The porcupine is a large rodent instantly recognizable by the dense coat of barbed quills covering its body. This animal is one of the continent’s most widely distributed mammals, found from the Arctic to northern Mexico. The only species native to the United States is the North American Porcupine, and its geographical presence across the country is explored here.
The North American Porcupine
The North American Porcupine (Erethizon dorsatum) is the second-largest rodent in North America, surpassed only by the beaver. An adult typically measures two to three feet in length and weighs between 10 and 30 pounds. Its most remarkable feature is a defensive armor of up to 30,000 quills, which are modified hairs with barbed tips covering the body except for the underbelly and face.
This species is adapted for an arboreal lifestyle, using strong claws to navigate tree branches. The porcupine is an herbivore with a generalist diet that shifts seasonally. During the summer, its diet includes grasses, berries, and leaves. In the winter, it subsists primarily on the inner bark and needles of various evergreen trees.
Distribution Across the Western States
The largest and most continuous portion of the porcupine’s range extends throughout the western United States, stretching from Alaska down to northern Mexico. This distribution encompasses a wide array of ecosystems, including mountainous coniferous forests and arid scrublands. Porcupines are common across the Rocky Mountains, inhabiting states like Montana, Wyoming, Colorado, and New Mexico.
In this region, they frequently forage on the inner bark of Ponderosa pine trees during colder months when other food sources are scarce. The range continues westward into the Pacific Northwest, covering Oregon and Washington. Here, they are often found in mixed coniferous and hardwood forests, with the greatest density east of the Cascade Range.
They also occupy the arid Great Basin region, utilizing rock outcroppings and juniper trees for winter cover. The species extends into the Southwest, including Utah, Arizona, and northern California, where the habitat transitions to desert chaparral and high-desert shrubland. Southern populations, such as those in Texas, use pinyon pines and oaks for both feeding and resting.
Range in the Eastern and Midwestern US
The porcupine’s range in the eastern US is more fragmented and concentrated in northern latitudes. In the Northeast, populations are established across the New England states, including Maine, New Hampshire, and Vermont, and extend into New York. They inhabit mixed forests, frequently selecting eastern hemlock and sugar maple as winter food sources.
The range sweeps westward into the upper Midwest, covering the Great Lakes region, where they are found in Michigan, Wisconsin, and Minnesota. White pine is often utilized for foraging during the winter months in these forests. South of these core regions, the distribution becomes scattered.
Remnant populations extend down the Appalachian Mountains into states like Pennsylvania, West Virginia, and Maryland. These eastern forest habitats provide the dense tree cover and the variety of deciduous and coniferous plant material necessary to support the species year-round.