The yellow-eyed penguin—a rare species named for its distinctive band of golden feathers—has become one of New Zealand’s most prominent cultural icons (second to the kiwi, of course). Images of the penguins are stamped on the country’s $5 notes and splashed across airport billboards. Tourism centered on the birds contributes some $100 million NZD to the local economy each year. But a new study suggests that these beloved penguin populations are perilously declining, Kendra Pierre-Louis reports for Popular Science.
New Zealand’s yellow-eyed penguins make their home on the Otago Peninsula, on the east coast of South Island. Extensive records of the birds’ population have been kept since the 1940s; researchers from the University of Otago relied on data recorded at Kumo Kumo Whero Bay between 1937 and 1948, and data recorded at at Boulder Beach between 1982 and 2015.
The study, published in the journal Peer J, used prediction models to estimate the influence of climate in penguin populations size. The results suggest that increases in sea surface temperature is one of the biggest factors influencing survival of the birds.
Models were then used to estimate future population size, and the results suggest that the birds will be locally extinct by 2060. And when researchers factored in sudden die-offs—like the one that occurred in 2013—the date of extinction became much sooner. The birds could be locally extinct as early as in the next 25 years, Dr Stefan Meyer, one of the study’s the co-authors, says in a University of Otago press release.
But as Pierre-Louis reports, researchers caution that they do not have enough data to fully quantify human impact on penguin populations. “Climate data is wildly available, so we have all of this climate data that we can use in our models, but we have hardly any quantifiable data for fisheries impact, rate of pollution, the impact of tourism, and so on,” Thomas Mattern, lead author of the study, tells Pierre-Louis. Gillnets, for instance, likely pose a significant threat to penguins; the nets are hung vertically in the water to catch fish, but penguins become entangled in them and drown.
Mattern also notes that if climate change were the only threat to penguin populations, the birds would probably be able to adapt and survive. In 1943, the waters of Kumo Kumo Whero Bay warmed so much that the yellow-eyed penguin population should have declined—but it did not. Mattern suspects that the birds’ ability to thrive under these conditions can be attributed to the fact that many New Zealanders were overseas fighting in WWII.
The study, however, could spell trouble for other creatures, Michelle LaRue, a research ecologist at the University of Minnesota, told Rae Paoletta at Gizmodo. “What I can say about penguins in general is that they are important ‘canaries in the coal mine’ when it comes to ocean health,” she says. “Generally speaking, understanding how penguins are doing gives us some insight into how the ocean ecosystem may (or may not) be functioning.”
The study's findings are pretty grim, but there is an upside: while climate change may be a tremendous problem to tackle, other factors causing the penguins’ decline can be “managed on a regional scale,” Mattern said in the press release. It’s imperative that swift and bold action be taken to conserve the yellow-eyed penguin, before the creatures permanently disappear from New Zealand’s coasts.