Why Do Pandas Eat Bamboo?

It’s often raised as a criticism against our cuddly friend – “Why would a huge bear end up relying so heavily on bamboo as its main food source?” And they’re not kidding either, the giant panda gets over 99% of its food in the wild from the bamboo plant, only occasionally diverting to eat small rodents, fish or eggs when the opportunity presents itself.

Even in captivity where the pandas have access to other foods such as rice, apples or other vegetables they still choose to consume bamboo for up to 75% of their diet.

Part of the giant panda’s charm is undoubtedly its uniqueness in the animal kingdom and a part of that unique character is its complete dependency on one of the densest and most demanding foods imaginable – bamboo.

First of it’s important to put into context just how much bamboo pandas actually consume. You might think you really enjoy your food, but trust us when we say, everyone’s appetite looks tame compared to the pandas love of bamboo.

I’m sorry, how much?

In the wild pandas will consume between 10 and 15 KILOS of bamboo A DAY. Within a fortnight the average panda will have eaten well over it’s own bodyweight in bamboo.

Pandas have to munch this obscene quantity for two reasons:

1. Bamboo isn’t all that nutritious. Although the leaves are much easier to eat, the tough and chewy stalk is a lot of hard work for not all that many calories.
2. Giant pandas have a carnivore’s digestive system with only a simple stomach and short small intestine, unlike some herbivores that rock multi-chambered stomachs (Cows, our black and white brethren, we’re looking at you). This means that pandas do not digest dense plant matter very efficiently.

But why would they do that?

I hear you screaming already – this just doesn’t make any sense, why are pandas eating this stuff if there’s so little gain for them? The simple answer is that bamboo is everywhere in their natural habitats, it is an incredibly plentiful food resource that regrows quickly and that few other animals use.

Some scientists have theorised after looking at pandas DNA that the adaptation occurred approximately 4 millions years ago. At a time when many of the earth’s animals were going extinct, it’s suggested that the panda’s ancestors began to rely on bamboo as one of the few remaining food sources. Even as the animal population rebounded, the panda’s ancestors kept to their new niche diet and the rest is history!

I’d get so bored, how do they keep it up?

The giant panda has adapted in many weird and wonderful ways to it’s diet and all of these changes are things that distinguish this animal as a truly unique specimen.

Firstly pandas have extremely strong jaws, thanks to a denser skull than other bears that supports bigger muscles surrounding the mouth. Panda’s teeth are large and flat, ideal for grinding up and breaking down dense bamboo. This jaw and teeth combo means food can be broken down mechanically before digestion, alleviating the stress placed on the panda’s carnivorous digestive tract.

Secondly pandas have a unique elongated wrist bone that acts as a sort of thumb, allowing them to grip bamboo stalks with added dexterity. This means it’s easier for the panda to strip a bamboo stalk of its leaves quickly  and efficiently! Pandas will always favour eating the leaves where possible and will only result to the denser, less nutrient rich stalk when necessary.

Finally some scientists have suggested that bamboo might produce a reward response in the giant panda’s brain. Similar to the happy feeling humans experience when we eat sugary and fatty foods, pandas also experience a dopamine bump when they eat bamboo. So there you have it, the best news ever, not only do pandas look adorable when they’re sat munching away, they’re also having the time of their lives.

But it has it’s drawbacks…

Even though eating bamboo as your main food source does make you unique, it comes with it’s fair share of drawbacks.

You may be aware that unlike other bears the giant panda doesn’t hibernate and the main reason is that bamboo simply doesn’t provide them with enough calories to fuel the big sleep.

A bamboo diet also means that pandas are not able to producer as high a quality of milk as other bears and so typically spend much longer rearing their young. Pandas only spend 2 to 3 months pregnant compares to most bears 6 months and panda babies weigh just a third of other bear cubs, in a 90 to 130 grams, compares with 300 to 400 grams for other bear species.

Finally and most crucially, the panda’s reliance on bamboo means there are only very specific places in the wild they can survive and thrive and not only that but each panda needs a large area to feed from. These factors contribute massively to the threat of extinction facing our beloved bear. As human settlements encroach further upon the panda’s natural territory, the amount of land that can sustain pandas (and numerous other animals within a complex ecosystem, is in decline.

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