North American Porcupine: Facts, Quills and Habitat

Appearance: what does a porcupine look like?

A North American porcupine has a stocky, rounded body, a small blunt face, short legs and a short, thick tail. Its coat is dark brown to black, often with yellowish or white tips on the long guard hairs and quills, which gives many animals a frosted look. Western porcupines tend to be paler and more yellow than eastern ones.

The quills are the famous feature. They are modified hairs: hollow, stiff spines with a sharp tip covered in tiny backward-pointing barbs. Most are around 7.5 cm (3 in) long, with shorter ones on the head and the longest on the rump. Normally they lie flat under the softer hair. When the animal is alarmed, muscles in the skin raise them into a bristling shield.

The quills cover the back, sides and tail but not the belly, face or feet, which are covered in coarse hair. A white-and-black pattern on the lower back and tail stands out at night, warning predators of what they are facing.

How big is a North American porcupine?

This is the largest of the New World porcupines and the second largest rodent in North America, after the North American beaver.

Males are larger than females. Weights also swing through the year: porcupines are at their heaviest in the fall and steadily lose weight over winter, when their food is poor in protein.

Habitat and range

The North American porcupine has the most northerly range of any porcupine. It lives from Alaska and the Yukon across most of Canada to Labrador and Nova Scotia. In the eastern United States it reaches New England, New York, Pennsylvania and the Appalachians of West Virginia and Maryland. In the west it ranges through the Rocky Mountains, the Pacific Northwest, the Great Basin and the Southwest into northern Mexico.

Coniferous and mixed forests are its classic home, but it is surprisingly adaptable. It also lives in deciduous woods, riverside cottonwoods, sagebrush and desert scrub, mountain slopes and the edges of the tundra. The key needs are trees or shrubs to feed on and safe dens for winter.

Dens are usually in rock crevices, caves, hollow logs or hollow trees. Where no den is available, a porcupine may spend the winter sitting in a thick conifer, such as a hemlock, that gives shelter from wind and snow.

Diet: bark, needles and a love of salt

Porcupines are herbivores, and their menu changes with the seasons. In spring and summer they eat buds, new leaves, twigs, flowers, grasses, clover and water plants. In the fall they add fruit such as apples, plus acorns and beechnuts, and build up fat. In winter they switch to the inner bark of trees and to evergreen needles, especially hemlock, pine and fir.

Winter food is low in nitrogen, the building block of protein, so porcupines slowly lose weight until spring. Their long gut and large cecum, a pouch where bacteria break down plant fiber, help them get the most out of bark and needles.

Porcupines also crave salt (sodium). Plant food is low in sodium, and in spring and summer porcupines seek it out wherever they can, gnawing on road salt, sweaty tool handles, gloves, boots, plywood and the shed antlers of deer and moose. Read more in What do porcupines eat?.

Behavior: a solitary, nocturnal climber

Porcupines are mainly nocturnal. They spend much of the day resting in a tree or den and come out at dusk to feed. They are excellent climbers: long, curved claws and naked, pebbly soles grip bark, and stiff quills under the tail brace the body against the trunk. They often fall, though, and hollow quills help them float, so they are also capable swimmers.

Adults live alone for most of the year and defend feeding areas, but in harsh winters several may share a good rock den. Winter home ranges can be tiny, sometimes just a few hectares around a den, and an individual knows its trees and dens closely. They are not fast, and they do not need to be. Their defense is so effective that a porcupine can afford to waddle slowly in the open.

Porcupines communicate with grunts, moans, whines and shrieks, especially in the mating season. When threatened, they chatter their teeth, raise their quills and release a strong, sour smell from a patch of skin on the lower back. Only if these warnings fail do they turn their back and swing the tail.

How porcupine quills work

Contrary to a very old myth, porcupines cannot shoot their quills. The quills are loosely anchored in the skin, so they come out easily when an attacker touches them or when the porcupine slaps its tail into a face or paw. The barbs then grip the flesh, and normal muscle movement can work a quill deeper over time.

Lost quills are replaced by new ones. The quills also carry fatty substances that slow the growth of some bacteria, which may help a porcupine that falls from a tree and spears itself. For the full story, see Can porcupines shoot their quills?.

Reproduction and life cycle

Porcupines mate in the fall, mainly in October and November. Females are receptive for only 8–12 hours a year, and they advertise it in advance with scent and calls. Males compete fiercely, then court the female with an unusual ritual that includes spraying her with urine. Mating takes place on the ground, with the female holding her tail and quills flat.

Pregnancy is very long for a rodent, about 205–217 days (around seven months). In spring the female gives birth to a single young, called a porcupette. It is born with its eyes open and soft quills that harden within about an hour. Within days it can climb.

The young porcupette hides on the ground by day while its mother rests in a tree, and they meet at night to nurse. It is weaned at around four months and becomes independent in the fall. Females usually breed for the first time at about two years old.

How long do porcupines live?

Porcupines live long lives for rodents. Many die within their first few years, but adults commonly reach 5–7 years, and wild porcupines have been recorded at about 18 years. Wear on the cheek teeth may limit how long they live, since old animals feed less efficiently.

Predators and threats

The best-known predator is the fisher, a cat-sized member of the weasel family that attacks the porcupine’s unprotected face. Cougars, bobcats, coyotes, wolves, wolverines, black bears, golden eagles and great horned owls also kill porcupines, though many attacks end with the predator full of quills. See What eats porcupines? for how each predator copes.

Other causes of death include starvation in late winter, falls from trees and collisions with vehicles. Porcupines are often hit on roads, partly because they are slow and partly because road salt draws them to the roadside.

Conservation status

The IUCN Red List classifies the North American porcupine as Least Concern. It is common across most of its range in Canada and the western and northeastern United States. It is scarcer at the southern edges, however, and the small, scattered populations in northern Mexico are considered at risk there.

In the past, some states paid bounties on porcupines because they damage trees by stripping bark. Fishers were also released in several US states and Canadian provinces in the 20th century, partly to bring porcupine numbers back into balance with the forest.

Myths and facts

• Myth: porcupines throw their quills. They cannot. The quills detach on contact.
• Myth: porcupines hang upside down by their tails. The North American porcupine’s tail is not prehensile. Some tropical American porcupines can grip branches with their tails, but this species uses its claws and braces with its tail instead.
• Myth: porcupines are related to hedgehogs. They are not. Porcupines are rodents; hedgehogs belong to a different order of insect-eating mammals and evolved spines independently.
• Fact: New World and Old World porcupines are separate families. The North American porcupine belongs to a family of tree-climbing porcupines from the Americas, while the crested porcupines of Africa, Asia and Europe are ground-living relatives.

Porcupines and people

Indigenous peoples of North America have long used dyed porcupine quills to decorate clothing, bags and baskets, a craft called quillwork that is still practiced today. Hikers and forest workers know the porcupine for its habit of chewing salty boots, saddles and tool handles left outside overnight. Given space, a porcupine is a calm and harmless neighbor that simply wants to be left alone.