One penguin does not make climate change | Polarjournal
The adult Adélie penguin, which came ashore south of Christchurch, was filmed by a couple as they strolled along the beach. The bird has since been released to swim back towards Antarctica on its own. Image: Screenshot Video Evening Standard / Facebook page Harry Singh

Antarctica is far from any civilization thanks to the Southern Ocean and the Antarctic Convergence Line, a kind of biological barrier. Most Antarctic species stay on the southern side of this line, as conditions such as food and temperature are less optimal north of it. But every now and then single individuals stray into northern regions, which attracts media attention… and unfortunately also misconceptions, as in the example of a little Adélie penguin in New Zealand.

Last week, a little Adélie penguin became a media hit after the newspaper Stuff reported its unexpected arrival in New Zealand. Adélie penguins are native only to Antarctica and its nearby islands, and reports of stray birds outside this region are extremely rare. The nearest major colony of Adélies is at Cape Adare, over 3,000 kilometres away, at the entrance to the Ross Sea region. The bird was captured and examined by a local conservation society. Aside from dehydration and starvation, the animal was in good condition. Since there was no other option, the Adélie penguin, called “Pingu” by the locals, was then released back into the open sea.

Experts in New Zealand were very surprised by the visitor. New Zealand has recorded only two other Adélies on its coasts so far. One of them had been dead already when it was discovered. Adélies barely cross the Antarctic convergence line, which forms a kind of boundary. Here, the cold waters from the Antarctic meet the warmer waters of the north and sink below them, as the Antarctic water is somewhat heavier. This displaces the underlying water masses and brings them to the surface from the very bottom. With it, many nutrients that lead to abundant plankton and krill, the food base of Adélie penguins and many other Antarctic inhabitants. But krill is not available everywhere and Adélies have to swim long distances if they want to replenish their reserves after the breeding season in autumn. That’s why the achievement of the little visitor is not the distance swum per se, but the fact that he had swum beyond the convergence line and made it to New Zealand… with no ice floes to rest on and hardly any food or water (Adélies cover their water needs via snow and food).

This graph from the National Snow and Ice Data Center shows the progression of Antarctic sea ice extent. The blue line shows this year’s trend, which was much higher than average until the beginning of September, indicating a much larger expansion than usual. Thereafter, the curve drops steeply, indicating the rapid retreat of sea ice. Graphic: NSIDC

The find gave rise to a brief but intense media hype on numerous news portals. The story as such, while remarkable, is not a sign of climate change in the breeding grounds, as a Swiss media portal had portrayed it, or an escape from poor conditions in Antarctica. Adélie penguins, as well as other Antarctic species, spend their winter period (May/June – October) close to the pack ice edge, which extends north relatively quickly, roughly doubling the area of Antarctica by September. When the pack ice retreats rapidly afterwards, it can cause individual animals to “blur” and move further north in search of food. A glance at the map this year in Antarctica showed an above-average spread of pack ice until early September, followed by a rapid retreat. Professor Philip Seddon of the University of Otago in New Zealand also disagrees that a penguin makes a climate change. “I think if we started getting annual arrivals of Adélie penguins, we’d go actually, something’s changed in the ocean that we need to understand.”

Adélie penguins breed in areas with pebbles, which they need to build their nests. These nests are defended against everything and everyone, also against small foreign penguin chicks. Picture: Michael Wenger

According to the IUCN Red List, the number of Adélie penguins is currently around 10 million adults and rising. However, this does not mean that the animals lead a carefree life in Antarctica. Some of the colonies have experienced local declines, according to experts, likely related to food availability. But new, large colonies have been discovered in other places. Adélies mainly need krill, but also eat other crustaceans. And krill have declined, especially on the warming west coast of the Antarctic Peninsula. In addition, krill fishing and pollution are other threats that are slowly increasing. In fact, our knowledge of the numbers of Adélie penguins, as well as other penguin species, is still riddled with gaps. Projects like Penguin Watch from Oxford University, the counts made by researchers in the field or the analysis of high-resolution satellite images are, however, helping to continuously improve our knowledge of “Pingu” and his companions… and thus also of the state of his habitat, which is sensitive but also highly complex in its response to current changes.

Dr Michael Wenger, PolarJournal

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