North American Porcupine
North American Porcupine
Erethizon dorsatum
Erethizon dorsatum
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Population, Conservation Status, Threats:
Considered least concern by the IUCN, with populations that appear to be stable. Porcupines are occasionally killed for being nuisance animals, prone to damaging trees, buildings, and equipment by chewing on wood, leather, and rubber. Mortality from road collisions is high, and a long gestation time and small litter size makes it hard for porcupine populations to grow or rebound quickly.
Physical Description:
Porcupines are the second-largest rodent in North America, following the beaver. They are slow, round, and largely tan-to-brown, with flat leathery paws, a wide tail, and white-tipped quills. These quills - most densely found on the rump and tail - are used for defense, and very loosely held by follicles in the skin, allowing them to "shed" easily. When a predator comes into contact with the sharp, barbed quills, they become embedded in its skin, and in fact continue to work their way into the skin over time.
Overall North American porcupine range from Montana Field Guide. Porcupines are found throughout Alaska and Canada. In the lower 48 states, they are seen primarily in the western half of the country.
Habitat:
Porcupines are able to live in a wide variety of habitats, including high and low elevations, hardwood and softwood forests, and even grasslands and shrublands.
Behavior:
Porcupines are largely solitary, though they may bunk down with other porcupines during stretches of severe cold to conserve heat. They den in rock crevices, tree cavities, and shallow caves. They are primarily active at night, and are agile climbers, often found using trees to escape danger and to find food. They are also competent swimmers. When threatened, porcupines utilize a variety of warning signals to attempt to dissuade predators. They are capable of producing a pungent musky odor from a patch of skin on the tail called a rosette, which serves as a chemical warning. They will also raise their quills, swinging their tail raised to swing at an attacker, further disseminating the warning scent. Finally, they may vocalize, chattering and clacking teeth, and slapping their tail against the ground. If all else fails, porcupines will turn their back to their attacker to insure that it makes contact with their quills.
Diet:
Porcupines eat a wide variety of plant material, including seeds, nuts, grasses, and fruit when available. In the winter, the bulk of their diet is made up of tree products, primarily evergreen needles and the nutrient-dense cambium of trees. Cambium feeding can become problematic to trees when porcupines strip an entire ring of bark from front to back, girdling the tree and eventually killing it. Because their plant-based diet is low in sodium, porcupines must supplement their diet with salts in other ways, finding natural mineral licks or, more frequently near human settlement, road salt or even items with accumulations of human sweat.
Reproduction:
Porcupines breed in the fall, with males competing for access to mates. During courtship, the male finishes his display by spraying urine on the female, who indicates willingness to breed by curling her tail up over her back in order to cover most of her defensive quills and allow mating. After a gestation period of a remarkable 210 days, a single porcupette is born. Young stay with their mothers through the summer until the breeding season, at which point they become independent. Females reach sexual maturity at 1 year of age, while males mature at 2 years.
Associated Species:
Fishers have developed an effective strategy to predate upon porcupines, baiting and dodging attacks until the porcupine can be flipped onto its back and killed, at which point the fisher will eat it from the underside out, leaving the back and the dangerous coat of quills untouched. Mountain lions and wolverines have been known to practice similar hunting strategies in order to predate upon porcupines.
Illustration by Willow Sedam
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