Squirrels are remarkably resilient creatures that can survive in a wide range of temperatures. However, extreme cold can be dangerous and even deadly for these bushy-tailed rodents. If you’ve ever wondered just how low the thermometer has to dip before your neighborhood squirrels are at risk, read on to learn everything you need to know about squirrels and cold weather tolerance.
If you’re short on time, here’s the quick answer: once temperatures drop below 20°F (-6°C), squirrels can start to experience life-threatening hypothermia if they’re exposed for too long.
Squirrels Survive Freezing Temperatures By Hunkering Down
Squirrels don’t hibernate but do spend more time in nests
Although squirrels do not truly hibernate during the winter, they do make behavioral adaptations to survive the cold (1). When temperatures start regularly dropping below freezing, squirrels will spend significantly more time in their nests to conserve energy (2).
They enter a state known as torpor, where their body temperature and metabolism slows down (3). This allows them to use up far less energy during periods of extreme cold.
While in torpor, squirrels will not leave the nest at all for up to several days at a time. They can allow their body temperature to decrease to close to freezing, raising it temporarily every few days before lowering it again.
This gives their body a break from constantly generating heat and allows them to rely on insulation from their nest instead (4).
Insulated tree cavities and leaf nests protect squirrels
Squirrels cleverly build winter nests, called dreys (5), that protect them from frigid temperatures and wind. The most common nests are built high up in the forked branches of trees (6). They create an outer shell of interwoven twigs lined on the inside with soft materials like dry grass, moss, fur and leaves for insulation (7).
The spherical shape and dense materials trap the squirrel’s body heat efficiently (8). Cavities in tree trunks also provide excellent refuge for squirrels during winter.
Leaf nests assembled on the ground provide further refuge spots (9). Squirrels construct these emergency shelters by tightly packing leaves into piles or hollows in logs or roots. The dry leaves prevent cold air drafts and rain from permeating the nest interior, while the squirrel’s huddled curled up posture retains body heat (10).
By cycling between ground nests and tree nests, squirrels ensure they always have backup shelter if unusually extreme weather occurs (11).
During short periods of warmer weather, squirrels will venture out to access their food caches (12). But they generally try to minimize time outside below 32°F to avoid cold stress and fatal loss of body heat (13).
Though resilient, squirrels caught out very long in bitter temperatures may develop frostbite on extremities like toes, ears and nose (14). Tree cavities and leaf nests protect them from the worst effects of harsh winter conditions.
How Cold is Too Cold for Squirrels?
Squirrels are remarkably resilient creatures that can survive in a wide range of temperatures. However, there are limits to what even these hardy rodents can endure. Here’s a look at when it gets too cold for squirrels:
Once below 20°F, squirrels risk hypothermia
Squirrels have an internal body temperature around 100°F. If the outside air temperature drops below 20°F, squirrels have to work harder to maintain their body heat. Prolonged exposure to temperatures below 20°F can lead to hypothermia.
During cold snaps, squirrels will spend more time in their nests to conserve body heat.
Wind chill and exposure time also danger factors
Wind chill is an important consideration on top of air temperature. A blustery 10°F day will require more energy for a squirrel to stay warm than a calm 20°F day. Length of exposure also matters. Squirrels can tolerate brief forays into subzero temperatures when food is scarce, but prolonged exposure is high risk.
Squirrels may die in temperatures below -10°F
Once temperatures drop below zero degrees Fahrenheit, it becomes life-threatening for squirrels. At -10°F and beyond, squirrels are in danger of freezing to death. Even in their nests, the cold can be deadly. Their winter fur insulation is simply no match for extreme subzero cold.
In fact, research shows that squirrels can die within an hour at -10°F if exposed.
The key is shelter from the elements. Well-insulated dreys and leaf nests help squirrels survive cold snaps. Plentiful food stores also provide energy to get through frigid temps. By hunkering down and living off cached nuts and seeds, squirrels can make it through cold winter days.
But consistent below-zero temperatures take a dangerous toll on these backyard acrobats.
Other Dangers of Winter for Squirrels
Lack of food sources in winter
Winter poses several dangers to squirrels beyond just the cold temperatures. One major challenge is the lack of readily available food sources during the winter months. As temperatures drop, many of the nuts, seeds, fruits, and other foods that squirrels rely on become scarce or disappear altogether.
Deciduous trees lose their leaves in winter, eliminating acorns and other tree nuts as a food option. The insects and new plant growth that squirrels eat in warmer months are also absent. With their main food sources depleted, squirrels can face malnutrition and starvation during harsh winters.
According to wildlife experts, starvation is one of the leading causes of death for squirrels in winter.
To survive, squirrels have to switch to cached or stored foods. During warmer months, squirrels spend time gathering and caching nuts, seeds, and other foods to eat later in the winter. However, their food stores are not unlimited.caches. But their food stores are not unlimited.
After depleting an acorn cache, a squirrel may struggle to find its next meal. Supplemental feeding and access to winter bird food can help sustain squirrels when natural food sources are scarce. But it is still a daily challenge for the animals to find sufficient calories and nutrition during the coldest months.
Increased risk of predators
Along with hunger, squirrels also face an increased risk from predators in winter. When less food is available, squirrels venture out of their dens more frequently in search of sustenance. This exposes them to predators like hawks, coyotes, foxes, cats, and others.
The bare trees provide less cover for squirrels to hide from predators. And deep snow on the ground makes it harder for squirrels to escape by climbing trees or running quickly. Even crows and magpies may prey on young squirrels in their nests during winter, when other food is scarce.
Statistically, nearly half of all squirrel deaths occur during the winter season, and predators are responsible for many of these fatalities. Even those that survive may suffer injuries and trauma from close calls with predators, making their winter survival even more difficult.
Staying tucked away in their dreys or nest boxes as much as possible is a squirrel’s best defense against hungry predators on winter days. Providing supplemental food sources can also help minimize the time they need to spend exposed to danger while foraging.
How to Help Squirrels Survive Cold Weather
Provide supplementary food sources
As temperatures drop below freezing, squirrels burn extra energy trying to stay warm. Providing supplementary food sources can help squirrels conserve calories and survive the winter. Some great options are unsalted nuts, seeds, dried fruits, and even suet.
Place food items in feeders or platforms near trees or nesting sites. Just be sure to maintain and refresh food supplies consistently, since squirrels may come to rely on them. An inconsistent food source could negatively impact overwinter survival if squirrels hunt less due to expecting free food.
Ensure access to unfrozen water
Like all animals, squirrels need water to survive. But their water sources can freeze solid in winter. Provide accessible water by installing a squirrel bird bath heater or placing out fresh water daily in shallow bowls. Position water bowls in sheltered areas away from the wind.
Adding large rocks helps prevent spillage. Water is critical for squirrels to maintain metabolism and digestion when eating extra foods.
Build or provide insulated nest boxes
Insulated nest boxes provide squirrels a warm, dry refuge from harsh winter conditions. You can build or buy squirrel nest boxes and place them 15-30 feet high on trees. Face the entrance away from prevailing winds and line the box with straw or natural fiber batting for insulation.
Monitoring and maintenance is key – regularly check nest boxes and replace soggy, soiled bedding. Nest boxes give tree squirrels, who usually make leaf nests, a more durable winter home. It may even allow them to safely raise an early spring litter!
With a little help, squirrels can survive the coldest months. Providing food, water and insulated shelter mimics their natural food caches and dreys. While not every squirrel can be saved, these measures can make a difference for many.
Let’s give our furry neighbors the resources they need to stay happy and healthy even during winter’s harshest bite!
Conclusion
Squirrels are well-equipped to handle cold weather, but they can still succumb to hypothermia and freezing temperatures. Once the thermometer dips below 20°F, squirrels need access to insulated nests and cavities to ride out frigid conditions.
With a little help from humans, these resourceful rodents can continue to thrive even during harsh winter weather.
