July 27, 2017 4.50am BST
A tall, bulky and probably near-flightless black swan once roamed New Zealand. But it was hunted to extinction not long after people arrived during the late 13th century, and then replaced by its Australian cousin.
Our research, based on ancient DNA and morphology, shows that the New Zealand species — dubbed Poūwa — was unique and genetically separate from the Australian species.
Poūwa was heavier and larger, a bit like an All Blacks rugby player, and it was well on the way to becoming flightless when it became extinct.
A potted history of the black swan
The black swan, Cygnus atratus, is a quintessential Australasian bird. Until their first voyages to Australia, 18th century European explorers assumed that all swans were white.
By the time Europeans arrived in New Zealand, there were no black swans. But naturalisation societies introduced Australian birds from Victoria during the 1860s.
At the same time, black swan bones were being found in fossil and archaeological deposits in New Zealand and the Chatham Islands. Scientists concluded that the Australian black swan formerly inhabited the New Zealand region but that the local population had been hunted to extinction. Until recently, this was still the prevailing view.