Hibernation is among the most fascinating and misinterpreted behaviours in animals. Like many other types of animals, bears have adapted in this fashion because hibernation offers them the best opportunity to survive each winter’s food shortage. There are many debates over hibernation of bears as their body temperature doesn’t drop in that period, it can be termed as “light hibernation”. In this write-up, we will discuss why do bears hibernate and what happens to them during that period.
Why Do Bears Hibernate?
As winter approaches each year, bears prepare for hibernation – a state of inactivity and metabolic depression. The reasons for the hibernation of bears are –
1. Lack of Food Sources
So, why do bears hibernate? One of the primary triggers for hibernation in bears is the dearth of available meals at some stage in the wintry weather. Bears are omnivores and have a various food regimen. But a lot of their desired foods, like berries, nuts, and fish, aren’t conveniently available in wintry weather. The lack of food makes it tough for bears to preserve their body weight. Hibernating permits them to conserve energy when food is scarce. While hibernating, bears do not eat or drink and can lose up to one third of their body weight.
2. Energy Conservation
Hibernation lets bears conserve strength in the course of the tough winter months while limited food is available. Their metabolic rate slows drastically, their coronary heart price drops, and their body temperature decreases barely. This metabolic slowdown reduces their strength requirements. Bears usually spend the summer time and fall building up fat reserves to behave as insulation and nourishment during their long winter sleep.
3. Giving Birth
If you are wondering why do bears hibernate, the female bears who are pregnant will often hibernate in the winter to give birth. By hibernating, pregnant mothers are able to conserve energy and nutrients for their developing cubs. They give birth during hibernation and nurse their cubs while still in the den. The warm, sheltered den provides protection for vulnerable newborn cubs. Mother bears do not eat, drink or defecate while hibernating.
4. Avoiding Harsh Winter Conditions
Bears hibernate to escape from the bitterly cold and icy conditions of winter. Their dens provide insulation from low temperatures and storms. Without this refuge, bears could freeze to death when exposed to the elements for extended periods. Dangerously low temperatures and wind chills make food-seeking difficult and inefficient.
5. Protection from Predators
To be safe and protected from predators is another reason to know if you are looking for why do bears hibernate. While hibernating, bears are kept safe from potential predators. Their remote forest dens shield them from attack when they are in a prolonged state of lethargy. Hibernation minimises their visibility and the amount of time spent outside. Large predators like wolves or cougars are less likely to threaten a hidden den.
6. Heal Injuries
The winter hibernation period allows injured bears to take some time for rest. They make little to no movement in this period and this helps them prevent worsening of the injury. As we mentioned earlier they go through metabolic changes to conserve energy, it helps them heal the affected area. The immobility also reduces strain on damaged muscles or bones.
What Happens During Hibernation Period?
Now that you know why do bears hibernate, let’s have a look at the physiological and behavioural changes during hibernation period:
1. Lowered Body Temperature
A bear’s body temperature drops by only 7-8 degrees Celsius during hibernation, going from their normal 37-38°C down to about 30-33°C. This lower body heat helps conserve energy when bears are inactive. Their lowered temperature is still high enough to avoid tissue damage.
2. Slowed Heart Rate
A hibernating bear’s heart rate slows drastically, from 40-50 beats per minute to just 8-19 beats per minute. This resting heart rate reduces the energy usage of cardiac muscle. But the heart continues steadily pumping blood to supply the brain and vital organs.
3. Slowed Breathing
Breathing rates also decline. Instead of 6-10 breaths per minute, a hibernating bear takes 1-2 breaths per minute. This respiratory decline is another energy-saving mechanism. Lungs still exchange just enough gases to fulfill metabolic needs.
4. Metabolic Changes
A bear’s metabolic rate can drop by up to 75% of normal levels. Protein and fat metabolism are halted. The bear instead relies on stored fat reserves for energy. This metabolic adjustment prevents muscle wasting despite immobility.
5. Birth and Nursing
Pregnant female bears give birth during hibernation and nurse their cubs. Milk production relies on metabolising stored fats. The warmth of the den protects vulnerable newborn cubs.
Frequently Asked Questions
Q: How long do bears hibernate?
A: Bears hibernate for 4-7 months, depending on the regional climate and species. In colder climates, bears hibernate longer.
Q: Do hibernating bears wake up?
A: Bears periodically wake up from their dormant state for a few hours before going back into a deep sleep.
Q: Do bears eat, drink or go to the bathroom during hibernation?
A: No, bears do not eat, drink, urinate or defecate the entire time they hibernate.
Q: How do bears keep warm in their dens?
A: Body heat and insulation from their fur keeps bears’ core body temperature from dropping too low in the cold dens.
Q: Do bears hibernate alone or together?
A: Bears hibernate alone except for female bears who give birth and care for cubs while hibernating.
Q: What do bears do when they emerge from hibernation?
A: When bears wake up in spring, they are hungry and search for food. Their top priority is eating and drinking to replenish depleted energy stores.
Knowing why do bears hibernate gives us an idea of their behaviour during that certain time and what happens to them. By modifying their body temperature, heart rate, breathing, metabolism, and waste production, bears can survive an extended dormancy until conditions improve. They emerge fit and prepared to resume normal summer activities after hibernation.