DNA sequence comparisons have yielded the conclusion that kiwi are much more closely related to the extinct Malagasyelephant birds than to themoa with which they shared New Zealand.[6] There are five recognised species, four of which are currently listed asvulnerable, andone of which isnear threatened. All species have been negatively affected by historicdeforestation, but their remaining habitat is well protected in large forest reserves and national parks. At present, the greatest threat to their survival is predation byinvasive mammalian predators.
The vestigial wings are so small as to be invisible under their bristly, hair-like, two-branched feathers. Kiwi eggs are one of the largest in proportion to body size (up to 20% of the female's weight) of any order of bird in the world.[7] Other uniqueadaptations of kiwi, such as short and stout legs and using their nostrils at the end of their long beak to detect prey before they see it, have helped the bird to become internationally well known.
The kiwi is recognised as anicon of New Zealand, and the association is so strong that the termKiwi is used internationally as the colloquialdemonym for New Zealanders.[8]
Etymology
TheMāori language wordkiwi is generally accepted to be "of imitative origin" from thecall.[9] However, some linguists derive the word fromProto-Nuclear Polynesian*kiwi, which refers toNumenius tahitiensis, thebristle-thighed curlew, a migratory bird that winters in the tropical Pacific islands.[10] With its long decurved bill and brown body, the curlew resembles the kiwi. So when the first Polynesian settlers arrived, they may have applied the word kiwi to the newfound bird.[11] The bird's name is spelled with a lower-casek and, being a word ofMāori origin, normally stays askiwi whenpluralised.[12][failed verification]
The genus nameApteryx is derived fromAncient Greek 'without wing':a- (ἀ-), 'without' or 'not';ptéryx (πτέρυξ), 'wing'.[13]
Taxonomy and systematics
Although it was long presumed that the kiwi was closely related to the other New Zealand ratites, themoa, recentDNA studies have identified its closest relative as the extinctelephant bird ofMadagascar,[6][14] and among extant ratites, the kiwi is more closely related to theemu and thecassowaries than to the moa.[6][15]
Research published in 2013 on an extinct genus,Proapteryx, known from theMiocene deposits of theSaint Bathans Fauna, found that it was smaller and probably capable of flight, supporting the hypothesis that the ancestor of the kiwi reached New Zealand independently from moas, which were already large and flightless by the time kiwi appeared.[16]
Species
There are five known species of kiwi, with a number of subspecies.
The largest species, standing about 45 cm (18 in) tall, with females weighing about 3.3 kg (7.3 lb) and males about 2.4 kg (5.3 lb). It has grey-brown plumage with lighter bands. The female lays one egg a year, which both parents incubate. The population is estimated at over 20,000, distributed through the more mountainous parts of northwest Nelson, the northernWest Coast, and theSouthern Alps of the South Island.[18]
A small kiwi the size of abantam, standing 25 cm (9.8 in) tall, with the female weighing 1.3 kg (2.9 lb). She lays one egg, which is incubated by the male. This small, docile kiwi is unable to withstand predation by introduced pigs,stoats and cats, leading to its extinction on the mainland. There are about 1350 on Kapiti Island and it has been introduced to other predator-free islands, where it appears to be getting established with about 50 on each island.[19]
TheOkarito kiwi, first identified as a new species in 1994,[20] is slightly smaller than the North Island brown kiwi, with a greyish tinge to the plumage and sometimes white facial feathers. Females lay up to three eggs in a season, each one in a different nest. Male and female both incubate. Distribution is now limited to a small area on the West Coast, but studies of ancient DNA have shown that, in prehuman times, it was far more widespread on the western side of the South Island and lived in the lower half of the North Island, where it was the only kiwi species detected.[21]
Almost as big as the great spotted kiwi and similar in appearance to the brown kiwi, though its plumage is lighter in colour. It is relatively numerous. Ancient DNA studies have shown that, in prehuman times, the distribution of this species included the east coast of the South Island.[21] Several subspecies are recognised:
The northern Fiordland tokoeka (Apteryx australis ?) and southern Fiordland tokoeka (Apteryx australis ?) live inFiordland, the remote southwest part of the South Island. These subspecies of tokoeka are relatively common and are nearly 40 cm (16 in) tall.[citation needed]
The Haast southern brown kiwi orHaast tokoeka,Apteryx australis 'Haast', is the rarest taxon of kiwi with only about 300 individuals. It was identified as a distinct form in 1993. It occurs only in a restricted area in theHaast Range of the Southern Alps at an altitude of 1,500 m (4,900 ft). This form is distinguished by a more strongly downcurved bill and more rufous plumage.[22]
A. mantelli (orA. australis before 2000 and still in some sources) females stand about 40 cm (16 in) tall and weigh about 2.8 kg (6.2 lb), while the males weigh about 2.2 kg (4.9 lb). The plumage is streaky red-brown and spiky. The female usually lays two eggs, which are incubated by the male.[23] The North Island brown has demonstrated a remarkable resilience: it adapts to a wide range of habitats, including non-native forests and some farmland. It is widespread in the northern two-thirds of the North Island and is the most common kiwi, with about 35,000 remaining.[24]
Description
Clockwise from left: brown kiwi (Apteryx australis), little spotted kiwi (Apteryx owenii) and great spotted kiwi (Apteryx haastii) at Auckland War Memorial Museum1860s drawing ofApteryx, illustrating its distinctive features, including long beak, short legs and claws, and dark hair-like feathers.
Their adaptation to a terrestrial life is extensive: like all the otherratites (ostrich,emu,rhea andcassowary), they have nokeel on thesternum to anchor wing muscles. Thevestigial wings are so small that they are invisible under the bristly, hair-like, two-branched feathers. While most adult birds have bones with hollow insides to minimise weight and make flight practicable, kiwi havemarrow, like mammals and the young of other birds. With no constraints on weight due to flight requirements, brown kiwi females carry and lay a single egg that may weigh as much as 450 g (16 oz). Like most other ratites, they have nouropygial gland (preen gland). Their bill is long, pliable and sensitive to touch, and their eyes have a reducedpecten. Their feathers lackbarbules andaftershafts, and they have largevibrissae around thegape. They have 13flight feathers, no tail and a smallpygostyle. Theirgizzard is weak and theircaecum is long and narrow.[25]
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 anocturnal lifestyle, but kiwi rely more heavily on their other senses (auditory, olfactory, andsomatosensory system). The sight of the kiwi is so underdeveloped that blind specimens have been observed in nature, showing how little they rely on sight for survival and foraging. In an experiment, it was observed that one-third of a population ofA. rowi in New Zealand under no environmental stress had ocular lesions in one or both eyes. The same experiment examined three specific specimens that showed complete blindness and found them to be in good physical standing outside of ocular abnormalities.[26] A 2018 study revealed that the kiwi's closest relatives, the extinctelephant birds, also shared this trait despite their great size.[27]
Unlike virtually every otherpalaeognath, which are generally small-brained by bird standards, kiwi have proportionally largeencephalisation quotients. Hemisphere proportions are even similar to those ofparrots andsongbirds, though there is no evidence of similarly complex behaviour.[28]
The call of a male North Island Brown KiwiApteryx mantelli
Behaviour and ecology
Before the arrival of humans in the 13th century or earlier, New Zealand's only endemic mammals werethree species of bat, and theecological niches that in other parts of the world were filled by creatures as diverse as horses, wolves and mice were taken up by birds (and, to a lesser extent, reptiles, insects and gastropods).[29]
The kiwi's mostly nocturnal habits may be a result of habitat intrusion by predators, including humans. In areas of New Zealand where introduced predators have been removed, such as sanctuaries, kiwi are often seen in daylight. They prefer subtropical and temperatepodocarp and beech forests, but they are being forced to adapt to different habitat, such as sub-alpine scrub, tussock grassland, and the mountains.[25] Kiwi have a highly developed sense of smell, unusual in a bird, and are the only birds with nostrils at the end of their long beaks. Kiwi eat small invertebrates, seeds, grubs, and many varieties of worms. They also may eat fruit, small crayfish, eels and amphibians. 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.[25] This sense of smell is due to a highly developed olfactory chamber and surrounding regions. It is a common belief that the kiwi relies solely on its sense of smell to catch prey but this has not been scientifically observed. Lab experiments have suggested thatA. australis can rely on olfaction alone but is not consistent under natural conditions. Instead, the kiwi may rely on auditory and/or vibrotactile cues.[30]
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.[31] They are unusual among other birds in that, along with some raptors, they have a functioning pair ofovaries. (In most birds and inplatypuses, the right ovary never matures, so that only the left is functional.[25][32][33])
Kiwi eggs can weigh up to one-quarter the weight of the female. Usually, only one egg is laid per season. The kiwi lays one of the largest eggs in proportion to its size of any bird in the world,[34][a] 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.[37] The eggs are smooth in texture, and are ivory or greenish white.[38] The male incubates the egg, except for the great spotted kiwi,A. haastii, in which both parents are involved. The incubation period is 63–92 days.[25] 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. Two to three days before the egg is laid there is little space left inside the female for her stomach and she is forced to fast.[39]
It was believed that the large eggs were a trait of much largermoa-like ancestors, and that kiwi retained large eggs as an evolutionarily neutral trait as they became smaller. However, research in the early 2010s suggested that kiwi were descended from smaller flighted birds that flew to New Zealand and Madagascar, where they gave rise to kiwi and elephant birds. The large egg is instead thought to be an adaptation forprecocity, enabling kiwi chicks to hatch mobile and with yolk to sustain them for two and half weeks. The large eggs would be safe in New Zealand's historical absence of egg-eating ground predators, while the mobile chicks would be able to evade chick-eating flying predators.[40]
Traffic sign in New Zealand cautioning drivers of nearby kiwi
Nationwide studies show that only around 5–10% of kiwi chicks survive to adulthood without management.[47][48] As of 2018[update] over 70% of kiwi populations are unmanaged.[49] However, in areas under active pest management, survival rates for North Island brown kiwi can be far higher. For example, prior to a joint1080 poison operation undertaken by DOC and theAnimal Health Board inTongariro Forest in 2006, 32 kiwi chicks were radio-tagged. 57% of the radio-tagged chicks survived to adulthood.[citation needed]
Efforts to protect kiwi have had some success, and in 2017 two species were downlisted from endangered to vulnerable by the IUCN.[50] In 2018 theDepartment of Conservation released its current Kiwi Conservation Plan.[49]
Sanctuaries
In 2000, theDepartment of Conservation set up five kiwi sanctuaries focused on developing methods to protect kiwi and to increase their numbers.[51]
There are three kiwi sanctuaries in the North Island:
North Island brown kiwi were introduced to theCape Sanctuary inHawke's Bay between 2008 and 2011, which in turn provided captive-raised chicks that were released back into Maungataniwha Native Forest.[66]
Sanctuaries for kiwi are also referred to as 'kōhanga sites'[61] from the Māori word for 'nest' or 'nursery'.[67]
The West Coast Wildlife Centre, atFranz Josef on the southern West Coast of New Zealand, is part of Project Nest Egg, breeding the vulnerable local species of kiwi known as therowi.
Operation Nest Egg
Operation Nest Egg is a programme run by the BNZ Save the Kiwi Trust—a partnership between theBank of New Zealand, the Department of Conservation and theRoyal 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. An Operation Nest Egg bird has a 65% chance of surviving to adulthood—compared to just 5% for wild-hatched and -raised chicks.[68] The tool is used on all kiwi species exceptlittle spotted kiwi.
In 2004, anti-1080 activist Phillip Anderton posed for the New Zealand media with a kiwi he claimed had been poisoned. An investigation revealed that Anderton lied to journalists and the public.[69] He had used a kiwi that had been caught in a possum trap. Extensive monitoring shows that kiwi are not at risk from the use of biodegradable 1080 poison.[70]
Threats
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.[48]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.[48] 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. Badly setpossum traps often kill or maim kiwi.[71]
Habitat destruction is another major threat to kiwi; restricted distribution and small size of some kiwi populations increases their vulnerability to inbreeding.[48] Research has shown that the combined effect of predators and other mortality (accidents, etc.) results in less than 5% of kiwi chicks surviving to adulthood.[47]
Relationship to humans
Detail of the bottom edge of akahu kiwi, showing the distinctive hair-like nature of the kiwi feathers.
TheMāori traditionally believed that kiwi were under the protection ofTāne Mahuta, god of the forest. They were used as food and their feathers were used forkahu kiwi—ceremonial cloaks.[72] Today, while kiwi feathers are still used, they are gathered from birds that die naturally, through road accidents, or predation, and from captive birds.[73] Kiwi are no longer hunted and some Māori consider themselves the birds' guardians.[11]
Scientific documentation
In 1813,George Shaw named the genusApteryx in hisspecies description of the southern brown kiwi, which he called "the southern apteryx". Captain Andrew Barclay of the shipProvidence provided Shaw with the specimen. Shaw's description was accompanied by two plates, engraved byFrederick Polydore Nodder; they were published in volume 24 ofThe Naturalist's Miscellany.[74]
In 2023,Zoo Miami apologized for mistreating a kiwi, after footage of visitors patting the nocturnal bird under bright lights caused outrage in New Zealand.[79]
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. Soon after, the kiwi appeared in many military badges; and in 1906, whenKiwi Shoe Polish was widely sold in the UK and the US, the symbol became more widely known.[80]
During the First World War, the name "Kiwis" for New Zealand soldiers came into general use, and a giant kiwi (now known as theBulford kiwi) was carved on the chalk hill aboveSling Camp in England. Usage has become so widespread that all New Zealanders overseas and at home are now commonly referred to as "Kiwis".[81]
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. At the national level, the red silhouette of a kiwi is in the centre of theroundel of theRoyal New Zealand Air Force.[38][82] The kiwi is featured in the logo of theNew Zealand Rugby League, and theNew Zealand national rugby league team are nicknamed the Kiwis.
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. Incurrency trading theNew Zealand dollar is often referred to as "the kiwi".[83]
In popular culture
A song, "Sticky Beak the Kiwi", with words by Bob Edwards and music by Neil Roberts, was recorded in 1961, sung by Julie Nelson (aged 14) and accompanied by the Satins and the Don Bell Orchestra ofWhangārei. A Christmas song, it portrays Sticky Beak as insisting on pulling Santa Claus's sleigh when distributing presents south of the equator.[84]
"How the Kiwi Lost its Wings" is a fable written by broadcaster Alwyn Owen in 1963. It uses elements of Māori mythology, such asTāne Mahuta, and the World War I symbol of cowardice,white feathers, in apourquoi story explaining features of New Zealand birds. Owen portrays the kiwi as nobly sacrificing its wings and flight in order to protect the trees from depredation by ground-dwelling creatures, and thereby winning its unique renown. Owen's story is sometimes described as "A Maori Legend".[85][86] It has been recorded as a children's story,[87] published as a book,[88] was made into an animated film in 1980,[89] set to music for theAuckland Philharmonia Orchestra by Thomas Goss as "Tāne and the Kiwi" in 2002 (recorded forRNZ byOrchestra Wellington in 2008[90]), and performed as a ballet by theRoyal New Zealand Ballet in 2022.[91]
^Hemming, Francis, ed. (1958) [1916]."Opinion 67. One hundred and two bird names placed in the Official List of Generic Names".Facsimile Edition of Opinions 1–133. Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature. Vol. 1B. London: International Trust for Zoological Nomenclature. p. 179.Archived from the original on 19 January 2020. Retrieved4 November 2017.
^Gotch, AF (1995) [1979]. "Kiwis".Latin Names Explained. A Guide to the Scientific Classifications of Reptiles, Birds & Mammals. London: Facts on File. p. 179.ISBN978-0-8160-3377-5.
^McLennan, J.A. (1988). "Breeding of North Island Brown Kiwi, Apteryx Australis Mantelli, in Hawke's Bay, New Zealand".New Zealand Journal of Ecology.11:89–97.JSTOR24052821.
^BirdLife International (2008)."Northern Brown Kiwi".BirdLife Species Factsheet.Archived from the original on 3 January 2009. Retrieved6 February 2009.
^abcdeDavies, S.J.J.F. (2003). "8 Birds I Tinamous and Ratites to Hoatzins". In Hutchins, Michael (ed.).Grzimek's Animal Life Encyclopedia (2nd ed.). Farmington Hills, Michigan: Gale Group. pp. 89–90.ISBN978-0-7876-5784-0.
^Corfield, J.; Wild, J.M.; Hauber M.E. & Kubke, M.F. (2008). "Evolution of brain size in the Palaeognath lineage, with an emphasis on New Zealand ratites".Brain, Behavior and Evolution.71 (2):87–99.doi:10.1159/000111456.PMID18032885.S2CID31628714.
^Save the Kiwi,archived from the original on 10 June 2015, retrieved3 July 2021, formerly Kiwi Recovery.
^Fitzpatrick, F.L., (1934). Unilateral and bilateral ovaries in raptorial birds. The Wilson Bulletin, 46(1): 19–22
^Kinsky, F.C., (1971). The consistent presence of paired ovaries in the Kiwi (Apteryx) with some discussion of this condition in other birds. Journal of Ornithology 112(3): 334–357.
^"Wilderness New Zealand",Official Guide Book, Auckland Zoo
^Kerry-Jayne, Kerry-Jayne."Petrels, Breeding".Te Ara. Te Ara – the Encyclopedia of New Zealand.Archived from the original on 12 April 2019. Retrieved13 April 2019.
^Clay, Theresa (1960). "A new genus and species of Menoponidae (Mallophaga, Insecta) fromApteryx".Annals and Magazine of Natural History. Series 13.3 (33):571–576.doi:10.1080/00222936008651059.
^Palma, Ricardo L. (2017).Phthiraptera (Insecta) A catalogue of parasitic lice from New Zealand. Fauna of New Zealand. Vol. 76. Lincoln, New Zealand: Landcare Research. pp. 39–41,186–188, 245.doi:10.7931/J2/FNZ.76.ISBN978-0-947525-19-4.
^Shaw, George; Nodder, Frederick P. (1813)."Apteryx australis. The Southern Apteryx".The Naturalist's Miscellany.24. Plates 1057–1058.Archived from the original on 7 November 2017. Retrieved4 November 2017.
Burbidge, M.L., Colbourne, R.M., Robertson, H.A., and Baker, A.J. (2003). Molecular and other biological evidence supports the recognition of at least three species of brown kiwi.Conservation Genetics,4(2):167–77
Cooper, Alan et al. (2001). Complete mitochondrial genome sequences of two extinct moas clarify ratite evolution.Nature,409: 704–07.
Le Duc, D., G. Renaud, A. Krishnan, M.S. Almen, L. Huynen, S. J. Prohaska, M. Ongyerth, B. D. Bitarello, H. B. Schioth, M. Hofreiter, et al. 2015. Kiwi genome provides insights into the evolution of a nocturnal lifestyle. Genome Biology 16:147–162.
_(14728011026).jpg)
_white_background.jpg)
