Life cycle

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Finding a home

The Lifecycle of a  Kiwi




Establishing a Territory and Finding a Mate.

Before a male can attract a mate he must first establish his own territory. If unoccupied land cannot be found, he may have to fight another male for space. Kiwi are very territorial birds and fiercely protect their land, which can be as much as 100 hectares. They protect their land by calling or even fighting if necessary.

Calling duels take place on the borders between territories. Kiwi occasionally kill each other fighting over land. Thir sharp claws and powerful legs and feet are used as weapons.



The Nest

Kiwi may dig a burrow a month or two before the egg is laid or just use an existing one. Burrows can be dug in a bank or slope. Kiwi use their strong legs and claws to loosen dirt and push it out to form an entrance. Alternatively the nest may be built in a hollow tree, under logs, between rock cracks or within dense clumps of vegetation.

A kiwis burrow is usually lined with dogy leaves, grass and moss. When inside, kiwi often drag leaves and sticks across the entrance to camoflage it and insulate the burrow.



Mating

Breeding season for a kiwi is from June throught to March. This is when the food supply is most plentiful. Males can reach sexual maturity at age 18 months in captivity, but in the wild usually don't breed until a lot older. Females first lay their eggs at 3-5 years old.
Because male kiwis don't have colourful plumage to attract females like other birds, they have to develope some interesting strategies to win a female's attention
The male follows the female about, grunting at her. If she is uninterested, she may run away or even chase him away.

Kiwis mate about 3 weeks before the egg is laid and at the peak of activity, three or more times a day. The male taps or strokes the female on her back near the base of her neck. She crouches low, with her head streched forward and resting on the ground. He must climb onto her back and balance while mating takes place. As the male has no wings or tail, it can be difficult to maintain balance while mating. He will often grab the hen's back feathers in its bill to help from falling. The female calls the shots and sometimes wander away if she loses intrest.



The Egg

X ray of kiwi with egg To produce this enormous egg the female kiwi must eat about three times as much food as usual. The Kiwis egg is the largest of all birds, in comparison to body size and contains the largest proportion of yolk. The egg has a smooth, thin, white or greenish-white shell and is about 120mm long and 80mm in diameter, this is six times as large as it would be for a normal bird of this weight.

A pregnant female's belly bulges so much that it touches the ground and has to walk with her legs wide apart to accomodate it. The egg makes up 15-20 percent of her body weight. Pregnant kiwis sometimes stand up to her belly in cold water to soothe the inflamed stretched skin and to temporarily relieve the weight she is carrying. Just before the egg is laid it almoat fills the kiwi's whole body, leaving little room for food in her stomach. She therefore goes hungry for two or three days before laying the egg.

The egg is laid quickly, then the female leaves the burrow so the male can take over the incubation of the egg. If the female is to lay another egg, it will have already begun developing inside her. This egg will be laid about 24 days after the first one. It is very rare, but does happen, for a third egg to be laid. The North Island Brown Kiwi will often lay 2-3 clutches each year.



Incubation

For kiwis it is the male that has the job of incubating the egg. He develops a bare patch of skin on his belly, which is known as a brood patch. It is used to keep the egg warm during incubation. The males long bill is used to tuck the egg beneath him. If two eggs are laid the nest becomes quite crowded and sometimes eggs are broken by the parents' large feet.

The incubation time for kiwis is between 70-80 days which is twice as long as the normal for birds. This was thought to be because the egg was so big now seems more likely that it is because of the lower body temperature of kiwis.



Hatching

Kiwi eggs hatch after 70-80 days and if there's a second egg in the clutch it hatches faster than the first. The first chick to hatch can be 1-3 weeks old before the second arrives.


It takes about 3 days for the kiwi to finish the hatching process. At first the egg just jiggles around a little, then may lay still for 20 minutes, then jiggle again. After a while the chick makes a minute hole in the air-filled sack inside the end of the egg. It pokes the tip of its bill through and breathes air for the first time. Following this the chick may sleep for 12-48 hours. When it wakes it starts to kick and push against the shell wall, which flexes and bells out as the baby bird struggles inside, mewing loudly. The kiwi chick has to kick its way out with its huge feet. Eventually a crack or hole appears in the shell and so the chick's bill pokes through. The chick continues to break itself out until it is finally free.

The used shell is stomped down by the parent and buried in the nest. The newly hatched chick is covered in a slimy coat which dries and flakes off within 24 hours.

The chick has its eyes open at birth and has a soft pink beak and feet. At first it is unable to stand due to a yolk sac which it feeds on until it can stand and forage for itself. After 2 or 3 days enough of the yolk sac has been absorbed which allows the chick to stand and shuffle around the nest.


The Chick

At the start the kiwi chick stays near the nest and hunts only pebbles and tiny twigs, these are stored in the bird's gizzard to help with food digestion later. On the next trip ont of the nest the chick eats its first meal. As its beak is not strong enough to dig into the ground, it forages in the leaf litter. After about 2 weeks the chicks weight will have decreased to around 80% of its hatching weight, but it can easily survive 2 weeks of partial fasting.

In the first 3-4 weeks, the young kiwi eats both at night and in the day. This makes it very easy for predators. About 95% of kiwi chicks born in the wild are killed and eaten by predators in the first six months of life. At around 2-6 months old the chick doesn't need to return to the burrow each day.


The Young Kiwi

The North Island Brown Kiwi leaves its parents territory at 4-6 weeks old. The Southern Tokoeka can stay with their parent for around 4-5 years. The young reach adult weight by about 2-3 years, and grow slowly untill about 4 years old. When kept in captivity a young male kiwi can begin breeding at 18 months, and females can lay their first eggs at about three years old.