Sub-zero temperatures, blizzards, and a poor diet of tree bark and needles – these are some of the harsh conditions the North American porcupine has to endure every winter.
This slow-moving, solitary herbivore doesn’t look like it has a lot of tools to survive the months-long extreme cold in its forest habitats. But porcupines truly are much tougher creatures than we might think!
Join Floofmania as we learn about the different adaptations in the porcupine’s bodies and the behaviors that help them power through the roughest winters!
Do Porcupines Hibernate or Migrate To Warmer Climates In Winter?
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Porcupines do not hibernate during winter. They remain active through the season, without long periods of sleep, and maintain a steady body temperature.
They do not migrate to warmer locations either. Porcupines move very slowly on the ground and migration would just expose them to predators.
How Do Porcupines Prepare For Winter?
Because porcupines stay in their usual habitats and remain active during winter, their bodies have to adjust and prepare for the cold season. They build up fat reserves and a heavier coat of fur to aid in temperature and energy management.
How Much Weight Do Porcupines Gain For Winter?
Porcupines can put on as much as 50% body fat in preparation for winter.
They feast on the abundance and variety of plants and other vegetation available from spring to fall. Buds, grass, tubers, flowers, leaves, berries, fruits, and nuts, which are nutritious and calorie-rich, help them put on a lot of weight and build up fat stores.
This significant increase in body fat not only adds insulation against the cold but also provides important reserves of energy for when there is limited food in winter.
Do Porcupines Grow A Winter Coat?
The porcupine grows out a winter coat in the fall, as temperatures start to go down. This dense undercoat of inch-long fur can be as thick as a sheep’s wool. Together with the quills and guard hairs, it provides layers of insulation from extreme cold.
A study of porcupine body temperatures in winter illustrates the importance of the winter coat. Researchers observed that the porcupine frequently assumes a ‘lotus position’ where the areas of the body without fur or with thinner hair are tucked close to keep warm.
The naked feet, the base of the tail, and the abdomen are some of the body parts that do not have this thick winter coat protection. So the porcupine oftentimes is found sitting upright in a position to cover these more vulnerable parts.
Heat loss is also minimized when quills are pressed against the skin while the fur is held erect, creating a protective layer against the cold.
You may notice that during cooler months porcupines look fuller and fluffier, with a nice downy halo concealing their quills. In the spring and summer when temperatures go up, they shed their winter jacket and look a lot more slim and spiky.
Every fall this winter coat is regrown as part of the preparation for the cold winter months.
Do Porcupines Behave Any Differently In Winter?
When winter finally arrives, porcupines adjust some of their habits so they can find enough food while staying warm and conserving energy. The main changes are in:
- What they eat.
- When they eat.
- Where they sleep and rest.
- Social behavior.
- Their activity level.
What Do Porcupines Eat In Winter?
Tree bark and pine needles pretty much make up the porcupine diet in winter, since this is all that is available in their snow-covered habitat. They will feed on the inner bark and any leaves or needles of hemlock, pine, spruce, cedar, birch, elm, oak, and other coniferous and deciduous trees, depending on where they are located.
These are very high fiber, low-calorie foods that have very little nutritional value, compared to what they feast on from spring to fall. Some of these tree parts even have toxins that are meant to discourage animals from eating them.
At this time of year, the porcupine’s sharp incisors, strong jaw muscles, and well-adapted digging skills come in very handy to digest their woody winter meals. The stomach and intestines make up about 75% of their body cavity, and it has a special section called a cecum that helps process all the fiber they eat.
Food stays in the digestive tract for 38 hours, allowing more time for microbes and enzymes to break down the plant matter. They extract as much nutrition as possible from this meager winter diet and excrete any toxins through urine.
In spite of this very limited diet, a study of Alaskan porcupines noted that they do not lose lean mass but rather use up their fat stores throughout the winter season. This impressive feat shows a very efficient metabolism that has adapted to the seasonal availability of food and makes the most of what the body has saved up!
Would you like to see what a porcupine winter feeding tree looks like? Take a look at this video, which also shows porcupine snow trails and a winter den:
Do Porcupines Change Their Eating Patterns In Winter?
While porcupines are primarily nocturnal in the warmer months, when winter arrives, they are observed to be awake and feeding at any time of the day or night.
This may be because of the low caloric and nutritional value of their winter diet, which requires more hours of feeding. Or perhaps to avoid harsher nighttime temperatures the porcupine takes advantage of daytime feeding.
Where Do Porcupines Spend Their Time In Winter?
The quilled rodent is remarkably resilient to the cold and has been observed to stay atop tree branches for days on end in the middle of winter. When the weather becomes very severe, they will retreat to dens that provide more protection.
These dens are mostly found in rocky outcrops, rock piles, or hollows of trees. Sometimes they will also find shelter underneath sheds or other human constructions, an abandoned burrow of another animal, or blown-over trees.
Aside from providing protection from the elements and predators, it is important that the den is close to a group of trees from which the porcupine can feed daily with as little effort as possible.
The porcupine spends more time at ground level hiding places like these in the winter, which provide better protection against wind, heavy snowfall and blizzards. They sometimes hide in their dens for days at a time, until the extreme weather clears up.
Here is a very detailed blog with photos and videos of porcupine winter dens, and how porcupines and other species compete for these prized shelters.
Do Porcupines’ Social Behavior Change During Winter?
Porcupines have been observed to congregate during winters to share dens, sometimes in pairs or in larger groups. They benefit from sharing body heat when they allow others to take shelter in their den. Sharing dens also conceals more porcupines from predators.
To make do with the limited food available in the winter, they have also been found feeding together, sharing mineral licks, or some other winter food source.
The porcupine is primarily a solitary creature that maintains separate home ranges from others of its kind. But when temperatures drop and food is scarce, they can tolerate the presence of others in their den or feeding spot.
Are Porcupines Less Active In The Cold Months?
The reduction in physical activity is a major component of the porcupine’s winter adaptation. Lower activity levels mean their bodies can survive on the limited calories they eat and their fat stores.
This also means some calories can be allocated to keeping warm and for the long and intensive digestive process of their woody winter diet.
How Do Porcupines Reduce Their Activity Levels In Winter?
One way is by limiting their area of movement. Porcupines are known to reduce their home range by 80 to 90% compared to their summer home range. They do not forage as far and will stick to feeding from just a few trees, sometimes spending days eating bark and needles from just one tree.
As mentioned before, they choose to den at a spot very close to the trees they feed on. They are happy to find suitable feeding trees about 100 yards from their den, compared to their summer foraging distance of up to 1 mile from their den. This saves a lot of time and energy to get to their daily feeding trees.
To minimize effort in walking through deep snow, porcupines retrace their path towards a feeding tree repeatedly. This packs down the snow in their chosen path, which makes it much easier to walk through compared to creating a new route each time on freshly fallen, fluffy snow.
Here is a short clip demonstrating how carving new trails in deep snow can be very challenging for low-set and wide-bodied animals, and why reusing existing trails is very energy efficient.
Should You Put Out Feed For Porcupines In Winter?
After learning about the challenges of the porcupine during winter, you might be feeling the urge to extend a bit of help to this unique forest dweller.
Should you put out food for them? You can, but you should be very careful. Consider the following risks if you do decide to give some winter sustenance to the hardy porcupine.
First of all, putting out food may invite porcupines to regularly return to whatever location you choose. You need to make sure this location does not expose them to predators or vehicular traffic or provide access to plants or wooden items that you don’t want them to feed on.
Secondly, you do run the risk of encouraging the porcupine to get used to human contact. Remember that this animal has a keen sense of smell, and so the human scent can easily be associated with food that is otherwise unavailable to them in the winter environment.
This can lead to future trouble if the porcupine decides to follow human trails and invade their properties to look for dole-outs. They might get too comfortable and help themselves to someone’s garden or their plywood porch.
And then there’s the other risk that they run into an overly enthusiastic pet dog that could end up getting a face full of quills!
Lastly, you may accidentally be inviting other creatures with the food you put out for porcupines. They may be herbivores too, but you may want to think through what the other consequences might be of inviting snowshoe hares or squirrels to your feeding spot.
Author: Eleanor Tan
Eleanor grew up with rottweilers and pit bulls and loved the James Herriot books about animals as a kid. She thinks animals are endlessly fascinating, and that we can learn a lot from them, all creatures, great and small.