New Zealand's iconic national bird, the kiwi, didn't come from Australia as long believed, a new study suggests; in fact its closest relative is an extinct giant bird that once roamed Madagascar, 7,000 miles away.
Previously thought related to Australia's flightless emu, DNA studies by the Australian Center for Ancient DNA at the University of Adelaide have shown kiwis are related to the extinct elephant bird of Madagascar, a 9-foot-tall, 600-pound flightless bird that may have still been living on the African island into the 1800s.
The DNA study of elephant bird bones and kiwis found a link between the two species despite some physical dissimilarities and their wide geographical separation, the researchers say.
The findings also suggest the kiwi hasn't always been flightless.
"This result was about as unexpected as you could get," Kieren Mitchell, a doctoral candidate at the DNA center, says. "New Zealand and Madagascar were only ever distantly physically joined via Antarctica and Australia, so this result shows the ratites [a group of flightless birds] must have dispersed around the world by flight."
New Zealand and Madagascar, once part of an ancient supercontinent, separated around 50 million years ago, but the DNA research suggests a common ancestor of kiwis and elephant birds was alive more recently, scientists say.
"That shows they can't have been separated by continental drift," says Alan Cooper, who led the DNA center's research. Instead, he says, each species must have evolved from an ancestor capable of flying across oceans.
"You can't get from Madagascar to New Zealand without flying," Cooper says. "There isn't any other way."
The world's flightless birds -- kiwis, emus, cassowaries, rheas and the extinct moas of New Zealand and the extinct Madagascan elephant birds -- have all lost the ability to fly on six separate occasions over 10 million years, the researchers said.
In five of those episodes they also grew into giants, possibly because the extinction of the dinosaurs, their main plant-eating competition, opened an evolutionary window for them to flourish in.
"Nothing is eating trees and browsing and grazing," says Cooper, so the birds could move into that evolutionary niche and take over that food source.
With no predators and facing no competition for food, the birds grew into giants and lost their ability to fly, the researchers said.
