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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, with a small population near Haast being
another possibly distinct species, the Haast Tokoeka.
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. This seems evident in
areas of New Zealand where introduced predators have been removed, such as
sanctuaries, where kiwis are often seen in daylight. Kiwis are creatures with a
highly developed sense of smell, most unusual in a bird, and 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. Unlike other birds, the kiwi can locate insects and worms
underground without actually seeing or feeling them. This is due to their long
beaks, with nostrils at the end of them.
After an initial meeting during mating season (March to June), kiwi usually live
as monogamous couples. The pair will meet in the nesting burrow every few days
and call to each other at night. These relationships have been known to last for
up to 20 years. (Source: KiwiRecovery.org) Kiwi eggs can weigh up to one quarter
the weight of the female. Usually only one egg is laid. Although the kiwi is
about the size of a domestic chicken, it is able to lay eggs that are up to ten
times larger than a chicken's egg. (Source: Grzimek's Animal Life Encyclopedia)
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
save 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 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. (Source: News In Science)
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 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 in 1813.
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