---
title: "What the sources say about the North Island Brown Kiwi | AnimalTracks.wiki"
description: "45 claims from the North Island Brown Kiwi profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/north-island-brown-kiwi-1.webp"
canonical: "https://animaltracks.wiki/animals/north-island-brown-kiwi/sources/"
---

# What the sources say about the North Island Brown Kiwi (*Apteryx mantelli*)

> 45 claims from the North Island Brown Kiwi profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [North Island Brown Kiwi](https://animaltracks.wiki/animals/north-island-brown-kiwi/)

## North Island brown kiwi. Smithsonian's National Zoo and Conservation Biology Institute.

https://nationalzoo.si.edu/animals/north-island-brown-kiwi

| The page says | The source says |
| :--- | :--- |
| nostrils near the tip | The kiwi's long, curved, pale gray-brown bill is unique in the bird world in having the nostrils located near the tip. |
| A kiwi plunges that bill again and again into the leaf litter of the forest floor. | the bird forages by plunging it repeatedly into the leaf litter of the forest floor in search of prey |
| It often snuffles audibly as it searches, a sound that may come from a valve behind the nostrils that stops it inhaling dirt. | often snuffle audibly when searching for food. The snuffling may be produced by the opening and closing of a valve behind the nostrils that prevents the bird from inhaling dirt and debris |
| A female kiwi lays an extremely large egg, an average of 15 percent of her body weight. It weighs about 450 grams and is over 60 percent yolk. | The female lays a single extremely large egg — an average of 15 percent of her body weight. Producing such a large (about 1 pound) and energy-rich (over 60 percent yolk) eggs (note: task #986: the source gives "about 1 pound"; 1 lb is 454 g, stated in grams to match the metric body) |
| Kiwi are stout birds that stand 0.5 to 0.6 metres tall. | Kiwi are stout birds, standing 1.5 to 2 feet tall (0.5 to 0.6 meters) tall (note: Smithsonian text is for kiwi; kept scoped to kiwi) |
| Females are heavier than males, at 2 to 3.9 kilograms against 1.4 to 3.2 kilograms. | females at 4.5 to 8.5 pounds (2 to 3.9 kilograms) weighing more than males at 3 to 7 pounds (1.4 to 3.2 kilograms) |
| earthworms, beetles, snails, crayfish, insects, fruits and berries | Brown kiwi have an extremely varied diet that includes earthworms, beetles, snails, crayfish, insects, fruits and berries. |
| Kiwi forage actively from dusk to dawn. | Kiwi are nocturnal birds. They forage actively from dusk to dawn. |
| A territory covers 5 to 50 hectares depending on habitat quality, and each one holds several burrows. | Territories range in size from 12 to 124 acres (5 to 50 hectares) depending on the quality of the habitat. Kiwi excavate several burrows within each territory. |
| she leaves the male to incubate the eggs, which takes about 68 to 91 days | She then leaves the male to incubate the eggs, which takes about 68 to 91 days. |
| Adults are usually feisty enough to defend themselves against smaller predators, but eggs and newly hatched young are very vulnerable. | adult kiwi are usually feisty enough to defend themselves against the smaller predators, their eggs and newly hatched young are extremely vulnerable to predation. |
| Predators include rats, weasels, cats, dogs and pigs. | Predators include rats, weasels, cats, dogs and pigs. |
| Nostrils near the tip of a long, curved bill | The kiwi's long, curved, pale gray-brown bill is unique in the bird world in having the nostrils located near the tip. |
| A flightless night forager with its nostrils near the tip of its bill | Kiwi are flightless, nocturnal birds native only to New Zealand. |
| With its feet. A kiwi chick has no egg tooth and kicks its way out of the shell. | Kiwi chicks have no egg tooth and must use their feet to kick their way out of the shell. |
| It hatches fully developed and looks like a miniature adult. | They are fully developed chicks, looking like a miniature replica of an adult. |
| Most kiwi species are independent by four weeks of age, but the birds do not reach adult size until they are 18 to 20 months old. | Although most species are completely independent by four weeks of age, they do not reach adult size until they are 18 to 20 months old. |
| Their eyes are small, while their ears are unusually large. | Though their eyes are small, their ears are unusually large. |
| an egg that averages 15 percent of its mother's weight | The female lays a single extremely large egg — an average of 15 percent of her body weight. |
| Its long, curved bill is unique in the bird world in having the nostrils near the tip. | The kiwi's long, curved, pale gray-brown bill is unique in the bird world in having the nostrils located near the tip. |
| A female kiwi lays an extremely large egg, an average of 15 percent of her body weight. | The female lays a single extremely large egg — an average of 15 percent of her body weight. |
| The North Island brown kiwi (Apteryx mantelli) is a flightless bird that forages at night. | Kiwi are flightless, nocturnal birds native only to New Zealand. |
| Kiwi use that bill to sniff out food. | They use their unique bill to sniff out food |
| A kiwi snuffles audibly as it hunts, a sound that may come from a valve behind its nostrils | often snuffle audibly when searching for food. The snuffling may be produced by the opening and closing of a valve behind the nostrils that prevents the bird from inhaling dirt and debris (note: vibe.reason) |

## Brown kiwi. New Zealand Department of Conservation.

https://www.doc.govt.nz/nature/native-animals/birds/birds-a-z/kiwi/brown-kiwi/

| The page says | The source says |
| :--- | :--- |
| Every brown kiwi lives on New Zealand's North Island, in lowland and coastal native forest and subalpine areas. | All brown kiwi live in the North Island. |
| lowland and coastal native forest and subalpine areas | Found in: Lowland and coastal native forest and subalpine areas in the North Island |
| There are four distinct forms: the Northland, Coromandel, Western and Eastern brown kiwi. | Four geographically and genetically distinct forms have been identified: Northland brown kiwi Coromandel brown kiwi Western brown kiwi Eastern brown kiwi. |
| New Zealand's Department of Conservation says other kiwi live to be 40 to 65 years old, but the Northland form of this species averages only 14 years. | Other kiwi live to be 40-65 years old, but the Northland brown kiwi averages only 14 years. |
| Brown kiwi breed faster than other kiwi, with up to two eggs a clutch and one to two clutches a year. | The brown kiwi is faster at breeding than other kiwi, producing up to two eggs a clutch, and one to two clutches a year |
| A 1996 estimate said North Island kiwi had probably declined by at least 90% over the previous century | In 1996, it was estimated that North Island kiwi had probably declined by at least 90% during the previous century. |
| the Department of Conservation puts the population at about 26,000 | Threat status: Not Threatened (conservation dependent) Population: About 26,000 |
| Lowland and coastal native forest and subalpine areas of New Zealand's North Island | Lowland and coastal native forest and subalpine areas in the North Island |
| Even so, numbers are falling. | much of that good reproductive work is undone by the ravages of dogs, stoats, and loss of habitat |
| Even so, numbers are falling. | the population is steadily declining |

## Butler & McLennan. Kiwi Recovery Plan. New Zealand Department of Conservation, Threatened Species Recovery Plan Series No. 2.

https://www.doc.govt.nz/globalassets/documents/science-and-technical/tsrp02.pdf

| The page says | The source says |
| :--- | :--- |
| tags: insectivore | Earthworms, cicada nymphs and beetle adults and larvae are their main foods, supplemented by a few seeds and leaves and a wide variety of other invertebrates (note: tags, task #986: grubs and insects are the main foods and plants 'a few', so insectivore stands; omnivore's 'plant matter, fruits, insects, and meat' overstates the plant share) |

## Corfield et al. (2014). Anatomical Specializations for Enhanced Olfactory Sensitivity in Kiwi, Apteryx mantelli. Brain, Behavior and Evolution.

https://doi.org/10.1159/000365564

| The page says | The source says |
| :--- | :--- |
| Scientists compared kiwi with 55 other bird species, and the kiwi's olfactory bulbs | we examine the size of the olfactory bulbs in kiwi and compare them with 55 other bird species |
| were proportionately larger than any other bird's in the study | Kiwi were a clear outlier in our analysis, with olfactory bulbs that are proportionately larger than those of any other bird in this study. |

## Cunningham, Castro & Alley (2007). A new prey-detection mechanism for kiwi (Apteryx spp.) suggests convergent evolution between paleognathous and neognathous birds. Journal of Anatomy.

https://doi.org/10.1111/j.1469-7580.2007.00786.x

| The page says | The source says |
| :--- | :--- |
| The bill tip holds mechanoreceptors, cells that sense vibration and pressure, set in pits arranged like those of sandpipers and snipe. A kiwi may be able to locate prey the same way. | Apteryx possess an arrangement of mechanoreceptors within pits similar to that in Scolopacidae species and may therefore be able to localise prey using a similar vibrotactile sense. |
| Touch may help too. | may therefore be able to localise prey using a similar vibrotactile sense |

## Martin et al. (2007). Kiwi Forego Vision in the Guidance of Their Nocturnal Activities. PLoS ONE.

https://doi.org/10.1371/journal.pone.0000198

| The page says | The source says |
| :--- | :--- |
| A study of kiwi eye structure, visual field and brain found minimal reliance on vision and more reliance on touch and smell. | Kiwi show minimal reliance upon vision indicated by eye structure, visual field topography, and brain structures, and increased reliance upon tactile and olfactory information. |
| Sight is not their main tool. | Kiwi show minimal reliance upon vision |

## Taborsky & Taborsky (1991). Social Organization of North Island Brown Kiwi: Long-term Pairs and Three Types of Male Spacing Behaviour. Ethology.

https://doi.org/10.1111/j.1439-0310.1991.tb00292.x

| The page says | The source says |
| :--- | :--- |
| In one radio-tracking study of 51 North Island brown kiwi in Waitangi State Forest, behavioural evidence suggested long-term pairs. | We observed 51 kiwi by radiotracking for an average period of 2.3 months each, in Waitangi State Forest, New Zealand. ... behavioural evidence suggests a monogamous mating system with long‐term pair bonds. |
| 22.1% of fully grown males in 1986 and 37.3% in 1987 had no mate. | A surplus of fully grown males (22.1% in 1986, 37.3% in 1987) remained unpaired. |

## Apteryx mantelli. The IUCN Red List of Threatened Species 2017: e.T45353580A119177586.

https://doi.org/10.2305/iucn.uk.2017-3.rlts.t45353580a119177586.en

| The page says | The source says |
| :--- | :--- |
| The IUCN Red List rates the species Vulnerable. | IUCN Red List category: Vulnerable (VU). |
| Vulnerable | IUCN Red List category: Vulnerable (VU). |