Kiwi
- This article is about the bird genus. For the fruit, see Kiwifruit.
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Kiwi (plural: Kiwis or kiwi) is the common name for any of the flightless birds endemic to New Zealand comprising the genus Apteryx, characterized by rudimentary wings, short and stout legs, dark plumage, poor vision, and a long, slender, pointed bill with nostrils uniquely opening at the tip rather than base. About the size of a domestic chicken, kiwis are by far the smallest living ratites—a group of flightless birds that also includes ostriches, emus, rheas, and elephant birds. There are about five species of kiwis.
The kiwi is so associated with New Zealand that it is a national symbol of the nation, with the term used to refer to any inhabitant of New Zealand, as well as being a slang term for the New Zealand dollar. Kiwi also is the common name of a fruit (kiwi fruit or kiwifruit; also known as the Chinese gooseberry). Applied to the people of New Zealand, the term is capitalized, with the plural as Kiwis. Applied to the bird, the term usually is uncapitalized, with the plural either the anglicized "kiwis" or, consistent with the MÄori language, appearing as "kiwi" without an "s" (CNZ 2008). (Kiwis will be utilized as the plural in this article, following the standard of the 2002 Oxford American College Dictionary.)
Kiwis are shy birds that nest in deep burrows and are usually nocturnal. Kiwis are notable for laying eggs that are very large in relation to their body size. A kiwi egg may equal 15 to 20 percent of the body mass of a female kiwi. In some species, the males incubate the eggs, while in others both the males and females incubate.
The unique adaptations of kiwis, such as their large eggs, unique form, or using their nostrils at the end of their long beak to detect prey before they ever see it, have added to the wonder of nature and helped kiwis to become internationally well-known. However, all species of kiwis are endangered, with the causes generally related to humans: Loss of habitat and imported predators such as dogs and stoats (ermines).
Overview and description
As with other ratites, kiwis are characterized by a flat, raft-like sternum (breastbone) lacking the keel for attachment of wing muscles that is typical of most flying birds and some other flightless birds. Kiwis are by far the smallest extant ratites. Other ratites include the African ostrich, the Australian emu, the Australian and Oceania cassowary, and two species of South American rheas. Recently extinct forms include elephant birds and moas.
Kiwis comprise the genus Apteryx, which is the only genus in the family Apterygidae. They are chicken-sized birds, ranging in size from about 25 centimeters (10 inches) tall and 1.2 kilograms (2.7 pounds) in the little spotted kiwi (Apteryx owenii) to about 45 centimeters (17.7 inches) high and 3.3 kilograms (7.3 pounds) in the great spotted kiwi (Apteryx haastii). Their rudimentary wings are hidden within the soft, hairlike, two-branched feathers; their tail also is very short. They have clawed, four-toed feet on short, sturdy legs, and a long, slender, pointed and downcurved bill that may be 15 centimeters (6 inches) long. Unlike other birds, the nostrils end on the tip of this beak rather than at the base. (Because a bird's beak is generally measured from the tip to the nostril, this (technically) gives the kiwi the shortest beak of any bird.) While birds generally have hollow bones to save weight and make flight practicable, the flightless kiwi have marrow, in the style of mammals.
Kiwis have a highly developed sense of smell, which they use to find small insects and grubs in the soil. Kiwis have poor vision.
The word kiwi {kÄ“'wÄ“; kee-wee) comes from the MÄori language, a Malayo-Polynesian language of the Austronesian family, spoken by about 100,000 of New Zealand's inhabitants. The name may originate from the cry that the kiwi makes, which sounds like "kiwi, kiwi." The word first appeared in the English language in 1835, in describing this bird (Metcalf 1999).
The scientific name Apteryx means wingless. The name was given by George Shaw, an English botanist and zoologist, based on a kiwi skin brought to him by Captain Andrew Barclay aboard the ship Providence, who was reported to have been given it by a sealer in Sydney Harbor around 1811. George Shaw drew sketches of the way he imagined a live bird to look, which appeared as plates 1057 and 1058 in volume 24 of The Naturalist's Miscellany in 1813.
It was long presumed that the kiwi's closest relatives were the other New Zealand ratites, the now-extinct moas. However, recent DNA studies indicate that the ostrich is more closely related to the moa and the kiwi's closest relatives are the emu and the cassowaries (Cooper et al. 2001). This theory suggests that the kiwi's ancestors arrived in New Zealand from elsewhere in Australasia well after the moa. According to British scientists, the kiwi may be an ancient import from Australia. Researchers of Oxford University have found DNA evidence connected to Australia's emu and the ostrich of Africa. Upon examining DNA from New Zealand's native moa, they believe that the kiwi is more closely related to its Australian cousins (ABC 2001).
Behavior and ecology
Prior to the arrival of humans in the thirteenth century or earlier, New Zealand's only endemic extant mammals were three species of bat, and the ecological 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).
Kiwis are shy and usually nocturnal. Their 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.
Kiwis 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 without actually seeing or feeling them.
Once bonded, a male and female kiwi tend to live their whole lives together 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 (BNZ 2008a). Kiwi eggs can weigh up to one quarter the weight of the female. Usually only one egg is laid per season. Although 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 (BNZ 2008b). With no constraints on weight from flight requirements, some brown kiwi females carry and lay a single 450 gram egg.
Species
Currently, there are five accepted species (one of which has four sub-species), plus one to be formally described.
- Great spotted kiwi (Apteryx haastii). The largest species is the great spotted kiwi or roroa, which stands about 45 centimeters high, with females weighting about 3.3 kilograms and males about 2.4 kilograms. It has gray-brown plumage with lighter bands. The female lays just one egg, with both sexes incubating. Population is estimated to be over 20,000, distributed through the more mountainous parts of northwest Nelson, the northern West Coast, and the Southern Alps.
- Little spotted kiwi (Apteryx owenii). The very small little spotted kiwi is unable to withstand predation by introduced pigs, stoats, and cats and is extinct on the mainland because of these reasons. About 1350 remain on Kapiti Island and it has been introduced to other predator-free islands and appears to be becoming established with about 50 "little spots" on each island. A docile bird the size of a bantam chicken, it stands 25 centimeters (9.8 inches) high and the female weighs 1.3 kilograms. She lays one egg, which is incubated by the male.
- Rowi or Okarito brown kiwi (Apteryx rowi). The rowi is a recently identified species, slightly smaller, with a grayish tinge to the plumage and sometimes white facial feathers. Females lay as many as three eggs in a season, each one in a different nest. Male and female both incubate. Distribution of these kiwi are limited to a small area on the west coast of the South Island of New Zealand.
- Tokoeka (Apteryx australis). Tokoeka is a relatively common species of kiwi known from the south and west parts of South Island and occurring at most elevations. It is approximately the size of the great spotted kiwi and is similar in appearance to the brown kiwi, but its plumage is lighter in color.
- Stewart Island tokoeka (Apteryx australis lawryi). The Stewart Island tokoeka is a subspecies from Stewart Island.
- Haast tokoeka (Apteryx australis). This is the rarest subspecies (possibly species) of kiwi, with only about 300 individuals. It was identified as a distinct form in 1993. It only occurs in a restricted area in South Island's Haast Range at an altitude of 1,500 meters. This form is distinguished by a more strongly downcurved bill and more rufous plumage.
- Northern Fiordland tokoeka (Apteryx australis) and Southern Fiordland tokoeka (Apteryx australis). These two subspecies live in the remote southwest part of South Island known as Fiordland. These Tokoeka sub-species are relatively common and are nearly 40 centimeters (16 inches) tall.
- North Island brown kiwi (Apteryx mantelli; known as Apteryx australis before 2000 and still in some sources). The North Island brown kiwi is widespread in the northern two-thirds of the North Island and, with about 35,000 remaining, is the most common kiwi. Females stand about 40 centimeters (16 inches) high and weigh about 2.8 kilograms, with the males about 2.2 kilograms. The North Island brown has demonstrated a remarkable resilience: It adapts to a wide range of habitats, even non-native forests and some farmland. The plumage is streaky, red-brown and spiky. The female usually lays two eggs, which are incubated by the male.
Analysis of mitochondrial DNA, ecology, behavior, morphology, geographic distribution, and parasites of the North Island brown kiwi has led scientists to propose that the brown kiwi may be three distinct species (Burbidge et al. 2003). These are the North Island brown kiwi; the Okarito brown kiwi (rowi), whose distribution is restricted to a single site on the West Coast of the South Island of New Zealand; and the Southern tokoeka, distributed in the in lowland forest to the north of Franz Josef glacier in the South Island and on Stewart Island.
ReferencesISBN links support NWE through referral fees
- Australian Broadcasting Corporation (ABC). 2001. Kiwi may be Australian export. ABC Science Online February 9, 2001. Retrieved August 20, 2008.
- Bank of New Zealand (BNZ) Save the Kiwi Trust. 2008a. Mating. Bank of New Zealand Save the Kiwi Trust. Retrieved August 20, 2008.
- Bank of New Zealand (BNZ) Save the Kiwi Trust. 2008b. Producing an Egg. Bank of New Zealand Save the Kiwi Trust. Retrieved August 20, 2008.
- Burbidge, M. L., R. M. Colbourne, H. A. Robertson, and A. J. Baker. 2003. Molecular and other biological evidence supports the recognition of at least three species of brown kiwi. Conservation Genetics 4(2):167-177.
- Cooper, A., C. Lalueza-Fox, S. Anderson, et al. 2001. Complete mitochondrial genome sequences of two extinct moas clarify ratite evolution. Nature 409: 704-707. Retrieved August 20, 2008.
- Culture of New Zealand (CNZ). 2008. Kiwi. ExperienceFestival.com. Retrieved August 20, 2008.
- Metcalf, A. A. 1999. The World in So Many Words: A Country-by-Country Tour of Words That Have Shaped Our Language. Boston: Houghton Mifflin. ISBN 0395959209.
- Santa Fe Writers Group. 1993. Bizarre and Beautiful Noses. Santa Fe, N.M.: John Muir Publications. ISBN 1562611240.
External links
All links retrieved April 20, 2018.
- Great Spotted Kiwi - ARKive.
- Robertson, H. A. 2003. Kiwi (Apteryx spp.) recovery plan 1996–2006. Department of Conservation, Wellington, New Zealand. Threatened Species Recovery Plan 50.
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