KEY POINTS:
New research suggests yellow-eyed penguins are relative newcomers to mainland New Zealand and filled a niche left by a newly identified penguin species.
A study led by University of Otago researchers estimates yellow-eyed penguins colonised the South Island from about 500 years ago.
Otago zoology PhD student Sanne Boessenkool said the group had set out to investigate changes in the New Zealand yellow-eyed penguin population since human settlement.
However, they surprisingly identified a previously unknown penguin species that roamed South Island shores until just a few hundred years ago.
"It is estimated that the so-called Waitaha penguin became extinct between AD1300 and 1500, soon after Polynesian settlement," Ms Boessenkool said.
"The penguin's extinction, combined with Maori cultural shifts and changes in predator populations, created an opportunity for the yellow-eyed penguin to colonise NZ's mainland around 500 years ago."
The Waitaha penguin was identified by using ancient DNA from prehistoric bones, combined with traditional techniques, such as studying bone structures.
"We found that the extinct species was closely related to the yellow-eyed penguin, which is now assumed to be a relatively recent arrival from the sub-antarctic Auckland and Campbell Islands," Ms Boessenkool said.
Researchers said competition between the two penguin species might have previously prevented the yellow-eyed penguin from expanding north, but environmental changes in the predator population, such as the severe decline of sealions, might have facilitated their colonisation of the South Island.
The yellow-eyed penguin is considered one of the world's rarest penguin species, with an estimated population of 7000 in New Zealand, and is the focus of an extensive conservation effort.
The findings of the team, which includes University of Adelaide students and Canterbury Museum, have been published in the research journal Proceedings of the Royal Society B: Biological Sciences.
- NZPA
