How does hibernation help animals survive?

You’ve probably heard a million times that hibernation is a survival strategy adopted by some species of mammals and birds in order to cope with the inhospitable climate of the winter season.

But how exactly does hibernation jump start animals from winter to spring? How exactly do animals survive through winter while being consistently motionless in a partly insulated den? How exactly does hibernation work in the first place?

If you desperately want answers to these questions, then you have no other option but to continue reading this post. You’ll find them all, plus more. 

How does hibernation help animals survive?

Its simple. Hibernation essentially padlock animals into a state of suspended animation so they never have to search for food in the biting cold of the winter climate, or deal with the extremely plummeting temperatures and shiver-inducing precipitations of winter for the most part.

If you don’t observe crucial biological processes like breathing, pumping of blood, feeding, digestion or even sleeping, or you greatly reduce these activities to levels below the quintessential, then you only need very little amount energy to survive days, weeks or even months on end, and thats exactly how hibernation works, and thats additionally why dead and resurrected bodies neither eat nor drink too. (Their case isn’t hibernation though).

The problems of winter and then hibernation as a solution

Hibernation prevents animals from feeling the bitter cold of winter for the most part. Most hibernating animals are small, weighing less than 70g or so, and therefore have a relatively large surface area to volume ratio.

This larger surface area to volume ratio cause them to loose greater amount of heat relatively faster than their larger counterparts, who by the grace of nature, are blessed with a smaller surface area to volume ratio.

This in turn means that smaller animals feel the burning impact of cold weather more easily than larger animals. Their bodies eagerly give off heat so they must constantly forage and consume food in order to consistently supply the energy needed to warm up their bodies and maintain them at euthermic conditions.

This presents a serious constraint, you cant keep eating, generate body heat and then continue to loose this body heat to the outer surrounding.

It’s taxing and not feasible. Either of the two sides on the tug-of-war rope has to triumph. Either the animal or the savage winter. You really cannot beat nature, but you can definitely avoid some of it’s hurdles, at least by some decent degree.

If the mammal or bird really wants to enjoy the fresh succulent berries and the productive vegetations of early spring, then it needs to come up with an energy efficient strategy of stopping the consistent heat loss, and also a way to avoid the severe beating and savageness of the winter cold.

That strategy? It’s hibernation. And that’s the evolution of hibernation. Going out to forage in the middle of winter while constantly loosing body heat isn’t a viable option at all, it’s a death sentence.

Food becomes scarce and partly or completely buried underneath snow cover and ice. Taking up shelter in neat burrows rooted deeply into the belly of the earth, or inside dens, or caves or hollows, and then coming out occasionally to forage wont work when you’re tinier than 100g either.

At some point, you’ll reach a breaking point. The point where the fierceness and bitterness of winter is no longer bearable.

For how long and how far would you forage for scarce and enshrouded food? Only nature knows. One thing is certain though, you’ll eventually give up the ghost and die on a cold sunken stomach.

The only feasible, enforceable and bearable option is to hibernate. Hibernation isn’t without it’s own problems too but at least it strips off the need to forage amidst the biting cold of winter. It completely (or rather for the most part), shelters the animal in question from the frosting cold of winter. If only humans could do it. If only they could. If only…

How hibernation works

This sections explains how hibernation works in mammals and birds.


Hibernation is basically a specialized season reduction of metabolism concurrent with the environmental pressures of food unavailability and low environmental temperatures. We’ve explained all these unnecessary grammar in the section above.

Packing ‘fat’ snacks

Before animals can hibernate, they need energy reserves. Something they can fall onto and completely rely on for the entire period of dormancy. The winter alternative to summer foraging.

For the reserves, animals accumulate food caches in their hibernating dens, build on their current fat reserves, or apply both of these methods when they begin sensing the “overt clues” of winter: dwindling food resources, colder ambient temperatures, shortening of day and elongation of the nights, browning of forests and many many more.

Some animals only depend on their internal biological clock to become aware of the coming of winter.

The accumulation of energy reserves by hibernating animals happens months before the onset of winter; the period where they enter into hibernation.

How much reserve an animal gathers right before entry into hibernation is a crucial factor in accessing whether or not the animal might make it to spring.

That’s the main reason why many infant hibernators, mostly juveniles and sub adults, perish on their first hibernation attempts. They simply do not pack enough snack or fat reserves to last them through winter.

Turning down physiological functions

So animals have amassed a chunk of food cache, fat reserves or build in their dwindled fat reserves and external food cache. So what next?

Here’s what’s next. They enter into their dens and begin hibernating when winter approaches with full force. By this we mean that they tame down many physiological processling like breathing rate, metabolic rate, heart rate, and body temperature.

All these bodily functions consume a lot of energy and can account for a chunk of the energy expended on a normal body and on a normal day.

By significantly cutting down on these rates, through hibernation; triggered and controlled by several hormones secreted by glands in the body, animals are able to significantly reduce their energy expenditure on a daily basis and on the long run.

Reduction of these activities also means that animals become totally oblivious to their surrounding. Their senses no longer care whether it’s winter or summer, hot or cold, and whether there are predators on the outside and competitors to struggle with, they’re simply transitioned into a state of suspended animation, just like robots without a power source.

Their only taste to the bitter side of mother nature is when they prepare for their obligatory periodic arousal.

All hibernating animals must awaken every now and then and transition their bodies into euthermic condition (a normal body condition). This can happen as often as 2 to 3 days as observed in the arctic marmots, or every two or three months as observed in some hibernating bears.

This periodic arousal on a very frequent schedule consumes a lot of energy. Indeed, studies found out that nearly 60 to 80 percent of the energy generated directly generated from fat reserves or indirectly from food caches of hibernating animals goes to this arousal.

Some say that this arousal is necessary to in order to prevent infections from eating up the animals as they hibernate. Others are of the opinion that the arousal is necessary in order for the animals to pay up their sleep debt accumulated while hibernating, or that animals must awaken in order to eat defecate and perform other crucial biological processes.

Whatever the case may be, time and future researches might eventually tell.

More interesting articles

Cite this Article (APA Format)

Bunu. M. (2020, June 24). How does hibernation help animals survive?. Retrieved from

Leave a Comment