Porcupine (Erethizon dorsatum). The Porcupine, is the second largest of all rodents with a small head, large, chunky body covered with quills, short legs, and thick, muscular tail. It weighs from 10 to 40 pounds and is generally solitary, nocturnal, and herbivorous, spending much of its time in trees. It is found throughout all the North American desert regions, and the entire west, north to Canada, usually in woods and woodlands.