Kiwi parents do not need to feed their young because the chick can survive off the rich egg yolk for several days. At the end of this time, a kiwi chick may weigh only 80% of its hatching weight.
Leaving the burrow
After two or three days, enough of the yolk sac has been absorbed to allow the baby kiwi to stand and shuffle around the nest. On about day five it begins to venture out of the burrow.
The kiwi chick initially does not go far from the nest, and eats only pebbles and tiny twigs that will be stored in its gizzard to help with food digestion.
On its second trip out of the burrow, the chick eats its first meal. Because its beak is not yet strong enough to dig into the ground, it forages in the leaf litter.
All this time it continues to draw nourishment from the yolk sac, and can easily survive two weeks of partial fasting.
Vulnerable to predators
During its first three-to-four weeks, the baby kiwi feeds at night, and sometimes during the day. This makes it extremely vulnerable to predators. Around 90% of kiwi chicks born in the wild die within their first six months – 70% of them killed by stoats and cats. Only about 5% of kiwi chicks survive to adulthood.
Young kiwi continue to grow slowly until they are about four years old. Just when they leave home depends on the social system for each variety. For example, some brown kiwi leave their parents’ territory when four-to-six weeks old and are fully independent, but great spotted kiwi juveniles stay in their parents’ territory for a year or more, and Stewart Island tokoeka and rowi can remain with their parents for up to seven years, helping raise their siblings.
Whichever the taxa, when the young birds are old enough to establish territories and find a mate, the cycle begins again.
Kiwi are potentially very long-lived, with some individuals living for 50-60 years. Research has not been going on long enough to be sure.