The kiwi’s egg is enormous. In fact, in proportion to its body size the female kiwi lays a bigger egg than almost any other bird.
While an ostrich lays the world’s largest bird’s egg, it is actually the smallest in proportion to the mother at just 2% of her body weight. In fact, kiwi eggs are six times bigger than other birds of the same size.
In humans, a baby at full term is 5% of its mother’s body weight. By comparison, the kiwi egg takes up about 20% of the mother’s body.
Kiwi are also known as being very reproducive. In fact, a female kiwi can lay up to 100 eggs in her lifetime.
The advantages of a large egg
While laying such a large egg is painful, there is an advantage. Most bird eggs are 35-40% yolk, but the kiwi’s egg is 65% yolk. The nutritious yolk produces kiwi chicks that hatch fully feathered and independent, and is so enormous that it continues to sustain them for the first week of life. By that time, chicks can provide for themselves and kiwi parents seldom have to feed their offspring.
Why such a big egg?
It is still not clear why the kiwi produces such a large egg. Some researchers believe the kiwi has always been a small bird, and that its egg has grown. Others suggest the kiwi was once much larger and, while the bird shrank over time, its egg did not.
It seems the latter explanation is more likely, because gradual evolutionary changes to an adult bird’s characteristics are more likely to be survived than changes to an egg or fetus.
If the latter theory is true, the kiwi’s ancient ancestor would have probably been about the size of a cassowary, measuring up to 1.5 metres tall.
Part of the ratite whānau
Kiwi are part of a group of largely flightless birds known as ratites. Ostriches, emu, and the extinct moa are also part of this group.
The kiwi is sometimes referred to as an honorary mammal because of its un-birdlike habits and physical characteristics.
The hidden bird of Tāne
In Māori tradition, all living things on Earth originate from the union of Rangi-nui (the Sky Father) and Papatūānuku (the Earth Mother).
Flightless ... but has wings
The kiwi is one of New Zealand's many flightless birds. They didn't need to fly because there weren't any land mammal predators before man arrived to New Zealand 1000 years ago.
Feathers like hair
Because kiwi do not fly, their feathers have evolved into a unique texture to suit a ground-based lifestyle.
An unusual beak
The kiwi has an extremely unusual beak. Not only does it provide a keen sense of smell, it also has sensory pits at the tip which allow the kiwi to sense prey moving underground.
In proportion to its body size, the female kiwi lays a bigger egg than almost any other bird. While a full term human baby is 5% of its mother's body weight, the kiwi egg takes up 20% of the mother's body.
Kiwi life cycle
Kiwi make their home in many different environments and have been described as 'breeding machines'. With the eradication of predators, the kiwi could be successful once again.
Being nocturnal, kiwi can be quite elusive but they do leave signs as to where they have been.
Bird of the night
Kiwi are nocturnal. Like many other New Zealand native animals, they are most active in the dark.
Kiwi call at night to mark their territory and stay in touch with their mate. The best time to listen for kiwi is on a moonless night, up to two hours after dark, and just before dawn.
What kiwi eat
Kiwi are omnivores. Their gizzards usually contain grit and small stones which help in the digestion process.
How kiwi came to Aotearoa
Just how did the kiwi journey to New Zealand? Three very different theories have been put forward to explain the mystery.
How kiwi evolved
It is thought that today’s kiwi evolved from one kiwi ancestor that lived about 50 million years ago: a proto-kiwi.
Kiwi experts are keen to dispel myths surrounding the kiwi - and there are quite a few!
Learn more about kiwi
All kiwi are the same, right? Wrong. There are actually five different species of kiwi, all with their own unique features.
Threats to kiwi
The national kiwi population is under attack from many different threats, including predators, loss of habitat, and fragmentation of species.
Where to see kiwi
Many facilities around New Zealand are home to kiwi, plus there are places where, if you're lucky, you could see one in the wild too.
How you can help
Many hands make light work. Keen to join the mission to save the kiwi? Here are some ways you can help.
For kiwi to thrive, we all need to work together. Find out what you can do to help save the kiwi, wherever in Aotearoa you happen to be.
To continuing saving the kiwi, conservation groups need funding. Support the mission by making a donation, setting up a fundraising project, or engaging with other fundraising initiatives.
Shop for kiwi
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