University of Otago researchers, led by Otago zoology PhD student Sanne Boessenkool, were investigating changes in the threatened yellow-eyed penguin population since human settlement.
While using a combination of traditional techniques and DNA from prehistoric bones, they were surprised to find an entirely new penguin species. The so-called "Waitaha" penguin was estimated to have become extinct between AD1300 and AD1500, soon after Polynesian settlement, Sanne Boessenkool said.
The penguin's extinction, combined with Maori cultural shifts and changes in predator populations, created an opportunity for the now highly-endangered yellow-eyed penguin to colonise the mainland about 500 years ago, she said.
"We found the extinct species was closely related to the yellow-eyed penguin, which is now assumed to be a relatively recent arrival from the subantarctic Auckland and Campbell Islands."
The team's findings demonstrated that the yellow-eyed penguin was not a declining remnant of a previous abundant population.
"Competition between the two species may have previously prevented the yellow-eyed penguin from expanding northwards, but environmental changes in the predator population, such as the severe decline in sea lions, might have facilitated their colonisation in the South Island," she said.
The research also involved the University of Adelaide and Canterbury Museum, and was supervised by University of Otago Associate Profs Jon Waters and Phil Seddon.
Dr Waters said it was a fascinating discovery and could mean a reassessment of other species, especially from the South Island, was needed.
"The ancient DNA approach used in this penguin study is enormously powerful, as it provides a direct means of characterising historical biodiversity.
"When coupled with more traditional techniques, this method has potential to revolutionise our understanding of the past."
While it was a tragedy the Waitaha penguin, named for an historical northern South Island iwi, had become extinct, it showed how nature could respond to the conditions.
The yellow-eyed penguin was considered one of the world's rarest penguin species and was the focus of an extensive conservation effort.
Yellow-eyed Penguin Trust field manager Dave McFarlane said the research was very exciting, but did not mean any changes in the trust's conservation efforts.
"This informs us and gives us a greater understanding of its origins, and we look forward to finding out more detail about its current relationship with the subantarctic populations," he said.
The researchers' findings have been published in the international research journal Proceedings of the Royal Society B: Biological Sciences.
