back to the female, spreads his wings in display and walks backwards towards her. The duration of attempted copulation is between 2 to 14 minutes. Once the birds have mated, 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.
Female Kakapo lay up to three eggs per breeding cycle. They nest on the ground under the cover of plants or in cavities such as hollow tree trunks. They incubate the eggs faithfully, but are forced to leave them every night in search of food. Predators are known to eat the eggs and the embryos inside can also freeze to death in the mother's absence. Kakapo eggs usually hatch within 30 days, bearing fluffy gray chicks that are quite helpless. After the eggs hatch, the female feeds the chicks for three months, and the chicks continue to remain with the female for some months after fledging. The young chicks are just as vulnerable to predators as the eggs, and young have been killed by many of the same predators that attack adults. Chicks leave the nest at approximately 10 to 12 weeks of age. As they gain greater independence, their mothers may feed the chicks sporadically for up to 6 months.
Because Kakapo are quite long-lived, they tend to have an adolescence before beginning breeding. Males do not start to boom until about 5 years of age. It was previously thought that female Kakapo's reached sexual maturity at 9 years of age, however in the 2008 breeding season this idea was debunked when two 6 year old females named Apirama and Rakiura laid eggs. Generally females do not seek out males until they are between 9 and 11 years old. This long delay before they start to reproduce leaves plenty of time to perpetuate the species. Kakapo do not breed every year and have one of the lowest rates of reproduction among birds. Breeding occurs only in years when trees mast (fruit heavily), providing a plentiful food supply. Rimu mast occurs only every three to five years, so in rimu-dominant forests such as those on Codfish Island, Kakapo breeding occurs as infrequently.
Another interesting aspect of the Kakapo's breeding system is that the females can alter the sex ratio of their offspring in relation to maternal condition. Females that eat protein-rich foods produce more male-biased offspring (males have 30–40% more body weight than females). Females produce bias offsprings towards the dispersive sex when competition for resources (such as food) is high and to the non-dispersive sex when food is plentiful; a female Kakapo will likely be able to produce eggs, even when there are few resources, while a male Kakapo will be more capable of perpetuating the species when there are plenty, by mating with several females. This is in support of the Trivers-Willard hypothesis. The relationship between clutch sex ratio and maternal diet has conservation implications, as a captive population maintained on a high quality diet will produce fewer females and therefore fewer individuals valuable to recovery of the species.
From the 1840s, European settlers cleared vast tracts of land for farming and grazing, further jeopardising the Kakapo and their habitat. They brought more dogs and other mammalian predators, including domestic cats, black rats and stoats. Europeans knew little of the Kakapo until George Gray of the British Museum described it from a skin in 1845. As the Māori had done, early European explorers and their dogs fed on Kakapo. In the late 1800s, Kakapo became well-known as a scientific curiosity, and thousands were captured or killed for zoos, museums and collectors. Most captured specimens died within months. From at least the 1870s, collectors knew the Kakapo population was declining; their prime concern was to collect as many as possible before they became extinct.
In the 1880s, large numbers of mustelids (stoats, ferrets and weasels) were released in New Zealand to reduce rabbit numbers, but they also preyed heavily on many native species including the Kakapo. Other browsing animals, such as introduced deer, competed with Kakapo for food, and caused the extinction of some of its preferred plant species. Kakapo were reportedly still present near the head of the Whanganui River as late as 1894, with one of the last records of a Kakapo in the North Island being a single bird caught in the Kaimanawa Ranges by one Te Kepa Puawheawhe in 1895.
In 1891, the New Zealand government set aside Resolution Island in Fiordland as a nature reserve; in 1894, the government appointed Richard Henry as caretaker. A keen naturalist, Henry was aware that native birds were declining, and began catching and moving Kakapo and kiwi from the mainland to the predator-free Resolution Island. In six years, he moved more than 200 Kakapo to Resolution Island. By 1900, however, stoats had swum to Resolution Island and colonised it; they wiped out this nascent Kakapo population within 6 years.
In 1903, three Kakapo were moved from Resolution Island to the nature reserve of Hauturu/Little Barrier Island north-east of Auckland, but feral cats were present and the Kakapo were never seen again. In 1912, three Kakapo were moved to another reserve, Kapiti Island, north-west of Wellington. One of them survived until at least 1936, despite the presence of feral cats for part of the intervening period.
By the 1920s, the Kakapo were extinct on the North Island and their range and numbers on the South Island were declining. One of their last refuges was rugged Fiordland. There, during the 1930s, they were often seen or heard, and occasionally eaten, by hunters or roadworkers. By the 1940s, reports of Kakapo were becoming scarce.
By the early 1970s, it was uncertain whether Kakapo was still an extant species. At the end of 1974, scientists located several more male Kakapo and made the first scientific observations of Kakapo booming. These observations led Don Merton to speculate for the first time that Kakapo had a lek breeding system. From 1974 to 1976, 14 Kakapo were discovered but all appeared to be males. One male bird was captured in the Milford area in 1975, christened "Richard Henry", and transferred to Maud Island. This raised the possibility that all the females had died and that the species was functionally extinct. All the birds the Wildlife Service discovered from 1951 to 1976 were in U-shaped glaciated valleys flanked by almost-vertical cliffs and surrounded by high mountains. Such extreme terrain had slowed colonisation by browsing mammals, leaving islands of virtually unmodified native vegetation. However, even here, stoats were present and by 1976 Kakapo were gone from the valley floors and only a few males survived high on the most inaccessible parts of the cliffs.
Prior to 1977, no expedition had been to Stewart Island/Rakiura, despite government workers seeing a Kakapo there and snatching feathers from it in 1949. In 1977, sightings of Kakapo were reported on Stewart Island. An expedition to the island found a track and bowl system on its first day; soon after, it located several dozen Kakapo. The finding in an 8,000 ha area of fire-modified scrubland and forest raised hope that the population would include females. The total population was estimated at 100 to 200 birds.
Mustelids have never colonised Steward Island/Rakiura, but feral cats were present. During a survey, it was apparent that cats killed Kakapo with a predation rate of 56% per annum. At this rate, the birds could not survive on the island and therefore an intensive cat control was introduced in 1982, after which no cat-killed Kakapo were found. However, to ensure the survival of the remaining birds, scientists decided later that this population should be transferred to predator-free islands; this operation was carried between 1982 and 1997.
|Translocated to||Number of Kakapo||Deaths < 6 months||Survived as of November 1992|
|Maud Island (1974–81)||9 (6♂, 3♀)||3 (2♂, 1♀)||4 (2♂, 2♀)|
|Little Barrier Island (1982)||22 (13♂, 9♀)||2 (1♂, 1♀)||15–19 (10–12♂, 5–7♀)|
|Codfish Island (1987–92)||30 (20♂, 10♀)||0||20–30 (13–20♂, 7–10♀)|
|Maud Island (1989–91)||6 (4♂, 2♀)||0||5 (3♂, 2♀)|
|Mana Island (1992)||2 (2♀)||1 (1♀)||1 (1♀)|
|Total||65 (43♂, 22♀)||6 (3♂, 3♀)||41–55 (27–36♂, 14–19♀)|
|Note: ♂ = males, ♀ = females.|
In 1989, a Kakapo Recovery Plan was developed and a Kakapo Recovery Group established to implement it. The New Zealand's Department of Conservation replaced the Wildlife Service for this task. The first action of the plan was to relocate all the remaining Kakapo to suitable islands for them to breed. None of the New Zealand islands were ideal to establish Kakapo without rehabilitation by extensive revegetation and the eradication of introduced mammalian predators and competitors. Four islands were finally chosen: Maud, Hauturu/Little Barrier, Codfish and Mana. Some islands had to be rehabilitated several times when feral cats, stoats and weka kept appearing. Sixty-five Kakapo (43 males, 22 females) have been successfully transferred onto the four islands in five translocations. As of November 2005, Hauturu/Little Barrier Island and Mana Island were replaced with Chalky Island (Te Kakahu) and Anchor Island as Kakapo sanctuaries.
A key part of the Recovery Plan is the supplementary feeding of females. Kakapo breed only once every two to five years, when a certain type of plant species, primarily Dacrydium cupressinum (rimu), produces protein-rich fruit and seeds. Observations of the relationship between intermittent breeding and the plant's mast year help biologists choose which suitable supplementary foods to increase Kakapo breeding frequency. In 1989, six preferred foods (apples, sweet potatoes, almonds, brazil nuts, sunflower seeds and walnuts) were supplied ad libitum each night to 12 feeding stations. Males and females ate the supplied foods, and females nested on Little Barrier Island in the summers of 1989–91 for the first time since 1982, although nesting success was low.
Supplementary feeding not only increases the Kakapo breeding frequency, but also affects the sex ratio of Kakapo offspring, as maternal conditions influence this ratio. (See section "Reproduction" for more information on this topic.) This finding was subsequently used to increase the number of female chicks by deliberately manipulating maternal condition. During the winter of 1981, only females below 1.5 kg weight were given supplementary feeding to avoid raising their body condition, and the sex ratio results in 1982 were close to parity, eliminating the male-biased sex ratios in the unrestricted feeding.
Though breeding can be improved by supplementary feeding, the survival of young Kakapo is hampered by the presence of Polynesian rats. Of 21 chicks that hatched between 1981 and 1994, nine were either killed by rats or died and were subsequently eaten by rats. Nest protection has been intensified since 1995 by using traps and poison stations as soon as a nest had been detected. A small video camera and infra-red light source watch the nest continuously, which will remotely scare approaching rats by small bang and flash lights. To increase the success rate of nesting, a nest watcher places a small thermostatically controlled electric blanket over the eggs or chicks, whenever the female leaves the nest for food. The survival rate of chicks has increased from 29% in unprotected nests to 75% in protected ones.
To monitor the Kakapo population continuously, each bird is equipped with a radio transmitter. Every known Kakapo has been given a name by Kakapo Recovery Programme officials. It is an affectionate way for conservation staff to refer to individual birds, and a stark reminder of how few remain. Artificial incubation of eggs and hand-raising of chicks interventions were often used to strengthen conditions of the eggs and the chicks. As of November 2005, the population comprised 41 females and 45 males, including four fledging (3 females and 1 male) bred in 2005. The oldest surviving Kakapo, "Richard Henry", is thought to be between 35 and 50 years old.
In 2006, the Kakapo Recovery Programme presented a new management plan that would run from 2006 to 2016. The key goals of this plan are to increase the female population to a minimum of 60 by 2016, increase genetic diversity, maintain or restore a sufficiently large habitat to accommodate the expected increase in the Kakapo population, and maintain public awareness and support.
The Kakapo Recovery Plan has been a successful program as the numbers of Kakapo increase steadily. The adult survival rate and their productivity have both improved significantly since the programme's inception. However, the main goal is to establish at least one viable, self-sustaining, unmanaged population of Kakapo as a functional component of the ecosystem in a protected habitat. To accept this conservation challenge, two large Fiordland islands, Resolution (20,860 ha) and Secretary (8,140 ha), have been prepared for re-introduction of Kakapo with large-scale ecological restoration activities.
In breeding years, the loud booming calls of the males at their mating arenas made it easy for Māori hunting parties to track them down, and they were also hunted while feeding or when having dust baths in dry weather. The birds were caught, generally at night, using snares, pitfall traps, or by groups of domesticated Polynesian dogs which accompanied the hunting parties — sometimes they would use fire sticks of various sorts to dazzle the birds in the darkness, stopping them in their tracks and making the capture easier. Cooking was either done in a Hāngi or in gourds of boiling oil. The flesh of the birds could be preserved in their own fat and stored in containers for later consumption — hunters of the Ngāi Tahu tribe would pack the flesh in baskets made from the inner bark of Totara tree or in containers constructed from kelp. Bundles of Kakapo tail feathers were attached to the sides of these containers to provide decoration and a way to identify their contents.Also taken by the Māori were the bird's eggs, which are described as "white-ish but not pure white", and about the same size as a kererū egg.
As well as eating the meat of the Kakapo they killed, Māori would use Kakapo skins — with the feathers still attached — to create cloaks and capes. Each one required up to 11,000 feathers to make. Not only were these garments very beautiful, they also kept the wearer very warm. They were highly valued, and the few still in existence today are considered Taonga (treasures) — indeed, the old Māori adage "You have a Kākāpō cape and you still complain of the cold" is used to describe someone who is never satisfied. Kakapo feathers were also used to decorate the heads of taiaha, but were removed before actual use in combat.
Despite all, the Kakapo was also regarded as an affectionate pet by the Māori. This was corroborated by European settlers in New Zealand in the 19th century, among them George Edward Grey, who once wrote in a letter to an associate that his pet Kakapo's behavior towards him and his friends was "more like that of a dog than a bird".