The word "kiwi" often brings to mind the image of something small, brown, fuzzy, and found in the produce section of your local supermarket. But the kiwi is not a fruit-that's kiwifruit, which is native to eastern Asia! The kiwi is a unique and fascinating bird species endemic to New Zealand. There are five recognized species of kiwi: Apteryx haastii, A. mantelli, A. rowi, A. australis, and A. owenii. All species have been negatively affected by historic deforestation, but their remaining habitat is well protected in large forest reserves and national parks.
Evolutionary History and Classification
Like its larger cousins the cassowary, emu, ostrich, and rhea, the kiwi is classified as a ratite. Most birds have a special ridge on their sternum, called a keel, where flight muscles attach, but ratites don't need keels because they don't fly. DNA sequence comparisons have yielded the conclusion that kiwi are much more closely related to the extinct Malagasy elephant birds than to the moa with which they shared New Zealand.
Physical Characteristics
Regardless of what it’s related to, this odd-looking bird resembles a large, hairy pear! Its wings are only about 1 inch (3 centimeters) long and are useless, completely hidden under the feathers. The vestigial wings are so small as to be invisible under their bristly, hair-like, two-branched feathers. The kiwi has no tail but does have very strong, muscular legs, which make up about a third of the bird’s total body weight, that are used for running and fighting. Four toes (other ratites have only two or three) on each thick foot allow the flightless bird to pad silently through the forest in search of food.
Looking quite different from any other bird, the kiwi has many body parts that make it seem more like a mammal. While most birds have thin skin and hollow bones to make them lighter for flying, the kiwi's skin is a bit thicker and tough, and its bones are heavy and filled with marrow. Like most other ratites, they have no uropygial gland (preen gland).
The kiwi is the only bird in the world that has nostrils at the tip of its bill. It also has a highly developed sense of smell. They have a unique beak with nostrils and specialized vibration/pressure-sensing nerve endings located at its tip to allow them to both smell and detect movement of prey in the soil. Female bill length ranges from 4.4 to 6.2 inches. Their bill is long, pliable and sensitive to touch, and their eyes have a reduced pecten.
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Their feathers lack barbules and aftershafts, and they have large vibrissae around the gape. They have 13 flight feathers, no tail and a small pygostyle. The eye of the kiwi is the smallest relative to body mass in all avian species, resulting in the smallest visual field as well. The eye has small specialisations for a nocturnal lifestyle.
Habitat and Behavior
The kiwi lives in forested areas of New Zealand that tend to be very steep and wet, surrounded by shrubs and trees found nowhere else on Earth. They prefer subtropical and temperate podocarp and beech forests, but they are being forced to adapt to different habitat, such as sub-alpine scrub, tussock grassland, and the mountains. Since it is not able to fly up into trees to nest, rest, or escape from danger, the kiwi makes its home in burrows in the ground of its swampy forest or grassland habitat. The bird digs multiple burrows within its territory, using strong toes and claws. The kiwi digs burrows instead of building a nest.
Most birds sleep at night, and it has long been thought that the kiwi is nocturnal, since it is rarely seen during the day. But conservation scientists studying the bird on New Zealand's Stewart Island have seen them out and about during the day. Still, the kiwi usually rests in deep underground burrows or hollow logs during the day, and as night begins to fall, it slowly pokes its bill out to sniff the air.
Kiwis evolved sharing their habitat with another bird, the weka, that eats their eggs, so they had to get “sneaky” in hiding their burrows. However, their casual “sleeping burrow” has a noticeable dirt arrow pointing right to it, as the kiwis fling the dirt behind them while making the opening!
A kiwi is very protective of its own territory-it doesn’t want other kiwis taking all the good food and burrows it worked so hard to make. So, the kiwi patrols its area every night, leaving smelly droppings to mark boundaries to keep other kiwis away-a very unbird-like behavior. To keep track of each other in the dark, kiwis can shriek loudly, a half scream, half whistle that also serves to scare others away. This cry sounds like “kee-wee, kee-wee,” which is how the bird got its name. Kiwi pairs use gentle grunts and snuffles with each other and their chicks, and males purr during mating. Pairs do fight, and the larger female may kick the male away if she is not in the mood for his company. Once bonded, a male and female kiwi tend to live their entire lives as a monogamous couple. During the mating season, June to March, the pair call to each other at night, and meet in the nesting burrow every three days. These relationships may last for up to 20 years.
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Diet and Foraging
Using only scent to find food and sensory pads at the tip of the bill to catch its food, the kiwi lives on grubs, worms, bugs, berries, and seeds. Kiwis eat small invertebrates, seeds, grubs, and many varieties of worms. They also may eat fruit, small crayfish, eels and amphibians. The majority of a kiwi's diet consists of small invertebrates including earthworms, beetle larvae, caterpillars, crickets, snails and crayfish. Because their nostrils are located at the end of their long beaks, kiwi can locate insects and worms underground using their keen sense of smell, without actually seeing or feeling them. This sense of smell is due to a highly developed olfactory chamber and surrounding regions.
Foraging from dusk to dawn, these birds can be heard snuffling around in their territory; if alarmed, they run off and then stick their bills into the air, sniffing to see if it's safe to return. Their ears are large, giving them a very good sense of hearing.
Reproduction and Life Cycle
An adult male and female kiwi typically pair for life, but a female may choose a new male if a more desirable one wanders by. The male doesn't have beautiful songs or fancy feathers to attract a female. Instead, he follows one around constantly while grunting.
Breeding season is late winter to early summer. The female kiwi lays up to six eggs every year. Kiwi eggs are smooth and white, off-white, or pale green in color. They are also huge in comparison to the mother: one egg might reach up to 20 percent of her weight; that would be like a 120-pound (54 kilograms) human female giving birth to a 24-pound (11 kilograms) baby! Kiwi eggs contain almost twice as much yolk as most birds their size and have natural antibacterial and antifungal properties. They are unusual among other birds in that, along with some raptors, they have a functioning pair of ovaries.
The kiwi lays one of the largest eggs in proportion to its size of any bird in the world, so even though the kiwi is about the size of a domestic chicken, it is able to lay eggs that are about six times the size of a chicken's egg. Kiwi eggs can weigh up to one-quarter the weight of the female, helped by their inability to fly that could limit the extent by its body weight; brown kiwi females carry and lay a single egg that may weigh as much as 450 g (16 oz). Producing the huge egg places significant physiological stress on the female; for the thirty days it takes to grow the fully developed egg, the female must eat three times her normal amount of food.
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After the egg is laid, the male takes over parenting duties. He incubates the egg and maintains the nest for nearly 75 to 85 days, but if the female returns to lay another egg, the male has to sit on the clutch that much longer. The incubation period is 63-92 days. Lacking an egg tooth, the chick must kick its way out of the shell. It hatches wearing shaggy adult feathers and looking like a miniature version of its parents. No ugly baby phase for these birds! The youngster is not fed by the adults but gets its nourishment from a large reserve of yolk in its abdomen. The chick stays in the nest for its first few days, gaining strength. The young kiwi then leaves the burrow and, accompanied by Dad, begins the search for food.
Conservation Status and Threats
When the Maori people established themselves in New Zealand in the 1300s, they used kiwi feathers to adorn cloaks worn by their chiefs and used the birds as food, hunting them at night by imitating kiwi calls. But in the late 1800s, settlers moved into kiwi territory, bringing dogs, cats, ferrets, stoats, and rats that ate kiwi eggs or the birds themselves. The settlers prized kiwi feathers, too-for trout flies! The kiwi existed for millions of years with only one natural predator-the now-extinct laughing owl-and no threats of any kind.
Because they did not evolve with any mammal predators around, kiwis lack the appropriate anti-mammal predatory response; kiwi chicks are vulnerable to nonnative predators like domestic cats and dogs, as well as stoats, weasels, ferrets, and rats. Introduced mammalian predators, namely stoats, dogs, ferrets, and cats, are the principal threats to kiwi. The biggest threat to kiwi chicks is stoats, while dogs are the biggest threat to adult kiwi. Stoats are responsible for approximately half of kiwi chick deaths in many areas through New Zealand. Young kiwi chicks are vulnerable to stoat predation until they reach about 1-1.2 kg (2.2-2.6 lb) in weight, at which time they can usually defend themselves. Cats also to a lesser extent prey on kiwi chicks. These predators can cause large and abrupt declines in populations. In particular, dogs find the distinctive strong scent of kiwi irresistible and easy to track, such that they can catch and kill kiwi in seconds. Motor vehicle strike is a threat to all kiwi where roads cross through their habitat.
Today, 80 percent of kiwi habitat has been destroyed, and the birds continue to fall prey to dogs, weasels, cats, ferrets, pigs, people, cattle guards, cars, swimming pools, and possum traps. Nationwide studies show that only around 5-10% of kiwi chicks survive to adulthood without management. As of 2018 over 70% of kiwi populations are unmanaged.
New Zealand passed a law in 1908 prohibiting the hunting, capture, or killing of kiwis, but the $100 penalty did little to control the situation, and in 1921 the kiwi was declared an “absolutely protected bird.”
Conservation Efforts
A few years ago, New Zealand began a kiwi recovery program. People living near kiwi areas have learned to keep their dogs leashed and to slow their cars when they see a kiwi caution sign by the road. Important data can also be gleaned from radio-tracking devices on the birds. The birds are identified with transponder tags, such as those used to microchip domestic pets. The radio transmitters reveal a great deal about where the birds go and how far they travel for food. One area of study is mate choice and how long kiwis stay together. Ongoing conservation work will compare hormone levels and also observe chick dispersal patterns for this long-lived bird.
Operation Nest Egg is a programme run by the BNZ Save the Kiwi Trust-a partnership between the Bank of New Zealand, the Department of Conservation and the Royal Forest and Bird Protection Society. Kiwi eggs and chicks are removed from the wild and hatched and/or raised in captivity until big enough to fend for themselves-usually when they weigh around 1200 grams (42 ounces). They are then returned to the wild.
In 2009, San Diego Zoo Wildlife Alliance formed collaborations with local ranchers on a private island off the coast of western New Zealand, Massey University, in-country scientists, and the indigenous Maori people to delve into the ecology of the brown kiwi, which has been in decline for decades. Learning about the reproductive ecology of this bird is the only way to ensure that its populations will survive and thrive. Techniques were developed in our labs to identify individual kiwis by their DNA and, and ultrasound procedures were used to monitor growth of ovarian follicles to estimate egg-laying time. This newfound knowledge was then successfully applied to birds on the island.
The Kiwi as a National Symbol
Its popularity grew, and the kiwi was adopted as New Zealand’s national emblem. Coins, postage stamps, fighting troops, and shoe polish all carry the name or image of the unique bird. The kiwi as a symbol first appeared in the late 19th century in New Zealand regimental badges. It was later featured in the badges of the South Canterbury Battalion in 1886 and the Hastings Rifle Volunteers in 1887. During the First World War, the name "Kiwis" for New Zealand soldiers came into general use, and a giant kiwi (now known as the Bulford kiwi) was carved on the chalk hill above Sling Camp in England. The kiwi has since become the best-known national symbol for New Zealand, and the bird is prominent in the coat of arms, crests and badges of many New Zealand cities, clubs and organisations. A kiwi has featured on the reverse side of three New Zealand coins: the one florin (two-shilling) coin from 1933 to 1966, the twenty-cent coin from 1967 to 1990, and the one-dollar coin since 1991.
The Little Spotted Kiwi
The little spotted kiwi (Apteryx owenii), also known as little grey kiwi or kiwi pukupuku, is a small flightless bird in the kiwi family, Apterygidae. It is the smallest of the five kiwi species, at about 0.9 to 1.9 kg (2-4+1⁄4 lb), about the size of a bantam. It is endemic to New Zealand, and in pre-European times occurred in both main islands, but is now mainly restricted to a number of small offshore islands and mainland reserves protected by pest-exclusion fences. The little spotted kiwi was on the brink of extinction when a conservation effort took place 100 years ago. Five individuals were translocated from the South Island to Kapiti Island.
The little spotted kiwi is a ratite and belongs to the Apterygiformes order, and the Apterygidae family. The genus name Apteryx means 'without wings' and the species is named owenii after Sir Richard Owen. The little spotted kiwi was first described in 1847 by John Gould from a specimen obtained by Frederick Strange and sent to England. These is a subspecies called Apteryx owenii iredalei, from the North Island, but its status as a subspecies is not universally accepted as valid. The North Island little spotted kiwi went extinct sometime in the late 19th century for unknown reasons; most likely from introduced invasive species such as stoats, feral cats, and other related species, or from human activity in the region.
The little spotted kiwi has a length of 35 to 45 cm (14-18 in) and the weight of the male is 0.88 to 1.36 kg (1 lb 15 oz - 3 lb 0 oz) and the female weighs 1 to 1.95 kg (2+1⁄4-4+1⁄4 lb), making it the smallest species of kiwi. Their feathers are pale-mottled grey, with fine white mottling, and are shaggy looking. They lack aftershafts and barbules. They have large vibrissae feathers around the gape.
Studies on Kapiti Island show that they prefer flax, seral, and older forest habitats. Little spotted kiwis eat grubs and other small insects that are found underground, and occasionally eat berries. As they cannot fly and their eyesight is very poor, they depend on a keen sense of smell, long beak and talons for finding food. Little spotted kiwi are nocturnal, and will call occasionally each night to advertise its territory and maintain contact with partners; often pairs will duet. They nest in an excavated burrow, dug by both birds and sometimes lined with plant material. Eggs are laid from July to January. The clutch size is one to two eggs (15% have 2), which are incubated by the male for 63-76 days.
At the time it was described (in the 1840s), the species was common on the western side of the South Island and in Marlborough. A regular trade in skins sprang up and large numbers were collected for European museums. In 2000, about 20 little spotted kiwis were released into Zealandia. As the smallest species of kiwi, they would be very vulnerable to the main kiwi predators like cats, dogs, and stoats, if not mostly restricted to several off-shore island reserves (mainly Kapiti Island) which are mostly free of introduced predators.
The little spotted kiwi's conservation status is listed as "range restricted" by Save the Kiwi, with a growing population. Formerly classified as "vulnerable" by the IUCN, it was suspected to be more numerous than generally assumed. Following the evaluation of its population size, this was found to be correct, and it was consequently downlisted to "near threatened" status in 2008 as, although not rare, its small range puts it at risk. The lack of predators, apart from weka, is important to its increasing numbers. In May 2025, 40 birds (20 males and 20 females) were translocated from Kapiti Island to the Brook Waimārama Sanctuary in Nelson, the largest fenced sanctuary in the South Island.