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List of Animals That Hibernate in Winter

Updated on July 16, 2014
Animals that hibernate--Bears
Animals that hibernate--Bears

Did You Know

  • Most animals that hibernate do not urinate. The urea is converted into amino-acids and the water reused.
  • Most of the water that animals that hibernate consume during hibernation is from the stored body fat
  • Some animals that hibernate stop breathing completely
  • An animal in hibernation will need a lot of energy to come out of that state and if you were to arouse it, the energy reserves in the body would not last till the end of winter. The animal would die.

What is Hibernation?

Hibernation is the process where animals enter into a period of inactivity in response to certain conditions in their environment.

Hibernation is the slowing down of biological functions in an animal as a response to the deficiency of energy in the environment. The animal enters a state of dormancy so as to conserve the available energy until the environmental conditions improve. There are two type of hibernation:

  • Obligate Hibernation- This kind of hibernation occurs spontaneously at a certain time of the year, irrespective of the environmental conditions prevalent at the time. It appears that the tendency to go into this kind of dormant state has been biological programmed through evolution. During the period when they are hibernating, animals will tend to occasionally go back to the normal temperature and heart rate. This phenomenon has not been fully understood, but scientists think that it may be a way for the immune system to respond to an attack.
  • Facultative Hibernation- Animals which exhibit this form of hibernation only go into a state of dormancy when the environmental conditions are too severe for them to operate normally. The environment conditions which trigger such a state may be severe cold or lack of enough food in the environment.

Brown Bear Hibernation Facts

  • Brown bears (or grizzly bears) are solitary animals who spend most of their time looking for sustenance.
  • Bears will occasionally break the solitary routine when they are mating or caring for their offspring
  • The bear's diet mainly consists of leaves, fruit and roots. They will also consume a variety of insects and remains of animals
  • Although bears will not normally predate, they will occasionally eat the young of mammals like elk.

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Why do animals hibernate?

Scientists have also tried to separate the active substances that are involved in the process of hibernation in order to better understand what really triggers the state. Some success has been achieved in this area and scientists feel that the hibernation inducing substances may have applications in areas such as the preservation of organs before transplantation.

The hibernation phenomenon is yet to be fully understood as there are exceptional behaviors that happen with hibernating animals. For example, there have reports that due to an unusually warm winter in Nevada, United States, bears have not gone into hibernation and are scavenging for food in the garbage left behind by human beings. This behavior occurs when there is a warmer than usual winter season and the bears’ biological triggers do not make them go into hibernation. This situation causes conflict with humans and the food chain is disrupted as the bears eat what is eaten by non-hibernating animals.

How do animals hibernate

Hibernation is controlled by the endocrine or hormonal system in the body of an animal. The activities that are controlled by the endocrine system are:

  • Metabolism and the rate of activity which is controlled by the thyroid glands.
  • Growth of winter coats is controlled by the hormone melatonin
  • Heart and breathing rate is controlled by the pituitary gland
  • Energy levels are affected by the amount of glucose in the blood and this is regulated by the hormone insulin

The animal’s body temperature falls up to a certain point which when reached, the animal temporarily heats up again. There are many things that happen with an animal when it goes into hibernation:

  • Dropping of heart rate to almost 3% of the usual level
  • Reduction of breathing rate by up to 55%. There are some animals which stop breathing completely when they are hibernating.
  • The animals are not aware of their environment
  • Water is from recycled urea and fat reserves

List of Animals that Hibernate

The list of animals that hibernate is quite long and is quite impossible to get through in a single article. The hibernating animals listed here are the most common ranging from reptiles, amphibians, mammals and insects.

What you will realize is that the most important reason that animals enter into a hibernal state is to survive long periods of harsh environmental conditions that would decimate their populations if they did not have the ability to sleep through it as it were.

This animal adaptation gives them the ability to preserve their species and is a cycle that has been encoded into their genetic make-up – only waiting for the appropriate trigger for it to kick in. When the process starts, the metabolism of the animals decreases to an almost unnoticeable rate which serves as a necessary process because there is little consumption of energy.

There are many animals that hibernate. Some go into the long winter hibernation while for others, they hibernate for a short while, awake to stock up on the food and defecate then go back into hibernation. The following are the best known animals that hibernate:

Hedgehogs Hibernation Facts

Hedgehogs feed on insects and when the winter season comes are unable to get a constant supply of their main food source which has either died off substantially or has gone into hibernation. This lack of food is what triggers the process of hibernation in hedgehogs which converts them into cold-blooded creatures for the duration of the cold season. The brain and heart of the hedgehog, which are the most vital organs in the animal, slow down but continue functioning unlike the rest of the body organs which slow down to an almost stop.

Animals that hibernate--Hedgehogs
Animals that hibernate--Hedgehogs

Temperature around these organs is higher than around other organs of the body and the animal appears to be in a very deep state of sleep. However, terming hibernation as a deep sleep state is an understatement because it is much more than that.

When an animal is asleep under normal conditions, it will have dreams which means that the brain has some sort of activity. But during hibernation, hedgehogs in fact seem to put their nervous system in a state of stupor and brain activity will be almost nil.

An important fact during the hibernation of hedgehogs is that they will notice when the temperatures are too low within the den, the animal will briefly awake and move to a more insulated location then go back to the state of hibernation.

How do Toads Hibernate?

Frogs are very versatile animals and can be found in a variety of environments from the coldest to the warmest. They use the two types of seasonal inactivation depending on whether they are in a cold region (hibernation) or in a hot environment (aestivation). In cold climates, the frogs go into hibernation when the temperatures fall below manageable levels.

They first prepare the place where they are going to hibernate which will protect them from external conditions as well as possible predators. The different types of frogs hibernate under different conditions depending on whether they are aquatic or terrestrial frogs. The terrestrial variety will spend the winter on land while the aquatic variety will do it partially submerged in water.

Toads are animals that hibernate
Toads are animals that hibernate

Lizard Hibernation Facts

Like many other reptiles and amphibians, lizards hibernate during the winter because they are cold-blooded animals. They do this to stay avoid the harsh weather in which there are reduced numbers of foods sources that are also going through the same conditions.

The lizards are able to hibernate because, being cold-blooded animals, they get their heat from the environment and with the diminished heat, they easily slip into a state of inactivity. But not all lizards go into the seasonal sleep though – some just migrate to warmer climates and return when the winter season is over.

When the time for hibernating comes, most lizards will look for an appropriate crevice in which to hide themselves for the duration of the season. On the opposite end of the spectrum, lizards in very hot climates will do the opposite of hibernation – estivation – and dig deep into the earth to find cooler conditions.

Animals that hibernate--Lizards
Animals that hibernate--Lizards
Alligators are among animals that hibernate
Alligators are among animals that hibernate
Animals that hibernate--Gopher Tortoise
Animals that hibernate--Gopher Tortoise
Animals that hibernate--Squirrels
Animals that hibernate--Squirrels
Animals that hibernate--Bats
Animals that hibernate--Bats

Other animals that hibernate

  • Long eared hedgehog
  • Horseshoe bat
  • Lesser horseshoe bat
  • Little bent wing bat
  • Noctule bat
  • Serotine bat
  • Black bears
  • Brown bears
  • Polar bears
  • Prairie dogs
  • Himalayan marmot
  • Chinese alligator
  • Adder
  • Normal lizard
  • Grass snake
  • Indian rock python
  • Sand lizard
  • Smooth snake
  • Eastern box turtle
  • Gopher tortoise
  • Common frog
  • Common toad
  • Marsh frog
  • Natter jack toad
  • Palmate newt
  • Siberian salamander
  • Bufftailed bumble bee
  • Common wasp
  • Hornet
  • Great diving beetle
  • Harlequin
  • Lady bird
  • Seven spot lady bird

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