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NATURE HAPPENINGS - January 2007


Winter’s Picklepigs
by Damian Fagan

Porcupines (also known as “picklepigs”) are vegetarians that feed on the soft, inner bark of deciduous or coniferous trees, and on buds, leaves and grasses. Though their preference seems to be willows, cottonwoods and aspen, they also feed on pinyons and orchard trees. How much vegetation they consume in a day is beyond me, but their conservative approach to life must not require an excessive amount of fuel, for they move at a glacier’s pace most of the time. I have watched them scoot along canyon washes or through open forests with surprising speed, but that activity level is not the norm.

Porcupines, with their stout pairs of incisors, are the largest members of the Rodent Family. Covered with a formidable set of quills (somewhere around 30,000 per animal), a porcupine is not an easy target. Their scientific name Eerethizon dorsatum is a combination of Greek and Latin words that mean “irritates with the back.” This reference is to the obvious quills, which are really stiff and flexible modified hairs. Each quill is armed at the tip with overlapping barbs and these hairs easily break free from the skin and embed themselves in the nosiest of noses.
A quill’s hollow tip swells and expands with the attacker’s blood – a design feature to make extraction more difficult. Of course, while the animal is busy yelping in pain and trying to dislodge the quills, the porcupine retreats to a safer location.

Most of my porcupine encounters involved searching leafless trees in winter and keying in on the larger masses in the crowns. Sometimes these blobs turned out to be raptor nests or deadfall, but many times they indicated a sleeping or feeding porcupine.
From these safe perches a porcupine can enjoy its winter slumber while not worrying too much about predators or pesky pets. Though their aerial chambers may lack a variety of escape routes, their spiny pelts provide them ample protection from most predators. Cougars, bobcats, coyotes, martins, fishers, great horned owls, and bald eagles have been known to take porcupines as prey.

Though predators often get a mouth or nosefull of quills, porcupines are not immune to predation. Cougars and coyotes know that quill-throwing porcupines are a thing of legends, and that either the soft underbelly of a porcupine or its quillless face are little match for razor-sharp claws. When confronted, a porcupine will turn about, look over its shoulder and use its tail to swipe at a predator. Also, a porcupine will stamp its feet and arch its back as defensive signals – just like a skunk. Maybe that is why cougars prefer to run down a mule deer than to tangle with a porcupine.

The common name porcupine is derived from the Latin porcospinus and this translates into “quilled pig.” Though named for its hairs, the porcupine also has long, sharp claws and rough foot soles that provide a good grip while climbing. The texture of these pads is evident when observing the porcupine’s tracks, especially in sandy conditions.

But these dimpled soles are not the only clue that betrays a porcupine’s passage down a canyon wash. The porcupine’s bow-legged gait is another helpful clue in track identification. Of course, dragging behind the tracks is the “spiny” tail, which leaves an impression of a broom being used to sweep up behind the feet.

Active throughout the year, porcupines don’t hibernate in winter. They will sleep for several days if the weather is very cold and may “den up” in a cave, tree hollow or stump with other porcupines. When several porcupines occupy the same winter den they are referred to as a “pickle of porcupines.” Seriously.
Porcupines rely on their weight gained during the spring and summer to carry them through winter. Sometimes people observe porcupines chewing on an old boot, wooden handle or saddle, but this is not a starvation survival technique. Rather, this rodent is obtaining salt residue left on from sweat or urine. Porcupines may chew on these and other calcium-rich objects like antlers, bones or bleaching skulls any time of the year.

For a female porcupine, winter is not just a season for one. Adult females are partway through their 6 ½ to 7 month gestation period, having bred sometime in November or December. This is a long gestation period for a rodent, and unlike mice or rabbits, porcupines generally give birth to one young (called a porcupette - seriously) in late spring or early summer.

What seems like an extremely painful birthing process is somewhat relieved by the young being born headfirst in a placental sac. The soft quills are appressed to the body and will not harden until about an hour after birth. The young are mobile shortly after birth and are good climbers like the adults.

For a wild adult porcupine, old age is around 5-7 years old. Though they occupy a place in the web of nature, porcupines have been given a bad rap because of their tree-girdling tendencies. Years ago in Central Oregon, there were highway signs that stated “Please kill all porcupines” to motorists. Crossing the roadway to get to the proverbial other side was a danger greater than predators.

So if you encounter a winter picklepig, take a moment to observe its activity. Don’t regard it is a “killer of trees” but as a unique creature of the canyons, quills and all.

Porcupine

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