North American Porcupine
Erethizon dorsatum

These slow-moving rodents are found in Minnesota’s forest lands. They protect themselves from predators with an unusual defense: 30,000 long, sharp quills-actually modified hairs over a sheet of muscle-that can be lodged in and even kill an attacker.

What They Eat
In summer, porcupines eat leaves, nuts, and berries. During other seasons they favor the bark, buds, and needles of trees.

Where They Live
Porcupines are found in all of Minnesota’s forests and even in wooded farming areas. There may be several porcupines in a square mile of forest.

What They Do
Porcupines have such an effective defense that they don’t need to move quickly. They tend to stay close to home, which is often high in a tree.

How They’re Doing
Porcupines are doing well in Minnesota, and are considered stable throughout their entire North American range.

North American Porcupine

A young porcupine is armed and dangerous within minutes after birth. Its quills harden quickly and the youngster is soon capable of lashing out with its painful little tail.

American Indians may use the porcupine as a source of food and adornment. The hollow quills are woven into baskets and headdresses, and cut sections are used like beads to decorate birch bark boxes, moccasins, and clothing.

Quills are equipped with barbed tips, and can only move in one direction (forward) once embedded.

Besides a means of defense, quills help porcupines in another way. Each is filled with a spongy, pith-like substance that provides buoyancy for porcupines when they swim.

Porcupines often get stuck by their own quills. Most of the time they are able to remove these quills with their teeth and front paws. An antibiotic is present in the quill, which prevents infections from occurring.

A Unique Defense

Porcupine quills (actually modified hairs) grow dorsally from in front of the eyes to the tip of the tail, and are longest at the shoulders. A muscular sheath controls the quill area, so they can be erected when the animal is alarmed. When relaxed, porcupines quills lie flat and point backwards. When attacked, porcupines try to protect themselves by rolling into a ball and arching their back toward their enemy. They may also lash their tails quickly from side to side. Contrary to popular belief, porcupines do not “shoot” their quills. The quills are loosely attached to the skin and become easily embedded on contact. The tips have overlapping scales that swell up when embedded in flesh, making them hard to remove.

North American Porcupine

Nature’s pincushions, porcupines are stocky, short-legged rodents with small ears and eyes, and an enlarged nasal cavity. In addition to their stiff quills, porcupines also have a soft undercoat and a thick layer of body fat for warmth.

Range and Habitat: Porcupines range throughout the northern U.S. and Canada, and down to northern Mexico. Occasionally they are seen in deserts or prairies, but most often in deciduous or coniferous forests.

Habits and Adaptations
Porcupines are primarily nocturnal, wandering in search of food at night. They are well adapted to life in trees. Their claws are long and strong, and the rough, knobby soles of their feet provide them with traction on bark. The undersurface of the tail is covered with stiff bristles that brace the animals while climbing. In the winter porcupines make use of ground shelters such as caves, culverts, hollow logs, and brush piles during their sleep periods. They are active during the winter, often digging snow tunnels to and from their dens.

Diet
Porcupines eat tree bark, leaves, needles, summer blossoms, berries, and pond plants. Their quills provide them with buoyancy, and they willingly enter water in search of water lilies. Bones and antlers are also eaten as a source of minerals.

Reproduction
Between October and December males follow a female around, serenading her with grunts and humming. When ready to mate the pair will roll, tumble, and gently cuff one another. After 7 months a single kit is born, eyes open and covered with fur and quills. The quills are soft and pliable at birth, but harden within a few hours. Mothers nurse their young until summer, when they teach them about den sites and food trees. Gradually they start spending more time apart. In October, the females are ready to mate again and the young set out on their own.

Porcupines and Fishers
Fishers are one of the few animals able to successfully kill porcupines. They use their speed to stay out in front of the porcupine, weakening them by biting the face until they can be flipped over. Other predators may occasionally take porcupines, but their risk of injury is greater. When porcupines feed they "girdle" or completely strip the outer bark around the tree trunk. Fishers are very important in controlling their populations. When fishers were trapped excessively for their pelts, porcupine numbers increased and heavy tree loss resulted.