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Groundhog/Eastern Marmot/land-beaver
Marmota monax

Scientific classification:

    Erethizon dorsatum
    Class: Mammalia
    Order: Rodentia
    Family: Erethizontidae
    F. Cuvier, 1823

Porcupines are slow moving, medium size mammals with white-banded quills. The North American Porcupine is the largest porcupine, yet smaller than a bever. Adults are 24 to 40 inches (2-3ft) long. The tail is five to twelve inches. They weigh between 8 and 40 pounds, with average under 20. They have a rounded stocky body with a small head, ears, eyes (nearsighted) and darker face. They have large front teeth. The legs are short and strong. The tail is short and thick.

Like all other rodents, the North American Porcupines have four toes on their front feet and five on the hind feet. Each toe has a strong curved claw. The hind foot is 3 to 3 1/2 inches long. The soles on the feet are hairless.

Adults are dark gray to black and various shades of dark brown to brownish-yellow fur. Older porcupines appear gray or white. Porcupines have soft fur, with a wooly underfur, and stiff guard hairs. The porcupine may have as many as 39,000 quills, on all parts of its body, except for its stomach. The single quills are interspersed with bristles, underfur and hair. The longest quills are on the rump and tail. The shortest quills are on the cheeks. The quills are modified hairs coated with thick plates of keratin and barbed tips on the ends. Quills are solid at the tip and base and hollow for most of the shaft. Quills are released by contact with them, or they may drop out when the porcupine shakes its body. New quills grow to replace lost ones.

Porcupines range from Alaska to Northern Mexico. Porcupines are found throughout the upper two-thirds of Minnesota. There may be several porcupines in a square mile of forest habitat. The porcupines found in Minnesota are good climbers. They generaly live in coniferous hardwood, deciduous and mixed forests. Porcupines fall out of trees fairly often because they are highly tempted by the tender buds and twigs at the ends of the branches. So the porcupine has antibiotics in its skin. This helps prevents infection when a porcupine falls out of a tree and is stuck with its own quills upon hitting the ground.

The word porcupine comes from the middle or old French word porcespin which means spiny pig. Its roots derive from the Latin words "porcus" or pig and "spina" meaning thorns. Other colloquial names for the animal include quill pig. It is also referred to as the North American Porcupine, Canadian porcupine or common porcupine. The porcupine's genus species name, Erethizon dorsatum can be loosely translated as "the animal with the irritating back." There are several native American names such as the Lakota name "pahin" meaning quill.

They are a solitary animal, although it may den with other porcupines in the winter. It makes its den in caves, rock outcroppings, decaying logs and hollow trees. They do not hibernate, but may stay in its den during bad weather. The porcupine is a good swimmer, its hollow quills help keep it afloat. It has a wide variety of calls including moans, grunts, coughs, wails, whines, shrieks and tooth clicking.


Porcupines are often found in trees eating the inner and outer bark, tender buds & twigs, leaves, and the needles of trees. Sometimes, porcupines strip bark to the extent that the trees die. If the animal girdles a tree chews all the way around the trunk, interrupting the flow of water and nutrients the tree may end up deformed or dead. They also eat crops such as alfalfa, nuts, herbs, berries, roots, stems, flowers, and green plants like cabbage and clover. Salty items are consumed with relish, including axe handles, canoe paddles, outhouses, and even automobile radiator hoses. Porcupines are also known to gnaw on bones and antlers from the ground due to their high mineral content. It is mostly nocturnal, but will sometimes forage for food in the day.

Predators & Lifespan

The porcupine uses its quills for defense. When a predator approaches, the porcupine will turn its back, raise the quills and lash out at the threat with its tail. If the porcupine hits an animal with its quills, the quills become embedded in the animal. Body heat makes the barbs expand and they become even more deeply embedded in the animal's skin. Each of the modified hairs is tipped with microscopic barbs that cause the quill to be continually driven into the muscle of predators.

Predators of the porcupine will attempt to stun or cause massive blood loss with an attack to the face and then will spin them over to their unprotected underside. Predators include the fisher, bobcat, wolf, coyote, wolverines, bears, and cougars. To avoid predators, porcupines often climb trees at the first sign of danger. Dispite their very slow movements they are often hit by vehicles while crossing roads. The average lifespan is five to eight years.

Porcupines are edible and were an important source of food, especially in winter, to the Natives of Canada's boreal forests. In some parts of the world they are considered a delicacy. The guardhairs & quills are used by Native Americans. The main quills may be dyed, and then applied or sewn to decorate clothing, knife sheaths, headdress, baskets and leather bags.


Males seek receptive females beginning in late summer to Late fall. Mature females (15-18 months) may announce their readiness to breed by "screaming" from a tree top. Males often fight over females. A very interesting and detailed courtship takes place involving extreme vocalization, a very elaborate and somewhat comical dance, and then after the dance the male showers the female with urine. When porcupines are mating, they tighten their skin and hold their quills flat, so as not to injure each other.

Seven months after mating, spring to early summer, the female gives birth, usually to a single offspring. The newly born porcupine has a complete set of soft quills, a full set of teeth and the eyes are open. The quills harden soon after birth. Once the quills are dry, the young porcupine can defend itself from some predators. Porcupine young are able to climb soon after they are born; their feet have long curved claws. The female will nurse the new-born porcupine. After a few days the young porcupine begins to forage for food. The young will continue to nurse for another four months and stay with the female for about six months.

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