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Large forest birds

by  Gerard Hutching

New Zealand’s forests are home to some intriguing large birds. The kākāpō is a flightless nocturnal parrot; the feisty weka helps itself to people’s food and belongings. The takahē was thought to be extinct until it was rediscovered in 1948, and the kōkako’s haunting song has been described as ‘rare forest music’.


New Zealand’s large forest birds

Some strange and outlandish large birds live within New Zealand’s forests. Some of them have evolved in isolation over many millions of years. Others arrived in the country later, and their descendants became bigger than their relatives elsewhere.

A number of large birds of the bush have become extinct within the last few hundred years. But the decline of other species has been halted, thanks to efforts by conservation workers and the public.

Large native forest birds include the weka and takahē (both rails), kererū (a fruit pigeon), kākāpō and kākā (both parrots), and kōkako. All are endemic species (found only in New Zealand), and are protected by law.

Birds that can’t fly

In the course of their evolution, some of these birds lost one of the most bird-like characteristics – the ability to fly. Of the larger forest birds discussed here, only kererū and kākā are able to fly long distances.

Others have semi-functional wings. Kōkako rarely use their wings to gain altitude, typically gliding to the next tree. Kākāpō occasionally use their small wings like a parachute, to slow a free fall from low trees and bluffs.

Why fly?

Loss of flight is thought to be an adaptation to certain conditions as these birds were evolving:

  • a low risk of predation on the ground, as there were no mammal predators
  • a higher risk of predation when flying, from giant eagles, falcons and harriers
  • a lack of browsing and ground-foraging mammals, so foods near the ground were abundant
  • large, continuous areas of forest, reducing the need to fly from one patch to another.

Saving energy

Some flightless birds have unusual feathers. All five kiwi species and the kākāpō have feathers that are fluffed out for better insulation, not flattened and streamlined for flight. Their metabolic rate (heart rate, body temperature and oxygen consumption) is lower than that of most other birds, which conserves energy. Their large size also reduces heat loss, as they have less surface area relative to their body volume.

Long-lived, slow breeders

Many New Zealand birds are relatively long-lived and have small numbers of offspring. For most of their history there were few predators, so a high rate of reproduction would not have been necessary – but since mammal predators were introduced, this has counted against them.

Growing bigger

Free of the need to fly, birds could also become larger. This was an advantage for birds that fed on low-quality leaf material, as this takes time to digest and needs to be carried in the digestive tract long enough to break down and release nutrients. Their size also made it possible to reach higher foliage, and was carried to the extreme in the case of the extinct moa – some were over 2 metres tall.

World records

New Zealand’s birds hold several size records – including the world’s largest parrot (kākāpō) and largest rail (takahē). The parea (Chatham Island pigeon) is one of the world’s largest pigeons.

The country was also home to an even larger rail (the adzebill), the largest known eagle, and exceptionally large geese – all now extinct. The biggest moa species was among the world’s largest birds. Moa were related to an ancient group of birds that also includes South American tinamous and the ostrich, emu and kiwi.

Foods of the forest

The forests and forest margins have varied resources spread through the various layers – worms, grubs and bugs in soil and leaf litter; grasses and leaves; insects at all levels; and berries on shrubs and in the tops of the highest trees. Among them, these birds have evolved different strategies to exploit this diversity.

Human impact

When the Polynesian ancestors of Māori arrived in New Zealand around 1250–1300 AD, large and mainly flightless birds roamed the forests and forest fringes. The new settlers developed techniques to trap the birds, catch them with the help of kurī (dogs) or flush them out with fire. But the slow breeding rate of many of these birds could not sustain the level of harvest, and most became scarce or extinct within a few hundred years.

Smaller forest birds met with a similar fate, but for different reasons. They were devastated by the mammal predators that Polynesian and European explorers and settlers brought with them.


Weka

The weka (Gallirallus australis), a flightless rail, has an engaging and resourceful nature. Weka are most often seen or heard shrieking around dusk. They emerge from dense undergrowth and scurry, neck outstretched, across open space to the next available cover. Weka live mainly at forest margins, and make forays onto farmland and gardens, where they helpfully eat grubs and unhelpfully pull up seedlings.

Weka subspecies

There are four subspecies:

  • the North Island weka
  • the western weka (found in north-west Nelson, Marlborough and the West Coast)
  • the Stewart Island weka
  • the buff weka (extinct in the eastern South Island, but introduced to the Chatham Islands).

The buff weka became extinct in its eastern South Island range around 1920, but was introduced to the Chatham Islands. Several attempts have been made to re-establish populations in Canterbury and Otago.

Weka are protected throughout their natural range – the North, South and Stewart islands – but may be hunted on the Chatham Islands and some tītī (muttonbird) islands off Stewart Island.

Weka culture

On the Chatham Islands, 800 kilometres east of New Zealand, weka are part of life. Hunting and feasting on them is a social pastime. Just as mainland New Zealanders are often called Kiwis, the nickname for a Chatham Islander is Weka.

Appearance

Weka are large brown rails, about 50 centimetres long, with a strong tapered bill, sturdy legs and reduced wings. Depending on the subspecies, male weka weigh around 1 kilogram and females 700 grams. All have brown plumage streaked with black, but the shade varies from the pale-brown buff weka to the western subspecies, some of which are almost black.

Weka are sometimes confused with the smaller banded rail. Unlike the weka, this bird has black and white horizontal bars on the underside, and can fly.

Feeding

Weka are omnivorous – animal foods form 30% of their diet, and plant foods make up the rest. Animal foods include earthworms, larvae, beetles, wētā, ants, grass grubs, slugs, snails, insect eggs, slaters, frogs, spiders, rats, mice, and small birds and eggs. Plant foods include leaves, grass, berries and seeds. Weka are important in the bush as seed dispersers. They distribute seeds too large to be spread by smaller berry-eating birds.

Home run

For a flightless bird, the weka can travel remarkable distances. Conservation workers report that it took one weka just three weeks to walk from its release site, the Waitākere Range near Auckland, to Tāneatua, 300 kilometres away. It was heading for its home near Gisborne.

Breeding

Female weka lay three creamy or pinkish eggs on average. After a month the chicks hatch, and are fed by both parents until they are fully grown at between six and ten weeks. The breeding season varies, but when food is plentiful, weka can breed year round, raising up to four broods.

Weka and humans

The meat, skin, oil and feathers of weka were important resources for Māori, and for European explorers, who called the birds bush hens or woodhens. Weka are easily tamed with food, and forest campers learn not to leave food or shiny objects lying within reach of these inquisitive, acquisitive birds.

Introduced to islands

Weka have been introduced to many islands, where they have done well in the absence of other predators. However, they have sometimes become a pest to other endangered species, as they eat small birds, lizards and insects. In the 1870s they were introduced to Australia’s subantarctic Macquarie Island as food for sealers, and helped drive the Macquarie Island parakeet and a land rail to extinction. Weka were eradicated from the island in 1988.

In 1905, 12 buff weka were introduced to the Chatham Islands. Their descendants now number around 60,000, and islanders are allowed to harvest them, with an estimated 5,000 birds taken each year. Weka may also be killed on the Tītī Islands around Stewart Island.

Weka as pests

Because they prey on endangered species, weka have been removed from important conservation islands. In the 1980s, thousands were moved from Codfish Island to neighbouring Stewart Island to protect endangered Cook’s petrels and South Georgian diving petrels, and to prepare Codfish Island for the release of kākāpō.

Bird biathlon

Weka have been regularly removed from Maud Island in the Marlborough Sounds, a predator-free sanctuary. But the birds aren’t easily deterred. In 1978, three weka were given numbered bands before being released several kilometres away on the mainland. The trio were back on the island within days, after a long trudge and a 900-metre swim against a 4-knot current.

Threats to weka

Despite their feisty nature, weka are in decline through most of their natural range. Dogs, ferrets, stoats and cats kill them, and disease and drought are also a factor. The main remaining North Island population, in the Raukūmara Range, was estimated at 2,000 birds in 2005.

In the 1990s conservationists started a breeding programme for the North Island weka. They released birds on the Russell Peninsula in Northland, and on Pakatoa Island (Hauraki Gulf) and Whanganui Island (Coromandel) – islands without other endangered species that the weka could harm. The island populations have thrived. Islands on Otago lakes are also home to buff weka, relocated from Chatham Island.


Takahē

The South Island takahē, a large flightless rail, hit headlines in the late 1940s. Takahē were thought to be extinct – but then, in 1948, Geoffrey Orbell rediscovered the South Island species (Porphyrio hochstetteri) in Fiordland’s Murchison Mountains. However, the North Island takahē (Porphyrio mantelli) is extinct.

South Island takahē

Weighing up to 4 kilograms and 63 centimetres long, the South Island takahē is the world’s largest rail. Several million years ago its ancestors flew from Australia to New Zealand, where, without ground predators, the takahē became flightless. This colourful bird has brown-green and navy plumage, with a white undertail and bright orange-red bill and legs. Today South Island takahē remain in the Fiordland mountains, and have been introduced to several predator-free island and fenced mainland sanctuaries.

North Island takahē

The ancestors of the taller but slighter North Island species arrived in New Zealand more recently than those of the South Island bird. The North Island takahē was possibly last seen in the late 19th century, in the Ruahine Range.

Takahē relations

Both takahē species are related to the pūkeko (Porphyrio melanotus), which came to New Zealand from Australia just hundreds of years ago, and can still fly.

New Zealand once had up to nine endemic flightless rails. The South Island takahē and the weka are the only two to survive human colonisation.

Habitat and feeding

The remnant takahē population in Fiordland feed on snow tussock shoots in summer. In winter they retreat to nearby forest, where they eat fern rhizomes. People assumed this harsh environment at 1,100–1,400 metres altitude was the takahē’s preferred habitat. But to survive on the low-nutrient foods there, it has to eat continuously for up to 19 hours a day, and must withstand snow and alpine temperatures.

It is now understood that the alpine environment is the takahē’s last refuge – the conditions were harsh enough to limit numbers of introduced predators and competitors. Takahē bone remains show that, until recently, they mostly occupied the edges of dense shrublands and dry forests around lowland swamps and rivers, from Canterbury to Southland. But the surviving birds have probably been in the high country long enough to adapt to subalpine conditions.

Breeding

A takahē female lays one to three off-white eggs between October and December, often while snow still lies on the ground. The male and female take turns incubating the eggs for a month. Juveniles can breed in their first year, but often remain with their parents for up to two years, and even help them raise chicks. Takahē guard their breeding territories fiercely.

Takahē – lost and found

Māori hunted the takahē, which made a good-sized meal. By the 1840s it was considered rare. Between 1850 and 1898 four birds were killed and mounted as museum specimens, but after that the trail ran cold, despite reported sightings in the Fiordland wilderness.

Big thighs

In 1949 an 80-year-old man who had eaten a takahē remarked that it was good eating but ‘all drumstick’.1 Each leg and thigh of a takahē contains five times more meat than the breast.

As a young man, Geoffrey Orbell had been intrigued by the stories of the ‘lost bird’. He roamed Fiordland and thought takahē might be found near Te Wai-o-pani, an alpine lake now known as Lake Orbell. On 20 November 1948 he and three companions finally discovered the elusive bird. Once abundant throughout the South Island, its numbers had plummeted to just a few hundred.

Race to save the bird

In 1982 the Fiordland takahē population was estimated at 121 – a 40% decline in a decade. This coincided with the rapid spread of feral deer, which damage the tussock grasses that takahē eat. So scientists launched a conservation programme which saw the number of wild Fiordland takahē rise to 171 by 2005. It involved:

  • controlling deer
  • protecting the takahē from predators, especially stoats
  • raising chicks in captivity for release in the wild
  • establishing other populations on islands.

Takahē were placed on Kapiti Island, near Wellington, in 1980, in case the mainland population became extinct. The move was a gamble, as some believed they would not survive on a diet of introduced grasses. But the birds have survived and bred – although some eggs are infertile, possibly because of young birds breeding, inbreeding, or the sudden change of environment and social structure.

By 2012 there were 107 takahē on Maud, Mana, Kapiti and Tiritiri Matangi islands and at mainland restoration sites.

Footnotes
    • Quoted in Richard B. Sibson, Birds at risk: rare or endangered species of New Zealand. Wellington: Reed, 1982, p. 113. › Back

Pigeons – kererū and parea

Kererū

The kererū or New Zealand pigeon (Hemiphaga novaeseelandiae) is a plump purple and bottle-green pigeon with a white bib, and red eyes, bill and legs. Kererū are about 50 centimetres long and 650 grams in weight.

Feeding

Kererū eat the fruit of native plants such as miro, tawa, pūriri, taraire, kahikatea, nīkau and coprosma, and introduced plants like privet, elderberry and plums. When fruit is scarce they eat leaves, favouring kōwhai, tree lucerne, willow and poplar.

Spreading seed

Since the extinction of large birds such as the moa, the kererū plays a vital role in the regeneration of forests. A member of the fruit-pigeon subfamily, it is now the only fruit-eater large enough to swallow fruit with large seeds, ensuring that future generations of trees such as tawa, miro, karaka and nīkau are widely spread.

Māori and kererū

To Māori, the plump kererū was an important source of food, being plentiful and tasty eating. In Northland and parts of Canterbury the bird is known as kūkupa.

In one tradition, it gained its striking plumage when the demigod Māui, trying to find out where his mother went each day, hid her skirt to delay her. When she went to the underworld without it, Māui changed into a white pigeon and followed her. He was still holding the skirt, which became the kererū’s white breast and purple-green neck feathers.

Distribution

Kererū occur throughout mainland New Zealand, and on Stewart Island and many offshore islands. They are most common in the lowland forests of Northland, the King Country, Nelson and the West Coast, but are in danger of becoming locally extinct in Northland because of poaching and predation.

Breeding

Kererū perform spectacular mating displays, flying high into the air from a perch, then diving steeply before pulling out of the headlong fall. Their nest is an untidy platform of sticks in the fork of a tree or among vines. Laying begins in September (spring) and can continue through to February, depending on fruit availability. Kererū lay a single white egg, which both adults incubate for a month. They can breed again after fledging a chick, and sometimes raise three chicks in a season.

Long way for a meal

Kererū fly considerable distances in search of food, including across 30-kilometre Foveaux Strait, between Stewart Island and Invercargill. By contrast, their Chatham Islands relative, the parea, rarely flies further than 5 kilometres.

At first, the rapidly growing chick is fed a rich milky secretion from both parents’ crops (pouches in their upper digestive tracts). It is later fed on regurgitated fruit for four to six weeks. After the chick fledges, the parents continue feeding it by regurgitation for several weeks. When food is abundant, adults may renest, even while still feeding the fledgling. Kererū can live at least 21 years.

Kererū at risk

Protected from hunting since 1912, kererū remain at risk for four major reasons:

  • They have a low breeding rate, breeding only when forest fruit is abundant.
  • Possums and rats compete for the same food.
  • They are an easy target – cats kill adult birds feeding on low plants, and rats and stoats take eggs and chicks from the nest.
  • They are hunted by people for food, despite being protected.

Parea

The parea or Chatham Island pigeon (Hemiphaga chathamensis) is closely related to the kererū. But it is paler on the back, and a fifth larger, weighing 800 grams – making it one of the world’s largest pigeons. The parea population dropped to less than 50 in the 1980s, due to forest clearance and introduced predators, but it has rebounded to over 600 thanks to work by the Department of Conservation and the local community.


Kākāpō

The kākāpō (Strigops habroptilus) – literally ‘parrot of the night’ in Māori – is famous worldwide for its unusual behaviour, size and rarity. This large, flightless parrot is so different from other parrots that it has its own endemic subfamily, Strigopinae. Its nearest relatives are the kākā and kea, the only other members of the family Strigopidae. The kākāpō has a soft moss-green cloak flecked with brown and yellow, and round patches of pale feathers around each eye which give it an owlish appearance.

Heavyweight parrot

At a maximum weight of 4 kilograms (although averaging 2 kilograms), the male kākāpō is the heaviest parrot in the world. The average weight of females is 1.5 kilograms. Like other parrots, it has two forward-pointing and two backward-pointing toes, which it uses like a hand to cling to branches or grasp food. The herbivorous kākāpō eats large quantities of forest fruit, seeds, leaves and roots.

Long-lived slow breeders

Kākāpō live at least 60 years, maybe 100, and do not breed every year. To breed they require abundant food supplies – especially fruit – to support hungry chicks. Such prolific ‘mast’ fruiting only occurs every few years. Kākāpō are vulnerable to predators, and in 1995 there were just 51 known survivors. Determined conservation efforts have stopped the decline. In 2005 there were 86 kākāpō, and in 2011 there were 129, including 11 chicks born that year.

Kaboom!

The male kākāpō’s booming call can be heard as far as 5 kilometres away. One was recorded making 17,000 booms in one night. Some birds keep this up for three months – a feat that they can only achieve with an adequate diet.

Booming and breeding

To breed, males gather in a ‘booming arena’ in summer, between December and March. They inflate their air sacs and make a low booming sound which carries far into the night to attract mates. As females arrive, males compete for their attentions.

Attracting females to a central courtship arena is known as a lek system of breeding. The kākāpō is the only parrot and the only nocturnal bird that breeds in this way.

Solo mother

After mating, the female makes a nest, hatches two to four eggs, and feeds the young – while the male goes his solitary way until the next breeding season. Juveniles are vulnerable to predators because the female has to leave the nest at night to search for food, sometimes jogging several kilometres two or three times a night. The kākāpō breeding cycle spans five months, leaving the female’s reserves severely depleted.

Kākāpō or volcano?

The geologist James Park travelled to Dusky Sound in 1890. He wrote that his companion, the explorer William Docherty, supposedly knew kākāpō well, yet failed to recognise their booming as the call of a bird. ‘So sudden and startling was the sound that he maintained to the last that it was a subterranean noise in some way connected with volcanic action.’ 1

Declining numbers

In 1899, the explorer Charlie Douglas forecast that the kākāpō was ‘doomed to extinction long before the Kiwi and the Roa [great spotted kiwi] are a thing of the past’.

Partial to boiled kākāpō himself, Douglas noted that ‘they could be caught in the moonlight, when on the low scrub, by simply shaking the tree or bush till they tumbled on the ground, something like shaking down apples. I have seen as many as a half a dozen Kakapos knocked off one tutu bush this way.’ 2

He noted their decline through Westland as introduced predators spread. Kākāpō were already extinct in the North Island by the 1840s, their fate sealed by Māori hunting.

Early intervention

In the 1890s, concerned about plummeting numbers of kākāpō, conservationist Richard Henry transferred hundreds to an inshore Fiordland island. But they lost the battle when stoats invaded, swimming the short distance from the mainland.

Brink of extinction

During the 20th century, kākāpō numbers dropped steeply, almost to extinction. Between 1974 and 1977, 18 birds – all males – were found in Fiordland. Then in 1977, miraculously, a population of up to 200 male and female birds was found in a remote part of Stewart Island. This group boosted hopes for the species’ survival, but it was being decimated by feral cats.

Parrot pals

Both Māori and Europeans found that kākāpō made affectionate pets. Governor George Grey wrote to a friend about a pet kākāpō which acted more like a dog than a bird in its interactions with humans. A lighthouse keeper at Puysegur Point in Fiordland had a kākāpō called Major, which used his dog, Hector, ‘as a cushion to sleep upon … As soon as [Major] had had sufficient sleep, he began to pull the dog’s ears, nose, tail, toes, and hair, running all over his body, apparently to Hector’s thorough enjoyment.’ 3

Kākāpō comeback

Conservation efforts from the 1950s to the 1980s focused on finding kākāpō and moving them to safety. At first a few birds placed in captivity died, but others that were set free on island sanctuaries such as Codfish Island, west of Stewart Island, have formed the nucleus of a successful breeding programme. Years of research to develop effective management strategies, along with eradicating pests from island sanctuaries, have increased the success rate of breeding and raising chicks.

To encourage kākāpō to breed, conservation workers supplemented their natural diet with nuts and specially formulated pellets. However, not until a bumper fruiting year of rimu trees in 2002 did the population increase significantly – from 62 to 86.

Footnotes
    • James Park, ‘Takahe versus kakapo.’Transactions and Proceedings of the New Zealand Institute 23 (1890), › Back
    • Charlie Douglas, Mr Explorer Douglas: John Pascoe’s New Zealand classic. Revised by Graham Langton. Christchurch: Canterbury University Press, 2000, p. 250. › Back
    • Quoted in Murdoch Riley, Māori bird lore: an introduction. Paraparaumu: Viking Sevenseas, 2001, p. 120. › Back

Kākā

The kākā (Nestor meridionalis) is a noisy and sociable bird of the forest. It is related to the alpine parrot, the kea (Nestor notabilis).

In 1877 ornithologist Walter Buller wrote of Māori catching 300 kākā a day in the Urewera forest, during the rātā blooming season. Today it is estimated that there are fewer than 10,000 left in all New Zealand, most of them on islands.

North and South island kākā

There are two subspecies, the North Island and South Island kākā.

At 575 grams, the South Island male is 100 grams heavier than his North Island cousin (females weigh 500 and 425 grams respectively). The North Island kākā has olive-brown plumage; the South Island subspecies differs in its brighter green plumage and almost white crown.

The bird’s most common call resembles a creaky door, and it also mimics other species. Kākā can live 20 years, but few reach that age in the wild.

Discovered too late

In 2014 a new species of kākā was discovered – unfortunately, several hundred years after it became extinct. The Chatham Islands kākā (Nestor chathamensis), identified by DNA analysis of fossilised bones, was descended from mainland kākā that found their way to the Chatham Islands 1.7 million years ago. It was about the same size as its mainland relative, but had larger thigh bones, a broader pelvis and a longer beak.

Distribution

Strongholds for kākā on the mainland include large tracts of forest from the Coromandel Peninsula south to the Aorangi Range in the Wairarapa, and the central North Island forests of Pureora and Whirinaki. In the South Island they are most numerous on the West Coast. On islands without predators, kākā are prolific breeders – after possums were eradicated from Kapiti Island in 1986, kākā numbers approximately doubled to around 1,000 by 2001. Following their release in the Zealandia sanctuary in 2002–7, they were a common sight in parts of Wellington.

Feeding

Kākā eat nectar, fruit, berries, seeds, sap, insects and grubs. Enthusiastic feeders, they often leave a trail of debris as they tear out long strips of bark in search of insects and sap. Like honeyeaters, they use their spoon-tipped, bristle-edged tongues to lap up honeydew or nectar from flax and rātā flowers. Often hanging upside down to feed, they become increasingly comical and acrobatic as they get drunk on nectar.

Energy-rich foods are important in bringing the kākā into breeding condition. One reason that breeding has declined, especially in the South Island, is that pests such as wasps and possums compete for honeydew and nectar.

Breeding

Starting in September (spring), the kākā lays an average of four white eggs in a hollow tree or branch. The chicks take over two months to fledge and another five months to become totally independent. Nesting in tree hollows, they are vulnerable to predators.

Parrots apart

New Zealand’s native parrots – the kea, kākā and kākāpō – may have evolved separately from other parrots after New Zealand separated from the Gondwana supercontinent, around 85 million years ago. Kākā and kea belong to an endemic subfamily, Nestorinae.


Kōkako

Hauntingly beautiful songsters, the North Island kōkako (Callaeas wilsoni) and South Island kōkako (C. cinerea) are wattlebirds.

The other New Zealand wattlebirds are the rare saddleback (Philesturnus carunculatus and P. rufusater) and the extinct huia (Heteralocha acutirostris). Together they form the endemic Callaeidae family. Not related to the Australian wattled honeyeaters, they are among New Zealand’s most ancient flying birds. Their ancestors (which included the ancestor of the stitchbird, Notiomystis cincta) may have been on the land mass that split from the supercontinent of Gondwana to become New Zealand.

Appearance

Kōkako weigh around 230 grams and are 38 centimetres long. They have long legs and a long tail, and a short, strong bill. The North Island kōkako has distinctive blue wattles (fleshy pads hanging from each corner of the bill), while the South Island bird’s wattles were orange. Named the blue-wattled crow and orange-wattled crow by early Europeans, both have striking blue-grey plumage and a black face mask.

The grey ghost

The South Island kōkako is rarely seen, with the last accepted sighting near Reefton in 2007. Occasional reports of its call or other signs give tantalising hope of finding a remnant population of this blue-grey bird.

Magic song

Of all New Zealand forest birds, the kōkako is considered to have the most beautiful song. Bushmen called it the ‘true bellbird’ or ‘organ-bird’. In 1870, ornithologist Walter Buller wrote:

I have often heard two or more Kokakos, each in a different key, sounding forth these rich organ-notes with rapturous effect; and it is well worth a night’s discomfort in the bush to be awakened at dawn by this rare forest music. 1

Its other calls sound like a cackle, a mewing cat, and the soft tolling of a distant bell.

Kōkako song varies from region to region, and the birds respond less to kōkako from outside their home patch. South Island kōkako only called around breeding time, which has added to the difficulty of locating them.

Territory and habitat

Single kōkako as well as pairs establish year-round territories of 4 to 12 hectares, where they feed and breed. They sing to maintain their boundaries and to attract a mate. Their short, rounded wings allow flights and glides of up to 50 metres. Otherwise they move along tree branches from one level up to another, running and hopping on their long legs. They prefer diverse lowland forest, which has a range of storeys and enough variety for year-round food.

Feeding

Kōkako have a mixed diet which varies with the seasons. Leaves, fern fronds and some insects keep them going through the winter, and once spring arrives, nectar and leaf buds are more plentiful. Over summer they mainly eat moths, caterpillars, wētā and other invertebrates, as well as fruit.

Breeding

When food is abundant, kōkako raise more than one brood of chicks a year. Nesting can take place from October to March. The female lays two or three pinkish-grey eggs, which she incubates alone for 20 days. The male feeds her on or near the nest, and later both feed the chicks, which fledge in 30 to 45 days. Young remain partially dependent for food from four months to a year.

Kōkako under threat

Kōkako were once abundant, but today North Island kōkako remain in just a handful of places – mainly in the northern Urewera, Bay of Plenty, and the King Country. A few also survive in Northland’s kauri forests.

The species is now endangered. In the late 1980s, it was estimated that 350 pairs remained. Thanks to conservation efforts, by 2006 there were around 1,400 birds, including 640 breeding pairs.

Kōkako need large unbroken areas of diverse forest, so the loss or fragmentation of forest is one reason for their decline. Today their remaining forests are largely protected. But rats, possums and stoats raid kōkako nests for eggs and chicks. One study found that for every 10 breeding pairs, just one chick a year survived – not nearly enough to maintain the population.

Kōkako conservation

Conservation efforts focus on improving the breeding success of kōkako.

Māui’s mate

In Māori tradition the kōkako carried water in its wattles to the demigod Māui, to help him in his battle against the sun. Māui rewarded the bird by making its legs long and slender so it could move easily through the forest.

‘Mainland islands’

Some kōkako populations have done well in ‘mainland islands’ – conservation areas on the mainland, intensively managed to reduce predators and restore vegetation. Kōkako have also recently been reintroduced to two forests where they existed up until the mid-1900s. To preserve genetic diversity, birds from tiny remnant populations are rescued for breeding programmes.

Nearshore islands

Kōkako transferred to Hauturu (Little Barrier Island) from the 1980s show how well they can do with fewer predators. The 34 birds increased to 200 pairs by 2005. Recent transfers to predator-free Kapiti and Tiritiri Matangi islands are also proving successful.

Footnotes
    • Walter Buller, Buller’s birds of New Zealand. Rev. ed. Christchurch: Whitcoulls, 1967 (originally published 1888), p. 4. › Back

External links and sources

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How to cite this page: Gerard Hutching, 'Large forest birds', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/large-forest-birds/print (accessed 24 October 2017)

Story by Gerard Hutching, published 24 Sep 2007, reviewed & revised 17 Feb 2015