Porcupines form a separate family of rodents. Their hair is modified into spines. Its neck and shoulders are crowned with the crest of bristles 6 to 12 inches long. The quills on the back are very profuse. It prefers rocky hill sides and inhabits both open land and forests. During day time, it shelters in caves or in burrows dug by itself. Porcupines come out after dark and their manin food items are vegetables of all kinds, fruit, grain and roots. When irritated or alarmed, they erect their spines, grunt and puff and rattle their hollow tail quills. Their method of attack is peculiar. The animal launches itself backwards with incredible speed and clashing its hind quarters against an enemy, drives its erect quills deep into it with painful or even fatal result.