Why Do Chinstrap Penguins Take Micronaps?

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Anyone deeply sleep-deprived is probably familiar with microsleep. Microsleep occurs when you fall asleep for only a few seconds. For humans, these episodes can be dangerous if you’re driving a car or operating heavy machinery. But for Chinstrap penguins, taking micronaps may be the answer for getting some shut-eye, while staying vigilant to the world around them.

Recent research has revealed that Chinstrap penguins can accumulate 11 hours of sleep per day by taking micronaps. The penguins in the study needed to stay attentive, either to protect their eggs from predators or to guard against other aggressors. These penguins took tiny naps to be sure they were always ready to move into action if needed. The video above shows this fascinating (and adorable) behavior in action.

How Did the Researchers Measure Sleep?

The scientists implanted electrode devices into the penguin’s neck muscles and brain, which measured brain waves and the location of the animal. The scientists could tell if the penguins were standing, swimming, or lying down and when their brains were engaged in slow-wave sleep. Amazingly, the nesting penguins were in and out of slow wave sleep almost continuously, while the penguins at sea did take brief naps, but slept less overall.

Why Micronaps?

The researchers found the penguins dozed for about four seconds at a time — at a rate of over 10,000 times per day. This accumulation of sleep was enough for the nesting penguins to successfully hatch their chicks while remaining aware of their surroundings to protect them from egg-hunting predators. Unlike other birds that pair up to raise their young, penguin parents are left alone to watch the egg while the other parent heads for the ocean to search for food. The parent left behind may be alone for days at a time with the important task of keeping the egg safe.

If the penguin parent that was left behind to guard the egg slept for longer periods, researchers believe predators would have the opportunity to sneak up and grab the eggs. By sleeping for tiny amounts at at time, the parent is always ready to defend its nest. Another factor, Chinstrap penguins live in large colonies of noisy birds. With the entire group never asleep at the same time, it’s always a loud environment, and likely hard to stay asleep for long in the ruckus. And finally, even when not nesting, Chinstrap penguins need to watch out for other predators including orcas and leopard seals.

What Animals Eat Chinstrap Penguin Eggs?

Penguin parents need to watch out for birds that will swoop in and steal their eggs such as giant petrels, skuas, gulls, and other birds. These aggressive birds look for any opportunity to snatch an egg from a parent’s nest. Penguin parents must be ready to chase the birds away at a moment’s notice. The penguins aggressively attack any birds near their nest by slapping at them with their wings and chasing them with open bills. This is why sleeping for more than a few seconds at a time is dangerous business.

How Many Eggs Do Chinstrap Penguins Have?

Chinstrap penguins generally mate for life, returning to the same partner year after year. The fathers arrive to the breeding grounds about a week earlier than the females. When the females arrive, the mated pairs build nests out of pebbles, being sure to stay close to other nests for protection. A nest on the outskirts would be too much of a temptation for predators.

The mothers typically lay two eggs in December. Because it’s very hard work guarding eggs until they hatch and raising the baby chicks, it takes both parents to be successful. The parents trade off shifts of around 5 to 10 days each where one guards the egg while the other travels to the sea and hunts for food. The parents keep this up for a month, until the egg hatches. And then it’s another month of caring for the tiny chick until it’s about a month old when it joins a group of other baby chicks called a creche.

Habitat

Chinstrap penguins live on the Antarctic Peninsula and small islands located in the South Atlantic Ocean. They are a protected species and fall under the Antarctic Treaty System. Although their numbers are abundant and the penguins are a species of least concern, recent evidence has suggested their population is declining due to the loss of Antarctic krill, their main food source. The krill fish is a small but important marine creature that is suffering from the impacts of overfishing and climate change.

The largest penguin colony on Earth of not just Chinstrap penguins, but any type of penguin is found in the South Sandwich Islands. It’s here on an active volcano where 1.5 million Chinstrap penguins wander Zavodovski Island. For birds living in a colony with 1.5 million noisy penguins, it makes sense it would be hard to get much sleep beyond a few seconds at a time.