Global warming is a major source of stress for most species, but some penguins in Antarctica are actually reaping the benefits of rising temperatures. In a surprising new study, scientists have discovered that Adélie penguins are much happier and more productive when there is less sea ice.
As Arctic ice continues to decline, sea ice in Antarctica has shown steady growth in recent decades. Climate models predict that this trend will soon reverse and Antarctica’s sea ice will rapidly melt throughout the rest of this century.
Sea ice retreat will transform the habitats of polar species, but the new research suggests that many Antarctic penguins will not suffer from a lack of ice.
Previous studies have shown that Adélie penguins thrive in numbers during years with less Antarctic sea ice and experience frequent breeding failures in years with the most ice. However, the underlying cause of the link between low ice conditions and population growth has been unclear.
To investigate, a team of scientists from Japan’s National Institute of Polar Research tracked 175 Adélie penguins with GPS devices, accelerometers, and video cameras during four seasons with different sea-ice conditions. The experts analyzed the walking, swimming, foraging, and resting behavior of the penguins.
“It turns out that these penguins are happier with less sea-ice,” said lead researcher Yuuki Watanabe. “This may seem counter-intuitive, but the underlying mechanism is actually quite simple.”
According to Watanabe, penguins are able travel more in ice-free conditions. “For penguins, swimming is a whopping four times faster than walking. They may be sleek in the water but are pretty slow waddlers overland.”
The scientists observed that when sea ice was abundant, the penguins were forced to walk long distances searching for cracks in the ice to access food, and often took lengthy breaks to rest.
On the other hand, with little sea ice, the penguins could dive anywhere they wanted – often right by their nests. This saved the penguins time and energy and greatly expanded their foraging range.
The extended range likely reduces competition for food and allows Adélie penguins to catch more krill. In addition, more sunlight enters the water when it is ice-free, increasing the numbers of plankton and krill.
The researchers noted, however, that sea ice retreat only benefited penguins that live on the continental part of Antarctica. Penguins that live on the Antarctic peninsula were negatively impacted by sea ice loss, and the team plans to investigate further.
The study is published in the journal Science Advances.