Adélie penguins in Antarctica show a huge preference for the reduced sea-ice conditions caused by global warming, a new study has found. This observed behavior makes this aquatic bird a rare, unexpected winner of climate change.
As per satellite observations, Antarctica has witnessed a gradual increase in its sea-ice coverage over the past 30 years, with the yearly average sea-ice (frozen water) extent reaching a record high in 2014. However, a sharp decline has been observed in the subsequent years, and the overall trend is expected to head downwards as climate change intensifies. While this spells bad news as far as the planet is concerned, one species could benefit and thrive immensely due to this phenomenon.
Adélie penguins, the most common species of penguin in Antarctica, witness a spurt in population during years of sparse sea-ice. In fact, it’s the growth in sea-ice that hits them hard, causing massive breeding failures among these creatures.
While these correlations were established years ago, scientists were unaware as to what caused them—until now. Through a new study, researchers with Japan’s National Institute of Polar Research (NIPR) have found an answer, and it happens to be fairly simple.
The research team electronically tagged 175 penguins with GPS devices, accelerometers, and video cameras, so as to observe their walking, swimming, resting, and hunting behavior, and track their trips across four seasons with different sea-ice conditions.
Subsequently, they found that the penguins were indeed happy with low sea-ice conditions, essentially because less frozen water allowed them to swim rather than walk, thereby making their lives easier.
“It turns out that these penguins are happier with less sea-ice,” said lead researcher Yuuki Watanabe at the NIPR. “This may seem counter-intuitive, but the underlying mechanism is actually quite simple.”
Penguins move four times faster while swimming as compared to walking. However, in the midst of heavy sea-ice, they are forced to walk and sometimes toboggan—lay on their stomachs and slide across the ice—for long distances to find access to water, where they hunt. These tiring journeys also compel them to take long rests along the way.
On the contrary, when there is less sea-ice, penguins can simply dive-in wherever they want, and even enter the water directly from their nests. This not only saves time and energy but also expands their foraging range and reduces competition while hunting.
Another indirect benefit to these polar predators is the fact that less sea-ice allows more sunlight to enter the water, causing larger blooms of the plankton upon which krill—penguins’ main prey—feed upon.
All in all, Adélie penguins well and truly thrive in the midst of low sea-ice, as this environment presents the most favorable and ironically, the most “chill” conditions for the birds to eat, move around, and reproduce.
However, it is interesting to note that these observations are only restricted to penguins that live on the main, “continental” part of Antarctica. The exact opposite happens with the penguins living on the thin Antarctic peninsula, and researchers continue to dig deep to find out why.