Species Spotlight: Erethizon dorsatum, the North American Porcupine

January 10, 2023

“I could a tale unfold whose lightest word
Would harrow up thy soul, freeze thy young blood,
Make thy two eyes like stars start from their spheres,
Thy knotted and combined locks to part,
And each particular hair to stand on end
Like quills upon the fretful porpentine.”


Quiet your quills and fret not! Today’s Species Spotlight falls on one of the shyest and most peculiar characters in our own woodland theater, the North American Porcupine.  

While they’re often difficult to spot in the wild, the porcupine is one of the most recognizable animals in the forests of New York. It is also one of our most misunderstood creatures, with myths and falsehoods reaching back hundreds of years. Hopefully this short time in the spotlight will dispel some of the common misconceptions.

Let’s first boil down this distinctive name. Porcupine is ultimately derived from the Latin, “porcus spina”; porcus = hog, spina =spine; ergo, “spiny hog”. The porcupine is decidedly NOT a hog, however. Porcupines are actually classified in the order of rodents, “Rodentia”, and are the second largest rodent in North America, just behind beavers. The grouping of porcupines is further broken down into the “new world” and “old world” porcupines and relegated to the western and eastern hemispheres, respectively.

North American Porcupines live in a wide range of habitats and can be found from the Pacific to Atlantic coasts through much of the US and Canada and into Mexico. For our purposes, we’ll focus on the populations found in New York. In this portion of their range, the North American Porcupine is primarily arboreal, meaning it spends the majority of its life in the forest canopy. This is because the porcupine is an herbivorous animal that feeds on woody and leafy vegetation. Much like their cousins, the Canadian Beaver, the front teeth of porcupines (incisors) grow continuously throughout their life to account for the constant wear that comes from chewing on wood. Also like beavers, their teeth have an orange color due to an iron-oxide imbued enamel covering, giving them added strength and durability.

The preferred diet of the porcupine varies according to the season. They’ll pursue energy-rich leaf buds of the Sugar Maple in the early spring months of the year, before moving onto tasty soft woods like aspen, willow, and basswood. In the autumn season they can be found foraging for acorns and beech nuts, while in the winter they shelter and feed primarily in the cozy boughs of Eastern Hemlocks. Porcupines also have a notorious reputation for chewing on human-made structures, primarily wooden door frames, eaves, and steps!

North American Porcupines do not hibernate and are quite active during the winter, and while they’ll visit the canopy to forage, they prefer to shelter in rocky outcroppings and dens. Karst topography, unique geologic formations distinguished by deep, narrow rifts in solid stone, which are found in many areas throughout the NY Capital Region, are a favored shelter of porcupines. Karst is especially prominent along the Helderberg Escarpment and surrounding areas. In fact, Thacher State Park is thought to have some of the highest population densities of porcupines anywhere in the state!

While porcupines are difficult to spot, there is often ample evidence of their presence if you know the signs. Similar to deer or rabbits, porcupine droppings generally take the form of pellets due to their high-fiber diet. These pellets are pill shaped, brown to reddish-brown, and perhaps ½-1 inch in length. Sometimes, you may find small piles of such droppings near the base of some of their preferred browse trees. Other times, you may find monstrous piles of these droppings which means you’ve stumbled onto a porcupine abode! Porcupines may reside in hollowed out trees, and trees and will often relieve themselves at the entrance to their homes. Porcupines are known to live up to 20 years, and they may shelter in these hollows for extended periods of time resulting in impressive mounds of droppings. The photos below show some of my encounters with these monuments to porcupine excess. The second photo shows a toppled tree that was found during a visit to Switzkill Farm in Berne, NY. The large hemlock stump had fallen across a trail and split open lengthwise, revealing a grand porcupine deposit within that must have been over 6 feet in depth at the peak of its glory.

Other porcupine sign may take the form of middens near the base of a tree, these are small piles of fallen debris and foliage, evidence of a feasting porcupine above. The chewing of porcupines as they eat is also known to be quite distinct; seek testimonials from your rural friends that lose sleep while their porches are devoured overnight. Porcupines may be most easily spotted as they lumber about on the ground. While they’re extremely accomplished climbers, they’re not overly graceful at ground level. They’re also known to be quite clumsy and falls are not uncommon. Porcupine skeletons often show evidence of fractures and breaks because of these frequent tumbles.

We can’t speak about porcupines without discussing their most prominent feature, the quills! These spines are modified hairs with thick keratin coatings. The quills themselves are barbed at the tip and loosely attached at the base. Porcupines CAN NOT eject or throw their quills; this is the most common myth surrounding these prickly pals. They will bristle and stand on end when feeling threatened, however, and they’re known to swish their quill-covered tails as an added defense. The North American Porcupine has, on average, a whopping thirty thousand of these quills surrounding its body, excepting the underside which is spine-free. The quills of baby porcupines, AKA “porcupettes”, are soft and will harden several days post-birth. Porcupine quills are quite common across the forest floor where the critters are present. They’ll be 2- 4 inches in length, with white tips, which remain sharp while the quill itself softens and loses stiffness within several days.

The North American Porcupine is common to most mature-forested natural spaces and are present at most of the MHLC preserves. I encourage you not to seek out a porcupine for any sort of close encounter and please give them plenty of space and respect if one happens to cross your path. Now that you know the signs, you may be able to spot them during their warm daylight naps or hear them chewing away high above. These docile animals serve an important ecosystem function, as browsers and nutrient recyclers. While they are currently listed as a species of least concern, their habitat is increasingly fragmented and diminished. Your support and involvement with Mohawk Hudson Land Conservancy and other conservation organizations is vital to preserving natural spaces and protecting the pokey porcupine in perpetuity.

For additional reading and information about the North American Porcupine, read The North American Porcupine, by Uldis Roze, PhD.

Marshall Lefebvre
MHLC Stewardship Coordinator