Erethizon dorsatum
Chuck Fergus  

The porcupine is a blackish, quill-armored, slow-moving rodent with an appetite for tree bark and salt. It lives in forests and often can be seen hunched into what appears to be a black ball high in a tree. While it doesn’t occur in all parts of Pennsylvania, the porcupine is one of our best-known and most easily identified wild animals. Its taxonomic name is Erethizon dorsatum. The word “porcupine” comes from two Latin words, porcus (“swine”) and spina (“thorn”), which also reflect the species’ colloquial name, quill pig. In the East, porcupines inhabit Canada and New England south into Pennsylvania; they range through the northern Midwest and the Pacific Northwest, south in the forested Rocky Mountains nearly to Mexico, and north to Alaska. They live at all elevations from sea level to timberline.

The most distinctive aspect of a porcupine’s appearance is its coat of quills. Quills cover the animal’s upper parts and sides from the crown of its head to the tip of its tail. They’re 1 to 4 inches long (those on the animal’s back are longest), yellow or white tipped with black, and lined with a foam-like material composed of many tiny air cells. An individual porky may have up to 30,000 quills. When a porcupine is relaxed, the quills lie smoothly along its body, but when it feels threatened, online casino muscle contractions cause the shafts to rise. In reality, quills are specialized hairs. The rest of the pelt consists of long, stiff guard hairs and soft, wooly underfur. Two molts occur each year: in spring, short hairs replace winter underfur; and in fall, the long, insulating underfur grows back in. At all times, quills are present and are replaced as they fall out.

To defend itself, a porcupine turns its back to a potential enemy, tucks its head between its front legs (or under a convenient shrub), and flails its quill-studded tail back and forth. It may back toward an adversary, chattering its teeth.  Porcupines cannot throw their quills, but because the quills are loosely attached, they dislodge easily on contact and stick in a victim’s flesh. A single quill has a needle-shaped tip covered with hundreds of minute, overlapping, diamond-shaped scales. The scales slant backward and act as barbs. When a quill lodges in tissue, actions of the victim’s muscle fibers engage the tips of the scales, drawing the quill or quill fragment inward up to an inch a day. A wild animal badly impaled in the body will suffer intensely; quills may pierce its heart, arteries, or lungs and cause death, or they may sever the optic nerves and cause blindness.



Pennsylvania Game Commission
Bureau of Wildlife Management
Attn: Mammal Atlas Coordinator
2001 Elmerton Avenue
Harrisburg, PA 17110
Pennsylvania Game Commission
Bureau of Wildlife Management