Erethizon dorsatum bruneri Swenk




 Photographed in Clark County, KS

Color photo by Galen Pittman.
Copyright 2002.   All rights reserved.

Description:   Porcupines are large, slow-moving rodents that can be distinguished from other Kansas mammals by: 1) heavy body and relatively small head and ears, 2) thick muscular tail, 3) brownish-black to black upperparts with light yellow guard hairs, and yellow, barbed spines tipped with black, loosely attached to the skin, and concentrated on the rump and tail, 4) buffy and spineless underparts, 5) broad, orange-red incisors, and 6) large feet with naked soles and strong, curved claws. Sexes are alike in color and size; young are darker than adults.

Size:   Adults may attain the following dimensions: total length 630-872 mm; tail 175-285 mm; hind foot 70-116 mm; ear 30-37 mm; weight 12-15 kilograms.

Range and Habitat:   Porcupines occur throughout Kansas except perhaps in the southeastern portion of the state. They inhabit forests, riparian communities, and associated rock outcrops.

Reproduction:   Porcupines breed in late autumn after an elaborate courtship ritual initiated by the females. After a gestation period of about thirty weeks a female will give birth in the spring to a single young (rarely two). At birth the large (500 g) young porcupine has long thick black hair and short soft spines. Its incisor teeth ar already present, and its eyes and ears are open and functional at birth. In ten days it is weaned and capable of climbing trees. In two years the young porcupine becomes sexually mature. Females have two pairs of nipples.

Habits:   Porcupines move slowly with a swaying gait. Their sight is poor, but they evade enemies by taking a defensive posture, arching their back to expose their barbed spines, and drawing their head partly under their body or forcing it into a protected area against rocks or logs. If a predator encounters a porcupine, the porcupine forcefully slaps its tail against the head of the predator, firmly imbedding the spines in the face, lips, and mouth where they gradually penetrate and may eventually cause the predator's death by starvation. A porcupine's face and belly are the only vulnerable areas of its body, and clever predators can sometimes use this vulnerability to kill a porcupine, though usually with limited success. Porcupines are primarily nocturnal, but is also active during the day. It does not hibernate, but in winter when there is deep snow on the ground spends much of its time in trees Although porcupines are basically solitary, several sometimes share the same winter den. Winter home range is small (ca. 5 hectares), but in summer it is larger (up to 14 hectares). While in trees the porcupine may feed on the inner bark to the extent that large areas of bark are removed; this may kill the tree, but seldom is of importance to the ecology of the community unless porcupine population density is very high. Population densities fluctuate from year to year, and may range from one to ten animals per square kilometer. Although not territorial, porcupines sometimes defend their winter feeding trees from other individuals. Porcupine trails on snow are easily identified by the striae made by spines on the edge of the trail. Porcupines do not make a nest or burrow; they den in rock crevices or tree hollows.

Food:   Winter food of porcupines consist mainly of the inner bark of trees and evergreen needles. In summer the diet is more varied and includes buds, foliage, small twigs, grass, and herbs. Bones, especially the shed antlers of deer, are chewed for the nutrient salts such as calcium that they contain.

Remarks:   Bobcats are the principal predators of porcupines in Kansas, although coyotes are capable of killing this animal. Forest fire is a threat to porcupines. The barbed, banded spines of the porcupine are actually modified hairs, and despite superstitious beliefs, cannot be thrown. Fecal pellets of porcupines are large, and resemble those of deer, but are more oval in shape. The life span of this mammal is as long as twenty years.

Return to the Mammals of Kansas index page.