The curious case of Little Blue Penguin in New Zealand has baffled scientist for years, as these waddling Australian invaders have long managed to blend in with the native New Zealand little blue penguins and now has just taken another mysterious twist.
Researchers recently revealed an Otago, NZ population of the world’s smallest — and possibly cutest — penguin species actually hailed from across the Tasman Sea and have now confirmed the immigrants arrived from Australia as recently as the past few hundred years.
It’s the latest instance in which DNA analysis has dramatically changed what we know about many of New Zealand’s supposedly native species.
Following startling findings in December that, for the first time, described two distinct species of little blue penguin in New Zealand, a paper published today in the Proceedings of the Royal Society B: Biological Sciences finds the newcomers probably arrived here between 1500 and 1900.
This up-ended previous theories that the Australians had been here for thousands of years.
As part of her PhD research at Otago University, Dr Stefanie Grosser analysed ancient DNA from the remains of more than 100 little penguins, including bones dating back to pre-human times and specimens from archaeological deposits and museums.
“Amazingly, all of the bones older than 400 years belong to the native New Zealand species,” she said.
Dr Grosser said the arrival apparently followed the decline of the native penguin, which early human settlers and introduced predators hunted.
The Australian species were set apart by a few subtle differences in their color, body and cranium size.
Other researchers had previously shown that calls differed between Australian and New Zealand little penguins and females preferred the calls of males of their own species.
“You could say the Aussies like hearing ‘feesh’, while ‘fush’ sounds better to Kiwi ears,” Dr Grosser joked at the time of the December findings.
But how they got here remains a mystery — and one we might never solve.
“It’s one of those unlikely events that they happened to rock up on the Otago coastline and got a foothold,” said study leader Professor Jon Waters, of Otago University’s Department of Zoology.
“You could make up a story that maybe an Australian ship picked up 10 and brought them over, but I’d find that really hard to believe.”
The Australian sub-population appears confined to Otago. DNA analysis from other colonies, such as Wellington, Kaikoura and Banks Peninsula, turned up only the New Zealand lineage.
“It’s possible we might find another colony of Aussies somewhere like Fiordland, we don’t know.”
Professor Waters believed the findings should bring about a different approach to the species’ conservation.
“We have to think about them as being not one thing, but two, and manage them separately — so there might be a real paradigm shift.”
The native penguin, which on average stands at just 25cm and weighs 1kg, is considered in decline in New Zealand. Dogs pose their greatest threat.
The research, supported by the Marsden Fund and the now-closed Allan Wilson Centre, also provides the latest example of penguins winding up on foreign shores far from home.
Little blue penguins have been found as far as Patagonia in South America.
Other famous penguin stories have included the Antarctic emperor penguin Happy Feet, which captured Kiwi hearts after it arrived in Kapiti in 2011, and Katrina, a Fiordland penguin that swam 3000km to Mt Gambier, South Australia, in 2013.