When we think about hibernation, we imagine wildlife sleeping over winter, ready and restored in spring. But hibernation is in fact closer to death than sleeping, because it involves the functions of the body to be reduced quite a lot. For example, body temperatures drop, hear rates decrease to only a few beats a minute, and respiration slows so there are only a few breaths over the space of a couple of minutes.
However, it’s not just a catch-all term for every animal that go dormant over the colder months. In fact, there are only three mammals in the UK that are true hibernators. These are hedgehogs, bats, and dormice.
They’re true hibernators because strictly, hibernation is restricted to winter. Hibernations takes place to help the mammals to conserve energy during a time period where resources are low. This allows the mammals to use their stores of energy much slowly than if they didn’t hibernate.
Though the term hibernation is used interchangeably, ‘torpor’ is perhaps the term that is often referred to. Torpor is ‘a state of physical or mental inactivity’, which is dormancy with many interruptions. Amphibians enter torpor, which is like a semi-hibernation because it takes place for a shorter period of time.
Similarly, insects and sometimes fish and birds, enter a state called diapause. This is a period of ‘suspended development’. This can be triggered by changes in temperature, daylight, or availability of food and nutrients.