Although they are considered to be carnivores, giant pandas mainly eat bamboo plants. They also sometimes eat rodents, green corn, honey, grasses, flowers and vines.
The digestive systems of giant pandas are not equipped to easily break down bamboo. Consequently, it is difficult for the pandas to get a sufficient amount of protein and energy from the plant; to compensate, they eat tremendous amounts. Giant pandas are capable of eating up to 84 pounds of bamboo in one day. This massive quantity causes giant pandas to evacuate their bowels as many as 40 times in one day.
Giant panda cubs nurse until they are approximately 18 months old. They begin eating bamboo between the ages of 7 and 9 months. The diet of giant pandas is responsible for the evolution of their round heads, as they adapted powerful jaws and large molars for crushing bamboo. Their low metabolisms and stationary way of living allow them to survive on food with minimal nutrients, which is why they are so large.
Giant pandas must live in areas with at least two species of bamboo plants to ensure that they have plenty to eat when one species reaches the death and regeneration phases of its life cycle. In a zoo setting, giant pandas eat bamboo with dietary supplements when necessary.