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Erethizon dorsatum (Linnaeus, 1758)
Porcupine
Family: Erethizontidae
Introduction to the Mammals of BC

Photograph

© Ian Gardiner     (Photo ID #6032)

Map


Distribution of Erethizon dorsatum in British Columbia.
Source: Map courtesy of David Nagorsen

Introduction


The Porcupine is a distinctive large species of rodent covered in defensive quills, and is the second largest rodent in Canada (the Beaver is larger) (Resource Inventory Committee 1998). It is dark brown or black in colour (sometimes with yellow or white quills), with a humped back, small head, small ears, blunt nose, small eyes, short bowed legs, large curved claws, and a short thick tail (Gunn 2001, Nagorsen 2005). The pelage or coat is made up of long thick-barbed quills, guard hairs and a woolly undercoat (Nagorsen 2005). The quills are hidden by the guard hairs until raised in defence (Gunn 2001). Young porcupines are born with soft, barbless quills, but these harden within hours and can be erected not long after birth (Gunn 2001). An adult porcupine can have up to 30,000 quills (Gunn 2001, Nagorsen 2005).

This species is found throughout most of North America, including Alaska and northern Canada (Nagorsen 2005). It is found throughout all of mainland British Columbia, but does not occur on any islands (Nagorsen 2005). It is not common on the coast, but is found in every mainland ecoregion in the province (Resource Inventory Committee 1998).

According to Nagorsen (2005), six subspecies of Porcupine are recognized and two occur in BC:

1) Erethizon dorsatum myops (extreme northern and northeastern BC)

2) Erethizon dorsatum nigrescens (northcentral and southern mainland of BC).

Species Information

The Porcupine is a distinctive large species of rodent covered in defensive quills, and is the second largest rodent in Canada (the Beaver is larger) (Resource Inventory Committee 1998). It is dark brown or black in colour (sometimes with yellow or white quills), with a humped back, small head, small ears, blunt nose, small eyes, short bowed legs, large curved claws, and a short thick tail (Gunn 2001, Nagorsen 2005). The pelage or coat is made up of long thick-barbed quills, guard hairs and a woolly undercoat (Nagorsen 2005). The quills are hidden by the guard hairs until raised in defence (Gunn 2001). Young porcupines are born with soft, barbless quills, but these harden within hours and can be erected not long after birth (Gunn 2001). An adult porcupine can have up to 30,000 quills (Gunn 2001, Nagorsen 2005). Griffin (2003) provides the following measurements for this species: (males) total length, 808 mm; tail, 235 mm; hind foot, 98 mm; (females) 737-230-81 mm, and the average weight is 5-11 kg. Males are larger than females.

Biology


The Porcupine is a mostly solitary animal that lives in dens (Gunn 2001, Nagorsen 2005). It is often observed resting in trees during the day, but forages on the ground at night; however, research has shown that porcupines don't spend much time away from their den (Nagorsen 2005, Resource Inventory Committee 1998).
Reproduction

Young porcupines (usually one) are born in the spring and are well developed—they have their eyes open, have quills that harden quickly, weigh between 340-640 grams and can forage on their own within one week (Nagorsen 2005, Smithsonian 2010).
Diet

The Porcupine is a herbivore or plant eater. During the summer and spring, porcupines forage on the ground and eat grasses, sedges, acorns, twigs, roots, stems, berries and other vegetation (and sometimes crops); in the winter, they mainly eat conifer needles and tree bark (they eat the bark, phloem, and cambium of trees, particularly conifers) (Smithsonian 2010).. They have been observed swimming out to lily pads, which are rich in salt, and have been reported wading into water to feed on floating liverworts (Curtis and Kozicky 1944, Nagorsen 2005). They are also reported to consume bones and antlers, which can provide a source of minerals for them (Resource Inventory Committee 1998).
Behaviour

Porcupines do not hibernate, but in winter they sleep a lot and stay close to their dens (Nagorsen 2005). Females are highly territorial and do not overlap ranges; however, males may be found in loose associations often with ovelapping home ranges (Nagorsen 2005). Usually only one porcupine is found in a den, but where winter dens are scarce, several may occupy one den (Nagorsen 2005). The porcupine will swing its quilled tail towards a perceived threat. Porcupines do not throw their quills, but the quills detach easily and may appear to have been thrown (Gunn 2001).
Predators

Although several carnivores are often listed as predators of the porcupine (e.g. Cougar, Bobcat, Coyote, Grey Wolf, Lynx, Red Fox, Fisher and Wolverine), the Fisher is the only mammalian predator adapted to kill porcupines—this increases the significance of the transplantation of Fishers into some areas of BC (e.g. the Khutzeymateen Valley) (Nagorsen pers. comm. 2010).

Habitat


Porcupines are dependent upon the availability of trees for food, and suitable denning sites and are primarily associated with forested areas from sea level to the sub- alpine, where dens are built under fallen trees, brush piles or stumps,in rock crevices and caves, and in burrows of other anmals (Nagrosen 2005). However, in Washington State, they are found in “unforested areas along riparian corridors with trees or large shrub growth, including lush sagebrush” (Lester 1997).

Distribution

Global Range

This species is found throughout most of North America, including Alaska and northern Canada (Nagorsen 2005).
Distribution in British Columbia

The Porcupine is found throughout all of mainland British Columbia, but does not occur on any islands (Nagorsen 2005). It is not common on the coast, but is found in every mainland ecoregion in the province (Resource Inventory Committee 1998).

Taxonomy


According to Nagorsen (2005), six subspecies of Porcupine are recognized and two occur in BC:

1) Erethizon dorsatum myops (extreme northern and northeastern BC)

2) Erethizon dorsatum nigrescens (northcentral and southern mainland of BC).

Comments


This species can live up to 18 years in the wild (Nagorsen 2005). An adult porcupine can have up to 30,000 quills (Nagorsen 2005. This is the only native North American mammal with antibiotics in its skin, which prevents infection if it is stuck with its own quills (Wikipedia 2010). Unfortunately, there is a high incidence of road-kills of porcupines (Nagorsen pers. Comm. 2010).

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
NativeS4YellowNot Listed



BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Notes

In British Columbia, Porcupines are not frequently encountered and are most often seen only as road-kills (Nagorsen 2009).

View a video of a porcupine.

Species References

Curtis, J. D., and E. L. Kozicky. 1944. Observations on the eastern porcupine. Journal of Mammalogy 25:137-146.

Griffin, Crista. 2003. Erethizon dorsatum (North American Porcupine). West Texas A and M University. Available online.

Gunn, Anne. 2001. Mammal Fact Sheets: Porcupine. Hinterland Who's Who. Ministry of Environment. Available online..

7) Lester, D. 1997. Washington GAP Analysis Predicted Distribution Map – Porcupine (Erethizon dorsatum). University of Washington, School of Aquatic and Fishery Sciences. (Appendix II). Available online.

Nagorsen, David W. 2005. Rodents and Lagomorphs of British Columbia. Royal BC Museum Handbook, Victoria.

Nagorsen, David W. 2010. Personal Communication.

Resource Inventory Committee. 1998. Inventory methods for mountain beaver, bushy-tailed woodrat and porcupine [computer file] (Standards for components of British Columbia's biodiversity. The Province of British Columbia, Integrated Land Management Bureau.Available online.

Smithsonian. 2010. Porcupine Fact Sheet. Available online

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