How Ground Squirrels Prepare for Winter

Squirrels are cute and intriguing little animals. How these critters prepare for winter is a great example of this.

It is important to remember that tree squirrels and ground squirrels handle the winter preparations a little differently. Many of the traits are similar, but not quite the same. The focus here will be on ground squirrels, such as the golden-mantled ground squirrel like the one in the picture. This is a widespread species.

Ground squirrels don’t suddenly start preparing for winter. The preparations actually begin during the warm weather of early summer. This is a time when the squirrels are busily eating, having young, and working on their underground tunnels and chambers. The big appetites help them to build up fat reserves that will be needed in the wintertime if they are to survive.

Chambers may also be lined with grasses and fur, which makes a cozy place to sleep when the weather finally turns bitter. The size of the chamber dictates how many squirrels can use it when it is time to hibernate.

Part of the food-gathering activities isn’t for eating and putting on fat. Squirrels will often bury or hide caches of seeds, grass and other foods for use specifically for winter. The animals may also store some food in smaller chambers off their main burrow tunnels. This allows for easier access when the animal is unable to get to the buried food outside the den. They often cram their cheek pouches full of food to transport it.

          Chubby Marmot  

Gradually, they become plump and go from being sleek to being rather chubby, as shown by the picture of the marmot above. Marmots, or groundhogs, are ground squirrels.

As warm temperatures give way to cooler temperature, there’s another change. Thicker fur, more suited for keeping the little animal alive in the cold, replaces the thinner summer pelt.

Food collection advances to a nearly feverish pace as if the squirrel understands that in a short time the collection is going to be difficult if not totally impossible. More food is brought into the burrow, with the squirrel digging new chambers for it if needed and more is stashed in chambers off the main tunnel.

Cold weather finally hits, and the squirrel instinctively reacts. First, they and any other squirrel living in the tunnel system begins to fill in the openings from the inside. The dirt usually isn’t tightly packed, nor does it need to be. A plug of loosely packed dirt still forms a good insulator against the cold. However, since the tunnels usually have multiple exits, each must be sealed to keep the heat inside.

Finally secure, the squirrels curl up together in the main bedding chamber and drift off to sleep. The sleep gets progressively deeper until they are hibernating.

Squirrels have a true hibernation in which their heart rate and respiration drops to nearly imperceptible levels. This saves greatly on the energy needed in order to survive the cold winter months, and it allows them to draw on their fat reserves for the energy they do need.

A squirrel in hibernation often appears to be dead, and can even be handled without waking up. However, they will come out of hibernation just long enough to eat some of the stored food and if the temperatures have risen enough, they may even dig out one of the exits in order to raid one of their exterior stashes, before returning and again burying themselves in so they can go back to their hibernation slumber.

          Tree Squirrel  

The main difference when it comes to tree squirrels is that the choice of nesting sites and the food storage sites are different. However, they have the same physical changes ground squirrels have and also gather and store food for winter, though most often in tree hollows and crevices.

I once raised a pair of golden-mantled ground squirrels from the time they were just starting to get teeth. They were kept in a tank partly filled with dirt, which allowed them to burrow and tunnel. While they were kept inside, they were local, and it was quite a shock when they apparently disappeared, just about the time the snow started falling outside.

Concerned, dirt was carefully dug up until the two were found, curled snugly against each other, apparently dead. As it turned out, they were merely hibernating and finally awoke long enough to drink a little water, raid one of their food caches, then return to their burrow, burying themselves in and once again curling up to return to hibernation.

How squirrels prepare for winter is just one fascinating trait for these small, endearing rodents. Squirrels are definitely cute and interesting little animals, well- suited for survival.