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What the sources say

Kakapo (Owl Parrot)Strigops habroptilus

Every figure, record and mechanism on the Kakapo (Owl Parrot) profile was written from a source, and this is the working table behind it: 66 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

New Zealand Birds Online

Kākāpō | Kakapo. New Zealand Birds Online.

The page sayscamouflaged in moss-green feathers
The source saysKākāpō are moss green mottled with yellow and black above ... kākāpō usually freeze and rely on cryptic colouration to hide them from predatorsNote: tagline
The page saysForested predator-free islands off New Zealand
The source saysThe transfer of the whole population to predator-free islands ... Kākāpō now occur only on forested islandsNote: stats.habitat, first clause
The page saysPlants only, including rimu fruit, leaves, buds, flowers, fern fronds, roots, bulbs and seeds
The source saysKākāpō 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
The page saysMottled moss-green camouflage
The source saysKākāpō are moss green mottled with yellow and black above ... kākāpō usually freeze and rely on cryptic colouration to hide them from predatorsNote: stats.superpower, first clause
The page saysIt is 58 to 64 centimetres long; males weigh 2 to 4 kilograms and females 1 to 2.5.
The source saysLength: 58 - 64 cm Weight: 2 - 4 kg (males), 1 - 2.5 kg (females)Note: the length is for the species, not males only
The page sayscan live for more than 50 years; the maximum is unknown
The source saysMaximum longevity Unknown but more than 50 years
The page saysBreeding in Good Fruit Years
The source saysKākāpō breed in summer and autumn, but only in years of good fruit abundance.Note: heading
The page saysOn islands in southern New Zealand they breed when the rimu trees fruit, once every two to four years.
The source saysOn 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
The page saysFreezing and relying on camouflage worked when the main predators were birds that hunted by sight
The source saysAway 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
The page saysIt is completely ineffective against mammals that hunt by smell, like introduced cats and stoats
The source saysAdult 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'
The page saysBefore humans arrived, kakapo were common throughout New Zealand's forests, until introduced predators brought them down
The source saysBefore 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.
The page saysMoving the whole population to predator-free islands and managing every stage of life has brought a steady increase
The source saysThe 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.

Source
02

New Zealand Department of Conservation

Kākāpō behaviour. New Zealand Department of Conservation.

The page saysrimu fruit
The source saysTheir diet is diverse, including fruit from the tips of high rimu branchesNote: stats.diet
The page saysa freeze-in-place defence
The source saysKākāpō freeze when they're disturbed, relying on their mottled feathers to camouflage them.Note: stats.superpower, second clause
The page saysThe Parrot That Lost Its Flight
The source saysKākāpō evolved without the presence and effect of mammals. They gained weight and lost their flying ability.Note: heading
The page sayshe booms every one to two seconds
The source sayshe emits a deep, low-frequency 'boom' every 1-2 secondsNote: vibe.reason
The page sayshis serenade can last eight hours a night
The source saysHis serenade can last for eight hours, every night for two or three months.Note: vibe.reason
The page saysIt 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.
The source sayslighter 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
The page saysIt eats only plants
The source saysKākāpō are herbivorous - they only eat plants.
The page saysA Boom From an Inflated Chest
The source saysSettled in his bowl, the male inflates his thoracic air sac. Then he emits a deep, low-frequency 'boom'Note: blockquote lead-in
The page saysDuring booming, a male kakapo inflates the air sac in his chest
The source saysSettled in his bowl, the male inflates his thoracic air sac.
The page saysIt can be heard hundreds of metres away
The source saysThen he emits a deep, low-frequency 'boom' every 1-2 seconds that can be heard hundreds of metres away.
The page saysKakapo are the only parrot species known to breed at a lek, where males display at fixed spots to attract females.
The source saysMale 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'
The page saysIn 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.
The source saysIn 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.
The page saysFemales can travel long distances to mate with the male or males they prefer, then raise the chicks alone.
The source saysAdult 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
The page saysA Smell That Gave Them Away
The source saysintroduced 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
The page saysKakapo evolved without mammals.
The source saysKākāpō evolved without the presence and effect of mammals.
The page sayssuch as the now-extinct Haast's eagle
The source saysIt's an excellent defence against predators that rely on sight, such as the now-extinct Haast's eagle
The page saysIn 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.
The source saysIn 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 malesNote: FAQ 2
The page saysNo other parrot species in the world is known to breed this way.
The source saysno other parrot species in the world is known to lek breedNote: FAQ 2
The page saysMales play no part afterward; the females raise their chicks alone.
The source saysAdult males and females meet only to breed, and the females raise their chicks alone ... they don't help to raise any offspringNote: FAQ 2
The page saysWhen 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.
The source saysKākāpō 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 eagleNote: FAQ 3
The page saysBut 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.
The source saysBut 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

Source
03

New Zealand Department of Conservation 2023

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

The page saysto 51 birds in 1995
The source saysrecovering from a population low of 51 birds in 1995
The page saysthere were 248 kakapo in July 2023
The source saysThe 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
The page sayswhen four males moved to a fenced mainland sanctuary, the first on the mainland in nearly four decades
The source saysFor 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

Source
04

New Zealand Department of Conservation

Kākāpō habitat and islands. New Zealand Department of Conservation.

The page saysa small group of males in a fenced mainland sanctuary
The source saysToday, kākāpō only live on protected offshore islands and in a fenced mainland sanctuary. ... This small population of male kākāpō is being closely monitoredNote: 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

Source
05

Powlesland, Merton & Cockrem 2006

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

The page saysThe heaviest parrot in the world
The source saysA combination of characteristics make the kakapo unique among parrots; heaviest parrotNote: tagline; Livezey 1992's 'most massive ... psittaciform in the world' agrees
The page saysbetrayed by its own strong scent
The source saysSince 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
The page sayscourting with a boom heard up to five kilometres away in ideal conditions
The source saysThe 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 kmNote: tagline; the source's 'under ideal conditions' restored. DOC's current page gives the everyday range, 'hundreds of metres', which the body states too
The page saysa booming courtship call heard up to 5 kilometres away in ideal conditions
The source saysThe 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 kmNote: stats.superpower, closing clause
The page saysThe kakapo (Strigops habroptilus) is the heaviest parrot in the world
The source saysA combination of characteristics make the kakapo unique among parrots; heaviest parrot
The page saysIts sense of smell is believed to be well developed.
The source saysThe sense of smell, however, is believed to be well developed and important in locating food
The page saysMeasured 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.
The source sayslongest 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, 28.7Note: the kiwi and vulture figures are kept only as the source states them: comparable ratios in birds known to smell well
The page saysWhisker-like feathers near its eyes and beak, called rictal bristles, may help it avoid injury in the dark, much like a cat's whiskers
The source saysRictal 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 page saysthe lower ones touch the ground as it walks
The source saysWhen walking, kakapo adopt a near-horizontal posture bringing the lower rictal bristles into contact with the ground.
The page saysgives a deep call below 100 hertz
The source says“booming”, a low-frequency (< 100 Hz), nondirectional, resonant callNote: 'below 100 hertz' restates '< 100 Hz'; audible sound, not infrasound
The page saysin ideal conditions up to 5 kilometres
The source sayswhich under ideal conditions can be heard at distances of up to 5 km

Source
06

Corfield et al. 2011

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

The page saysBuilt for the Dark
The source saysits visual abilities are characterized by the larger binocular visual field, enhanced low light sensitivity and poor visual acuity usual for nocturnal birdsNote: heading
The page saysA kakapo's eyes probably work well in dim light but see poorly in detail.
The source saysOverall, 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
The page saysIts eye sockets face further forward than other parrots', suggesting more overlap between its two eyes' views.
The source saysthe Kakapo's orbits are significantly more convergent than other parrots, suggesting an increased binocular overlap in the visual field
The page saysIts 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 source saysThe 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
The page saysa kakapo has a strong body odour
The source saysan obligate herbivore with a strong body-odour

Source
07

Livezey 1992

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

The page sayswith the smallest wings relative to its size of any parrot
The source sayshas the smallest relative wing size of any parrot
The page saysIts breastbone has only a vestigial keel, and its main breast muscles are greatly reduced.
The source sayspeculiarities of the sternum (vestigial carina, shortened spina externa) ... a greatly reduced Mm. pectoralis thoracica and supracoracoideusNote: 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 page saysThe kakapo is the most massive parrot in the world and has the smallest wings for its size of any parrot.
The source saysS. 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
The page saysIts 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 source saysthe 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. notabilisNote: FAQ 1; pectoralis thoracica and supracoracoideus are the two big breast muscles that power the wingbeat

Source
08

Savage et al. 2021

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

The page saysResearchers found that 61% of kakapo eggs fail to hatch, and 73% of those show no sign of development.
The source says61% of their eggs fail to hatch, and of these 73% show no sign of development
The page saysUndeveloped eggs were once blamed on male infertility, but 72% of the ones tested had been fertilised
The source saysUndeveloped eggs have previously been attributed to male infertility ... the majority (72%, n = 124) of undeveloped kākāpō eggs are fertilised
The page saysso early embryo death, not infertility, drives the low hatching rate
The source saysLow hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertilityNote: 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
The page saysMostly because embryos die early.
The source saysLow hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertilityNote: FAQ 4; the paper's title, a hand check; 'mostly' is 'driven by', and the abstract's 72% fertilised undeveloped eggs agree
The page saysResearchers found that 61% of kakapo eggs fail to hatch, and 73% of those show no sign of development.
The source says61% of their eggs fail to hatch, and of these 73% show no sign of developmentNote: FAQ 4
The page saysUndeveloped eggs were once blamed on male infertility, but 72% of the ones tested had been fertilised
The source saysUndeveloped eggs have previously been attributed to male infertility ... the majority (72%, n = 124) of undeveloped kākāpō eggs are fertilisedNote: FAQ 4
The page saysso early embryo death, not infertility, drives the low hatching rate
The source saysLow hatching success in the critically endangered kākāpō is driven by early embryo mortality not infertilityNote: FAQ 4; the paper's title, a hand check

Source
09

The IUCN Red List of Threatened Species 2018

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

The page saysCritically Endangered
The source saysIUCN Red List category: Critically Endangered (CR).Note: stats.conservationStatus
The page saysIt is still Critically Endangered.
The source saysIUCN Red List category: Critically Endangered (CR).

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.