The four seasons don’t always work in nature

I LOVE the autumn and in the part of the countryside I live this is a particularly fine one. The Indian Summer is lingering on even into November, which will help to shorten the winter.

Dividing the year into four seasons can be useful, but it’s an artificial concept that doesn’t always work in the natural world. Snails, for example, seal up their shells and go into a sort of hibernation in mid-winter. But if we get a period of hot and dry weather in the summer they do exactly the same thing. This is aestivation.

True hibernation only occurs in warm-blooded creatures, and snails, which are molluscs, are not warm-blooded so they don’t really hibernate. Because there are no bird species that are known to hibernate, the habit is confined to mammals, and not many mammals at that.