RESEARCH: Scientists think penguins in Antarctic prefer ice-free conditions

Scientists have been studying penguins in the Antarctic Region.

Polar biologists have seen populations of penguins increase during years when there is not a lot of ice in the region. They have also seen breeding reductions during the years when there is a lot of sea ice. However, they did not know why ice-free conditions made populations increase. But after this recent study, the polar biologists think they know why.

Polar biologists at the Japanese National Institute of Polar Research put electronic global positioning system (GPS) tags on 175 Adelie Penguins (Pygoscelis adeliae) in the Antarctic Region. They also put video cameras in different locations to monitor what happens during the four seasons of the year when there are different sea ice conditions.

The scientists tracked the penguins’ trips, walking styles, swimming periods, resting times, behaviour, food, diving patterns, weather, and the amount of ice in the sea.

Yuuki Watanabe of the National Institute of Polar Research said that penguins are happier with less sea ice. This seems to be a contradiction of what we think is better for penguins. 

The researchers found that when there is a lot of sea ice, the penguins have to walk (or toboggan and slide on their stomachs) a long way to find cracks in the ice to enter the ocean so that they can hunt for food. They eat krill (Euphausia superba), which are small marine shrimp-like crustaceans. 

When there is less sea ice, the penguins can dive anywhere they want to. They just dive into the ocean, near their nests, without having to travel long distances to look for a way to enter the water.

That means that penguins use less energy to look for food when there is less sea ice than if there is a lot of ice. Also, there is less competition for food when there is less sea ice. Less competition, and easy access to the ocean’s water means that the penguins can catch more food. 

Krill love to eat plankton. Plankton is a very small plant that float on the surface of sea water. Plankton grows when there is more sunlight. There is more sunlight when there is less ice in the water. That means that, when there is less ice in the water, there is more plankton, more krill, and more food for the penguins to eat. 

However, scientists say that this is only true for penguins that live on the mainland—the continental part of Antarctica. 

Other penguins that live on the thin Antarctic peninsulas (small strips of land that jut into the sea), and the penguins that live on small islands, prefer to have a lot of sea ice near their home. They don’t have to travel far on land to find gaps in the ice to enter the ocean, because the ocean is all around them all of the time. 

The scientists published their findings in the Science Advances journal. They wrote that mainland-living penguins on Antarctica spend 15% to 33% less energy looking for food when there is less sea ice, which means that they save energy. This saved energy is spent on reproduction and growth—which leads to more babies and increased populations. 

The scientists noted that over the past decades, Antarctica (South Pole) has increased the amount of its sea ice, but the Arctic (North Pole) has decreased the amount of its sea ice. 

Antarctica is projected to have a decrease in sea ice in the future. This is likely to have an impact on penguins, in the way they hunt for food, and the way they reproduce. Therefore, polar biologists need to monitor the penguins in the Antarctic Region (and the Arctic Region) and conduct ongoing research of both the mainland penguins and the island penguins to determine the impact of the changing habitats on penguins and their population numbers. 

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM

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