Do Squirrels Hibernate? Here Is What Happens

do squirrels hibernate

Most species of squirrels do not hibernate; they just store enough food in their underground tunnels or nests to sustain them throughout the cold season. However, scientists have discovered some peculiar species of ground squirrel in the American Midwest that hibernate in winter.

These squirrels include the arctic ground squirrels of Alaska that remain inactive throughout the cold season. Continue reading to know more about the questions: do squirrels hibernate and what happens when they hibernate.

What Is Hibernation?


Hibernation is how some animals survive the cold, dark winter season without having to feed or search for food or migrate to a warmer place. When in hibernation, these animals turn down their metabolisms to save energy. Animals living in hot climate areas also go through some form of hibernation known as aestivation.

Aestivation works the same way as hibernation, allowing animals in hot areas to survive extreme heat, drought, and lack of food. However, hibernation is more profound than just sleeping for months. From long, deep unconsciousness to light spells of inactivity, hibernation varies with the species of the animal.

In some animals like bats, the heart rate drops from 400 to less than 11 beats per minute. Others like wood frogs have natural antifreeze substances that prevent them from getting frozen.

To prepare for hibernation, most of these animals, especially mammals, feed heavily in the warm months, storing excess fat in their bodies that gets them through the cold season.

Do Squirrels Hibernate? How Do They Survive?


In-ground squirrels, metabolism and heart rate slow down, their body temperature plummets to almost -20°C, and their breathing slows down. This allows the tiny creatures to save a lot of energy, making it easier for them to go for months without food and water. Their hibernation is similar to that of bears and woodchucks.

To establish how some species of squirrels hibernate in winter, researchers in the Midwest tested blood fluids and serum of dozens of squirrels.

The sample squirrels were divided into three groups: the ones that remained active in winter, the ones that remained in a sleep-of-the-dead hibernation state referred to as torpor, and the ones that hibernated but remained in a drowsy in-between state.

High levels of serum in the body naturally make animals and humans feel thirsty. In this study, researchers discovered that the squirrels that remained in a torpor state had very low levels of serum.

They concluded that the low concentration of serum prevented these squirrels from waking up to search for water. Even when the researchers attempted to wake up the torpid squirrels, they wouldn’t drink a single drop of water.

To understand the reasons why the squirrels’ blood levels dropped so significantly during hibernation, the researchers filmed the squirrels a few months before the winter season to see if they would drink more water to dilute their blood. but the squirrels drank less water during this period than they would normally drink.

But after testing the blood samples collected from the squirrels with chemicals, the researchers discovered that the creatures regulate their blood flow by removing electrolytes such as sodium and other chemicals like glucose and urea from the blood and storing them in other parts of the body (mainly the bladder).

In their report published on Current Biology, the researcher concluded that the findings could also explain how other animals manage to stay hydrated when in hibernation.

Do Gray Squirrels Hibernate?

Gray Squirrels

Gray squirrels are commonly found in North America and the United Kingdom. However, they only became popular in the UK in the 19th century.

Since then, they have continued to thrive in British woodlands, even becoming the most common species of squirrels in the UK. Compared to Red Squirrels, Gray Squirrels are larger and don’t have tufts on their ear tips.

It is commonly presumed that gray squirrels hibernate during winter. But some studies have revealed that this species of squirrel doesn’t hibernate in the cold season. Instead, it has adopted various methods of surviving the cold season.

For instance, gray squirrels are known to forage in summer and autumn for food, including nuts and seeds. They then bury this food in the ground or in holes in the trees to sustain them in winter.

Although these squirrels do not need to eat or drink water to survive the winter, the stored food is just a little insurance in case they want to eat something.

Most people believe that gray squirrels hibernate in winter because they are seldom seen throughout the cold season. Nevertheless, these little creatures nestle themselves up in larger and warmer nests that they build in the warm months to keep them warm in winter.

What Squirrels Do to Get Through Winter

Get Through winter

Although some species of squirrels have shown signs of hibernation in winter, most of them do not hibernate. They just lie low waiting for the extreme weather to improve. So, if they do not hibernate, what do they do to survive the cold winter season?

All animals are created to adapt to different seasonal changes using the photo-neuroendocrine system, which is a collection of glands, hormones, and neurons. This system is wired to adjust an animal’s internal chemistry as a day changes.

When this photoperiod begins to lessen in the fall, squirrels, like other animals, take notice and their survival mode kicks in.

1. Building Large Warm Nests

Squirrels especially the flying and tree species sleep in nests all year round. These nests are made of twigs, leaves, and moss in tall trees.

Some of these squirrels will build nests in people’s attics while others will hide in holes dug by woodpeckers and other animals in huge trees. In autumn, these species of squirrel build large, warm nests to shelter them from the biting cold in winter.

2. Gathering Supplies

Squirrels, especially the tree species, are very clever about how they hide their food for the winter season. Instead of storing it in one place, they spread it out in different nests to confuse other animals that might want to prey on their food. This is commonly referred to as scatter-hoarding.

They collect a variety of food items, including nuts, seeds, berries, and grains for the winter season. In winter, the squirrels will return to their buried hoards at dawn and dusk. They use a method called spatial chunking to remember where they stashed the food.

3. Piling Up Fat Reserves

Even as they store food, squirrels also pile up fat in their bodies in readiness for the cold season. They do this by eating a lot of food in summer and autumn. The extra layer of fat supplies them with the energy they need to survive the extreme cold weather. It also keeps them warm when temperatures plummet.

It is also important to mention that squirrels are very industrious. So, they will stick around all year long. Therefore, it is important to protect your electricity cables from their clawing paws. Also, you can feed them in the cold season by leaving a bowl of seeds or grains outside.

In Summary

If you were wondering do squirrels hibernate in winter, now you know why they go missing in the cold season. You also have a clear picture of how their bodies adapt to the biting cold weather. If you wanted to feed squirrels, the cold season is the best time.

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