Kiwi: The Flightless Bird

Kiwis are natives of New Zealand and are flightless birds belonging to the genus Apteryx and family Apterygidae. Their body size is similar to that of chicken and lay largest egg in comparison to their body size. They are the smallest ratites living today. About 5 species of kiwis are known presently and all are under the category of endangered because of deforestation. These species are now protected in different national parks and animal reserves. Mammalian predators are one of the dangerous threats to these birds. They are the national symbols of New Zealand. It was earlier believed that kiwi is a close relative of moa. However, recent studies based on DNA have suggested that ostriches are more closely related to moa and kiwis are more close to emu and cassowaries. This theory suggests that they arrived New Zealand from Australasia after the arrival of moa.Before the arrival of humans on earth in the 13th century or earlier there were three species of bats in New Zealand
and all the ecological niches all over the world were occupied by horses, wolves and birds. Kiwi is a shy and nocturnal bird. Their nocturnal habits may be the result of intrusion by predators also including humans. Kiwis are seen during the day time only in the sanctuaries in New Zealand. They prefer to dwell in the subtropical and temperate podocarp and beech forests but some also dwell in the sub-alpine scrub, tussock grassland and the mountains. They bear well developed sense of smell. They feed on invertebrates, seeds, grubs and many types of worms. They also eat fruit, small crayfish, eels and amphibians. The nostrils are present along the edge of the beaks so they are able to locate worms and insects present underground just because of their keen sense of small.One a pair is formed the male and female live together throughout their entire lives as a monogamous couple. Mating season ranges from June to March and the mating couple produces a mating call and calls each o
ther in the night. Mating couple meets each other in the nesting burrow after every three days. This relationship may continue for about 20 years. They are unique among all birds in that they have a pair of functioning ovaries. The weight of the eggs may be about one quarter of the body weight of the female. Only one egg is laid per season. The egg of kiwi is about six times bigger than that of the egg of chicken. Eggs are smooth and may be either ivory white or greenish white in colour. Male is known to incubate the eggs except the Great spotted kiwi where both the partners are involved. The incubation period is of 63-92 days. Thirty days are required for the egg to become fully developed and the female requires three times more food in order to produce such a big egg. Two or three days before the egg is laid the female stops eating.Their adaptation to the terrestrial habitat is very remarkable. They lack keel on the breastbone to anchor flight muscles. Vestiges are very sm
all so they are invisible under the feather coat. Flying birds have hollow bones that lack bone marrow but the bones of kiwis have marrow a condition resembling with that of mammals. They also lack preen gland like other ratites. Bills are long, sensitive to touch and the eyes have reduced pecten. Feathers lack barbules and aftershafts and vibrissae are present. They bear 13 flight feathers, no tail but small pygostyle. Gizzard is weak but the caecum is long and narrow. Kiwi has derived its name from the Maori language. London zoo was the first zoo to hold kiwi in 1851. A number of programmes are now operating in order to save this flightless bird for example, BNZ save the Kiwi Trust, Moehau Environment Group, Rainbow Springs and Karori Wildlife Sanctuary Trust.

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