When Theodore Roosevelt proclaimed that the United States should, “Speak softly and carry a big stick,” he might have been describing the porcupine. If ever an animal served as an example of how to live in peace by being perpetually prepared for massive retaliation, it’s the porcupine.

Labeled as a “quill pig” by some Montanans, the porcupine has ranged over numerous and various landscapes for more than a million years. Along with saber-toothed tigers and elephantlike mammoths and mastodons, it has roamed forests and other habitats. While these larger and more aggressive animals have become extinct, the porcupine has survived. The natural selection process has designed the porcupine to make it a formidable presence in any ecosystem in which it resides.

A porcupine’s armor consists of some 30,000 multi-barbed quills strategically located on the head, back, flanks and tail. They are absent only on the nose, foot pads, belly and underside of the tail. The quills are modified hairs which have microscopic overlapping sheaths on the tips that function like barbs filled with a spongy matrix. The upper surface of its tail is heavily covered with quills, which provides a visual warning. The defensive position of the porcupine is with the back to the attacker, and a muscular tail ready to swat. A potent, penetrating chemical scent (R-delta-Deca lactone), described by biologists as the smell of exotic cheese, is released from a patch of skin on the porcupine’s back near the base of its tail (the ‘rosette’). A painful quill penetration associated with the distinctive odor serves as a strong reminder to a predator not to repeat the encounter.

A porcupine’s needle-sharp quills are sometimes five inches long, and crisscross in all directions, while the underside is covered in bristle-like hairs used to aid in climbing trees. Contrary to some beliefs, the quills are not venomous, nor can they be “shot” or thrown from the body. If attacked, the porcupine will lower its head and lash out with its tail. Because of the reverse barbs and the inevitable muscular contractions of the victim, quills are difficult to remove, and tend to work their way deeper into the body where the barbs swell and expand. For those wild animals badly impaled in the facial region, death or blindness is inevitable. Aside from man, only the fisher and mountain lion have much success in attacking the porcupine. Other predators, including the great horned owl, lynx, bobcat and wolverine are sometimes successful, but can pay dearly for their brashness.

When danger encounters the heavily bodied bearer of barbed mini-spears, the head is lowered, legs are braced, and the body pivots, presenting an armored back and tail. If the attacker pursues, it can expect to receive an excruciating impact of quills from a thrashing tail.

The danger from that flashing tail can’t be overemphasized. While attending a wildlife training course at a biological field station one summer, I watched employees with brooms maneuver a large, yellow-haired porcupine into a galvanized garbage can. Realizing it had backed into a dead end, the porcupine erected black-tipped quills and chattered its teeth in mock ferocity. Then it reversed directions and started to waddle out of the can. With brooms blocking its way and pushed against its unprotected muzzle, the animal pivoted, bumping the rim of the can during its exit. Its tail then moved in a blurred arc, striking the broom bottoms with a hard blow, resulting in a “shower” of quills flying in all directions. From this vantage point, it was easy to see how the erroneous belief that porcupines can “shoot” or throw quills started.

As many sportsmen will attest to, hunting dogs sometimes suffer after muzzling a porcupine. Home remedies are many, but few, if any, work. Because of the reverse barbs, the quills offer such stubborn resistance that the most humane action is a quick trip to the nearest veterinarian. If this is not possible, a quick jerk with a pair of pliers works best.

Porcupines are equipped with four red or orange-colored wood-chiseling incisors coated with an iron-rich enamel that continue to grow throughout the porcupine’s life. Constant gnawing on wood fiber with their beaverlike teeth keeps them worn down to perfect size. Porcupines are quite adept in chipping off a tree’s outer bark and feeding on the inner cambium layer between the phloem and xylem.

Because they are strictly vegetarians and most vegetable matter is very low in sodium, porcupines need additional sodium in their blood to balance potassium levels. As a result, they seek out salt sources such as natural salt licks, glue which bonds plywood together, human perspiration on axe handles, car fan belts and rubber hoses, canoe paddles, road salt, and some paints. They also feed on shed antlers and the bones of dead animals to obtain sodium and calcium. Because they tend to be somewhat sodium deficient, they avoid or minimize the intake of acidic foods that require more sodium to metabolize. In Montana, it’s often possible to see small, chewed patches on trees where a porcupine has sampled the cambium layer and moved on to better selections.

Active all year, porcupines are commonly afield at night. During the day, they hide in rock crevices, brush thickets, or hollow logs. In coniferous forests, porcupines prefer a “rest tree” instead of a den. As clumsy as a climbing porcupine may first appear, it is very much at home in trees. With hooked claws, tubercle-studded soles and a stumpy tail which braces the body, it can match any lumberjack in climbing. What the porcupine lacks in speed, it makes up for in tenacity. Porcupines can live up to about 19 years in the wild.               
                      

MATING AND REPRODUCTION   

The porcupine’s mating rituals would have to be rated as classic events. Even though porcupines are essentially loners for most of the year, they always manage to get together during the late fall mating season. Through a combination of high-pitched calls and urine scents, the two sexes finally meet and engage in erotic courtship displays, which include muzzling, squealing and teeth chattering. If more than one male shows interest in the same female, they will fight for the opportunity to mate. Males use their incisor teeth and quills when fighting; usually, the largest and heaviest male wins. The breeding male then splashes the female with urine. If she is not ready to mate, she shakes off the urine and leaves. If she is ready, she stays and the male mounts in the traditional posture with the female in front and the male in the rear. She will curl and arch her tail over her back, covering most of the quills. Sexual maturity for males occurs at 24 months and for females at 12 months.

The female gestation period lasts about 210 days, or seven months, extremely long for a rodent, and females bear a single precocious offspring (called a porcupette) covered with moist, long, grayish-black hairs and quills which quickly dry and harden. In less than an hour, the young porcupine is armed for defense. Porcupettes have erupted incisors at birth, nurse for up to four months and begin eating green vegetation before they are one-month old. When the female mates again, the young are fully weaned and wander off to face the winter alone.

CURRENT PORCUPINE STATUS, AND CONCERNS

Porcupines are declining in numbers in Northwest Montana at high-elevations, and the Montana Department of Fish Wildlife and Parks (DFWP) is considering it as a Species of Special Concern.  Porcupines, once numerous in this western sector of Montana, are experiencing a precipitous decline and now are “virtually exterminated,” says Jessy Coltrane, a wildlife biologist for DPWP. California currently lists the porcupine as a Species of Special Concern. Porcupines are also declining in other western states, but despite ongoing high elevation research studies in Montana and other states, the evidence is largely anecdotal and the reasons for the “quill pigs” decline are speculative.

• Climate change has had a noticeable negative impact on numerous avian and mammalian species in Montana and elsewhere. For the first time in the year 2024, planet earth reached more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) of warming compared to the pre-industrial average. Research data shows the planet would not see such a long sequence of record-breaking temperatures without the constant increase of greenhouse gases in the atmosphere driving global warming. Increased fire frequency and severity, coupled with mountain beetle epidemics, have impacted thousands of acres of habitat and trees in western Montana and other forested portions of the West that porcupines need. Climate change cannot be underestimated as being a major factor in the porcupine’s decline, along with that of other wildlife species. Intensifying drought, wildfire, and devastating storms pose near and long-term dangers for all wildlife, porcupines included.

INDESCRIMINATE MORTALITY - Porcupines have a low reproductive potential which includes a roughly 210-day gestation period (remarkably long for a rodent). They may not reproduce every year and, when they do, a female gives birth to just a single offspring (twins are rare), and they don’t become sexually mature until they are two or three years old. When a female lives out her full life span, she can give birth to 10 -12 offspring. When porcupines are killed by disease, predators, poison, hunters, habitat loss, roadkill, tree nursery owners, or for other unknown reasons, it does not take much to knock down a slow-growing population and prevent it from recovering. Porcupines can be injurious to commercial forests and reforestation projects by feeding on the terminal buds or eating the bark all the way around the trees. When such problems occur, site specific control may be necessary. Porcupines are considered non-game animals and are unprotected in states (including Montana) where they reside.

PREDATORS - As previously mentioned, the fisher ranks as a leading carnivore predator of porcupines. The weasel-shaped, short-legged, low-bodied and fast-moving fisher has learned to specialize on a diet of porcupine. In its attack strategy, the fisher circles around the porcupine, looking for an opening. The porcupine, in a defensive posture, slaps its tail hard against the ground while clacking its teeth. When an opening occurs, the fisher, like a fast-moving boxer, moves in quickly to bite the porcupine’s nose. After repeated bites to the nose and face, the fisher then flips the porcupine over to attack the quill-free belly. The porcupine is then eaten, leaving an empty, quill-covered skin. Sometimes the fisher fails to avoid the flashing tail armed with mini spears and gets a face of quills. Though a fisher is not immune to porcupine quills, they do not seem to have any life-threatening effects. Fishers have low densities in Montana and don’t prey on enough porcupines to cause a serious depredation problem.

EPIDEMICS - A factor in the porcupine population decrease under consideration is the possibility of an unknown rodent disease. More baseline field research by biologists is needed for answers to porcupine declines in Montana and elsewhere. Most likely, a combination of factors is driving down porcupine numbers at higher elevations in western Montana.

PORCUPINE FAST FACTS

• The name “porcupine” originates from the Latin porcospinus (spiny pig) and went through many name variations over the years before its current spelling.

• Porcupines evolved in South America and moved into North America about three million years ago, during the Great American interchange, when tectonics pushed the two continents together and a bridge was created in Central America.

• Porcupine quills are coated with fatty acids and have antibiotic properties; porcupines sometimes quill themselves when they accidently fall from trees.

• Porcupines have a cultural significance for many Native American tribes.          

• The average weight of an adult male porcupine ranges from 22 to 27 pounds, but some individuals can weigh up to 30 pounds. Adult females weigh 15 to 18 pounds (about ten percent less than males). After beavers, the porcupine is the second largest North American rodent.

• The porcupine has excellent senses of smell, hearing and taste. They make a wide variety of sounds, ranging from whimpers to screams, depending upon the circumstances.

• Porcupines are still commonly observed in central and eastern Montana counties, in contrast to significant declining numbers in coniferous forests west of the continental divide. Porcupine MT range: 381,295 km2 (all 56 counties); suitable MT habitat: 315,270km2 (83% of MT).

• Food habits: In winter, porcupines use the cambium, phloem, and foliage of woody shrubs and trees: ponderosa pine, lodgepole pine, and limited spruce and fir. Spring and summer food sources include reproducing parts and foliage of aspen, forbs, grasses, sedges, and succulent wetland vegetation.

• The porcupine’s scientific name, Erethizon dorsatum, can be loosely translated as “the animal with the irritating back.”

• Even though some consider the porcupine no more than a dull-witted “mammalian slug” and a seemingly useless prehistoric offshoot, it contributes to the diversity of our wildlife community. Its value as a wildlife species is enhanced when it is recognized and appreciated as something more than a slow-moving, waddling pincushion.