We love panda bears for their unique appearance, which is majestic yet cuddly. But these big black and white bears have other unique qualities, too; where else can you see a giant carnivore who survives on a diet that is 99% grass?
At first glance, it doesn’t make sense; bamboo has little nutrition to offer the panda bear, which means they have to eat several kilos a day to survive. Discover why pandas evolved this way and why they are carnivores at heart.
Why Do Pandas Eat Bamboo?
Panda bears didn’t always live on an exclusive diet of bamboo; their ancestors once enjoyed a more varied diet of plant and meat-based foods. So why did they ditch the meat in favor of bamboo when the latter offers minimal nutrition?
Like all creatures, the panda bear evolved the abilities it needed to survive in a changing world. Bamboo offers a plentiful food source within most panda habitats, and there is very little competition for the grassy plant because it is difficult to eat. If panda bears could find a way to survive on bamboo, they would have an unlimited source of food at their disposal - so that’s exactly what they did.
When pandas eat bamboo, they forage for the freshest shoots with higher protein levels. Researchers wanted to know how much of this protein the bears actually absorbed, so they analyzed panda bear manure to get the answer. They found that the ratio of protein to carbs and fat was similar in the bamboo the bear consumed and the feces they produced after eating it. This suggests that a panda’s body has adapted to absorb as much protein as possible from any given source.
How Much Bamboo Do Pandas Eat?
Panda bears eat between 12 - 38 kg of bamboo daily because the lack of nutrition means they require more significant quantities to function. The reason for this vast quantity is twofold. Firstly, bamboo is difficult to eat, meaning it takes energy to eat it, limiting the number of calories that the bear receives. Secondly, the carnivorous digestive system of the panda struggles to digest plant matter efficiently.
One study conducted by nutritional ecologist David Raubenheimer tracked two giant pandas via GPS to learn more about the diet of this iconic black and white bear. Their discoveries showed that pandas would follow the highest source of protein. A cycle would begin between August and April when the bears would forage in the low-lying areas of the Qinling mountains, where they could feed on young shoots.
However, as the shoots matured and grew, the protein diluted to higher fiber concentrations. When this happened, the pandas moved to higher ground where they could source fresh shoots. And when those shoots matured - they moved higher once more.
Are Pandas Herbivores or Carnivores?
Pandas spend almost their entire waking lives eating bamboo, so it would be easy to assume they’re herbivores. But studies reveal that their makeup is far more similar to carnivorous species than those who survive on a plant-based diet.
Around half of all the calories a panda consumes come from protein. This is similar to feral cats, wolves, and various other creatures that depend on meat for survival. In contrast, herbivores generally obtain less than 25% of their calories from protein. Classifying an animal as an herbivore or a carnivore is more complex than you might think. Just because an animal consumes plant-based foods does not mean it is a herbivore; it all depends on which part of the plant a creature consumes and where they obtain most of their calories.
Why Don’t Pandas Eat Meat?
Several million years ago, the ancestors of the giant panda had omnivorous diets that included plants and animals. Back then, their gut and the digestive system could metabolize both sources, and the umami taste receptors in the mouth allowed them to enjoy the savory flavors of the meat.
But roughly two million years ago, the panda began to adapt its makeup for a new diet. Their teeth and jaws evolved the strength to crush bamboo, while the wrist developed into a kind of pseudo-thumb to help them hold on to the stalks of the bamboo. At the same time, their umami taste receptors became inactive, meaning they would no longer appreciate the flavors that meat offers.
Occasionally a panda bear will eat a direct protein source such as fish, small rodents, or eggs, but these foods account for less than 1% of their dietary intake (the other 99% comes from bamboo). Even in captivity, where pandas have access to multiple food sources, they will still choose bamboo 75% of the time.
Opting for a bamboo diet allowed the panda bear to live a peaceful life with a plentiful food source. But as human activity causes increased habitat loss, these endangered creatures struggle to find enough food for survival. Still, these beautiful creatures are an ambassador for conservation work, and thanks to ongoing worldwide efforts their numbers have increased by 17% in the last decade.