This slow-moving rodent would rather be left alone than deploy its spiny quills.
Window On Nature
By Lowell & Kaye Christie, F47246
During the winter, when deciduous trees have lost their leaves, the bare branches provide views of things that are hidden during much of the year. Until the green of spring returns to provide shelter for the plants and animals living high in the trees, look closely at dense patches that don’t match the open structure of the bare twigs. Sometimes you’ll find a green growth of mistletoe, living as a parasite in the tree. Other times it will be a hawk’s nest, constructed in the fork of two branches. And sometimes it will be a sleeping porcupine.
Porcupines are the second-largest rodent in North America, somewhat smaller than a beaver. They can weigh from 12 to 30 pounds and may reach up to 35 inches in length. But while a beaver is known for chopping down trees, the porcupine is more likely to climb one in search of shelter and food. Most of their activity takes place at night, and except in the coldest weather they are likely to be found high in trees during the day.
Porcupines live in most regions of Canada and the western United States down to Mexico, as well as Wisconsin, Michigan, Pennsylvania, New York, and New England. Although they prefer forested areas, they survive even in deserts, where they can be found foraging among the creosote bushes.
The amount of time porcupines spend on the ground seems to be directly related to the amount and quality of ground cover available, as they are herbivores. Shrubs give them both food and protection from predators. But since most of the animals that would like to make a meal of the porcupine don’t climb trees, naptime usually takes place far above the ground. During the winter in snow country, a porcupine is likely to spend most of its time up a tree, since the tree’s inner bark is used as a dietary supplement when nothing else is available.
Porcupines are well-designed for climbing trees, with long claws and a pebbly surface on the pads of their feet. This texture increases the surface area and friction when the foot makes contact with a tree trunk or branch. Even the animal’s sharp quills come into play, helping to prevent it from sliding backward. The quills on its tail can be stabbed into the tree, helping with stability.
On the ground, a porcupine moves about with a slow, lumbering gait. With most of its body protected by quills, it doesn’t have to travel fast. Quills cover the animal except on the face, legs, underbelly, and underside of the tail. The lower surface of the tail has bristle-like hairs that help in climbing. Quills are actually modified hairs, and are interspersed with the animal’s soft, insulating body hair.
Although its eyesight is quite poor, the porcupine’s other senses are highly developed, and it is always alert to nearby dangers. When it feels threatened, its quills, which normally lie flat, are raised, and the critter faces away from any potential attacker so that its quill-covered tail can come into play.
A porcupine can’t actually throw quills, as some popular myths proclaim, but they are easily dislodged from the porcupine’s body and tail. If another animal is hit by the tail or tries to grab the porcupine’s body, the sharp quills penetrate the attacker. The quills have barbed tips, and once they become lodged in a predator, its body heat makes the barbs expand so they become very difficult to remove. An individual porcupine may have as many as 30,000 quills, and those lost will regrow.
In northern parts of North America, where their ranges overlap, the fisher (a member of the weasel family) is one of the porcupine’s main predators. Instead of directly attacking a porcupine, a fisher will circle it, snapping at its unprotected face. If it can wear the animal down, it eventually will flip the porcupine on its back and attack its unprotected belly. Of course, the porcupine doesn’t always lose this battle for survival, but in some areas fishers have been reintroduced to help control the porcupine population.
Porcupines are relatively long-lived mammals, perhaps in part because of their sharp and prickly defense system. Their average life in the wild is approximately 6 years, but the record is close to three times that span. A female can begin to reproduce at about 2 years of age and will typically have a single offspring. The young are born with soft quills that harden within an hour. Young porcupines become independent after about five months.
Because of their vegetarian diet, porcupines have a craving for salt that sometimes puts them in conflict with humans. They’ve been known to come into campsites at night to gnaw on canoe paddles, axes, and anything else that has picked up salty sweat from human use. They also will chew on structures built of plywood because of the glue used to make the material. They have been known to gnaw on car tires and electrical wiring if the vehicle has been driven on roads deiced with salt. Because salt that’s collected along roadsides may attract them, more porcupines are probably killed by cars and trucks in winter than by their natural predators.
Since porcupines limit their diet to vegetation and tree bark, their quills are used only for defense or during mating disputes between males. A lost quill may take several months to grow back, so porcupines avoid using them as a weapon unless they feel threatened. They even use their quills to give a warning to other porcupines of potential danger.
When a porcupine senses trouble, it tightens the skin on its back, raising the tips of the quills away from its body. Then it rustles the quills to create a rattling sound, much in the same way a rattlesnake warns others by shaking its tail.
Porcupines are fascinating creatures. Once you find one, it is easy to observe, because of its slow movements. Just remember that your approach to a porcupine should be the same as with a rattler “” look, but don’t touch.