In winter, porcupines take to their dens for protection from snow, wind and predators. Several porkies may use the same den site, together or at different times. An individual generally becomes resident at a den in November and uses it off and on until May. During winter, a porky may spend its days asleep in the den or in the top of a conifer in which it's been feeding. Porcupines do not hibernate.
Porcupines are solitary in summer.
Throughout the year they do most of their feeding and moving about at dusk, during the night, and at dawn. In Pennsylvania, porcupines are preyed upon by fishers, and to a lesser extent, foxes, coyotes, bobcats, dogs and owls. The fisher, reintroduced in Pennsylvania in the mid 1990s, has mastered the technique of flipping a porcupine onto its back, exposing the rodent's unquilled, vulnerable belly, and killing it with a swift bite. Fishers also kill porcupines with repeated bites to the face and head. Also, coyotes have been known to work in pairs to maneuver a porcupine onto its back.