One way of facing the cold winter months in the Alps is by going to sleep. As soon as days turn shorter several animal species in our mountains go into hibernation, only to become active again during spring when days are warmer, the snow has melted and more food is available. Alpine marmots (Marmota marmota) for example are known to sleep for six months a year!
No way of waking up a hibernating marmot
As soon as daily temperatures drop below 12 degrees Celsius, alpine marmots will hide in their underground burrows. Their hibernation starts at the end of September, and they’ll wake up six months later, at the end of March, missing all the difficult winter days. A marmot’s sleep in hibernation is so deep that you won’t be able to wake it up, even if you tried! Its heartrate drops drastically (it only beats five times per minute) and its body temperature drops to only ten degrees Celsius. Whilst hibernating a marmot loses quite a bit of weight. An alpine marmot that goes into hibernation weighing about 5,3 kilos, will in the beginning of spring only weigh about 3,5 kilos. It will have lost a third of its original weight!
Other hibernating mammals
Marmots aren’t the only mammals that go to sleep in winter. Hedgehogs (Erinaceus europaeus) will search for shelter in mountain villages where they find hiding places in gardens in for example piles of firewood. Several species of bats and dormice, like the fat dormouse (Glis glis), garden dormouse (Eliomys quercinus) and hazel dormouse (Muscardinus avellanarius) also spend their winter days sleeping. But not all of them find shelter outside, some of these little critters prefer to stay indoors; in old barns, stables, mountain refuges and even in people’s houses. Garden dormouse, for example, can be noisy little guests. When awake these small dormice are very social and very noisy, and they are mainly active at night.
Insects, amphibians and reptiles
Animals whose body temperature varies with that of the environment (often called cold-blooded animals, like insects, amphibians and reptiles) also rest during the harsh winter months. But this isn’t called hibernation. Insects for example will go into a state which is called diapause. Just before winter, when the days are getting colder, many insects will hide for example in a small crack of a tree trunk and their bodies will function very, very slowly. Most amphibians and reptiles spend winter hiding away in the ground or in the mud. They’ll become active again as soon as temperatures rise in spring.
To be continued…
This blog is part of a series in which I discuss some of the extraordinary strategies and adaptations of wildlife coping with winter in the Alps: