Pricklepigs — September - October 2001

How do you hug a porcupine?
You don't.

By Todd Whitesel

magazine spread.

Like a pincushion in reverse, the porcupine (Erethizon dorsatum) is covered in quills with the sharp ends sticking out. The word porcupine comes from Latin, meaning "quilled pig." Though this stocky creature might resemble a prickly pig, the porcupine is actually a rodent--Minnesota's second-largest rodent after the beaver. An adult porcupine weighs 15 to 20 pounds. Males are larger than females.

Porcupines have a wide range, from Alaska across Canada and down to northern Mexico. Minnesota, Wisconsin, and Michigan all have porcupines. Porcupines are most at home in coniferous forests but live in deciduous and mixed forests too.

Portrait of a Porcupine

The porcupine has small eyes and is nearsighted, so distant objects appear fuzzy. But it has good hearing and a sharp sense of smell.

The porcupine has four large front teeth, called incisors, which grow constantly. Like beavers, the porcupine keeps its teeth trimmed by gnawing on tree bark and other woody material. It chews first on one side of its mouth, then the other, to keep its front teeth even.

The porcupine has long, curved claws with four toes on the front feet and five toes on the back. It walks slowly in a pigeon-toed fashion, dragging its feet. Its tail quills drag and leave a pattern between footprints. Can you imagine a porcupine's tracks?

A great climber, the porcupine is well-adapted for life in tree limbs. The porcupine is strong and can hang from a limb by only one claw.

Of course, the porcupine's mark of distinction is its creamy white quills with black tips. These modified hairs, tipped with tiny barbs, can drive deep into the skin of another animal. As many as 30,000 quills, from 1 to 2-1/2 inches long, cover the porcupine's rump and tail, while shorter quills grow on its face. As its quills fall out, new ones grow in, replacing the lost quills in four to six months.

Piggy Appetite and Sounds

The porcupine is vegetarian. It lives alone and sleeps most of the day. At night it gets up and feeds on leaves, twigs, buds, flowers, berries, and the inner bark of trees. The noisy porcupine grunts, whines, moans, coughs, wails, and chatters as it searches for food. An excellent swimmer, it goes into lakes and ponds to feed on aquatic plants such as water lilies. Its hollow quills help the porcupine stay afloat.

The porcupine seems to love salt and will chew on almost anything for a taste. Something touched by a person's sweaty hands may have enough leftover salt to attract a porcupine. Canoe paddles and old clothes are salty snacks to the porky. To get a lick of salt, the porcupine may visit roads where salt was spread to melt ice during the winter.

Prickles at Home

Porcupines don't build nests, but in winter they might seek shelter in a cave or in a hollow log, stump, or tree. Though they have powerful claws, they prefer to find a natural opening or a den left by another animal. Porcupines seem willing to share space with each other during winter. Small groups, called prickles, sometimes gather and use a common shelter.

Porcupines don't hibernate during the winter but may sleep for several days when temperatures stay below freezing. When weather is good, they feed on evergreen needles and the inner bark of trees. Their short legs make travel through snow difficult, so they usually stay close to home.

Porcupines mate in the fall. The male serenades the female with a series of grunts. When the female is ready to mate, the two stand on their hind feet and grunt and whine together. The courting pair nuzzle each other's nose and place their paws on the other's shoulders in a type of porcupine dance. They flatten their quills when mating.

If more than one male is interested in the same female, they will fight for the chance to mate with her. They use their incisor teeth and quills as weapons. Usually the largest male wins the battle.

Pups are most often born in March and April in Minnesota. The mother normally has one pup each year. The pup, called a porcupette, weighs about a pound. Its soft quills harden almost immediately after being born, and it can climb trees just a few hours later. It stays with its mother for about six months and then gradually wanders off on its own.

Porcupines have lived 10 years in captivity, but they probably live about half this long in the wild.

Porcupine Foes

Armed with quills, the porcupine is generally safe in the forest, even though it is slow-moving and unaggressive. It does have enemies. Its most common foe is the fisher, a member of the weasel family. A fisher will attack the face first, biting at the nose. The fisher can then roll the porcupine over onto its back and get at the porky's soft belly.

Bobcats, coyotes, pine martens, great- horned owls, and bald eagles also attack porcupines. Bobcats and coyotes try to roll porcupines over as fishers do. Owls and other birds of prey attack the porcupine's face, where the quills are shortest.

In the past, people killed porcupines just for their quills. Today, quill gatherers tap a porky on the back with a piece of Styrofoam to dislodge the quills without harming the animal. Then the quills can be used for decoration.

When threatened, a porcupine may first try to escape to a den or up a tree. If this is not possible, it will arch its back, turn away from its attacker, and lash out with its tail. It sometimes stomps its feet as a warning. When alarmed, the porcupine pops up the quills on its rump and tail.

Porcupines don't throw or shoot their quills. The quills easily detach from the body, however, and become embedded in the attacker's muscles. As the attacker moves its muscles, the quill's barbs work it deeper into the body, about an inch per day.

An animal that bites into the quills of a porcupine can die--not because the quills are poisonous, but because the animal cannot eat with quills stuck in its mouth and tongue. It may also die from infection or internal injury.

Todd Whitsel, Superior, Wis., is a free-lance writer whose main interests are northern ecology and outdoor recreation. When not at the keyboard, he travels the back country of northern Minnesota searching for little-known trout waters.

A complete copy of the article can be found in the September - October 2001 issue of Minnesota Conservation Volunteer, available at Minnesota public libraries.