Aussies swan in after natives hunted to extinction - study
New Zealand native black swans were hunted to extinction by Polynesians and almost all the black swans living here are recent arrivals from Australia, new research shows.
These ancient native black swans probably arrived from Australia from 1 million to 2 million years ago and evolved to be heavier and taller than their Australian cousins.
Given another million years, they might have become flightless, said University of Otago palaeogenetics laboratory director Nic Rawlence, who led the research.
But Polynesians arrived about 1280 and the native black swan was hunted to extinction by about 1450, he said. Moa and about a third of other native species also died out in this ‘‘megafaunal hunting period’’.
By the time Europeans arrived in the late 1700s, there were no black swans established in Aotearoa, although there was good evidence they were arriving from Australia, but not breeding for long.
In the 1860s, black swans were introduced from Victoria and it was thought they were the same birds as found in the New Zealand fossil and archaeological record. There are now about 50,000 black swans here.
Rawlence and colleagues used DNA and skeletal analysis to show the birds were distinctly different.
The New Zealand birds had longer legs, smaller wings and weighed up to 10 kilograms, compared with about 6kg for the Australian birds. They could still fly, but spent more time on the ground than modern birds.
He said black swans were thin and lean like football players, while the ancient native swans were beefier and robust like rugby players.
The extinct New Zealand species was dubbed ‘‘pouwa’’ by Rawlence and colleagues after a Moriori legend about a black bird that lived in the Chatham Islands. Its bones were found in sand dunes there.
The research raised questions about what it meant to be ‘‘native’’. Rawlence wondered if the Australian black swan was a pest or something to be protected.
The research would be published in the Proceedings of the Royal Society B.