The Science Behind Groundhog Hibernation and Groundhog Day Predictions

Groundhogs can be found all across North America.  One thing that makes them so interesting is that they are deep hibernators.  To learn more about how they hibernate, read on for any questions you could have.

What Do Groundhogs Do In Winter?

Groundhogs go into a deep hibernation sometime around the first true frost of winter which is usually in late October or early November. They wake from hibernation in early spring (late March or early April).

This does not mean that they sleep from October until March. They can go from the torpor stage to the active stage depending on temperatures and food availability. If the temperatures in winter become unseasonably warm, it is possible for a groundhog to wake and leave its burrow.

Do Groundhogs Come Out At All, In Winter?

Once a groundhog burrows underground for the winter, he will not come out of his burrow unless the temperatures outside begin to warm up considerably.  

Groundhogs will go into their torpor stage where they are in their deep hibernation.  This usually lasts for about a week. They will then wake up for three or four days, but they do not leave their burrow during this time.

What Happens To A Groundhog As It Hibernates?

When a groundhog is hibernating, its heartbeat will slow down to about 5 beats per minute. During hibernation, their brains do not need as much oxygen as they do when awake.

In addition to the slowing of their heartbeat, a groundhog’s body temperature decreases from about 99 degrees to 41 degrees. This temperature drop allows the groundhog to achieve the low heartbeat and sleep that they need to stay in the torpor stage.

Do Groundhogs “Sleep” During Hibernation?

Although the torpor stage is the least active stage of a groundhog’s hibernation period, it is not considered to be a deep sleep. During the hibernation stage, the groundhog’s body temperature and heartbeat drop significantly, but this is not necessarily considered to be sleep.

Since this inactive stage only lasts about a week, followed by a more active stage that lasts three or four days, you can see that hibernation is not just being asleep from early winter to early spring.

How Do Hibernating Groundhogs Defend Themselves Against Predators?

A groundhog is perfectly capable of defending itself when it is awake due to its sharp teeth and nails. During their hibernation, however, this is not an option for a groundhog.

A groundhog will burrow about six feet down and create a den that can be about 20 feet wide to create a place for hibernation. The depth of its burrow will not only protect it from the cold weather, but it will also protect it from predators during this vulnerable time.

How Long Do Groundhogs Hibernate For?

Overall, a groundhog will hibernate for roughly three months in total.

Groundhogs will hibernate around the first part of winter until early spring.  This is typically from about late October or early November until late March.  

When Do Groundhogs Go Into Hibernation?

A groundhog will know it is time to hibernate when the first frost of the season occurs. This signals to the groundhog that the weather is too cold and it should start its hibernation. 

Groundhogs are very in tune with the changing weather patterns, which is why the tradition of Groundhog Day is the telltale sign of when spring will begin.

When the weather turns cold, food sources for the groundhog will become more scarce. A groundhog will hibernate to protect itself from starvation, as well as to protect itself from the cold temperatures.

How Do Groundhogs Know When To Hibernate?

When a groundhog begins its hibernation largely depends on the temperature outside.  A groundhog in Maine will begin to hibernate sooner than a groundhog in South Carolina.

The typical sign for a groundhog to begin its hibernation is the first frost of the season. The temperature will have begun cooling up until this point, which will tell the groundhog to hurry and prepare for hibernation.

During this part of the season when plants begin to go dormant for winter, the groundhog’s body will also release a hormone that guides it to hibernate.

Do Groundhogs Hibernate Non-Stop Without Waking?

Groundhogs do not hibernate non-stop without waking. They will be in a dormant state for about a week at a time when their body temperature and heart rate are very low. This torpor state allows the groundhog to pass the cold months in a way that allows them to survive.

During their more active stage, sometimes called a stage of arousal, the groundhog will wake, but will not leave its burrow. This stage lasts about three or four days.  

Groundhogs will repeat this process of sleeping and waking anywhere from 12 to 20 times throughout their hibernation period.  

When Do Groundhogs Come Out Of Hibernation?

Groundhogs will come out of hibernation once the ground temperatures begin to rise in the late winter or early spring.  

Most groundhogs will begin peeping out of their burrows at the beginning of February. This is where the holiday tradition comes into play. If a groundhog looks out of its burrow and sees its own shadow, it will retreat back into its burrow for typically another six weeks. This is the sign of late spring and extended winter.

If the groundhog does not see their shadow, this is a sign that the outside temperatures are beginning to rise and it is safe for them to emerge from their winter hibernation. This is how early spring is traditionally predicted.

Can Groundhogs Predict Spring?

Whether a groundhog sees their shadow or not is also mainly due to the presence of clouds. Contrary to what you may think, in original folklore if the groundhog peers out of hibernation on a clear day, this is the sign of a long winter. It is a cloudy day when the groundhog will not see their shadow and will fully come out of their winter hibernation.

While groundhogs will begin to emerge at the beginning of February, they may not fully come out of hibernation until March. Ultimately it is the weather that decides whether the groundhogs are ready to go back to their normal daily adventures or not.

Overall, watching groundhogs emerge from their burrows has been a tradition for over 100 years and is cherished by many people all over the country. It has been a great way for people to connect with this animal whereas they might not have if it wasn’t for this holiday tradition.

What Do Groundhogs Do When They Come Out Of Hibernation?

Groundhogs wake from hibernation in order to mate. They wake and prepare for mating during the first few weeks of February. 

Male groundhogs will typically wake earlier than female groundhogs. This is because they will scout out their new territory (near their own burrow). On average, a male groundhog’s territory will include several female groundhog burrows.

The males spend their time checking out these female burrows to see if the female is still there. Once the male groundhog has looked over his territory and found out where the female groundhogs are, he will go back to his burrow and hibernate for about another month.

Eating is not the immediate concern for groundhogs after hibernation, but once they have mated, they will begin again to forage. Groundhogs are herbivores who like a wide variety of twigs, grasses, plants, flowers, and weeds.  On average, a groundhog will eat about ⅓ of its weight each day.

How Do Groundhogs Prepare For Hibernation?

Groundhogs prepare for hibernation by eating lots of protein-rich foods in order to build up fat stores. These fat stores are what will allow the groundhog to hibernate for several months to avoid the cold months of winter and lack of food.

In addition to adding fat, the groundhog must also build a burrow for its winter hibernation. Most burrows are built in the same way for every groundhog.

Groundhogs’ burrows have one main entrance. These are typically known by the large mound of dirt directly outside this opening.  

A groundhog will begin digging inward for several feet and then dig upward for a few feet.  After this, the groundhog will dig a tunnel horizontally for about 20 feet.  This structure will prevent the burrow from flooding.  

Every groundhog burrow will have several rooms. One room will be a dedicated bathroom. Groundhogs are very clean animals and will not relieve themselves in their living area. Another room will be used for raising kits, sleeping, or hibernating.  

Don’t Groundhogs Eat Anything While Hibernating?

Groundhogs will not eat anything during hibernating. The simple answer is that groundhogs do not need to eat because they have spent months prior to their hibernation building fat stores.  

Eliminating the need to wake and eat during winter helps lengthen the lives of groundhogs. During winter food becomes more scarce, so the groundhog could risk starvation. In addition, if they have to come out of their burrows they are vulnerable to predators.

Do Groundhogs Hibernate Alone?

Groundhogs are very solitary creatures who do not like to live together. They do not share a burrow during hibernation or any other time of the year. The only exception to this rule is when a female groundhog has young babies who need to nurse.  

Female groundhogs would prefer to be alone as well, so they will begin to move their babies out of their den about a month and a half after they are born. By the time the babies are two months old, they will have dug their own burrow.