Do Bears actually Hibernate ?

[MikePal]

Things to ponder on a cold Feb morning

The question of whether bears actually hibernate still being debated

Do bears hibernate? We’ll have to sleep on that one for a bit.

So imagine our surprise when a single email from a reader flooded our system with news that bears do not, in fact, hibernate. “Frogs hibernate; Turtles hibernate,” the reader wrote. “Bears sleep, frequently wake, go outside and have a look around, before returning to sleep again.”

Included in the email was a link to the website of the International Exotic Animal Sanctuary in Boyd, Texas, which addresses the question by stating, “While bears tend to slow down during the winter, they are not true hibernators. Black bears, Grizzly bears and Brown bears do go into a deep sleep during the winter months, known as torpor.”

The Canadian Encyclopedia’s entry on black bears supports this notion. “Black bears do not truly hibernate,” it states, “but enter a state of lethargic sleep.”

But UWO biology professor Jim Staples, an expert in hibernation, says that the question of bears and hibernation is a recurring debate that depends a great deal on one’s definition of hibernation.

According to Staples, if one were to use body temperature as the sole criterion, then bears do NOT hibernate. One definition of hibernation states that mammals that hibernate allow their body temperature to fall below 10C. But the lowest temperature recorded of a (hibernating) bear, he notes, is 28C.

“There are many other criteria you could use,” Staples added, “and they tick all those boxes.” Bears’ metabolic rates, for example, fall by 75 per cent, and for the upwards of 120 days or so that they sleep, they do not eat, drink or produce waste.

And according to Ontario Parks, black bears do hibernate through the winter.

“They are unusual hibernators, for mammals,” added Staples, “because their body temperature does stay high and they gestate their young and give birth to them and start nursing them while they’re hibernating.

[Greenhorn]

They won't take a response of No. While in torpor,they will shed their paws during this period. The pads grow wider every winter. They consume their fat and produce new muscle mass. Strange but the young are born the last week of January or first week of February every year.

[MikePal]

I had never heard the term 'torpor' before.

Torpor is a state of decreased physiological activity in an animal, usually by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability.[1] The term "torpor" can refer to the time a hibernator spends at low body temperature, lasting days to weeks, or it can refer to a period of low body temperature and metabolism lasting less than 24 hours, as in "daily torpor".

Animals that undergo daily torpor include birds (even tiny hummingbirds, notably Cypselomorphae)[2][3] and some mammals, including many marsupial species,[4] rodent species (such as mice), and bats.[5] During the active part of their day, such animals maintain normal body temperature and activity levels, but their metabolic rate and body temperature drops during a portion of the day (usually night) to conserve energy. Torpor is often used to help animals survive during periods of colder temperatures, as it allows them to save the energy that would normally be used to maintain a high body temperature.

It helps to explain why I don't see the furbearing (Squirrels Chipmunks) for a lot of the winter, but on warm spells they are out at the feeders.

It is a common misconception that bears hibernate during the winter. While bears tend to slow down during the winter, they are not true hibernators. Black bears, Grizzly bears and Brown bears do go into a deep sleep during the winter months, known as torpor.

Hibernation is when animals “sleep” through the winter. During this sleep, the animals will not wake up when they hear a loud noise or even if they are moved or touched. While in torpor, the animal can wake up quickly and easily. During true hibernation, the animal’s body temperature drops to match the outside temperature, and their heart rate and rate of breathing slows down. During the bear’s dormant state or torpor, their heart rate is extremely low but their body temperature is relatively high, and they won’t eat or release bodily waste. Animals hibernate as a way to adapt to their surroundings. They have to be able to survive the cold weather. They hibernate to escape the cold and because food is scarce.
To get ready for hibernation, animals will eat more than usual during the fall to store up body fat. During hibernation and torpor, they will use up this extra body fat to live off of while not losing any muscle. This allows the animal to come out of hibernation thinner and still as strong as it was before winter. They will get their dens ready for hibernation during the late fall. The bears of IEAS get ready usually late November depending on when the cold weather hits. The black bears in Bear Orphanage have taken full advantage of the caves we offer, but there are those who still dig a den.

For the bears of IEAS, they react differently during the winter months. All of the bears, grizzlies and blacks, store up during the fall increasing their body fat. The four Grizzly bears will store up during the fall like normal, and once it really cools down (usually late November to mid December depending on the year) they will den up only to come out during the warmer days. When they do come out, it’s only for a short bit, and they are not very active during that time. They are quick to retreat back to their cave.
The black bears slow down and spend most of the time in their dens or caves; however they still snack a little throughout the winter. Dakar and Meyote did become dormant and actually dug their own den during their first winter in Bear Orphanage but have been a little more active during the winter seasons since then. We believe it’s due to the other bears residing in BO. Their first year, it was just the two of them. Now there are 8 bears residing with Dakar and Meyote

[toddy]

Interesting. There is a video on youtube of a guy who put a trail cam outside a bear den all winter. It shows the bear coming out of the den late winter almost daily then heading back in. Eventually the bear starts leaving for days at a time.

[lazyman]

Only when they're sleeping