Kiwi

This article is about the bird genus. For the fruit, see Kiwifruit. For other uses, see Kiwi (disambiguation).
Kiwi
Karuwai at August 2005 Health Check.JPG
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Struthioniformes
Family: Apterygidae
G.R. Gray, 1840
Genus: Apteryx
Shaw, 1813
Species

See text.

A kiwi is any of the species of flightless birds endemic to New Zealand of the genus Apteryx (the only genus in family Apterygidae). At around the size of a domestic chicken, kiwi are by far the smallest living ratites. All kiwi species are endangered. The kiwi is also a national symbol of New Zealand. The kiwi lays the largest egg in comparison to its body size.[1]

Contents

Species

Currently, there are five accepted species (one of which has four sub-species), plus one to be formally described.

Apteryx owenii, the Little Spotted Kiwi
The distribution of each species of kiwi

Analysis of mitochondrial DNA, ecology, behaviour, morphology, geographic distribution and parasites of the North Island Brown Kiwi has led scientists to propose that the Brown Kiwi is three distinct species. 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 a third distinct population of the North Island Brown Kiwi, the Southern Tokoeka, distributed in the in lowland forest to the north of Franz Josef glacier in the South Island and on Stewart Island/Rakiura, with a small population near Haast being another possibly distinct species, the Haast Tokoeka.

Etymology

Kiwi {kē'wē Pr: kee-wee], is given as from the Māori language (1825–1835)[4] and as "of imitative origin" from the call.[5]

Behaviour and ecology

Prior to the arrival of humans in the 13th century or earlier, New Zealand's only endemic 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).

Kiwi 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. 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 bill. 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 without actually seeing or feeling them.[6]

Kiwi on 1898 New Zealand stamp.

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.[7] 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.[8][9]

Their adaptation to a terrestrial life is extensive: like all ratites they have no keel on the breastbone to anchor wing muscles, and barely any wings either. The vestiges are so small that they are invisible under the kiwi's bristly, hair-like, two-branched feathers. While birds generally have hollow bones to minimise weight and make flight practicable, kiwi have marrow, in the style of mammals. With no constraints on weight from flight requirements, some Brown Kiwi females carry and lay a single 450 g egg.

It was long presumed that the kiwi's closest relatives were the other New Zealand ratites, the moa. 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. 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 at 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.[10]

North Island Brown Kiwi

Discovery and documentation

The first kiwi specimen to be studied by Europeans was a kiwi skin brought to George Shaw by Captain Andrew Barclay aboard the ship Providence, who was reported to have been given it by a sealer in Port Jackson (Sydney Harbour) around 1811. George Shaw gave the kiwi its scientific name and 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[Full citation needed] in 1813.

See also

References

  1. ↑ www.sandiegozoo.org/education/science_egg_in_a_bottle.html San Diego Zoo.
  2. ↑ Shepherd LD & Lambert DM (2008) Ancient DNA and conservation: lessons from the endangered kiwi of New Zealand Molecular Ecology 17, 2174–2184
  3. ↑ Shepherd LD & Lambert DM (2008) Ancient DNA and conservation: lessons from the endangered kiwi of New Zealand Molecular Ecology 17, 2174–2184
  4. ↑ Random House Unabridged Dictionary, © Random House, Inc. 2006
  5. ↑ The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2006 by Houghton Mifflin Company
  6. ↑ Because a bird's beak is generally measured from the tip to the nostril, this (technically) gives Kiwi the shortest beak of any bird.
  7. ↑ KiwiRecovery.org
  8. ↑ "Producing an Egg". Retrieved on 2007-08-13.
  9. ↑ "Birds: Kiwi". San Diego Zoo. Retrieved on 2008-09-19.
  10. ↑ News In Science

External links