New Zealand's little blue penguins are actually Australian invaders
One of New Zealand's best-loved penguin species is in fact an Australian immigrant, new research shows.
A University of Otago-led study published its findings in Proceedings of the Royal Society B: Biological Sciences.
In their study, researchers analysed DNA from the remains of more than 100 little penguins, popularly known as little blue penguins, including bones dating to pre-human times and specimens from archaeological deposits and museums.
In their analysis, the researchers found the bones that were more than 400 years old were of New Zealand origin, while the more recent ones had come from Australia.
As a result, they determined that Australian little blue penguins arrived on the Otago Peninsula and pushed out their Kiwi cousins somewhere between 1500 and 1900 AD.
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University of Otago Department of Zoology professor Jon Waters, who led the research, said the findings poked holes in the belief that New Zealand plants and animals had developed over thousands or even millions of years without overseas influence.
"It was a real surprise, though maybe not the news we wanted to hear," he said.
"In terms of biological timescales it's just the blink of an eye."
Waters said it was uncertain how the Aussie-origin penguins conquered New Zealand, but that two reasons might be the tendency of little blue penguins to travel great distances and to congregate in large groups.
"The Aussies congregate," he said.
"You can see hundreds in one place. The Kiwi species doesn't congregate in the same way."
Waters said there were still pockets of Kiwi resistance against the Australian invaders, primarily around Stewart Island, where the majority of little blue penguins were of New Zealand-origin. But Waters said the Kiwi penguins on the Otago Peninsula had been effectively wiped out by the Aussie onslaught.
In 2015, a team of researchers from the University of Otago and the University of Tasmania found that Australian and New Zealand little blue penguins were two separate species, rather than one as had previously been believed.
In the South Island, little blue penguins are most common off the Otago Peninsula and Banks Peninsula, as well as Oamaru.