Australian little penguins are a separate species from those living in New Zealand, a team of ornithologists led by University of Otago scientist Dr Stefanie Grosser has shown.

The little penguin (Eudyptula minor) is widely distributed in Australia – from Western Australia along the southern coast of Australia up to New South Wales.

It is also native to the coasts of New Zealand – from Northland to Stewart Island and the Chatham Islands.

As the smallest penguin on Earth, this bird stands at an average height of 12 inches (30 cm) and has a weight of 1.15 kg.

“Systematic and taxonomic questions surrounding this species have long been controversial,” Dr Grosser and co-authors said.

The scientists used genetic techniques to compare little penguin populations from Australia and New Zealand, and surprisingly found that they are not the same species.

“We found a very strong pattern, where New Zealand has its own distinctive genetic group that is clearly very different from the Australian penguin populations,” Dr Grosser said.

“Based on our multilocus genetic analyses and concordant biological evidence, we recommend the Australian little penguin to be elevated to full species status, Eudyptula novaehollandiae, with its type locality restricted to Port Jackson, New South Wales,” the scientists said.

“The New Zealand little penguin should remain Eudyptula minor with the type locality recognized as Dusky Sound, Fiordland.”

According to the team, the two species also seem to have developed their own ‘accents.’

“Other researchers have previously shown that calls differ between Australian and New Zealand little penguins, and females prefer the calls of males of their own species,” Dr Grosser said.

“You could say the Aussies like hearing ‘feesh,’ while ‘fush’ sounds better to Kiwi ears,” she added.

Another unexpected finding was the discovery that Eudyptula novaehollandiae is surprisingly also present in Otago, in the remote southeast corner of New Zealand’s South Island.

“Our genetic data suggest that the Otago and Australian populations are quite closely related,” Dr Grosser said. “Coalescent modeling suggests that the Australian little penguin only recently expanded into southern New Zealand.”

Prof. Jonathan Waters, a scientist with the University of Otago and a co-author on the study, added: “the new recognition of endemic species – unique to our region – is crucial for managing our natural heritage.”

“Elevation of the Australian little penguin to full species status warrants the reassessment of Eudyptula conservation status,” Dr Grosser and he colleagues said.

“While little penguins are globally evaluated as ‘least concern’, their general demographic trend is one of decline. In New Zealand, most populations are currently considered ‘at risk’, with substantial decline also documented in numerous Australian colonies. Currently, the absence of long-term demographic data precludes an accurate conservation assessment of these species.”

“Our study’s findings represent the second recognition of new extant penguin species diversity within a decade, and exemplify that cryptic diversity can remain undiscovered even in iconic taxa. Indeed, additional undescribed penguin diversity may exist elsewhere.”

“Our study further highlights the value of genetic approaches for assessing demographic histories of iconic taxa,” they concluded.

The results were published online December 14 in the journal PLoS ONE.

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Grosser S et al. 2015. Coalescent Modelling Suggests Recent Secondary-Contact of Cryptic Penguin Species. PLoS ONE 10 (12): e0144966; doi: 10.1371/journal.pone.0144966