Their summer diet consists of a variety of shrub and tree leaves. In winter, they feed on the cambium layer and inner bark of trees. Their fondness for salt often leads them to roadways where salt has been sprinkled to melt the ice. Around campsites, they will gnaw on anything containing salt, such as canoe paddles, axe handles, saddles, etc. The young are able to move about quite briskly shortly after birth and, unlike their stolid parents, are quite playful.
Porcupines are also excellent swimmers.