Pandas get their food by browsing in bamboo forests, because 90 to 99 percent of their diet consists of bamboo. To get the nutrition they need from various types of bamboo, pandas travel from higher altitudes in summer to valleys in autumn and winter.
Because bamboo does not contain much protein or energy, pandas must consume large amounts to survive. They typically spend from 12 to 16 hours a day consuming about 20 to 80 pounds of bamboo, depending upon the panda's size. Their paws have five fingers and elongated wrist bones that function as thumbs, allowing them to grasp bamboo stalks. They wad up the leaves and chew them after pulling them off the stalks. To get to the inner tissue of the stalks, they peel off the outer layers. Their round faces are due to the strong jaw muscles and large molars they need to crush and chew the tough bamboo. Although pandas can live almost solely off bamboo, they also consume rodents, birds, carrion, insects and fruit when these food items are available.
Pandas cannot digest the cellulose in bamboo, so much of the plant passes through their short, straight digestive systems. As a result, pandas defecate 40 or 50 times a day. Their slow movements and sedentary lifestyles are due to the low metabolic rate brought on by their bamboo diet.