Scientific Name: Erethizon dorsatum


The porcupine is familiar to nearly everyone. Second in size only to the beaver among Colorado rodents, porcupines are 27 to 32 inches long (of which ten inches is tail). Weighing up to 33 pounds, these are large mammals.

Their long, yellowish guard hairs and dense coat of quills give them a waddling gait and make them look fatter than they really are. Starting at the forehead and growing thicker and longer toward the hump of the back, the quills of a porcupine can reach four inches long. A single animal has between 15,000 and 30,000 quills. Although a threatened porcupine will spin quickly, slapping with its tail, it cannot throw its quills as popular belief suggests. Yet each quill is needle-sharp and barbed with tiny hooks that will work into the flesh of any animal or human unlucky enough to come within striking distance.


Porcupines occur throughout Colorado in wooded and brushy habitats but probably are most common in woodlands of ponderosa or pinyon pine.


The animals may den in unimproved rock shelters but often spend the night propped on their muscular tails in the crotch of a tree.


Several evenings of eating bark can severely damage a tree. The bulk of their summer diet is herbs.


These are solitary animals, coming together only to breed in November or December. Females usually produce a single young (rarely twins) after a gestation period of about seven months. That is very long for a mammal of this size. The newborn porcupine is well developed with eyes wide open and a full coat of quills, which harden when exposed to air.


By David M. Armstrong Department of Ecology & Evolutionary Biology Environmental Studies Program, University Museum of Natural History University of Colorado-Boulder

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