Did you know out of the 60 mammals in Will County, only two of them hibernate during the winter?
Before you jump to bears as an answer, know that we do not have any bears in Will County! The two animals that hibernate are bats and woodchucks. The rest of our furry friends either stay active or do a lighter version of hibernation.
What is Hibernation?
Hibernation (hi·ber·na·tion) is an extended period of time when an animal or plant is in a dormant state. Hibernation is more than just an animal sleeping. In order for the animal to survive, it has to prepare itself for what its body has in store for the winter months. It must eat tons of food before winter to store up fat. Next, the animals must find a safe place. Once it starts hibernating, it will be defenseless against predators. Then its body temperature and heart rate drops and breathing slows down. Slowing down all of its body functions is why it does not need to get up for food. Its body can use the fat stores that the animal made before it went down for the long winter’s nap.
Most bats hibernate in groups at sites called hibernaculas (hi·ber·nac·u·la). These sites could be in caves, abandoned mines, hollow trees, under bridges, or even in attics. Little brown bats can reach 1,300 heartbeats per minute while feeding in the summer. When hibernation hits, that number can be as low as 20 heartbeats per minute. Bats may start hibernation as early as October and will last until April, depending on the weather.
Willy the Woodchuck should be hibernating right now! Woodchucks hibernate in burrows that can be dug as far as six feet underground. In the summer, a woodchuck’s body temperature is around 99 degrees, but during hibernation it drops to 37 degrees. Humans et hypothermia once our body temperature drops to 95 degrees and could face death at 70 degrees.
Woodchuck is another name for a groundhog. Groundhog’s day is February 2 and is famous for waiting to see if a groundhog sees its shadow. If it does, there will be six more weeks of winter. If there is not a shadow, then spring is on its way. Although this may not always work to predict the future, male groundhogs do like to get up in February to search the area for a female. Once it finds a burrow belonging to a female, it will go down to sleep there for another month. In March they will wake up, eat a nice meal and get ready to start a family.
Deer, coyotes, foxes, mice are a few examples of animals that stay active through the winter.
However, the majority of mammals in Will County do something else besides stay active or hibernate. We call this strategy “deep sleep.” This is different from hibernation because these animals will get up to eat or search for food and go to the bathroom. Think of chipmunks in fall. They are constantly looking for acorns, seeds, and other nuts. The food gets stored for the winter. Chipmunks go underground to sleep once temperatures get too cold. When they are hungry, some of the food is stored underground with them is used for an easy snack. On nicer days in the winter, you can see chipmunks above ground digging up acorns or visiting bird feeders. Once the cold weather returns, they will head back underground to sleep once again.
There is debate whether or not bears are true hibernators. Their body functions slow down but their body temperatures do not drastically drop. Female bears have also been recorded to give birth during their hibernation.
Some fish can hibernate in a waterproof mucus sac if their lake dries up.
Wood frogs can completely freeze in the winter thanks to a special chemical in their bloodstream. Come spring, they can thaw out and hop away.
The Forest Preserve District of Will County offer’s an in-school field trip to Will County students called Getting Ready for Winter. A naturalist will bring nature to your classroom and teach your students five different strategies animals use to survive winter. One lucky student will even be transformed into a woodchuck to act out hibernation. Book now by filling out the online application.