Tidying up the garden in preparation for winter, I came across three hibernating garden snails hidden beneath an ornamental rock. Huddled together, I was immediately struck by the attractive and intricate patterns inscribed upon their spiral shells.

One of the snails became dislodged from the underside of the stone, and as I turned it over I could see that the opening at the bottom of the shell had been totally closed off with a crust of hardened mucous so as to seal the animal safely inside and prevent it drying out. The heartbeat rate drops dramatically too so as to save vital energy. In effect, this trio of snails were as close to death as one can get without actually tipping over the edge.

The different strategies our invertebrates adopt to see them through the winter is an endless source of fascination for me. Beneath the soil, or in cracks and crevices in walls, or within a rotting tree stump, there is a whole multitude of life lying unseen. Many of these creatures don’t even exist in the adult form at all, but instead see through the winter months as eggs or larvae waiting to burst into life the following spring.

For the wasp, only the pregnant queens remain, holed up in some crevice in a wall or perhaps the attic of a house, waiting for the warmer weather and the chance to start up a new colony. Some adult butterflies too may be hibernating such as small tortoiseshells and peacocks and it is not unusual to find an individual in the corner of a garden shed or even in a bedroom cupboard. On warm days in March they will be among the first insects to emerge.

Other invertebrates, however, don’t need to hibernate and can often be seen during damp and mild spells. The clouds of winter gnats dancing over the garden lawn are always a sight that cheers the heart. And while garden snails go for the hibernation option, it is not unusual to see slugs out and about on a mild winter’s evening.

It seems rather perplexing why some types of slugs venture out in winter, whilst the related garden snail prefers to hibernate. Although it does appear that the garden snail is generally not very tolerant of the cold and in Scotland tends to be only found in the milder, coastal areas.

What is for certain is that both slugs and snails are important winter food our birds. It would be a veritable feast for a song thrush if one were to happen upon the three slumbering snails beneath my garden rock. Although many Scottish song thrushes head further south to spend the winter, there are usually a few that stay behind.

I like song thrushes, but these snails were appealing in their own way too, so I carefully placed the rock back again in its original position, making sure in particular that the animal I had accidentally dislodged was firmly out of sight from any predatory eyes.