Erethizon dorsatum

Erethizon dorsatum is commonly known as the North American Porcupine measures 60 to 130cm long by 17 to 25cm wide and weighs 3.5 to 18kg. A tail made of protective quills is the signature feature of E. dorastum. Individual quills measure approximately 4cm (1.5 inches) long are easily embedded in an attacker and released from the tail. Once embedded, small barbs along the legth of the quill keep it in place. The male body is typically larger than the female, but the protective tail of the female is longer than that of the male.

The habitat type E. dorsatum is commonly found in includes the forest, tundra, chaparral and the rangelands, from sea level to high mountains in the west. Occurrances are rare to common depending on the location.

The geographic distribution ranges from northern Argentina north to Alaska and Canada. Though once ranging far eastward, E. dorsatum is extirpated throughout much of eastern North America and the midwestern states though reintroduction has been done in some places.

E. dorsatum is typically a solitary animal but will take a communal habit during the winter. Breeding can occur during any month, depending on location. Gestation lasts between 204 and 215 days, the young weighing 400 to 500g at birth.

An herbivorous species, E. dorsatum feeds on plant material, including the cambium layer of conifers, especially hemlocks. An indication of the species is shredded bark and leaves in a pile with feces or girdled tree trunks. In the spring, the feeding focus turns to more palatable wildflower stems, sedges and grasses. The summer provides abundant food in agricultural fields, especially fields of corn. In the winter when food is more scarce, E. dorsatum will supplement the confiers with acorns.

E. dorsatum is relatively slow moving, typically unaggressive and has poor eyesight. When threatened, the defense response involves erecting the quills of the tail, lowering the head and moving in reverse toward the threat with the tail waving.


Cogger, H.G., E. Gould, J. Forshaw, G. McKay and R.G. Zweifel (1993) The Encyclopedia of Animals. Fog City Press, San Francisco, California.

Kays, R.W. and D.E. Wilson (2009) Mammals of North America. Princeton University Press, Princeton, New Jersey.

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