About Porcupines

The North American porcupine is the second largest of all rodents. Porcupines have small heads and chunky bodies and grow up to 25 to 40 inches long from head to tail.  The tail can grow as long as 8 inches. The male and female are approximately the same size and can weigh between 10 and 40 pounds. The front of a porcupine’s body is covered with long, yellowish guard hairs, while the back and tail are covered with up to 30,000 quills which are interspersed among dark, coarse guard hairs. The quills are the most recognized and misunderstood porcupine feature.

Porcupines are slow-moving, near-sighted animals that would be ill equipped to avoid being killed by predators if they did not have this unique natural defensive system. They are usually benign creatures but like any other animal, they must be able to defend themselves from predators. When a porcupine feels threatened, he turns his backside to the enemy and tries to drive his tail against the assailant. Porcupines may also produce a noxious odor and chatter or clack their teeth as a warning sign. Contrary to popular belief, porcupines do not throw their quills. Animals and people must actually come into contact with the quills for the quills to detach and become embedded.

Porcupines are primarily nocturnal animals who rest during the day in hollow trees and logs, underground burrows or in crevices found in rocky areas. They are most commonly found in coniferous or evergreen forests but have also been found in deciduous woodlands and among Creosote in North American deserts.

Porcupines are strict herbivores and virtually all species of trees found within a porcupine’s range are eaten.  During warm months, porcupines eat leaves, buds, nuts, fruit, twigs and green plants.  During the winter, they chew through the outer tree bark to eat the tissue-like inner bark.  Porcupines have been known to strip or “girdle” tree bark from both the trunk and upper limbs with their two front teeth, which can sometimes kill the tree. A porcupine’s two large, front teeth will continue to grow throughout her entire life.

Breeding occurs in the fall or early winter and is followed by a 210 day gestation period (the longest rodent gestation period). In the spring, the female gives birth to one or two young. They are born with soft quills that harden within hours of birth and their eyes open approximately 10 days later. After two weeks, they start to eat solid food but they continue to nurse for 4 to 5 months. The average life expectancy of a wild porcupine is 5 to 6 years, while their captive counterparts have been known to live up to 10 years.


Porcupines have a benevolent disposition and, unless provoked to defend themselves, they cause no real harm. The primary conflict with porcupines occurs when a person or pet ignores the warning signals and ends up with quills lodged in their skin. Each porcupine quill has a greasy coating and at the tip is a small, backward projecting barb that serves to work the quills ever deeper into the flesh. Once imbedded, quills cannot easily be pulled out.

Serious injuries can result when humans or animals come in contact with a porcupine if the eyes, mouth or throat are afflicted. If a human or pet has been “quilled”, it is important to seek immediate medical or veterinary treatment to ensure that the quills are removed completely and correctly.

Due to a diet low in sodium, porcupines may try to satisfy their dietary need for salt by chewing on wooden structures, tools, and other materials used in outdoor work or recreation. They are attracted to almost any object that has been handled by humans because of the salt found in human sweat.  Porcupines are also attracted to the glue used to bond plywood on wooden structures.  Car tires and hoses may also be chewed on for their mineral content or road salt coating.

Solutions to conflicts with porcupines include tolerance, fencing and repellents.  Attaching a motion sensor to a sprinkler will encourage porcupines to move on as well.  Click here to go to our links and resources page to find vendors that sell these attachments and repellants.

If you need to protect trees from being chewed, you can place a metal band around the trunk of the tree, about 3 feet off of the ground. This will keep the tree from being climbed and the bark stripped. This band should not be left on the tree longer than necessary because insects may accumulate and lay eggs under it. If you are protecting a fruit-bearing tree during the winter, it is important that the band is placed 3 feet above the expected maximum level of snow. To protect plastic tubing and hoses, you can use a capsaicin-based “hot sauce” repellent that is registered for use against porcupines.


Porcupines do not carry any communicable diseases that are of concern to humans, except, as with any mammal, they can contract rabies. The main safety issue is the possibility of being quilled.  A veterinarian should treat pets that have had a run-in with a porcupine.  Humans who have embedded quills should consult a physician immediately.


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