There’s more to porcupines than quills

  • A porcupine nibbles on a bit of lunch. Porcupines have quills everywhere except their faces and bellies. pixabay.com

  • Porcupine —pixabay.com

Saturday, December 03, 2016

Human encounters with wildlife often come in the form of carcasses on the side of the road or an unfortunate run-in with our domestic animals. This is certainly true of the North American porcupine. The slow moving, near-sighted waddler is no match for our speeding vehicles. However, it is adapted with effective defense against predators, as any overly curious dog discovers when it ends up with a mouth full of quills.

There is much more to a porcupine than its protective spines, but quills are worth exploring, at least from a distance. Quills are a type of modified hair. They are filled with a spongy substance and vary in length from ½-inch to 3-inches. Each of the 30,000 quills on a porcupine is equipped with microscopic barbs that help the quills stick into a predator. Once embedded in the skin of an aggressor, the barbs also enable the quill to penetrate deeper into the skin, with every muscle contraction of the animal the barbs inch their way further in. Sometimes these miniature arrows reach a vital organ and can cause death to the attacker. The smallest of the quills are most likely to do this and thus are considered the most dangerous.

While they can be menacing weapons, the quills cannot be thrown by the porcupine. When a porcupine shakes, the quills may come loose and fly off, just as the hair of a dog will scatter when it shakes, but there is no active or purposeful projectile ability. New quills grow in to replace those that are lost. The largest quills are on the back and tail. These are presented to a predator if one gets too close, displaying a formidable shield of protection.

A porcupine’s face and part of its belly are free of quills and thus vulnerable. The porcupine’s prime predator, a large weasel called the fisher (also inaccurately called the fisher cat), takes advantage of that. When a fisher encounters a porcupine it will rapidly circle the rodent, prompting the porcupine to continuously turn to try to keep its back toward the fisher. Eventually the fisher out paces its prey and is able to attack the porcupine’s face. Once killed, the fisher flips the spikey creature onto its back, exposing the un-quilled belly. It will feed on the body, leaving only the skin and quills behind. This meal will provide enough nourishment to fortify the fisher for up to a month.

Tree climbing helps porcupines avoid predators such as foxes and coyotes. Long claws and textured foot pads provide grip and friction as they scale up the trunk of a tree. Short, stiff, bristle-like hairs on the underside of their tail act as a break, keeping them from slipping backwards as they ascend a tree.

Another reason that porcupines climb trees is to access food. Though strictly herbivorous, their diet varies by season. In the winter, they primarily eat buds, branch tips, nuts and the cambium or inner bark of trees. They will feed on maples, aspen, apples, red oak, beech or spruce, but Eastern hemlock is a favorite. Since the tips of branches are too flimsy to support their weight, the porcupine will chew off a branch closer to the trunk, then nibble the tender tips, letting the rest of the branch fall to the ground. Finding a hemlock with small branches scattered about on the ground is a sure sign that a porcupine has been feeding in the canopy above.

If you find such a place, look up. You might locate a dark blob resting against the trunk where it could spend several days. As winter approaches though, it is more likely that porcupines will retreat to a den in a rocky ledge, a hollow log or tree or even under a building. These hideouts are easily recognized because the inhabitant urinates and deposits scat (which look like brown elbow macaroni) at the entrance of the den. You will likely smell it before you see it.

You might also hear a porcupine before you see it. Their vocalizations occasionally include screams but mostly consist of low grunts, moans and mutters. Hearing the porcupine talking to itself is by far the most entertaining way to encounter this wild neighbor.