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New Zealand once had its very own species of black swan, which would have become flightless had it not been hunted to extinction.
Researchers who analysed ancient DNA and bones to prove the pouwa was a unique species also say the bird was even heavier and larger than their Australian cousins, which are now common around our waterways.
The study's lead author, Dr Nic Rawlence of Otago University's Department of Zoology, said the build of Cygnus sumnerensis was more like a rugby player compared with the Australian swan's smaller and slender soccer-player physique.
Like the moa, the species was wiped out soon after humans arrived in the late 13th century.
The findings - made by a team from the University of Otago, Canterbury Museum and the Museum of New Zealand-Te Papa Tongarewa, and just published in the Proceedings of the Royal Society B - were one of a "growing number of examples of extinction and colonisation since the arrival of people in New Zealand", Rawlence said.
Australian black swans first arrived in New Zealand about one to two million years ago, during the Pleistocene Ice Age.
On settling here and on the Chatham Islands they rapidly became bigger than their Australian cousins, weighing up to 10kg compared with 6kg, and developing elongated legs and becoming more terrestrial in habitat.
"One of the interesting findings comes from the highly elongated leg bones, which shows they were already on the path towards flightlessness," Rawlence said.