Porcupines (Erethizon dorsatum) are wide-ranging animals that can be found in Alaska, Canada, much of the U.S. and northern Mexico. In the Tucson area they live mainly in the surrounding mountains, but occasionally come to town for a visit. Their normal habitat is forested mountains and riparian areas at lower elevations. They usually sleep in trees during the day and forage at night.
An adult porcupine is 2- to 2.5 feet long making it the second largest rodent (after the beaver) in North America.
Porcupines are herbivores that feed mainly on the cambium layer (inner bark) of woody plants such as aspen, pine, and oak. In Arizona they also eat mistletoe, pine needles, oak leaves, acorns, fungi, buckbrush, and the fruit of prickly pear cactus, according the to Arizona-Sonora Desert Museum.
Porcupine young are usually born in the spring after a 7-month gestation period. They are born ready to go: their eyes are open, teeth are well-developed, and they can eat solid food. Their soft quills harden within hours.
Have you ever smelled a porcupine? They can give off a very strong turpentine odor.
Porcupines are famous for their quills which are just modified hair. The quills are easily detached. Under the quills is dense normal hair. Porcupines cannot shoot their quills at you, but the quills become instantly detached upon contact with an object. A porcupine flaps its tail at predators.
According to the National Park Service:
Another common myth about porcupine quills are that they are barbed like fish hooks. In reality, the ends of the quills have diminutive, overlapping scales which make the quills act as though they are barbed. Because of the configuration of the scales, the quills will move forward once embedded. This will cause the quills to become deeply embedded. The quills may move through the skin, up to a millimeter an hour.
There was once a porcupine researcher that studied the way in which quills moved through the skin. He found out the hard way. A quill was driven so deep into his arm, that he had to let it go. The quill moved all the way through his arm and came out the other side! Although he suffered great pain, there was no infection. A closer examination of the quill revealed that the quills contain an antibiotic. The porcupine, in this way, has an insurance policy against its own defense.
Porcupines also have antibiotics in their skin. Those antibiotics prevent infection when a porcupine falls out of a tree and is stuck with its own quills upon hitting the ground.
See an article and close-up photo of the scales of quills here. The scales make the quills very difficult to pull out.
Porcupines are sometimes preyed upon by foolish, very hungry mountain lions and bears.
The porcupine is a rodent whose ancestors rafted across the Atlantic from Africa 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. Source
Fossil porcupine middens up to 25,000 years old have been discovered in southwestern Arizona, south-central New Mexico, and southwestern Colorado. Source
You can learn more by watching an Arizona-Sonora Desert Museum video (3:27 minutes): https://youtu.be/pQWEhHsl-DA and you can see porcupines at the Museum.
See more about desert mammals: