The porcupine’s only real predator is the fisher. It takes a tough critter to eat a porcupine. Even coyotes, one of the state's apex predators, instinctually knows to leave porcupines alone – a trait that is sadly not shared by their domestic cousin, who rack up vet bills to have quills removed from their snouts.
Those quills really are something else. Porcupines actually have rather soft fur that is mixed with up to 30,000 quills that will lay flat on their back until they feel threatened. Then, just like when we get goose-bumps, the quills stand up. They don’t shoot off the body but they detach very easily when touched, and they have little barbs at the end that make them really hard to get out.
Porcupines pretty much do whatever they want. With so few predators they mostly just go about their business. Porcupines are active throughout the year, hanging out in trees eating bark, leaves, and fruit. You might find a tree that has been claimed by a family of porcupines. Generation after generation, porcupines will return to the same place, eating from the same "station tree", setting back its growth winter after winter.