Treadmill experiment: Fat king penguins less steady on feet than skinny ones

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Down in the chilly waters of the sub-Antarctic Crozet Islands, it’s only natural to develop an extra layer or two of winter fat.

And, newly released video shows some of the king penguins in a colony there running on treadmills.

It’s not some sort of avian weight loss program.

The exercise is part of an experiment by a team of scientists researching the biomechanics of the king penguin’s ungainly waddle.

The team, led by Astrid Willener from the University of Roehampton’s life sciences department, conducted the research at Baie du Marin on Possession Island, where hundreds of king penguins, the second-largest penguin species, come ashore to mate each year.

The researchers captured 10 heavy male king penguins and filmed them walking on a treadmill before and after a 14-day fast, to observe the differences in their gait in their fat and skinny states.

Willener said the penguins received training to walk on the treadmill, before they were tested at speeds up to 1.6 kph (1 mph) for up to 10 minutes.

“At the beginning, they would be a bit surprised, but actually they learned very fast,” she said. “The penguin gets used to it. They kind of knew that when the little beep was coming the treadmill would start.”

While most took to it quickly, some of the lazier birds cheated by lying back and “doing kind of a ski,” she said.

Fat penguins less steady on their feet

The king penguin, which can grow to 1 meter tall (3.3 feet) and weigh 16 kilograms (35 pounds), undergoes “a huge change of body mass” when it fasts during breeding season, losing up to a quarter of its body weight, Willener told CNN.

The researchers’ aim was to determine whether the species’ distinctive waddling gait changed with variations in its body mass.

King penguins spend most of their time swimming and have a fish and squid diet.

When they return to land during breeding season, they often walk long distances to the breeding colony, carrying a heavy frontal accumulation of fat, as well as food in their stomachs to feed their chicks.

On reaching the colony, with no access to fish, the penguins have to fast for up to a month, living off fat deposits to survive.

Willener said the researchers were curious about how the bird, which swims as its primary form of locomotion, managed to stay upright across such long distances and such drastic changes in its body mass.

The result showed that heavy penguins were less stable than thin ones – but on the whole were still able to walk steadily.

The findings were supported by previous observations that heavy king penguins returning from the sea were more likely to fall than ones that had been fasting, rendering them more vulnerable to predators.

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