NORTH AMERICAN PORCUPINE
The North American Porcupine is a large rodent in the New World porcupine family. The porcupine is a rodent whose ancestors rafted across the Atlantic from African to Brazil over 30 million years ago, and then migrated to North America during the Great American interchange after the Isthmus of Panama rose 3 million years ago. They range from Labrador to Alaska, as far north as the Arctic Sea and south to the northern edge of Mexico. They are commonly found in coniferous and mixed forested areas but have adapted to harsh environments such as shrublands, tundras, and deserts. They make their dens in holes in trees or in rocky areas. This species is the largest of the New World porcupines and is one of the largest North American rodents, second only to the American beaver in size. Their upper parts are covered with thousands of sharp, barbed hollow spines or quills (actually modified hairs), which are used for defense. Porcupines do not throw their quills, but the quills detach easily and the barbs make them very difficult to remove once lodged in an attacker. The quills are normally flattened against the body unless the animal is disturbed. The porcupine also swings its quilled tail towards a perceived threat. The porcupine is the only native North American mammal with antibiotics in its skin. Those antibiotics prevent infection when a porcupine falls out of a tree and is stuck with its own quills upon hitting the ground. Porcupines are nearsighted and slow-moving. Porcupines are mainly active at night (nocturnal) and on summer days they often rest in trees. During the summer, they eat twigs, roots, stems, berries, and other vegetation. In the winter, they mainly eat conifer needles and tree bark. They do not hibernate but sleep a lot and stay close to their dens in winter. The strength of the porcupine's defense has given it the ability to live a solitary life, unlike many herbivores, which must move in flocks or herds.