Squirrels are everywhere in the autumn. You’ll see them sitting in trees, at bird feeders, and scurrying across your yard. With all that prep you may be wondering do squirrels hibernate in the winter?
Ground squirrels are the only type of squirrel that will hibernate during winter. Tree squirrel species will go into a period of winter rest. Both of these behaviors are a type of dormancy for squirrels. This helps them to become less active during the winter to save energy. Sleeping and eating are the main priorities for winter resting squirrels to survive.
Now you’re probably wondering what’s the difference between hibernation and winter rest? And where do squirrels go to do all this? This guide will take you through everything you need to know about what squirrels do during the winter.
Sound good? Then let’s get started.
Hibernation and Winter Rest
Before we discuss what squirrels do in the winter, we need to talk about the different survival modes animals can use. These can often be easily confused as they are similar but have a few details that make each process different.
What is hibernation?
Hibernation is a state of being dormant for warm-blooded animals. This allows their heart rate, temperature, and breathing rate to drop. This allows the animal to save energy and survive during the cold months without needing to search for food. A state of hibernation can last a few days or even months.
Hibernation is not just a deep sleep. The animal’s body will shut down to minimal levels to save as much energy as possible.
During hibernation, the body will rely on fat stores so the animal does not need to wake to eat. The lack of food and water means they also do not need to get rid of any waste during this time.
Hibernation can be affected by the weather, seasons, and how much energy the animal has stored away.
What is Winter Rest?
Winter rest is another type of dormancy for animals. Just like hibernation, the aim is to save energy for the animals. However, winter rest is a much milder form of dormancy.
Winter rest means that animals will greatly reduce the activity they do during the winter months. They will still carry out their usual activates but not as often. Their day will mostly be filled with sleeping and eating. It’s normal for some squirrels to sleep for a few days at a time during winter rest.
During winter rest a squirrel’s heart rate will slightly drop. But, their metabolism and temperature will stay the same. This means squirrels can become active quickly if they need to.
Can Squirrels hibernate?
Ground squirrels can hibernate as they have the body mechanism which allows them to. The ground squirrel’s body has the ability to reduce essential functions like heart rate and urine production. This allows the ground squirrels to stay alive without eating, drinking, peeing, or pooing and minimal breathing. Their bodies are also designed to be resilient to muscle and cell loss during this time.
Other squirrel species do not have the same body abilities as ground squirrels to hibernate. That means that other squirrel species cannot physically hibernate. They would need to eat, drink or pee at some point.
What do squirrels do in the winter?
In winter food supplies are scarce and weather conditions are harsh for animals.
For squirrels to survive the winter period they need to do a lot of preparation to make sure they survive.
This mainly including keeping themselves, warm, safe, and fed over the winter months. Seasonal sunlight changes activate these activities.
Let’s look at how they achieve this.
1. Build nests
Squirrels will use nests (dreys) all year round. Yet in the winter these nests are beefed-up versions of their summer nests.
When preparing for the winter a squirrel’s nest will be made with lots of twigs, leaves, moss, and bird feathers. This helps to keep the nest well insulated and let out as little heat as possible.
Squirrels will also build several dreys located in a few different areas. This is a survival technique used to avoid predators and disease from parasites. The squirrels make these nests in summers. That way they don’t need to waste energy building a new nest in harsh winter conditions with fewer materials available.
Some squirrel species will share their drey during the winter months. This allows them to share body heat with each other to save energy.
2. Collect supplies
Squirrels are aware that there is not as much food available in the winter as there is in the summer.
Their solution is to create a ‘food cache’ during the summer months when food is plentiful. These are like small larders near their nests. This behavior is scatter-hoarding. It’s a smart technique that means their stash is spread out over several locations. It stops it all from being used up if another animal stumbles across it.
Squirrels are even known to pretend to stash food to confuse any pilfered who are watching and waiting to steal it afterward.
Squirrels will cache away nuts, seeds, berries, and insets. A squirrel’s diet is mainly made of nuts and seeds as these are the foods that store best in their caches.
Having small stores near their trees means they have only a short distance to travel for a good food supply during winter. This saves energy from foraging during periods of scarce food availability.
Squirrels are known to create special memories and have a good sense of smell. Both these abilities help the squirrels to relocate their food caches in the winter.
3. Fatten up
During the summer months, squirrels will try to eat as much as possible. Their aim is to put on as much fat as they can during this period. Red squirrels put on around 12% of their body weight for winter. Grey squirrels will add up to 25% of their weight.
The fat that squirrels put on for winter is a special type of brown fat. This acts in two different ways
- It helps to insulate and protect squirrels from harsh winter weather
- It can be used as energy when food supplies are limited
When brown fat is broken down it actually creates heat for squirrels, which keeps their temperatures high.
4. Grow a coat
Squirrels will make a few adjustments to their fur to help them survive the harsh winter weather.
The main change is that they will grow thicker fur in the run-up to winter. This gives squirrels a dual layer of top fur and underfur. The underlayer traps in heat and provides protection from wind and water. A squirrel’s winter coat is usually complete by December.
The extra hairs will often give the squirrel fur a darker appearance. A darker fur is beneficial for squirrels as it can help them to retain any heat from the winter sun. This is most obvious with black squirrels who can live in colder weather conditions.
Squirrels need to be careful to protect themselves from nest parasites during winter. These parasites can cause squirrels to lose hair. This can make the squirrels vulnerable to winter conditions.
5. Reduce Activity
The squirrel’s winter survival all rests on them reducing their activity as the winter draws in. This is their winter rest period.
A squirrel will normal be active during 12 hours hour daylight in the summer months. This will reduce to around a 4-5hour daily active period during the winter. Squirrels will sleep for around 18-20 hours a day during winter rest.
Most squirrel activities during these times will be collecting food from their caches. The other active time will be spent eating the food.
If weather conditions are very harsh a squirrel can spend a few days sleeping. Those essential brown fat stores help to give them the energy they need to survive, without eating during this time.
Each Squirrel is different
As each squirrel species is different they will all have their own special behaviors whether hibernating or in winter rest. There are over 200 species of squirrels, but let’s look at what the common squirrels will do.
Ground squirrels are the only true hibernating squirrel species. A ground squirrel will hibernate for 5-8 months of the year.
Hibernation for ground squirrel will start at the end of July through to September. They won’t emerge from their hibernation spot until late spring (around March).
Ground squirrels will hibernate deep in their underground burrows. Ground squirrels live in colonies. This means they hibernate alongside several other ground squirrels close by.
Grey squirrels will take a period of winter rest. They build their nests in tree forks to keep themselves protected from the elements. Grey squirrels are also known to build nests in attics or exterior walls.
Grey squirrel will try to stash away as much food as possible during the summer months. This means they can come back to hiding spots in the winter to collect an easy food supply without the effort of foraging.
During cold spells, grey squirrels will sleep for long periods of time. Then can even sleep up to a few days at a time to save energy.
Red squirrels are like grey squirrels in their winter prep and behaviors. That includes making dreys and storing food for later.
The difference between red and grey squirrels is that red squirrels prefer to nest in thick evergreen trees. Reds also tend to use tree cavities for nests for a bit more protection.
Red Squirrels will also have longer periods of rest than grey squirrels do. That’s why you’re more likely to see a grey squirrel than a red in the winter.
Fox squirrels don’t hibernate during winter. Just like the greys and red squirrels, they will build a warm nest and use food caches throughout the winter.
Fox squirrels are mostly solitary squirrels. However, they may nest together over the winter breeding season. Female fox squirrels will nest with their young babies during winter.
Flying squirrels also don’t hibernate in the winter. Their winter rest is a bit different from other squirrel species.
Flying squirrels like to spend their winters nesting in groups. This means that they can lower their metabolic rate and temperature to save energy.
The problem with living in groups is that you need food more often. Flying squirrels will have one or two short bouts of activity during the winter nights. This will only stop if temperatures dip below -4°F (-20°C).
Where do squirrels live in the winter?
Squirrels will mostly live in their dreys over winter. Tree squirrels will locate their nests in trees and ground squirrels will live in burrows.
Tree-dwelling squirrels will try to locate their drey in deep tree cavities and trunks to give them as much protection as possible from the wind.
You may even find squirrels nesting in attics, sheds, garages, and cavities outside of buildings. This will usually pose little issue over the winter. However, squirrels nesting in hoses can be seen as pests as they can cause damage to your external and internal structures.
Do Squirrel Migrate?
Historically some tree squirrels do migrate. This will usually only migrate a total distance of around 35-50miles. Squirrels that migrate are looking for better habitat. This is likely to be environmental-caused migration. Common causes are areas affected by crop destruction or flooding.
Seasonal migration does not happen annually with modern squirrels as they are well adapted to more urbanized areas.
Squirrels will reduce their breeding number if they are living in unfavorable environments. It is likely they will move on to a more favorable area after the breeding season ends.
All squirrels will go through a period of dormancy over the winter period. For ground squirrels, this is true hibernation. For tree squirrels, this is a winter resting period. Both of these behaviors are a way for squirrels to save energy and survive through harsh winter conditions.
To allow this to happen then squirrels needs to prepare by:
- Putting on weight
- Growing a winter coat
- Preparing a nest
- Stashing away food
This helps the squirrel to hibernate or to reduce their daily activity during winter. Each squirrel will have their own species-specific wintering behaviors.