New Zealand has long have been thought of as a "moa's ark", where an abundance of species flourished and evolved in our isolated prehistoric wilderness.

Yet, in revealing why so many of our native birds have Aussie cousins, scientists have further up-ended the notion that we've always been cut off from the rest of the world's ancient life.

In a new paper, Dr Michael Knapp of Otago University's Department of Anatomy and colleagues investigated how it was that many Australian birds managed to establish themselves here between two million and 2.5 million years ago.

Earlier findings had