Research into the kiwi’s DNA shows their closest relative is the now-extinct giant elephant bird (Mullerornis agilis) from Madagascar. So how did the kiwi get all the way from there, to here?
An ancient ancestor
The kiwi’s closest relative is the now-extinct giant elephant bird (Mullerornis agilis) from Madagascar. Kiwi are also more closely related to Australia’s emus and cassowaries than New Zealand’s other well-known ratite, the moa.
Madagascar is a very long 11,200 kilometres away for a bird that can’t fly, while Australia is about 4000 kilometres away. So how did the kiwi journey to New Zealand? Three very different theories have been put forward to explain the mystery.
Some suggest the kiwi’s ancestor was already around when New Zealand broke away from Antarctica and Australia 60 million years ago.
If true, this removes the question of whether or not the kiwi could ever fly. It would also mean our national icon originated around the same time as the dinosaurs.
Walking to New Zealand
Islands rise up and submerge as tectonic plates move. A string of islands have come and gone between New Caledonia and Northland during the past 50 million years. It is possible that the kiwi and other species moved from one island to the next as they rose and fell, using them like stepping-stones to reach New Zealand.
A flying kiwi
Once considered the least likely explanation, a flying kiwi seems more possible following DNA analysis linking kiwi with Madagascar’s extinct elephant bird. The findings make little sense if their common ancestor could not fly because how else could they have come to New Zealand?
Scientists estimate the common ancestor lived 50 million years ago and could have been a partridge-like bird that flew between landmasses in search of new homes.
The hypothesis challenges the long-held view that all ratites had a flightless ancestor. Of the ratites that are alive today, only the South American tinamous can fly – and not very well – making it very much the exception, not the rule.
Another argument against a once-flying kiwi is the theory that its ancestor was much bigger than today’s bird. The kiwi egg is so huge it should theoretically be laid by a bird two or three times bigger, perhaps closer to a cassowary in size. That would have been much too big to fly across the Tasman Sea, even millions of years ago when the gap was narrower.
The mystery of the kiwi’s arrival remains subject to debate.
Learn more about kiwi
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.