Why do animals hibernate?

Whilst some grow thicker fur or fly south for the winter, quite a few choose to hibernate instead. Hibernation is when an animal falls into a very deep sleep for either a few hours or, more commonly, a few months; this all depends on the species, their size, the time of year and the extent to which their environment has changed.

Hibernation is actually an extremely scientific process so don your biology hats if you want to know more! Well, not exactly; I guess the most important element to note is the preparation. In fact, preparation is vital if hibernation is to be successful. As soon as the animal (and I'll list some soon I promise) begins to detect a change in the temperature; when it begins to feel cooler, will he/she start to prepare. By this, I mean with the building of dens, tunnels and nests, or by finding a spot in a cave to nestle into. As well as this, the animals will also begin to eat more foods during the changing months to fatten up their bodies and they will store food within their hide-outs too.

And then onto the extra cool bit: during hibernation the body temperature lowers and almost reflects the colder temperature outside; the heartbeat and breathing slows right down, as does the animals' metabolism - all of this is to save energy. Some animals will wake now and again during hibernation to eat, drink or even stretch - this is perfectly normal.

There are quite a few animals that hibernate over the cold, winter months: here's three for thought:


Bears don't fully hibernate, but they can last for 100 days without eating or drinking. There are only four types of bear that do this: the American black bear, the polar bear, the brown bear and the Asiatic bear.



The bat also doesn't fully hibernate, especially as many of the females are woken to discover they have been impregnated during this time of sleep! Oh dear! In fact; the bat, the hedgehog and the dormouse are the only British animals to hibernate persae.


Queen Bumblebees

An interesting one that many of us don't think about: the queen bumblebee. The queen is the only bee to survive when the temperature drops; the male and worker bees die off. She also hibernates for six to eight months in places, such as rotten tree trunks and holes in the soil.

I always try and end my answers with a bit of useful information and, for us Brits, where we only have to worry about bats, hedgehogs and dormice; that is try not to approach and wake a hibernating animal. It's critical that we leave animals alone when they are sleeping as we could seriously harm them, or even risk their lives!