Known for their quills the porcupine’s body is covered with about 30,000 of them. Each quill has at its tip about 700 to 800 overlapping scales or barbs that enable the quill to readily penetrate the body of its victim. Porcupines cannot shoot their quills, but they do detach readily when touched. Quills are replaced continuously, taking just several months to grow one back. Latin name, Erethizon dorsatum, means quill pig.
Quills are specialized hairs and on the North American porcupine they vary from one to five inches. There are 29 species worldwide and some of the others have quills that can be up to 20 inches long. Quills contain tiny air pockets that help them float when swimming. Quills are hollow, fine and sharp, and largely concealed by fur until provoked at which time porcupines will arch their backs, erect their quills and raise their tails. Quills are not found on the legs, nose or belly. Tails are heavily covered with quills and undersides have bristle-like hairs. The bristles on their tails, pebbly pads and long toes on front and rear feet make them capable climbers.
Display of quills is a visual warning to predators, but they also produce a chemical scent that could be associated with a previous painful experience. When threatened it may also slap its tail against the ground and chatter and clack its teeth. They are capable of making a wide variety of sounds from whimpers to whistles to screams.
Fishers, a type of weasel, are the main predators. Fishers will bite the nose of the porcupine and flip it over to attack the quill-free belly. Humans are another predator, they were historically hunted for their quills, but today are often killed by cars as they seek out salt along the roadside. Porcupines are herbivores. In the winter they feed mostly on conifers with a preference for the bark of hemlock trees and the inner bark of white pines. They eat more herbaceous, non-woody, plants in the summer. Appearing to be selective eaters they prefer the buds of sugar maple trees and the acorns of white oak trees. You can see evidence of the twigs they have nipped with the 45o angle of the cut, typical of animals in the rodent family. They are the second largest North American rodent, the largest being the beaver.
After a meal in a tree porcupines have been seen resting on a horizontal branch, belly down, with all four legs dangling below. Porcupines will also venture out to the ends of branches to obtain buds. Quite often this attempt will result in them falling out of trees causing them to be stabbed by their own quills. Lucky for them the quills contain a fatty acid that acts as an antibiotic.
Because vegetable matter is low in sodium, salt, porcupines need to find sources of salt to balance potassium levels. They find this, as I mentioned, in road salt, but also in human perspiration on wooden tools and canoe paddles, glue that binds plywood and some paint. So when venturing out to a shed in the springtime you might be surprised to find these items chewed!
Porcupines have a gestation period of 217 days which is remarkably long for a rodent. It is twice the length of a beaver. The mother gives birth to one baby and it is a miniature of her, except the quills are not hardened. They harden within about an hour. The baby, called a porcupette, starts to climb trees at two days. It will nurse for 3 1/2 months, but starts to nibble green food in about a week. Quickly becoming independent and generally living a solitary life. Dens are found amongst ledges with crevices or any hole that they can find that is easily accessible to food. They aren’t the most sanitary of all critter piling scat outside their dens, believed to serve as a source of insulation and to deter other animals from taking over their dens. Porcupines have very short legs and fat bodies. They waddle around in a very small home range, mainly at night and are active throughout the year. Their lifespan is about 18 years in the wild.
Found in forested and mountainous areas in most of North America, including Alaska and Canada, from Mexico north but also Wisconsin, Michigan, Pennsylvania, New York and New England, not in the southeast.
The nearly lost art of Native American quillworking is perhaps the oldest form of Native American embroidery. Dyed porcupine quills were used to decorated war shirts, buffalo robes and dresses. Dolls, medicine bags, knife sheaths, moccasin, jewelry, baskets and birch bark boxes also featured this type of embellishment. Used particularly among the East Coast and Plains tribes quillworking flourished among the Native Americans in New England from the 1600’s to the mid-1800’s when easily attainable glass beads replaced quills. Native Alaskans today will use blocks of styrofoam to collect porcupine quills.
Quills are being studied by biomedical researchers to determine how they can enhance or design new biomedical devices. Quill inspired staples could be used to replace staples currently being used to hold some surgical incisions shut or develop needles. According to a Science magazine article – to pierce your skin a porcupine quill needs only about half the force of a hypodermic needle! As one researcher stated – “Just one more example of how what we see in nature can help us”.
Resources
Tracking and the Art of Seeing by Paul Rezendes
https://www.adfg.alaska.gov/index.cfm?adfg=northamericanporcupine.main
https://www.sciencemag.org/news/2012/12/porcupine-quills-reveal-their-prickly-secrets