Little penguins are recent Aussie invaders

Toto the little blue penguin is the oldest on record, she turned 25 last year (Christchurch Antarctic Centre)
Toto the little blue penguin is the oldest on record, she turned 25 last year (Christchurch Antarctic Centre)

Researchers have discovered the little blue penguins found splashing about in southern New Zealand are originally from across the ditch, making the journey some 100 years ago.

A new study by University of Otago researchers found the little penguin species belongs to an Australian species, and set out to find when the Aussies first came across the Tasman Sea.

They are the world's smallest penguin, standing just over 25 centimetres and weighing in around one kilogram. The penguins dine on a menu of small fish, crustaceans and squid.

The study was led by Professor Jon Waters from Otago's Department of Zoology with the help of Dr Stefanie Grosser as part of her PhD research.

Dr Grosser says previous studies have concluded the Australian species has been in New Zealand for hundreds of thousands of years. However, the new genetic study indicates the Australian species arrived in New Zealand much more recently.

Ancient DNA was analysed from the remains of more than 100 little penguins, with bones dating back to pre-human times, as well specimens from archaeological deposits and museums.

"Amazingly, all of the bones older than 400 years belong to the native New Zealand species," Dr Grosser says.

"Our results clearly show the Australian penguin colonised Otago very recently, between 1500 and 1900 AD, apparently following the decline of the native New Zealand little penguin, which was hunted by early human settlers and introduced predators."

While the results are exciting, the finding of wildlife extinction and replacement in the aftermath of human arrival is not a completely isolated case.

"Many of New Zealand's animal species, birds in particular, have suffered at the hands of people," Prof Waters says.

"The really exciting thing about these findings is that they show how quickly nature can respond to human impacts," he says.

The little penguins are protected by the Department of Conservation's (DOC) Wildlife Act. Data collected from DOC shows they are excellent swimmers, with the deepest dive recorded at 35 metres.

The team's findings have been published today in the international biological research journal Proceedings of the Royal Society B: Biological Sciences.