Marks made by the long claws usually show. The heel pads have a pebbly texture. This acts as a non-slip surface and helps them climb trees. Sometimes, a tail drag mark is visible in the trail. Porcupine scat is in pellet form, and often found in piles at the base of a tree where the animal has been feeding.
Fishers are predators that can eat porcupines.
They flip the porcupine over to get at the soft underside, which lacks quills. E-mail me and tell me about it.