That's according to new research which suggests the kiwi is more closely related to the Australian emu and not the large-sized New Zealand moa.
The study of two recently discovered fossils indicate that the kiwi didn't shrink over time, but grew bigger.
Presenter: Tom Maddocks
Speaker: Paul Scofield, Senior Curator of Natural History, Canterbury Museum, New Zealand
MATTOCKS: More than a decade ago, genetic techniques enabled British scientists to extract DNA from the New Zealand moa bird, extinct some 700 hundred years ago.
The research found that the iconic flightless, nocturnal bird known as the kiwi is actually more closely related to the Australian cassowary and emu than to the enormous moa bird.
It's puzzled palaeontologists.
Now new evidence based on fossils from the miocene period some 20 millions years ago suggests that the kiwi evolved from a much smaller Australian bird that was potentially able to fly across the Tasman sea from Australia to New Zealand.
SCOFIELD: Up until now we've had no early fossil record about the timing of arrival or the relationships of kiwi. So these new fossils are basically our first information about this iconic New Zealand bird.
MATTOCKS: Palaeontologist Paul Scofield is Senior Curator of Natural History at Canterbury Museum in Christchurch and part of the team behind the research.
Their discovery contradicts the long-held theory by evolutionary biologist Stephen Gould.
Essentially, he attempted to explain - like many of us do - the enormous egg the kiwi bird lays.
SCOFIELD: Well his hypothesis was that the kiwi was closely related to the moa, and the giant moa bird is from New Zealand, and due to the fact that they had been stranded on New Zealand since it drifted away from Australia, they had to compete with these giant moa and had become much, much smaller than the moa but they remarkable thing about kiwi is that they had this giant egg. And that giant egg was supposedly the smoking gun that showed that they had once been much larger and now they were very much smaller but they still had a giant egg.
MATTOCKS: The kiwi is arguably New Zealand's favourite bird and the knowledge that it may be an Australian export could prove a little cultural victory for the green and gold.
SCOFIELD: The kiwi has become this cultural icon for New Zealand and one of the great ironies of course being that the New Zealand Air Force have a kiwi on the wings of their aircraft. Being a flightless bird perhaps they could have chosen a more flighted representative of our fauna. I mean New Zealand does have all these remarkable birds which are completely unique: the kakapo, the New Zealand rens and the New Zealand wattle birds for example and each of these we have found fossils at St Bathans to show that they were indeed in New Zealand and have been right back as far as we can say. It's just this kiwi, this remarkable fossil that we've just found, that maybe this one actually flew here.