However, much new information has been gathered on the social systems of all kiwi species and varieties.
We now know that:
· Little Spotted Kiwi and Brown Kiwi breed in pairs and only the male incubates the egg
· Great Spotted Kiwi, Rowi and Haast Tokoeka breed as pairs, and both adults share incubation
· Southern Tokoeka, which live at high densities on Stewart Island, breed in stable groups and not only do the main male and female incubate, but some of the helpers also share with incubation. One trio is known to have stayed together for at least 15 years, although we do not know what the relationship between the two females is
It has been speculated that Rowi and Southern Tokoeka living on the mainland would share the behaviour of the Stewart Island birds if they were also found at high densities and produced enough juveniles.
Male Kiwi Incubate the Egg
The male kiwi develops a bare patch of skin on his belly, known as a brood patch. Free of feathers, it exposes the warm blood vessels close to the surface, ideal for keeping the egg warm during incubation.
The male uses his long beak to keep the egg tucked beneath him, warm and safe. However, if the female kiwi lays a second egg, the nest can become crowded and eggs do get accidentally broken under their large feet.
When the male kiwi incubates the egg alone, he leaves the nest unattended while he feeds. Early on during incubation he can leave the nest for most of the night, covering the eggs and burrow entrance with litter. He often returns with extra vegetation to maintain the nest lining.
Sometimes he will bathe when out feeding. It is thought his damp feathers may help maintain the correct humidity in the nest.
Close to hatching, the male will sit tight for several days at a time, sustained by his ample fat reserves.
A Long Incubation Period
Kiwi invest a lot of energy in incubating their eggs. The average incubation time is 70 - 80 days, more than twice what is normal for a bird and about the same as the gestation period of a mammal of similar size. This is one reason kiwi gained the title of ‘Honorary Mammal’.
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We once thought the incubation period was so long because the egg was too big for the kiwi to incubate properly.
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However, it now seems more likely it is due to the kiwi’s low body temperature. Once again, this is closer to a mammal that a bird – between 37° and 38°C. Most birds range from 39°C - 42°C, peaking with hummingbirds at 45°C.
Next: The egg hatches