Porcupines (Erethizontidae) are the second largest rodent in Alaska. The porcupine is 25 to 31 inches long and is covered with fur and quills of varying length. They migrated northward 3 million years ago from South America.
Porcupines are 25 – 31 inches long with quills of varying length. The quilled pelage of the porcupine makes in unique among mammals. The quills are modified hairs which have microscopic barbs on the tips and are filled with a spongy matrix.
Average adult males weigh from 15 to 18 pounds. Breeding is in the fall. After competing for dominance, the male splashes the female with urine. If she is not ready to mate, she shakes off the urine and leaves. Gestation is extremely long, 210 days, for a rodent. It is twice that of a beaver. They weigh 1-2 pounds; eyes are open and its body covered with hairs and quills. They are ready to leave their mothers by October.
During winter, porcupines roost in their dens during the day and during periods of cold weather. They use earth or rock caves, hollow logs and tress or even thicker vegetation in a tree for dens.
They eat the inner bark (phloem and cambium layers) of spruce is the major source of food in winter. In the spring and summer, buds and young green leaves of birch aspen and are eaten until tannin levels build too high for porcupines to tolerate. Because they are vegetarians and most vegetable matter is very low in sodium, porcupines need additional sodium in the blood to balance cell potassium levels. As a result, porcupines seek out salt sources such as natural licks, glue which bonds plywood together, human perspiration on tools, road salt and some paints. Porcupines also feed on shed antlers and the bones of dead animals to obtain sodium.
When threatened, the porcupine draws up the skin of the back to expose quills facing all directions, and it then presents its formidable bristling back. The porcupine tries to keep its back facing the attacker and strides back and forth with its tail. Although a porcupine cannot throw its quills, the quills are readily dislodged with the tail is shaken. When large numbers of quills become lodged in a predator, the animal will have to be anesthetized in order to remove them. In the wild, animals have been known to die from porcupine quills lodged in their skin.
Quills are used in native art today and in the past were used as wampum (money) by Northeastern Indian tribes.
Porcupines can be injurious to forests if they girdle a tree. Girdling is eating the bark from the entire circumference of the tree.