WELLINGTON, May 17 (Xinhua) -- Iconic yellow-eyed penguins could disappear from New Zealand's Otago Peninsula by 2060 due to climate change, latest research warns, calling for coordinated conservation action.
In a newly-published study in the international biomedical sciences journal PeerJ, Otago-based researchers have modeled factors driving mainland yellow-eyed penguin population decline and are calling for action to reduce regional threats.
According to the researchers' prediction models, breeding success of the penguins will continue to decline to extinction by 2060 largely due to rising ocean temperatures. But these predictions also point to where our conservation efforts could be most effective in building penguins' resilience against climate change.
The yellow-eyed penguin, classified as endangered by the International Union for Conservation of Nature, is a key attraction for New Zealand tourism. Yet, the chances of seeing the penguins in the wild are quietly slipping away, the new research suggested.
About 60 percent of the penguin population lives on the subantarctic islands, with the remaining living along the south-eastern coast of the South Island of New Zealand.
Even more concerning is that the penguins have had a particularly bad run since 2013 when 60 birds died in a single year. If the last few years of poor breeding are included in the models, it would suggest the yellow-eyed penguin could be locally-extinct on the mainland in the next 25 years, according to lead study author Dr. Thomas Mattern of the University of Otago.
Mattern said these mainland birds, iconic within New Zealand, greet visitors to the country on billboards in all major airports, are featured on the five-NZ dollar note, and are widely used for branding and advertizing.
"Yet despite being celebrated in this way, the species has been slowly slipping towards local extinction," he said.
"It is sobering to see the previously busy penguin-breeding areas now overgrown and silent, with only the odd lonely pair hanging on," said Dr. Ursula Ellenberg, who has researched yellow-eyed penguins for the past 14 years.
Increasing sea surface temperatures in part explain the negative trend in penguin numbers.
"The problem is that we lack data to examine the extent of human impacts, ranging from fisheries interactions, introduced predators to human disturbance, all of which contribute to the penguins' demise," said Mattern.
However, he said clearly, other factors play a significant role, as climate change explains only around a third of the variation in penguin numbers, and these factors could be managed on a regional scale.
Phil Seddon, director of Wildlife Management at the University of Otago, said besides shining an alarming light on the state of the yellow-eyed penguin on the New Zealand mainland, the study also underlines the importance of long-term data sets.
"In the current era of fast science, long-term projects have become a rarity. Without more than 35 years' worth of penguin monitoring data, we would probably be still at a loss as to what is happening to a national icon, the yellow-eyed penguin," Seddon said.
Despite this urgency, yellow-eyed penguins continue to drown as unintentional bycatch in nets set in penguin foraging areas, suffer from degradation of their marine habitat because of human activities, and die from unidentified toxins.
"Without immediate, bold and effective conservation measures, we will lose these penguins from our coasts within our lifetime," the authors said.