Many animals adapt their behaviour during the winter by hibenating or overwintering. Insects and birds, for example, hibernate.
The marmot is known to hibernate. From the end of September, it takes refuge in its burrow and sleeps soundly until April. During this hibernation period, it is in a "comatose state": its heart beats 5 times per minute and its temperature drops to around 10 Celsius (the temperature may somewhat vary, depending on the ground temperature).
Overwintering = spending the winter in a sheltered hideout
Hibernation = spending the winter sleeping