Montana Field Guide

Porcupine - Erethizon dorsatum

Common porcupine adults in the Northwest average 30 inches long and 20 pounds in weight. Round, short-legged, and slow in movement, they are protected by a coat of quills that covers all but their underside and the insides of their legs. Up to 30,000 of these modified hairs, yellowish white and black- or brown-tipped, mix with coarse guard hairs, and lay over thick, brownish underfur. The hollow quill shafts may be up to 5 inches in length and the guard hairs twice as long. They concentrate on the rump and short tail. The porcupine sheds this coat yearly. Long, heavy claws enable the porcupine to climb and curl up in trees. Its excellent hearing and sense of smell make up for poor vision (Foresman 2001). At night the porcupine's bright eyes appear red. Its grunts and high-pitched cries can be heard from a distance of (Burt & Grossenheider 1964). Newborns are born with teeth, eyes open, and soft quills that harden within an hour. They can climb the same day.

Montana Range

Non-migratory. However, in mountainous areas seasonal alti- tudinal migration may occur.

Common in montane forests of Western Montana, also occurs in brushy badlands, sagebrush semi-desert and alon streams and rivers (Hoffmann and Pattie 1968). Rockfall caves, ledge caves, hollow trees, or brushpiles for dens (Dodge 1982).

In winter uses cambium, phloem, & foliage of woody shrubs & trees--Ponderosa Pine, Lodgepole Pine, perhaps spruce & fir. In spring & summer uses reprod. parts & foliage of aspen, forbs, grasses, sedges & succulent wetland vegetation (Dodge 1982)

Has a tendency to return to familiar areas/trees. Predators include man, fisher, marten, mink, wolverine, mountain lion, lynx, and bobcat. Solitary most of year, but may den com- munally in winter.

May be polyestrous. Parturition occurs in late April or early May, some births as late as August. Pups can eat solid food within a week, but generally remain with female throughout the summer (Dodge 1982).