North Island Brown Kiwi (Apteryx mantelli)

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Image of a North island brown kiwi
Birds Kiwi

Introduction

The North Island brown kiwi, Apteryx mantelli, also known as kiwi-nui, is a flightless, nocturnal bird endemic to New Zealand’s North Island. It is one of five living kiwi species and is recognised for its shaggy plumage, unusually large egg, powerful legs and long bill with nostrils near the tip. The kiwi is also a taonga, or treasured species, for Māori and an important national symbol of Aotearoa New Zealand. (nzbirdsonline.org.nz)

Physical Description

The North Island brown kiwi is a compact, pear-shaped bird approximately 40 cm long. Males weigh about 2 kg, while females are larger at approximately 2.7 kg and have longer bills. The sexes are otherwise similar in appearance. (nzbirdsonline.org.nz)

Its plumage is dark brown, often streaked with reddish brown and black. The feathers are loose, shaggy and hair-like, with pointed tips that feel spiky to the touch. The small, vestigial wings are concealed beneath the body feathers and end in a small claw. The species has no visible tail and has strong legs, large feet and sharp claws adapted for running, digging and defence.

The long, pale bill is a key feature. Unlike most birds, the nostrils are positioned close to the bill tip, helping the kiwi locate prey beneath leaf litter and soil. The eyes are relatively small, while the senses of smell and touch are highly developed. Chicks hatch fully feathered and active, and their plumage remains softer and downier than adult plumage until they approach full size. (nzbirdsonline.org.nz)

Range and Habitat

The North Island brown kiwi is endemic to New Zealand and is the only kiwi species that occurs naturally in the wild on the North Island. It is distributed mainly across the northern two-thirds of the island, including Northland, the Coromandel Peninsula, the Bay of Plenty, Gisborne, parts of Hawke’s Bay, Taranaki, Whanganui and the central North Island. Populations have also been established on several offshore islands and at predator-controlled mainland sites. (nzbirdsonline.org.nz)

It occupies native forest, scrub, exotic forest, rough farmland and other habitats with suitable cover and food. The species occurs from sea level to about 1,400 m. It is sedentary and territorial rather than migratory, although young birds may disperse from their natal territories. (nzbirdsonline.org.nz)

Four geographically and genetically differentiated management forms are recognised: Northland, Coromandel, western and eastern North Island brown kiwi. These forms are not generally treated as separate formally described species. (dxcprod.doc.govt.nz)

Behaviour and Diet

North Island brown kiwi are primarily nocturnal. During the day they rest in burrows, hollow logs, natural cavities or dense vegetation, emerging shortly after nightfall to forage. They walk slowly while tapping or probing the ground with the bill, using smell and touch to locate prey in leaf litter, soil and decaying wood.

The diet consists mainly of small invertebrates, including earthworms, beetle larvae, cicadas, moth larvae, centipedes, spiders, crickets and wētā. Fallen fruit, seeds and some leaves are also eaten. Their probing and disturbance of the forest floor can contribute to soil turnover and nutrient cycling, although their principal ecological role is as a ground-foraging insectivore. (nzbirdsonline.org.nz)

The species is territorial. Pairs maintain contact and advertise their territories with repeated calls, often calling in duet. The male gives a high-pitched, ascending whistle, while the female gives a deeper, more guttural call. Pairs are generally monogamous and may maintain long-term bonds. Adults can defend themselves with their powerful legs and claws, but they remain highly vulnerable to introduced predators, particularly dogs.

Breeding may occur during much of the year, with peak egg-laying generally from June to November. The nest is usually in a short burrow, hollow log, rock crevice or cavity at ground level. A clutch normally contains one or two very large white eggs. The male alone incubates the egg, usually for about 75 to 90 days. (nzbirdsonline.org.nz)

Chicks hatch fully feathered and leave the nest to feed when only a few days old. They are not fed by their parents, although the male may shelter them during the day during the early weeks. Young birds remain vulnerable to stoats and other predators until they reach roughly 1 kg. (dxcprod.doc.govt.nz)

Identification Tips

In suitable habitat, look or listen for the following features:

  • A large, flightless, brown bird with shaggy, streaked plumage.
  • A long, pale bill, with the nostrils positioned near the tip.
  • No visible tail and only tiny wings concealed by the body feathers.
  • Strong legs, large feet and a low, forward-leaning posture.
  • Nocturnal activity, often detected by calls or rustling in leaf litter rather than by sight.
  • A repeated high-pitched whistle from the male or a deeper, guttural call from the female.

On the North Island, the species is unlikely to be confused with another kiwi in the wild. Weka may appear similar in colour, but they are generally smaller, have a much shorter bill and a more upright, chicken-like profile. Weka calls are also different, typically consisting of shorter two-syllable notes. (nzbirdsonline.org.nz)

Conservation Status

The North Island brown kiwi is classified as Vulnerable on the IUCN Red List. Under New Zealand’s current threat-classification information, it is listed as Nationally Vulnerable in the New Zealand Threat Classification System. National and global systems use different criteria and assessment frameworks, so their categories should not be treated as directly interchangeable. (iucn.org)

The principal threats are predation by introduced mammals, habitat loss and fragmentation, disturbance, vehicle strikes and the continuing risk posed by dogs. Stoats are a major threat to chicks, while dogs can kill adult kiwi even without appearing aggressive. Cats and ferrets may also kill kiwi, and rodents can compete for food or support larger predator populations. (dxcprod.doc.govt.nz)

Conservation measures include predator trapping, aerial pest-control operations, predator-proof fencing, habitat restoration, community monitoring and the protection of offshore-island populations. Operation Nest Egg and related programmes remove eggs or young chicks from vulnerable sites, raise them in safer conditions until they are large enough to withstand some predators, and return them to managed habitats. These measures have helped stabilise or increase some local populations, but long-term protection depends on sustained predator control and responsible dog management. (nzbirdsonline.org.nz)

The species also has major cultural importance. Kiwi are widely regarded as a national symbol of New Zealand, while Māori maintain longstanding cultural, spiritual and historical relationships with the bird. Kiwi feathers are traditionally valued in the weaving of kahukiwi, and tangata whenua are important partners in kiwi management and recovery. (dxcprod.doc.govt.nz)

Frequently Asked Questions

Where does the North Island brown kiwi live?

It occurs mainly in the northern two-thirds of New Zealand’s North Island, including Northland, Coromandel, the Bay of Plenty, Gisborne, parts of Hawke’s Bay, Taranaki, Whanganui and the central North Island. It also occurs on several offshore islands and at managed mainland sites.

Is the North Island brown kiwi nocturnal?

Yes. It generally rests during the day and emerges after dark to forage. It is more often heard than seen, particularly in dense forest or scrub.

What does the North Island brown kiwi eat?

Its diet consists mainly of earthworms and other invertebrates, including beetle larvae, moth larvae, centipedes, spiders, crickets and wētā. It also eats some fallen fruit, seeds and leaves.

How does the North Island brown kiwi find food?

It probes leaf litter, soil and rotting wood with its long bill. Its nostrils are near the bill tip, and its well-developed senses of smell and touch help it locate concealed prey.

Who incubates the North Island brown kiwi’s egg?

The male normally incubates the egg alone for approximately 75 to 90 days. The female may lay one or two very large eggs during a breeding attempt.

What threatens the North Island brown kiwi?

The main threats are introduced predators, especially stoats and dogs, together with cats, ferrets, habitat loss, fragmentation and other human-related hazards. Predator control, protected habitats, community conservation and managed chick-rearing programmes are important safeguards.

References

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