Why don’t pandas hibernate?

Bears are famous for their hibernation behavior. As most of us learned in school, bears, along with various other animals, enter a long, sleep-like state to escape the harsh winter cold. Can we blame them? After all, winter is harsh with scarce food and freezing temperatures. Many humans who love the sun would rather hibernate through the cold months and wake up to the warmth of spring. However, you might be surprised to know that the giant panda, also known as the "panda bear," doesn't follow this ancient, protective practice.

If you've read 'How Hibernation Works,' you're familiar with the many ways animals hibernate. But pandas don't participate in any form of hibernation, even by the broadest definitions. It’s not that they avoid sleep — far from it. Giant pandas sleep anywhere from eight to twelve hours a day. It’s also not because they can’t handle the cold — they have relatively little body fat to keep them insulated from low temperatures [source: Stone]. Rather, when the weather gets rough, pandas just move to more comfortable spots. Instead of hibernating when the temperature drops, they look for a better place to relax and enjoy bamboo.

Living in the mountains gives giant pandas an advantage in finding cooler, more comfortable temperatures. In the summer, they search for higher altitudes to escape the heat. While they typically live around 9,000 feet (2,743.2 m) above sea level, during hot summers, they climb as high as 11,500 feet (3,505 m) where bamboo still grows [source: Stone]. When colder months arrive, they descend to warmer elevations, sometimes as low as 4,000 feet (1,219 m).

Whether it's a bear or not, there’s more to the giant panda's preference for migrating instead of hibernating. The reason behind this lies in its unique diet, which makes hibernation impossible. Keep reading to learn more.

The Bamboo Root of the Problem: Giant Panda Eating Patterns

Giant pandas are somewhat of an evolutionary puzzle. Experts believe they evolved from meat-eating carnivores. In fact, the biological structure of a modern giant panda still resembles that of a carnivore. Its digestive system is designed to break down meat, not bamboo, making it inefficient at processing bamboo stalks.

This might surprise you since the first thing most people think of when it comes to pandas is bamboo. In fact, bamboo makes up nearly 99 percent of their diet. But with their carnivorous digestive system, would you ever find a panda hunting prey in the wild? The answer is no.

This doesn't mean that pandas are morally opposed to eating meat. Just as you won't see pandas hunting in the wild, you also won’t find them holding signs against a tiger’s meal of deer.

Though giant pandas may occasionally eat meat when it’s offered, they’re not adept hunters. Evolution may have favored pandas that relied on bamboo, as it’s available throughout the year. After consuming it for thousands of years, pandas have developed a strong preference for bamboo, so much so that they choose it over pre-killed meat and other foods.

This preference for bamboo comes with its own set of challenges. Pandas have short digestive tracts and lack the special bacteria and protozoans found in herbivores that help break down cellulose. As a result, they obtain very little nutrition from bamboo. While carnivores typically extract 60 to 90 percent of the energy from their meals, giant pandas only get about 20 percent from bamboo on a good day [source: Schaller].

To get enough energy throughout the day, giant pandas must consume large quantities of bamboo — roughly 40 pounds (18 kilograms) per day [source: Youth]. It's not that the panda's day is particularly active; they spend most of it (12 to 16 hours) eating. Add in 8 to 12 hours of sleep to conserve energy, and you've got an animal that eats just to have enough energy to keep eating.

One might assume that hibernation would be a perfect way for the giant panda to conserve energy. However, its bamboo diet is precisely what prevents it from engaging in a long sleep period. Giant pandas can't accumulate enough body fat to survive foodless months, as bamboo doesn’t provide sufficient energy for such extended breaks from eating.

But does this make the giant panda stand out among bears? Next, we’ll explore why the term "panda bear" might be misleading.

The Giant Panda Debate: Bear or Raccoon?

Humans have a tendency to name and categorize things, and these classifications certainly help us study animals. However, the science of animal classification is surprisingly imprecise. Problems arise when animals don't neatly fit into predetermined categories. The giant panda is a prime example of this.

It wasn't until 1869 that Westerners were introduced to the giant panda. Père Armand David, a Catholic priest, had the first look and compared the peculiar animal to a bear, using the Latin term "ursus" for bear in its name. This makes sense, as the giant panda does resemble a bear. However, shortly after, French scientist Alphonse Milne-Edwards examined a giant panda's remains and concluded it was more closely related to the red panda, a raccoon-like creature. He immediately renamed it and placed it in a separate category.

But the story didn’t end there. In fact, the debate over whether the giant panda is closer to a bear or a red panda has been ongoing for decades. Is it a small bear or a large raccoon? Red pandas weigh between seven and 14 pounds, with the heaviest raccoon ever recorded weighing just over 60 pounds [sources: Smithsonian, nature.ca]. By contrast, giant pandas often exceed 200 pounds, raising questions about their true relationship with red pandas [source: Youth]. Here’s a breakdown of the characteristics each side argues in favor of.

Similarities to a red panda: Both giant and red pandas consume bamboo, grip it in a similar manner, and share comparable snout, teeth, and paw characteristics. They also bear a striking resemblance to one another [source: Schaller].

Similarities to a bear: Clearly, the giant panda resembles a bear due to its size and shape. Additionally, it shares shaggy fur and exhibits the same walking and climbing abilities as a bear [source: Maher].

It is possible that both the giant panda and the red panda developed similar traits related to bamboo consumption (such as their grip) independently, through a phenomenon known as convergent evolution. Alternatively, the same process of convergent evolution could explain their similarities to bears.

Some have suggested revisiting the classification of the red panda to determine if it is correctly grouped with raccoons. With the advent of DNA technology, scientists have explored these questions. Some studies have indicated that the giant panda is more closely related to bears, while the red panda is more aligned with the raccoon family. However, these findings are not definitive, and the debate remains unsettled.

Alternatively, we could follow the perspective of George B. Schaller, author of "The Last Panda," who prefers to embrace the giant panda's mystery and uniqueness, stating, "the panda is a panda" [source: Schaller].