---
title: "What the sources say about the Kakapo (Owl Parrot) | AnimalTracks.wiki"
description: "66 claims from the Kakapo (Owl Parrot) profile, each beside the words of the source that backs it."
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---

# What the sources say about the Kakapo (Owl Parrot) (*Strigops habroptilus*)

> 66 claims from the Kakapo (Owl Parrot) profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Kakapo (Owl Parrot)](https://animaltracks.wiki/animals/kakapo/)

## Kākāpō | Kakapo. New Zealand Birds Online.

https://www.nzbirdsonline.org.nz/species/kakapo

| The page says | The source says |
| :--- | :--- |
| camouflaged in moss-green feathers | Kākāpō are moss green mottled with yellow and black above ... kākāpō usually freeze and rely on cryptic colouration to hide them from predators (note: tagline) |
| Forested predator-free islands off New Zealand | The transfer of the whole population to predator-free islands ... Kākāpō now occur only on forested islands (note: stats.habitat, first clause) |
| Plants only, including rimu fruit, leaves, buds, flowers, fern fronds, roots, bulbs and seeds | Kākāpō are entirely vegetarian. Their diet includes, leaves, buds, flowers, fern fronds, bark, roots, rhizomes, bulbs, fruit and seeds. (note: stats.diet; every item is in NZBO's list; rimu fruit is the next claim) |
| Mottled moss-green camouflage | Kākāpō are moss green mottled with yellow and black above ... kākāpō usually freeze and rely on cryptic colouration to hide them from predators (note: stats.superpower, first clause) |
| It is 58 to 64 centimetres long; males weigh 2 to 4 kilograms and females 1 to 2.5. | Length: 58 - 64 cm Weight: 2 - 4 kg (males), 1 - 2.5 kg (females) (note: the length is for the species, not males only) |
| can live for more than 50 years; the maximum is unknown | Maximum longevity Unknown but more than 50 years |
| Breeding in Good Fruit Years | Kākāpō breed in summer and autumn, but only in years of good fruit abundance. (note: heading) |
| On islands in southern New Zealand they breed when the rimu trees fruit, once every two to four years. | On islands in southern New Zealand they breed when the rimu trees fruit, which is once every 2 to 4 years. (note: NZBO (updated 2025) limits the rimu trigger to southern islands; DOC's 'only breed when rimu trees mass fruit' is broader, so the narrower current scope is used) |
| Freezing and relying on camouflage worked when the main predators were birds that hunted by sight | Away from nests, kākāpō usually freeze and rely on cryptic colouration to hide them from predators. While this strategy worked when the main predators were birds that hunted by sight |
| It is completely ineffective against mammals that hunt by smell, like introduced cats and stoats | Adult kākāpō are vulnerable to predation by cats and stoats ... it is a completely ineffective strategy to avoid mammalian predators that hunt by smell. (note: 'introduced' is DOC's 'introduced mammalian predators such as cats and stoats') |
| Before humans arrived, kakapo were common throughout New Zealand's forests, until introduced predators brought them down | Before humans arrived it was common throughout New Zealand’s forests, but predation by introduced mammals brought it to the brink of extinction - a low point of about 50 birds only in the mid 1990s. |
| Moving the whole population to predator-free islands and managing every stage of life has brought a steady increase | The transfer of the whole population to predator-free islands and intensive intervention in every stage of its life has led to a steady increase in numbers. |

## Kākāpō behaviour. New Zealand Department of Conservation.

https://www.doc.govt.nz/nature/native-animals/birds/birds-a-z/kakapo/behaviour/

| The page says | The source says |
| :--- | :--- |
| rimu fruit | Their diet is diverse, including fruit from the tips of high rimu branches (note: stats.diet) |
| a freeze-in-place defence | Kākāpō freeze when they're disturbed, relying on their mottled feathers to camouflage them. (note: stats.superpower, second clause) |
| The Parrot That Lost Its Flight | Kākāpō evolved without the presence and effect of mammals. They gained weight and lost their flying ability. (note: heading) |
| he booms every one to two seconds | he emits a deep, low-frequency 'boom' every 1-2 seconds (note: vibe.reason) |
| his serenade can last eight hours a night | His serenade can last for eight hours, every night for two or three months. (note: vibe.reason) |
| It walks and climbs: lighter females can glide across gaps of 3 to 4 metres, strong claws take it up 20-metre rimu trees, and it can walk several kilometres at a time. | lighter females can manage short glides across gaps of 3-4 m. They kept their head for heights though, using their strong claws to climb 20 m high rimu trees. They're also excellent hikers, with large strong legs. They can walk several kilometres at a time |
| It eats only plants | Kākāpō are herbivorous - they only eat plants. |
| A Boom From an Inflated Chest | Settled in his bowl, the male inflates his thoracic air sac. Then he emits a deep, low-frequency 'boom' (note: blockquote lead-in) |
| During booming, a male kakapo inflates the air sac in his chest | Settled in his bowl, the male inflates his thoracic air sac. |
| It can be heard hundreds of metres away | Then he emits a deep, low-frequency 'boom' every 1-2 seconds that can be heard hundreds of metres away. |
| Kakapo are the only parrot species known to breed at a lek, where males display at fixed spots to attract females. | Male kākāpō put on displays at fixed locations to attract female attention, and they don't help to raise any offspring. It's called lek breeding. No other New Zealand bird does it, and no other parrot species in the world is known to lek breed. (note: 'only ... known to' restates 'no other parrot species ... is known to') |
| In breeding years, each male forms a shallow bowl in the earth on a ridge, rock or hilltop and calls there for up to eight hours a night, every night for two or three months. | In breeding years, adult male kākāpō take to the stage in about December. Each male finds a prominent ridge, rock or hilltop with low-growing vegetation ... he forms a track-and-bowl system: a network of tracks radiating from a shallow bowl-like depression in the earth ... His serenade can last for eight hours, every night for two or three months. |
| Females can travel long distances to mate with the male or males they prefer, then raise the chicks alone. | Adult males and females meet only to breed, and the females raise their chicks alone ... Females can travel long distances to mate with their preferred male or males |
| A Smell That Gave Them Away | introduced mammalian predators such as cats and stoats use smell to hunt, and are active day and night. That's what makes them such a threat to the distinctive-smelling flightless kākāpō. (note: heading) |
| Kakapo evolved without mammals. | Kākāpō evolved without the presence and effect of mammals. |
| such as the now-extinct Haast's eagle | It's an excellent defence against predators that rely on sight, such as the now-extinct Haast's eagle |
| In breeding years, male kakapo take to prominent ridges, rocks or hilltops, form a network of tracks and shallow bowls, and call for up to eight hours a night, every night for two or three months, while females travel to the male or males they prefer. | In breeding years, adult male kākāpō take to the stage in about December. Each male finds a prominent ridge, rock or hilltop ... he forms a track-and-bowl system: a network of tracks radiating from a shallow bowl-like depression in the earth ... His serenade can last for eight hours, every night for two or three months ... Females can travel long distances to mate with their preferred male or males (note: FAQ 2) |
| No other parrot species in the world is known to breed this way. | no other parrot species in the world is known to lek breed (note: FAQ 2) |
| Males play no part afterward; the females raise their chicks alone. | Adult males and females meet only to breed, and the females raise their chicks alone ... they don't help to raise any offspring (note: FAQ 2) |
| When disturbed they freeze and rely on their mottled feathers for camouflage, an excellent defence against predators that hunt by sight, such as the now-extinct Haast's eagle. | Kākāpō freeze when they're disturbed, relying on their mottled feathers to camouflage them. It's an excellent defence against predators that rely on sight, such as the now-extinct Haast's eagle (note: FAQ 3) |
| But introduced cats and stoats hunt by smell and are active day and night, which makes them such a threat to a flightless parrot with a distinctive smell. | But introduced mammalian predators such as cats and stoats use smell to hunt, and are active day and night. That's what makes them such a threat to the distinctive-smelling flightless kākāpō. (note: FAQ 3) |

## Kākāpō return to mainland in historic translocation. New Zealand Department of Conservation, 2023.

https://www.doc.govt.nz/news/media-releases/2023-media-releases/kakapo-return-to-mainland-in-historic-translocation/

| The page says | The source says |
| :--- | :--- |
| to 51 birds in 1995 | recovering from a population low of 51 birds in 1995 |
| there were 248 kakapo in July 2023 | The current total kākāpō population is 248. (note: the release is dated 19 July 2023, so the figure is dated in the text rather than given as today's) |
| when four males moved to a fenced mainland sanctuary, the first on the mainland in nearly four decades | For the first time in nearly four decades, kākāpō will be living on mainland New Zealand. Date: 19 July 2023 The Department of Conservation in partnership with Ngāi Tahu is moving four male kākāpō ... Moving a group of the birds to the 3400ha fenced sanctuary |

## Kākāpō habitat and islands. New Zealand Department of Conservation.

https://www.doc.govt.nz/nature/native-animals/birds/birds-a-z/kakapo/habitat-and-islands/

| The page says | The source says |
| :--- | :--- |
| a small group of males in a fenced mainland sanctuary | Today, kākāpō only live on protected offshore islands and in a fenced mainland sanctuary. ... This small population of male kākāpō is being closely monitored (note: stats.habitat, second clause; DOC's current habitat page (the 2023 translocation release is archived). DOC's 1 May 2025 release says three of the ten males introduced remain, seven returned to the islands after fence breaches, so no count is given) |

## Powlesland, Merton & Cockrem (2006). A parrot apart: the natural history of the kakapo (Strigops habroptilus), and the context of its conservation management. Notornis.

https://doi.org/10.63172/605353vxtvye

| The page says | The source says |
| :--- | :--- |
| The heaviest parrot in the world | A combination of characteristics make the kakapo unique among parrots; heaviest parrot (note: tagline; Livezey 1992's 'most massive ... psittaciform in the world' agrees) |
| betrayed by its own strong scent | Since kakapo have a strong odour and remain motionless when approached, feral dogs would have had a devastating impact on kakapo populations. (note: tagline; DOC's 'That's what makes them such a threat to the distinctive-smelling flightless kākāpō' says the same of cats and stoats) |
| courting with a boom heard up to five kilometres away in ideal conditions | The most frequently heard call during the courtship season is “booming”, a low-frequency (< 100 Hz), nondirectional, resonant call (Higgins 1999), which under ideal conditions can be heard at distances of up to 5 km (note: tagline; the source's 'under ideal conditions' restored. DOC's current page gives the everyday range, 'hundreds of metres', which the body states too) |
| a booming courtship call heard up to 5 kilometres away in ideal conditions | The most frequently heard call during the courtship season is “booming”, a low-frequency (< 100 Hz), nondirectional, resonant call (Higgins 1999), which under ideal conditions can be heard at distances of up to 5 km (note: stats.superpower, closing clause) |
| The kakapo (Strigops habroptilus) is the heaviest parrot in the world | A combination of characteristics make the kakapo unique among parrots; heaviest parrot |
| Its sense of smell is believed to be well developed. | The sense of smell, however, is believed to be well developed and important in locating food |
| Measured against its brain's length, its smell-processing olfactory bulb is larger than in most non-passerine birds, parrots included, and comparable to a brown kiwi's or a turkey vulture's, two birds with a keen sense of smell. | longest diameter of the olfactory bulb / longest diameter of the brain ... The kakapo has a larger OBR than most non-passerines (19.6), including parrots, and comparable to that of species with a known acute sense of smell (e.g. brown kiwi, Apteryx australis, 34.0; turkey vulture, Cathartes aura, 28.7 (note: the kiwi and vulture figures are kept only as the source states them: comparable ratios in birds known to smell well) |
| Whisker-like feathers near its eyes and beak, called rictal bristles, may help it avoid injury in the dark, much like a cat's whiskers | Rictal bristles, near the eyes and beak, may have helped them to avoid injury when moving about in the dark, functioning much like the whiskers of a cat. (note: keeps the source's 'may'; 'whisker-like' is the monograph's own 'filoplumes resembling cat's whiskers') |
| the lower ones touch the ground as it walks | When walking, kakapo adopt a near-horizontal posture bringing the lower rictal bristles into contact with the ground. |
| gives a deep call below 100 hertz | “booming”, a low-frequency (< 100 Hz), nondirectional, resonant call (note: 'below 100 hertz' restates '< 100 Hz'; audible sound, not infrasound) |
| in ideal conditions up to 5 kilometres | which under ideal conditions can be heard at distances of up to 5 km |

## Corfield et al. (2011). Anatomical Specializations for Nocturnality in a Critically Endangered Parrot, the Kakapo (Strigops habroptilus). PLoS ONE.

https://doi.org/10.1371/journal.pone.0022945

| The page says | The source says |
| :--- | :--- |
| Built for the Dark | its visual abilities are characterized by the larger binocular visual field, enhanced low light sensitivity and poor visual acuity usual for nocturnal birds (note: heading) |
| A kakapo's eyes probably work well in dim light but see poorly in detail. | Overall, this suggests that the Kakapo has enhanced light sensitivity, poor visual acuity and a larger binocular field than other parrots. (note: 'probably' carries the source's 'suggests'; replaces the 2006 monograph's 'apparently its sight is not well developed (Higgins 1999)' with the 2011 anatomy) |
| Its eye sockets face further forward than other parrots', suggesting more overlap between its two eyes' views. | the Kakapo's orbits are significantly more convergent than other parrots, suggesting an increased binocular overlap in the visual field |
| Its eye shape fits nocturnal birds such as owls and nightjars but also falls within the range of daytime parrots, and some of its brain's sight regions are relatively smaller than other parrots'. | The Kakapo exhibits an eye shape that is consistent with other nocturnal birds, including owls and nightjars, but is also within the range of the diurnal parrots ... the optic tectum, nucleus rotundus and entopallium were significantly reduced in relative size compared to other parrots. There was no apparent reduction to the thalamofugal visual pathway. (note: 'some of' because the thalamofugal pathway is not reduced) |
| a kakapo has a strong body odour | an obligate herbivore with a strong body-odour |

## Livezey (1992). Morphological corollaries and ecological implications of flightlessness in the kakapo (Psittaciformes: Strigops habroptilus). Journal of Morphology.

https://doi.org/10.1002/jmor.1052130108

| The page says | The source says |
| :--- | :--- |
| with the smallest wings relative to its size of any parrot | has the smallest relative wing size of any parrot |
| Its breastbone has only a vestigial keel, and its main breast muscles are greatly reduced. | peculiarities of the sternum (vestigial carina, shortened spina externa) ... a greatly reduced Mm. pectoralis thoracica and supracoracoideus (note: the carina is the sternum's keel; pectoralis thoracica and supracoracoideus are the two big breast muscles. Final pass: 'wing muscles' was wider than the source's two named muscles) |
| The kakapo is the most massive parrot in the world and has the smallest wings for its size of any parrot. | S. habroptilus is the most massive and sexually dimorphic psittaciform in the world, and has the smallest relative wing size of any parrot. (note: FAQ 1) |
| Its breastbone has only a vestigial keel, its main breast muscles are greatly reduced, and for its weight the muscles of its forearm and hand are smaller than those of the kea, a close relative that flies. | the closely related, flighted kea ( Nestor notabilis ) ... peculiarities of the sternum (vestigial carina, shortened spina externa) ... a greatly reduced Mm. pectoralis thoracica and supracoracoideus ... Relative to mean body mass, all dimensions of the antebrachial, carpometacarpal, digital, and patagial muscles are smaller in S. habroptilus than in N. notabilis (note: FAQ 1; pectoralis thoracica and supracoracoideus are the two big breast muscles that power the wingbeat) |

## Savage et al. (2021). Low hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertility. Animal Conservation.

https://doi.org/10.1111/acv.12746

| The page says | The source says |
| :--- | :--- |
| Researchers found that 61% of kakapo eggs fail to hatch, and 73% of those show no sign of development. | 61% of their eggs fail to hatch, and of these 73% show no sign of development |
| Undeveloped eggs were once blamed on male infertility, but 72% of the ones tested had been fertilised | Undeveloped eggs have previously been attributed to male infertility ... the majority (72%, n = 124) of undeveloped kākāpō eggs are fertilised |
| so early embryo death, not infertility, drives the low hatching rate | Low hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertility (note: the paper's title, as the references list gives it; not in the cached abstract, so a hand check. The abstract's figures agree: 72% of undeveloped eggs are fertilised, so only about 20% of failed eggs (0.28 x 0.73) are unfertilised) |
| Mostly because embryos die early. | Low hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertility (note: FAQ 4; the paper's title, a hand check; 'mostly' is 'driven by', and the abstract's 72% fertilised undeveloped eggs agree) |
| Researchers found that 61% of kakapo eggs fail to hatch, and 73% of those show no sign of development. | 61% of their eggs fail to hatch, and of these 73% show no sign of development (note: FAQ 4) |
| Undeveloped eggs were once blamed on male infertility, but 72% of the ones tested had been fertilised | Undeveloped eggs have previously been attributed to male infertility ... the majority (72%, n = 124) of undeveloped kākāpō eggs are fertilised (note: FAQ 4) |
| so early embryo death, not infertility, drives the low hatching rate | Low hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertility (note: FAQ 4; the paper's title, a hand check) |

## Strigops habroptila. The IUCN Red List of Threatened Species 2018: e.T22685245A129751169.

https://doi.org/10.2305/iucn.uk.2018-2.rlts.t22685245a129751169.en

| The page says | The source says |
| :--- | :--- |
| Critically Endangered | IUCN Red List category: Critically Endangered (CR). (note: stats.conservationStatus) |
| It is still Critically Endangered. | IUCN Red List category: Critically Endangered (CR). |