The Bear Necessities
Brown, cinnamon, blonde, or even black, the American black bear, or the Ursus americanus, is very common in the Sawtooth Mountains. Black bears can be seen throughout the summer scavenging for food and looking for tasty treats. However, in the winter, black bears are not seen as often. They will go into hibernation and cozy up in their dens. For them to hibernate successfully, they need to prepare throughout the summer months. What happens when humans interfere in this natural process? Jakub Town discusses this situation in his article, “The Impacts Unnatural Foods Have on Hibernation and Health of American Black Bears.”
A black bear requires a lot of food and calories to be able to survive not eating all winter. In the spring and early summer, black bears will consume mostly green and flowering plants which are in high abundance at this time and provide a great source of nutrients. A little later in the summer, berries become a significant source of food for black bears. They can eat almost 30,000 in one season! Along with berries and plants, bears need some protein in their diet; only 10% of a black bear’s protein comes from animals including small mammals, eggs, snakes, fish, and many others. The rest of their protein comes from insects. During the summer months, a black bear will consume between 5,000-8,000 calories per day.
As the summer turns to fall, black bears begin to get ready for hibernation. Their caloric intake increases to 15,000-20,000 calories per day because they are storing up fat reserves for the winter. In addition, they drink large amounts of water to help process the food as well as help waste flow through their system. They spend around 20 hours per day looking for food and water.
One way for bears to know when to enter hibernation is that their energy balance becomes negative. This means it takes more energy for bears to look for food and forage than what they are consuming. When the temperature starts to drop, bears will enter their dens. Blood flow to their muscles slows down, and their heart rate drops. Their internal body temperature ranges between 88 and 95 degrees fahrenheit. This is a three to seven degree drop from their summer body temperatures. Hibernation for black bears can last between three to seven months. If a winter is harsher, has more snow, and lower temperatures black bears will be in hibernation for closer to seven months.
Bears hibernate in dens for protection and a place to conserve energy. Once they find the perfect location for their den they will create a “nest” inside. Black bears will use leaves, bark, and dirt for their nests. For female bears, dens provide a safe place for them to give birth and raise their young. They will give birth in late January and early February. While in their dens and during hibernation, bears will not produce any waste. During hibernation, black bears can burn as much as 4,000 calories per day resulting in a 20% weight loss by the end of hibernation. During a bear’s hibernation, they become more dormant. This allows them to wake up if necessary. Some things that might wake them up are if they become too cold or if there is a disturbance inside their den.
Too much human food can cause problems for black bears. When fed human food, bears may leave their dens too early and enter them too late. With the increase of people in the Sawtooth area, it is important to keep our food away from bears and let them eat what they are naturally meant to eat.
As cute as black bears are, it is important to remember to keep your distance. We want to keep our wild animals wild. So remember to store your food properly, keep your distance, and look for signs of wildlife everywhere.
Article by Jakub Towns
The Impacts Unnatural Foods Have on Hibernation and Health in American Black Bears.
Mari is a naturalist with SIHA. In her spare time she loves hiking and swimming. Her favorite animal is a black bear and she is patiently waiting till she sees one in the Sawtooths. She constantly gets distracted by all the tracks and scat she sees while hiking and loves trying to identify the animal.