North American Porcupines are large, slow-moving, tree-climbing rodents, protected from predators by their formidable quills. In winter, they eat the bark, phloem, and cambium of trees, particularly conifers. Learn more about the Erethizon dorsatum, more commonly known as a North American Porcupine, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.