Penguins find an upside to less sea ice

Global warming is undeniably bad for the world’s wildlife, but it may bring a surprising short-term advantage for Adélie penguins (Pygoscelis adeliae) in continental East Antarctica.

Scientists have discovered they were able to cover more ground in less time by swimming rather than walking as they searched for prey during an unusually ice-free breeding season in 2016-2017.

Without the need to locate cracks in sea ice for breathing, they also were also able to conduct shorter dives while catching more krill.

In turn, this higher foraging success led chicks to grow faster and increased the body mass of adult males and females, according to a paper in the journal Science Advances.

“It turns out that these penguins are happier with less sea ice,” says lead author Yuuki Watanabe from Japan’s National Institute of Polar Research. “This may seem counter-intuitive, but the underlying mechanism is actually quite simple.”

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A penguin with a video camera on its back and an accelerometer on its head. Credit: Yuuki Watanabe

To track foraging behaviour in detail across four breeding seasons within the past decade, Watanabe and colleagues monitored 175 penguins in the Lützow-Holm Bay by tagging them with animal-borne GPS loggers, accelerometers and video cameras.

The 2016-2017 season – the fourth – proved unusual, as a large quantity of sea ice in the bay broke up and drifted away with currents.

The study suggests the penguins may have expended an average of 15% to 33% less energy per trip that year compared with ice-covered seasons, putting saved energy into growth and reproduction.

There is even a chance, the researchers say, that Adélie penguins may experience a population boom in the years to come if Antarctica continues to lose sea ice as climate models predict.

However, all this only happens for those penguins that live on continental Antarctica. The 30% of the species that live on the Antarctic Peninsula or islands do not fare well when sea ice diminishes.

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