Figure 1. Porcupine, Erethizon dorsatum

Identification

Porcupines (Erethizon dorsatum), sometimes called “porkies” or “quill pigs,” (Fig. 1) are heavy-bodied, short-legged, slow, and awkward rodents, with a waddling gait. Adults are typically 25 to 30 inches (64 to 76 cm) long and weigh 10 to 30 pounds (4.5 to 13.5 kg). They rely on their sharp, barbed quills (up to 30,000 per individual) for defense.

General Biology, Reproduction, and Behavior

Porcupines breed in autumn, and after a 7-month gestation period usually produce 1 offspring in spring. Although the young are capable of eating vegetation within a week after birth, they generally stay with the female through the summer. Juvenile survival rates are high.

Predators of porcupines include coyotes, bobcats, mountain lions, black bears, fishers, martens, great-horned owls, and others. Coyote scats (feces) containing large numbers of quills are not unusual. How the quills are maneuvered through the coyote’s gastrointestinal tract is a mystery.

Porcupines are active year-round and are primarily nocturnal, often resting in trees during the day. They favor caves, rock slides, and thick timber downfalls for shelter.

Range and Habitat

Figure 2. Range of the porcupine in North America.

The porcupine is a common resident of the coniferous forests of western and northern North America (Fig. 2). It wanders widely and is found from cottonwood stands along prairie river bottoms and deserts to alpine tundra.

Food Habits

Porcupines eat herbaceous plants, inner tree bark, twigs, and leaves, with an apparent preference for ponderosa pine, aspen, willow, and cottonwood. Trees with thin, smooth bark are preferred over those with thick, rough bark. Porcupine feeding is frequently evident and has considerable impact on the cottonwood stands of western river bottoms.

Sanford D. Schemnitz, Professor of Wildlife Science, New Mexico State University, Las Cruces, New Mexico 88003