Do Bears Hibernate?
Yes, most bears do hibernate. A large percentage of bear habitat go’s through extremely cold conditions in the winter. During this time, not only is it cold, but their food supply becomes very limited. To complicate things more, if the snow piles too deeply, even mobility becomes difficult.
Over eons of time, most bears have developed physiological adaptations that enable them to live with these conditions. Essentially they stock up on extra calories when food is plentiful and then go into a den and sleep for a majority of the winter. While they’re sleeping their bodies break down their fat stores to use as energy and keep them alive at this time.
Most bears do hibernate in the winter. However, the process that they go through is slightly different than that of the animals that science classifies as deep hibernators. Bears are light hibernators along with raccoons and skunks. Their metabolism slows way down along with their pulse and respiratory rates, but their body temperature stays relatively warm, and they don’t sink into as deep a state of sleep as that of a “deep hibernator.”
I’ve heard it said that what bears enter into in the winter is not hibernation but merely a form of torpor. The first half of this statement is incorrect, while the second half is correct. We’ll explain why below.
Hibernation vs Torpor
Torpor
Torpor is a state of being where an animal’s metabolism slows way down. In medical terms, it’s a hypometabolic state. Animals go into torpor to reduce the number of calories they need to take in to survive during times of adverse conditions. Thermoregulation or the act of body temperature regulation uses 40 to 60% of the energy that an animal takes in. Source To cut down on energy costs when it’s cold, or food is scarce, some animals go into torpor.
Some animals, such as marsupials, go through daily torpor. Daily torpor lasts for less than 24 hours and is then followed by continued foraging.
Hibernation
Other animals go through long-term torpor. This long-term torpor can last for months where animals sleep and go without eating or drinking. This long-term torpor is otherwise known as Hibernation. Source
Bear Hibernation
According to the manuscript titled, “BEHAVIOR, BIOCHEMISTRY, AND HIBERNATION IN BLACK, GRIZZLY, AND POLAR BEARS” by Ralph A. Nelson, Edgar Folk, Egbert W. Pfeiffer, John J. Craighead, Charles J. Jonke, Dianne L. Steiger, Black and Grizzly bears pass through 4 physiological stages in a year.
Stage 1 – Hibernation. Studies by Edgar Folk, conclude that black bears and grizzly bears are true hibernators. They go through physiological modifications similar to those in deep hibernators. They have decreases in heart rate, metabolic rate, and body temperature. However, their hibernation differs from that of deep hibernators in that bears hibernate at near-normal body temperature and continuously sleep. On the other hand, deep hibernators such as bats and rodents hibernate at near ambient temperatures and wake up from time to time to eat, drink, urinate, and defecate.
Stage 2- Walking Hibernation. After bears emerge from their dens they go through a period of adjustment called walking hibernation. From 10-14 days they take in very little food or water. Annalisis of there urine and blood shows that even though they are awake, physiologiclly they are still in hibernation mode. Walking hibernation lasts for 2-3 weeks. Bears then begin to eat and drink normally and return to normal activity.
Stage 3- Normal Activity. From late spring to early fall bears are in stage 3. At this time they can consume 5,000 to 8,000 calories per day.
Stage 4- Hyperphagia. This is where they are packing on the fat for winter hibernation. Their daily food intake increases dramatically. Grizzly bears in hyperphagia observed in the wild feed up to 20 hours a day in the late fall to prepare for hibernation. During this time, bears transition from consuming around 8000 calories to packing on 15 to 20 thousand calories each day along with copious amounts of water to help them process all of that food.
Around the middle of October, the bear’s body goes through hormonal changes. They cease to be interested in gorging on food, and their appetite diminishes considerably. At this point, their body transitions into torpor mode.
They will soon enter their winter den and begin hibernating. The hibernation time for bears varies with the environment. In places like northern Canada and Alaska, bears hibernate up to six months out of the year. A hibernating bear’s heart rate drops to 8-10 beats per minute. Additionally, they only average 1 breath per minute. Their body temperature does not plummet like their pulse, and breathing rate does. A bear in hibernation still has a body temperature of 88° F (31°C). This is only 12° F lower than their normal temperature.
Even though they are asleep, hibernating bears still burn a lot of calories. By the time they wake up in the spring, they will have lost up to 33% of the weight they had before hibernation began. Source
Bear Hibernation in Contrast to the Hibernation of Deep Hibernators
The bodies of ‘deep’ hibernators shut down almost entirely during the winter. Their temperatures plummet to near-ambient numbers, as do their metabolic rates. Some of these species, like the chipmunk, periodically wake up for brief periods to move around, eat, drink, or pass waste, while others, such as the bat, go the entire winter without food or water.
This is not the case when it comes to bears. They do not sleep as deeply. While their metabolism slows down considerably, their body temperature drops only slightly compared to that of a deep hibernator. Their sleep is light enough that changes in the temperature of their surroundings, or any disturbance, will arouse them.
The Physiological Changes That Take Place During Hibernation.
The state of hibernation makes sure that the animal can survive harsh climatic conditions by causing physiological changes. So, with bears, what are these psychological changes?
When a bear is in hibernation mode, its body go’s into a state of metabolic suppression. Its heart rate and breathing rate both drop markedly. During the entire period of hibernation, the bear neither urinates nor defecates. As a result, the level of nitrogen in the blood increases significantly. If this happened in a human body, the damage to the liver and kidneys would be detrimental, maybe even fatal. However, the case is different with bears because nothing of the sort is observed.
Additionally, the bear’s body becomes resistant to insulin. Normally, insulin is essential in making sure that blood sugar levels remain at an optimal range. However, with an animal that has fasted for several months, insulin in the blood keeps glucose from being available to the brain. Source
Six months of continuous sleep for other animals would result in the muscles entering a state of atrophy. Additionally, the animal’s bones would become brittle and porous, a condition; known as osteoporosis. However, bears come through hibernation with no bone loss. They retain their muscle and bone mass in hibernation. They actually end up with more muscle mass, even though their bodyweight decreases by up to 33%.
The nitrogen in the bear’s body, a byproduct of fat metabolism, is synthesized to produce proteins, which are then used to maintain the organ and muscle mass. Moreover, the bear’s body can recycle its water, ergo avoiding dehydration and conditions like kidney failure.
Black bears, brown bears and grizzly bears generally do not eat, drink, urinate or defecate during hibernation. They normally survive on a fat layer built up during the fall and summer months. Note that their bodies produce waste, but they recycle it instead of disposing of it.
Bear Reproduction
It’s during the hibernation period that female bears give birth. Though bears mate in the summer season, the fertilized egg doesn’t implant in the female’s uterine wall until the winter starts. The female bear gives birth approximately 2 months later in late January or early February. The newborn bear cubs do not hibernate. They’re born hairless and blind but not completely helpless. They find their mother’s nipples and nurse to stay alive. They obtain all the nutrients they need through their mother’s milk. On the other hand their mother will be a state of on and off hibernation until she emerges from her den in the spring.
Do Black Bears in Florida Hibernate?
Bears don’t hibernate in Florida, but they do enter a light state of torpor. In more northerly latitudes, bears hibernate to escape the harsh climatic conditions that come with the winter and conserve energy since food sources become rare or completely unavailable.
Bears in Florida do not have to hibernate to escape cold temperatures because the state is relatively warm all year round. January is the coldest month in Florida, and the average temperature for the state is still 58.1°.
The Black bears in Florida enter a state of lethargy because even though conditions aren’t as severe as they are in northern latitudes, there’s still less food availability there than there is during the summer months. They don’t hibernate though.
When Do Black Bears Come Out of Hibernation?
Bears hibernate at different times, depending on their sex. For male bears, the state of hibernation starts around the middle of December and ends in the middle of March. Female bears, because they give birth during winter, normally take longer to come out of hibernation. Theirs starts in late November and ends in the middle of April when they emerge from their dens with their cubs.
How Long Do Bears Hibernate in Alaska?
The bears in the northern regions of Alaska hibernate for about six months. This is because the winter in Alaska is longer, and this affects the period of hibernation. In the southern, warmer regions of Alaska, the bears hibernate for 2 to 5 months. During this winter dormancy, bears are in dens that they’ve dug out beneath boulders or downed trees or some other sheltering object. They also may use a hollow tree or a natural cave as a winter denning site.
Do Polar Bears Hibernate ?
Polar bears go through the same physiological changes that black bears and grizzly bears do but there is no set pattern as to when it will take place. In general, they will go into a kind of walking hibernation in the summer months where they need and consume very little food. Blood tests done on some of these bears indicate that physiologically they are in a similar state to stage 2 for a Black or Grizzly bear. Some times they will even den in the summer but not always.
They spend the winter months hunting seals on the pack ice. This is the time that generally they’re laying on fat against the time when food is harder to find
Polar bears may temporarily den in the winter when the weather is especially severe. At this time they’re not in a state of hibernation.
Pregnant female polar bears do build and go into dens where they give birth and raise their cubs until they’re three months old. During this time, the female bear doesn’t eat or drink. Instead, she depends on her fat reserves to sustain herself and her cubs. Again, she is in a state of torpor at this time but not in a state of complete winter sleep.
Lloyd Bingham
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FAQs
Do bears drink water during hibernation? ›
Grizzly bears and black bears generally do not eat, drink, defecate, or urinate during hibernation. Bears live off of a layer of fat built up during the summer and fall months prior to hibernation. Waste products are produced, however, instead of disposing of their metabolic waste, bears recycle it.
What triggers bear hibernation? ›Hibernation is triggered by decreasing day length and hormonal changes in an animal that dictate the need to conserve energy. Before hibernating, animals generally store fat to help them survive the winter.
Where do bears hibernate? ›Bears sleep in dens they dig out in hollowed-out tree cavities, under logs or rocks, caves, banks and shallow depressions. Bears hibernate without eating, drinking, urinating or defecating.
How do bears hibernate without water? ›Hibernating bears enter a shallow torpor with a decrease in body temperature of only 10 degrees. It's metabolism and hear rate slows down. But it doesn't need to eat, drink or pass waste. In order to survive, fat in the bear's body breaks down into water and calories for the body to use.
How long can a bear live without eating? ›Grizzly and black bears can go for 100 days or so without eating, drinking, urinating, or defecating. They live off a layer of fat that they build up during the summer and fall. Female bears rouse during hibernation in their dens to give birth to up to four cubs.
Can you wake a hibernating bear? ›Bears can also come out of hibernation if they are disturbed. As previously mentioned, unlike other animals, bears do not slowly awaken from hibernation. So, if disturbed by loud noises or approaching danger, they can immediately wake up to defend themselves or their cubs.
Why do bears love honey? ›Research shows us that some bears do really like honey, but this is mostly because of the extra nutrition that comes with it. What is this? If a bear was presented with a jar of honey it might be less interested in it as there would be no hive, bees and larvae from which they get most their proteins.
Do bears actually like honey? ›A: Yes. Bears do love honey and are attracted to beehives. But unlike in Winnie the Pooh, the bears eat more than just honey. They will also consume the bees and larvae inside the beehive, which are a good source of protein.
Do hibernating animals poop? ›Even those hibernators that don't eat or drink anything at all sometimes defecate and urinate during hibernation (metabolizing stores of fat does produce waste), but these animals expel only a tiny amount during hibernation.
Do hibernating animals wake up? ›One misconception about hibernation is that animals do not wake while hibernating. They do wake up, but how and how often they do depends on whether they are true hibernators or light sleep hibernators, Russell said.
How Long Do bears sleep in hibernation? ›
How Long Do Bears Hibernate? Hibernation can last between just a few weeks to seven months. Temperature, sex, and food availability make all the difference. Grizzlies in frigid British Columbia, Canada, can hibernate for seven months while black bears in a more temperate Mexico only hibernate for three to four months.
How many days do bears hibernate? ›Bears have the ability to remain stationary for longer periods than rodents without feeding or eliminating waste. In northern areas of the U.S. and Canada, bears hibernate as long as 8 months without moving from their den. In the South, bears exhibit the same characteristics, only for shorter time periods.
Can humans hibernate? ›Firstly, our evolutionary ancestors were tropical animals with no history of hibernating: humans have only migrated into temperate and sub-arctic latitudes in the last hundred thousand years or so. That's not quite long enough to evolve all the metabolic adaptations we would need to be able to hibernate.
Where Do bears sleep at night? ›Bears prefer to sleep where it is cool, dark, and safe. For most bears, this is somewhere on the ground, when they're turning in at night. They'll typically sleep under trees, logs, rocks, or somewhere else where they can find shelter. They may also fall asleep in meadows.
What actually happens during hibernation? ›When hibernating, an animal's metabolism slows significantly: its heartbeat slows, it breathes more slowly (some animals even stop breathing for periods of over an hour) and its body temperature drops—in some extreme cases to below the freezing point of water (zero degrees Celsius).
Are bears friendly? ›No, bears are not friendly. One thing all bears have in common is that they're solitary creatures and aren't sociable, except for when mating or when mothers are raising their cubs. Experts studying bears think their intelligence surpasses that of dogs.
Is a panda a bear yes or no? ›Classification. For many decades, the precise taxonomic classification of the giant panda was under debate because it shares characteristics with both bears and raccoons. However, molecular studies indicate the giant panda is a true bear, part of the family Ursidae.
Do bears poop when they hibernate? ›A) Bears hibernate during winter, but aren't sleeping the whole time. Hibernation for bears simply means they don't need to eat or drink, and rarely urinate or defecate (or not at all). There is strong evolutionary pressure for bears to stay in their dens during winter, if there is little or no food available.
How do bears not poop during hibernation? ›During 5-7 months in dens, bears accumulate feces in the lower 7-15 inches of the intestine to form a “plug” 1½ to 2½ inches in diameter. The fecal plug is simply feces that have remained in the intestine so long that the intestinal walls have absorbed the fluids out of it, leaving it dry and hard.
Do bears cuddle during hibernation? ›Someone asked if the bears cuddle with each other... yes they do! Here is a video of some winter sleep happening in their inside den area.
What do bears eat after hibernation? ›
This means that they will not feed and will rely on the reserve they packed on during fall. However, many bears living in warmer climates forgo hibernation. Instead, they feed on human foods or garbage. Some feed on winter-killed animals.
Can bears get drunk on honey? ›Video footage showed a bear cub in Turkey that appeared to be intoxicated after reportedly eating copious amounts of a substance dubbed "mad honey," which has psychoactive elements.
Do bears like marshmallows? ›A pair of bears enjoyed some marshmallow treats at a wildlife center in Otisville, New York, footage shared to YouTube on October 10 shows. Co-founder of the Orphaned Wildlife Center Jim Kowalczik features in the footage, sharing the marshmallows with the large duo.
Do bees hurt bears? ›Bears also get stung while nabbing honeybees' nests and the honey inside, but the deliciousness of the food source outweighs the pain from the stings, Carraway said. I would be a really terrible bear, as I would pass out after several stings, then possibly die. But I'd have a belly full of delicious larvae.
What is a bear's favorite snack? ›Bears eat a large range of insects and worms, using their sticky tongues to sweep up the unlucky bugs. A bear's favorite insects include ants, grubs, grasshoppers, beetle larvae, moths, earthworms and caterpillars.
Do bears like peanut butter? ›“We learned our lesson, bears love peanut butter over honey.” Eating human food can cause bears to become accustomed to being fed.
What is the favorite food of bears? ›Bears spend most of their time perusing a patchwork of habitats throughout the year, feeding on vegetation, insects and other more reliable, though lower calorie food sources. Plant foods make up the majority of a bear's diet – sometimes as much as 90 per cent.
Is bear poop black? ›Black bear poop can take on many shapes. The color and composition of their poop will change with the seasons, as does their diet. In the spring, bears eat a lot of grass and insects, so their poop is often green and tubular, with grass visible.
Do animals pee in their sleep? ›Urinary incontinence means your pet cannot control his or her urination or urinates without realizing it, usually when sleeping or resting. Urinary incontinence is most common in middle-age spayed female dogs.
Do bears pee? ›Bears do not eat, drink, urinate, or defecate while in the den. Fat is metabolized to produce water and food, but instead of defecating or urinating to eliminate waste, bears recycle it.
What do black bears eat when they come out of hibernation? ›
This means that they will not feed and will rely on the reserve they packed on during fall. However, many bears living in warmer climates forgo hibernation. Instead, they feed on human foods or garbage. Some feed on winter-killed animals.
What do bears eat before they hibernate? ›They will eat grass, roots, berries, fish, insects and small animals. Black bears can gain up to 30 pounds per week during this pre-hibernation time. Some bears even collect food to store inside their den. Grizzly bears and black bears do not get up to eat or eliminate during hibernation months.
What happens if you wake up a hibernating animal? ›For hibernating animals, an early wake-up call isn't just an inconvenience—it can be downright lethal. Waking up from hibernation requires a lot of energy, depleting reserves that are key to surviving the winter. It's not just bears that are in danger if they wake up from hibernation at the wrong time.
What happens if a bear doesn't hibernate? ›Instead of hibernating, bears fall into a deep sleep called torpor. During torpor, heart rate and breathing rate decreases, body temperature reduces slightly and bears do not eat or release bodily waste. Bears can sleep more than 100 days without eating, drinking, or passing waste!
Can you smell a bear before you see it? ›A person can sniff the entrance of a suspected den and tell if it's just earth or a bear in there. But the light odor is pleasant, at least to us with a bias for bears.
Do bears like honey? ›A: Yes. Bears do love honey and are attracted to beehives. But unlike in Winnie the Pooh, the bears eat more than just honey. They will also consume the bees and larvae inside the beehive, which are a good source of protein.
How far can a bear smell? ›Conservative estimates of a black bear's sense of smell state that a black bear can smell a food source from over a mile away, while other sources claim a black bear can smell food from over two miles away.
What to do if you run into a bear? ›Remain still; stand your ground but slowly wave your arms. Help the bear recognize you as a human. It may come closer or stand on its hind legs to get a better look or smell. A standing bear is usually curious, not threatening.
What time do bears come out? ›Bears are usually active from dawn to dusk, but they may be seen any time of day or night. Bears in many places of high human use have become nocturnal in order to avoid people.
Which fruit can hibernate? ›Blueberries last 3-4 weeks and currants will keep for 2-3 months. Apples and pears, on the other hand, can be stored for up to 12 months.
What animal hibernates the longest? ›
What Animal Hibernates the Longest? It's harder than you'd think to award a prize for longest duration of hibernation. The obvious choice would be the edible dormice (Glis glis) Ruf works with—they can stay dormant for more than 11 months at a time in the wild.
Can humans go into hibernation? ›Human hibernation doesn't exist for many reasons, but the reason why is not quite as immediately obvious as you might think. Hibernation is a response to cold weather and reduced food availability.
Why can't humans hibernate? ›The heart cells of small hibernating animals are able to fine tune how much calcium they have, too much or too little and the heart can't pump blood. This let's them survive when their bodies are at near freezing temperatures. Human heart cells can't do this, and simply can't work when we get too cold.
How cold does it have to be for a bear to hibernate? ›Their hibernation temperature is around 88 degrees and waking temperature is 100 degrees F. This relatively high sleeping temperature allows black bears to become fully alert if aroused, perhaps to enable the bear to protect itself from predators and other dangers without unnecessarily taxing their energy reserves.
Where Do bears sleep at night? ›Bears prefer to sleep where it is cool, dark, and safe. For most bears, this is somewhere on the ground, when they're turning in at night. They'll typically sleep under trees, logs, rocks, or somewhere else where they can find shelter. They may also fall asleep in meadows.
Are bears pregnant during hibernation? ›Untrue. The mothers' metabolic rates are slowed by hibernation, but they wake up to birth and care for the cubs like other mothers do. Many “experts” spout this myth as fact without ever having seen a bear give birth.