Antarctica's Adélie penguins 'happier with less sea ice' as they hunt and breed better, scientists reveal

Over the next few years, Antarctica is expected to lose more of its sea ice, enabling the population to flourish, say scientists


                            Antarctica's Adélie penguins 'happier with less sea ice' as they hunt and breed better, scientists reveal
(Yuuki Watanabe, National Institute of Polar Research)

Even as climate change threatens to challenge the survival of wildlife, one bird species seems to be profiting from it. Sea ice melting could help Adélie penguins in Antarctica do a better job hunting and breeding, according to a new study. Over the next few years, Antarctica is expected to lose more of its sea ice, enabling the population to flourish, say scientists from Japan. "It turns out that these penguins are happier with less sea ice," says lead researcher Yuuki Watanabe at the National Institute of Polar Research, who added that he was surprised by these findings. For now, Antarctica appears to be more shielded from climate change, unlike the Arctic. But some studies have noted that sea ice around the former is falling since 2014, sparking concerns. The excess loss could lead to more heating of the planet, setting off a cycle of warming and melting.

Scientists studying the polar region have noticed something odd about Adélie penguins: their population shot up during ice-free conditions but dropped during high sea-ice conditions. To gain more insights into the bird's behavior, Watanabe and his team tracked 175 penguins with GPS devices, accelerometers, and video cameras through four seasons. These gadgets provide reliable data as it records the penguin's behavior, from walking, swimming to resting. It also collects data on the number of prey they capture during dives.

Krill sampled from penguin stomachs. Those sampled on the left (ice-free) are much larger than the ones sampled on the right (more ice) (Yuuki Watanabe, National Institute of Polar Research)

 

Their data showed that they do well in ice-free conditions. "This may seem counter-intuitive, but the underlying mechanism is actually quite simple," explains Watanabe. These species adopted swimming during ice-free conditions. Swimming, in turn, makes them faster, expanding their hunting grounds areas, the researchers explain in their study.  It is also more energy-efficient. When more ice covered the sea, the penguins had to walk, which slows them down as they take longer breaks. "For penguins, swimming is a whopping four times faster than walking. They may be sleek in the water but are pretty slow waddlers overland," he adds. "They came back to the nest quickly, which means that chicks waiting at the nest had food more often,” Watanabe, tells Guardian, adding the improved foraging conditions led to successful breeding. These birds, which are the tiniest species of penguins in the Antarctic, primarily feed on krill and small fish.

There is another benefit too. Lower sea ice allowed more sunlight into the sea, allowing phytoplankton to bloom. In response, krill, which feeds on these photosynthetic organisms, also flourishes, providing more food to the penguin. He added that the study throws light on the complex effects of climate change on wildlife. “Responses to climate warming will differ depending on species and regions,” he said explaining that predatory seabirds called skua, for instance, struggled to catch big and healthy penguin chicks. These findings, however, do not apply to all of them. Ice-free conditions are an advantage for penguins residing on the main, "continental" part of Antarctica. Those occupying the thin Antarctic peninsula that sticks out from the continent or lives on its islands lose out when sea ice melts.

The study is published in Science Advances.

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