QuestionNorth American porcupine
What Do Porcupines Eat? Bark, Leaves and Salt Cravings
North American porcupines are herbivores that eat the inner bark of trees and evergreen needles in winter, and leaves, buds, flowers, grasses and fruit in summer. They also have a strong craving for salt, which leads them to gnaw road salt, sweaty tool handles, plywood and shed antlers.
Contents
What porcupines eat through the year
A porcupine’s menu follows the seasons. Animal Diversity Web describes it as a generalist herbivore whose choices shift with small changes in plant chemistry and nutrition.
| Season | Main foods |
|---|---|
| Spring | Buds, catkins, young leaves, new shoots, flowers |
| Summer | Leaves of aspen, willow, maple and other trees, clover, grasses, herbs, water plants |
| Fall | Apples and other fruit, acorns, beechnuts, leaves, plus bark again |
| Winter | Inner bark (phloem) of trees, conifer needles, twigs |
In spring and summer, when protein-rich food is easy to find, porcupines feed less. In the fall they eat more and build fat reserves, which they will need in the hungry months ahead.
What do porcupines eat in winter?
Winter is the hardest season. Porcupines do not hibernate and do not store food, so they must keep feeding on what is left: the inner bark of trees and evergreen needles. In the east, eastern hemlock is a favorite for both food and shelter. In the Rocky Mountains, some porcupines eat almost nothing but ponderosa pine bark in winter. Fir, spruce, sugar maple, birch, aspen and oak are also eaten.
The part they want is the soft, living layer just under the rough outer bark. A porcupine gnaws through the outer bark with its long orange incisors and scrapes off the inner layer, leaving bare patches with tooth marks.
This food is high in fiber and low in nitrogen, the building block of protein. Porcupines have a long gut and an enlarged cecum, a pouch where bacteria break down plant fiber, and they are very good at holding on to the nitrogen they get. Even so, most lose weight steadily through winter and reach spring in their thinnest condition.
Why do porcupines crave salt?
Porcupines are famous for their salt hunger. Plant food is low in sodium but high in potassium, and in spring and summer, when porcupines eat lots of fresh green leaves, their need for sodium rises. Researcher Uldis Roze linked their salt-seeking to this imbalance.
To get sodium, porcupines:
- lick and gnaw road salt and the edges of salted roads;
- chew sweat-soaked items such as tool handles, gloves, boots, saddles and canoe paddles;
- gnaw plywood, which can contain salts from manufacture;
- eat water plants, which contain more sodium than land plants;
- chew shed antlers and old bones, which also supply calcium and other minerals.
Hikers and forest workers learn quickly not to leave boots or gear outside overnight in porcupine country. These salt trips are also why porcupines are often found near roads, where they risk being hit by cars.
How do porcupines find and eat their food?
Porcupines feed mainly at night. They climb high into trees and move out onto surprisingly thin branches to reach buds, leaves and fruit, gripping with long claws and naked, bumpy soles. They often bite off a twig, eat the tender tip and drop the rest, so a pile of clipped twigs under a tree is a classic porcupine sign.
They also feed on the ground, especially in summer, on clover, grasses and fallen fruit. Their sense of smell is good, and they return to the same productive trees again and again. Sometimes their appetite for buds at the tips of branches leads to falls from trees.
Like other rodents, porcupines have four large incisors that never stop growing. Constant gnawing on bark and twigs wears them down and keeps them sharp. Behind a wide gap are flat cheek teeth that grind tough plant food, and wear on these teeth may limit how long old porcupines can survive.
Do porcupines damage trees?
Yes, sometimes. By stripping bark in winter, porcupines can girdle a tree, removing a full ring of inner bark so that the top dies. Damage is usually patchy, and in natural forests it opens gaps and creates dead wood used by other animals. In plantations it can be costly, which is one reason porcupines were once targeted with bounties and why the return of predators such as the fisher has been welcomed. Read more in What eats porcupines?.
Porcupine diet compared with other rodents
Porcupines are not the only rodents that live on plants, but their reliance on tree bark and needles in winter is unusual. Most other large rodents graze on grasses or eat seeds.
| Animal | Diet type | Notable foods |
|---|---|---|
| North American porcupine | Herbivore | Inner bark, needles, leaves, fruit, salt |
| North American beaver | Herbivore | Inner bark of aspen and willow, water plants |
| Capybara | Herbivore (grazer) | Grasses and water plants |
The porcupine and the North American beaver both rely on inner bark in winter, but the beaver stores branches underwater in a food cache while the porcupine feeds directly in the trees. For the full picture of this quill-covered climber, see our North American porcupine profile.
Frequently asked questions
Do porcupines eat meat?
No. North American porcupines are herbivores and do not hunt animals. They do gnaw on shed antlers and old bones, but for minerals such as salt and calcium, not as a meat meal.
What do porcupines eat in winter?
In winter, porcupines eat mostly the inner bark of trees and evergreen needles, especially hemlock, pine and fir. This food is low in protein, so they lose weight until spring.
Why do porcupines eat wood and tools?
They are after salt. Sweat-soaked tool handles, gloves, boots and some plywood contain sodium, which is scarce in a porcupine's plant diet, so porcupines gnaw them.
Do porcupines eat apples?
Yes. Porcupines love apples and will travel to orchards and wild apple trees in the fall. They also eat acorns, beechnuts and other fruit and nuts when available.
How much does a porcupine eat?
Intake changes with the season. Porcupines eat less in spring and summer, when food is rich, and feed more heavily in the fall to build fat before winter.
Sources and further reading
- Animal Diversity Web (University of Michigan), "Erethizon dorsatum"
- Roze, U., The North American Porcupine, 2nd edition (2009)
- Encyclopaedia Britannica, "Porcupine"
Cite this page
“What Do Porcupines Eat? Bark, Leaves and Salt Cravings.” Animal Atlas, https://animals.bigworldlist.com/questions/what-do-porcupines-eat/.
