Torpor vs Hibernation: What’s the Difference?
As the weather gets colder, many animals go into a dormant state to survive. Bears are the most well-known example of this. Many people have heard that they hibernate for several months at a time.
While it’s true that bears essentially sleep through the winter, they actually don’t go into true hibernation like other species. Instead, they go into a state known as torpor, which is similar to hibernation but not quite the same.
So, when it comes to torpor vs hibernation, what sets them apart?
Torpor vs Hibernation Definitions
The National Park Service defines a true hibernator as an animal that displays three key behaviors: “reduced metabolism, slower heart rate, and lowered body temperature.”
Hibernation is a type of dormancy, but it’s only one specific type. Not all dormant animals experience hibernation due to varying behaviors that occur for dormancy.
Both torpor and hibernation involve reducing bodily functions to survive harsh winters. Torpor differs from hibernation because rather than lasting weeks or months, it’s usually only for shorter periods like a few hours at a time. These periods of dormancy allow animals to reduce activity and metabolism for most of the winter without being completely dormant the entire time.
So, Do Bears Experience Hibernation or Torpor?
What the general public knows about bears might lead people to assume it’s hibernation. However, they don’t experience all three key behaviors that define hibernation. They have a reduced metabolism and slower heart rate, but not a lowered body temperature.
Bears just seem like they’re sleeping for months on end because they keep to themselves and slow down bodily functions in the winter to protect themselves from food scarcity. Therefore, bears experience torpor rather than true hibernation.
Which Animals Go into Torpor?
Certain mammals and birds go into torpor when the weather gets colder. Some of these species include:
Bats
Badgers
Bears
Chipmunks
Ground Squirrels
Hummingbirds
Prairie Dogs
Raccoons
Skunks
Sugar Gliders
Please note that this only applies to certain species of the above animal groups. Species that live where it’s warm year-round don’t need to go into dormancy.
Which Animals Go Into Hibernation?
Only a few species experience “true hibernation,” which is described as going into dormancy for longer periods like weeks or months. Some of these animals are:
Bats
Groundhogs
Ground Squirrels
Hedgehogs
Marmots
You might notice that some of these animals (like bats and ground squirrels) are listed under torpor and hibernation. That’s because they do both. In the winter, they hibernate, but they can go into short-term dormancy whenever food is scarce.
What is Brumation?
Brumation is another form of dormancy but for cold-blooded animals. Like the mammals and birds listed above, reptiles and amphibians can undergo brumation in the winter by reducing activity levels, metabolism, and bodily functions.
Brumation is more like torpor rather than true hibernation because these animals occasionally wake up and move around, according to Ogden Nature Center. However, they move at a much slower pace than usual.
The temperature of cold-blooded animals depends on the outside temperature. So, winter is generally too cold for reptiles and amphibians to go about their daily activities. They retreat to safe, sheltered spots like burrows and crevices where they can go into brumation without becoming prey.
Most reptiles and amphibians go into brumation if they live somewhere that freezes in the winter. If the location is warm year-round, they may never need to enter this state.
Frequently Asked Questions
What Do Bears Do When They Wake Up in the Winter?
Bears may reposition themselves, search for food or water, nurse their cubs, or briefly step outside between states of torpor. They don’t continuously sleep for months on end like fictional stories make it seem.
Do Bears Give Birth in the Winter?
Yes, bear cubs are usually born in January or February. Bears wake up from torpor to give birth and nurse cubs throughout the winter.
Do Any Birds Experience True Hibernation?
Yes, the common poorwill is the only bird species known to experience true hibernation. It’s a nocturnal species similar to a nightjar, and they can hibernate for weeks or even months on end.
Where Do Turtles Go in the Winter?
Semi-aquatic animals like turtles go into brumation by sinking to the bottom of a pond or lake and burying themselves in mud. They survive by absorbing oxygen from the water rather than going to the surface to breathe.
Hibernation and Torpor are Similar, But Not Synonyms
Dormancy isn’t the same for all animals. Warm-blooded animals that go into dormancy for short periods enter torpor while true hibernation goes on for weeks or months at a time. Cold-blooded animals enter a state similar to torpor called brumation.
I find it fascinating how wild animals can survive harsh winters by simply reducing their functions. Animals will never cease to amaze me.
