The Tiny Kiwi Bird's Colossal Cousin

Judging by their looks, one would never guess that New Zealand's national bird - the tiny flightless kiwi and the colossal African elephant bird that roamed Madagascar until the 17th Century, had much in common. While the kiwi is roughly the size of a modern chicken and weighs between three to seven pounds, the elephant bird loomed a massive ten feet tall, and could weigh as much as 600 pounds! In addition to the difference in size, the two species lived 7,000 miles apart, making any connection between the two almost impossible.

Turns out, such is not the case. According to scientists from the University of Adelaide's Australian Centre for Ancient DNA, the two disparate birds share the same family tree! The team of scientists led by Alan Cooper stumbled upon this unexpected discovery accidentally, while sequencing the genetic data of the elephant bird.

What they had expected to find were similarities between the elephant bird and another member of the 'Ratite,' or 'flightless bird' family, the ostrich. Their hunch was based on the physical resemblance between the two as well as the fact that their natural habitats were relatively close until about 200 million years ago, when supercontinent Pangea broke apart into the world as we know it today.

Instead, they found that it was actually the kiwi and the elephant bird that shared the most recent common ancestor. According to the researchers who published their study in journal Science on May 22nd, the two species descended from this family line about 50 million years ago, shortly after the mass extinction of the dinosaurs.

The news that the kiwi had come all the way from Madagascar came as a big surprise to both experts and the residents of New Zealand.That's because until now they had believed that the bird was a descendent of the flightless emu and cassowary and had migrated from Australia.

So how did this now flightless bird get so far away from its roots? The researchers believe that the tiny birds could not have walked even when Madagascar and New Zealand were part of the giant southern landmass of Godwana. That's because the countries were still separated by the large landmasses of Australia and Antarctica. This has led them to conclude that the kiwis were once capable of flying and dispersed around the world on wings, before evolving into the land-dwelling birds we know today.

The scientists also have a theory about why the birds remained so small in comparison to their larger cousins. They believe that by the time the bird's ancestors arrived in New Zealand, the now extinct Moa, another flightless bird that was endemic to the country, had already established itself as the largest terrestrial herbivore. In order to survive alongside, kiwis not only remained small, but also, became nocturnal and insectivorous.

Unfortunately, even the evolution does not seem to have helped this national symbol of New Zealand against deforestation and invasive predators. Currently, of five known kiwi species, two are recognized as vulnerable, one as endangered, and another one as critically endangered. While the government of New Zealand is already taking measures to protect them, this study may spur them to get even more diligent about saving this tiny bird that boasts such an ancient and impressive lineage.

Resources: news.yahoo.com, australiangeographic.com