Porcupines are peculiarly-looking rodents named after the sharp quills on their backs. They are widespread throughout the world – there are over two dozen porcupine species out there, living on all continents except Australia and Antarctica. Porcupines can be found in varied climates and at varied elevations. Not all have to deal with cold winters, but how do those living in cold climates survive?
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Do Porcupines Hibernate?
Like most other rodents, porcupines don’t hibernate. However, even if they remain active throughout the year, they spend most of their time in dens during bad weather. On warmer winter days, porcupines go out and about, foraging or resting in trees. While porcupines are mostly nocturnal animals, they often change their behavior in winter to avoid foraging in freezing temperatures.
Porcupines belong to two different families, the Hystricidae and Erethizontidae. The former, also known as Old World porcupines, live in Europe, Africa, and Asia. The latter, or New World porcupines, inhabit the forests and other wooded regions across North America and the northern regions of South America.
While the Old World and New World porcupines share numerous similarities, they have different foraging preferences and could display different seasonal and social behaviors.
Old World Porcupines
There are 11 Old World porcupine species spread across three continents. They are mostly terrestrial rodents with a primarily – but not exclusively – herbivorous diet. Similar to beavers, porcupines feed on tree bark, roots, fallen fruits, but also on cultivated crops when their home range is close enough to a farm or garden.
In addition to their plant-based diet, Old World porcupines often gnaw on bones and antlers or can be seen eating animal carcasses to supplement their diets with nitrogen, especially in winter.
Old World porcupines living in colder climate areas do not hibernate but can spend a lot of time in their dens when the weather is bad.
New World Porcupines
There are 18 species of New World porcupines. The main difference between them and the Old World species – apart from their physical appearance – is the lifestyle pattern. Most New World porcupines are arboreal species, except for the North American porcupine, which can display either arboreal or a terrestrial preference, depending on where it lives.
Most arboreal species of New World porcupines built nests in hollow trees, stumps, and logs. The North American porcupine can also establish its den in a hollow tree, but also within caves, crevices, rocky ledges, or even inside abandoned buildings.
Like Old World porcupines, New World porcupines do not hibernate and survive the winters by feeding on the inner bark of trees.
Similar to beavers, porcupines prefer specific tree types, including pines, spruces, Douglas firs, cottonwoods, and pines. The summer diet is much more varied and also includes foliage, berries, fallen fruits, and aquatic plants.
North American porcupines not only remain active throughout the year, but winter is also their breeding season.
These porcupines generally mate between November and December, then give birth to porcupettes between late spring and early summer.
Do Porcupines Migrate?
Porcupines do not migrate in winter. Their diet is similar to that of beavers, and their main winter food is the inner tree bark. Living on land, porcupines don’t have to build food caches. Instead, they travel from their dens to a nearby tree to feed.
These rodents are routine creatures. Their travel time is limited in winter, especially when the weather is particularly harsh. Porcupines can visit the same tree for days or even weeks, always following the same, well-worn trail over the snow. On the coldest days, they remain in their dens and can survive without food for a few days.
Arboreal porcupines may also have to leave their dens for foraging. Despite nesting in trees, most porcupines choose different tree species for food than those used for dwelling.
In early winter, North American porcupines also breed. Like most rodents, porcupines are territorial animals. However, they are not social and generally lead solitary lives.
Females establish territories that do not overlap with the territories of other females. However, a male’s home range usually overlaps with that of several females.
It is common for one dominant male to breed with different females if they are willing. This ensures a good genetic inheritance for the offspring.
Juvenile porcupines establish a territory near their natal home range, except for the females. Young female porcupines disperse to new territories before reaching maturity. Young males may have overlapping territories but never overlap with the home range of a dominant adult male. As they mature, most male porcupines will expand their home ranges in size.
Other New World porcupine species display a similar breeding behavior. Things are different for Old World porcupines that are monogamous and don’t have a specific breeding season – they can breed several times each year. Old World porcupines are also social and live in groups.
Where Do Porcupines Go In Winter?
Porcupines live in dens, burrows, hollow trees, or within caves. In winter, they spend most of their time inside the den and only come out for food when the weather allows it.
However, even if you can’t spot them, porcupines don’t go anywhere in winter. They remain in their territory or, sometimes, move to the nearby territory of a fellow porcupine to share the den and increase their chances of survival.
New World porcupines sharing a den during winter will return to their original home range when the temperatures start to rise in spring.
How Do Porcupines Survive Winter Months?
Like all mammals that don’t hibernate and don’t migrate, porcupines employ different anatomical and behavioral mechanisms to survive the cold winter weather. Wondering how they stay warm? Let’s find it out.
Anatomical Adaptations
One of the most common winter survival mechanisms mammals use is growing a thick winter coat. Porcupines are no different, shedding their summer fur and replacing it with a double-layered coat that keeps them warm in winter.
Porcupines also have a very peculiar metabolism that enables them to survive on nutrient-poor food without losing lean body mass.
Unlike other rodents, porcupines don’t reduce their core temperature to prevent heat loss and conserve energy levels. Instead, they only use the fat deposits accumulated throughout the summer and fall. Although they lose a lot of fat mass during winter, they are not particularly affected by the lack of nutrients in the food.
Social Behavior
As we mentioned, New World porcupines are solitary creatures. However, this doesn’t stop them from spending the winters in groups.
When the weather is harsh, porcupines from adjacent territories will gather together in a larger den. Most species prefer a cave or rock shelter, if available. Groups can vary in size but usually consist of up to eight porcupines.
In addition to sharing a den, porcupines may also forage in groups. Foraging groups can be even larger, of up to 20 rodents.
This behavior is more likely a response to predators – porcupines are well-protected by their sharp quills; however, foxes, coyotes, cougars, lynxes, wolves, and bears could hunt them in periods of scarce prey availability. By sticking together, porcupines can discourage predators and increase their chances of survival.
Old World porcupines live in groups all year long. The group generally consists of a mated pair and their young, but the adults generally forage alone in the warmer months. Like New World porcupines, their foraging patterns tend to change in winter, when Old World porcupine families can be seen foraging in groups.
Foraging Patterns
Not only do porcupines shift their social behavior in winter, but they also change their foraging patterns.
In warm weather, porcupines are mostly nocturnal animals. This behavior shifts towards a diurnal preference in winter, most likely to avoid the harsh nighttime temperatures.
The food preference also changes.
In summer, porcupines eat nutrient-rich foods, including foliage, grasses, fruits, and berries. The diet starts to change in fall when a porcupine’s diet will slightly shift to include more seeds and nuts, as well as acorns and other fat-rich foods.
Not only do porcupines need these foods to build up fat, but these foods generally contain more nitrogen – an essential nutrient for porcupines.
In winter, porcupines mostly feed on inner tree bark and pine needles. These foods contain little nitrogen, but the fat reserves help porcupines get through the winter. Preferred winter trees porcupines feed on include sugar maple, hemlock, cottonwood, pines, and firs.
To End
Porcupines are large rodents inhabiting most continents. Their diet based on plants and tree bark enables them to remain active all year round. Porcupines do not hibernate, and they don’t migrate either. While they reduce their activity level in the winter, they still leave their dens and travel to a nearby tree for foraging purposes.