THE LONG SLEEP

As the cooler weather and shorter days approach when food is less available, many animals take a break from their daily feeding and breeding activities. Although the word is strictly defined more tightly in biology, in lay terms most people call this period “hibernation” and I will stay with that overarching term. We should just bear in mind that it includes various states of torpor, brumation, and general winter dormancy which scientific terminology differentiates.

Warm-blooded animals in hibernation are able to lower the temperature of their bodies, reduce their metabolic processes and breathe more slowly, only waking occasionally, perhaps on mild days, until spring. For these, the late summer is a vital time for binge eating to increasing fat reserves or for making stores of seeds, nuts and other food for access on winter days when they are awake, so the bountiful food usually available in late summer is essential. The dramatic loss of abundance and diversity of our invertebrates that we are now witnessing will therefore have a significantly adverse impact on those, like bats, that must rely on insect food. I have already observed much less insect life over our ponds and, in the evenings, far fewer bats than I used to see in late summer.

Reptiles and amphibians (and fish), being cold blooded, cannot internally regulate their body temperature. Many consequently become dormant in winter, hiding safely underground or in the bottom of ponds and other water bodies. Metabolism thus slows and food reserves are eked out to allow survival through the cold months. 

Insects and many other larger invertebrates display a range of strategies for winter survival. The cold months may be passed as ova, larvae or pupae, or as adults in a state of minimum metabolism. Some can even survive long periods of freezing, protected by “anti-freeze” enzymes. Amongst the moths, a taxon dear to my heart that I have recorded and observed since I was a boy, several species overwinter as caterpillars, the garden tiger moth’s woolly bear larvae that I have written about before being one example. In the wild, they hibernate when they are about a third grown, then pupate in spring. Other moths, whose larvae overwinter and can sometimes be seen warming themselves up on vegetation in the sun in spring, are the fox moth, drinker and oak eggar. 

I have not mentioned plants in this little news blog, but of course most of the species of our vegetation have evolved traits for winter survival whether as perennial roots or as seeds, tubers, corms or bulbs, shedding their leaves or displaying combinations of strategies for the cold months. The phytochemical processes that drive growth of vegetation slow down for the winter in response to lower temperatures and light levels.

Given what this winter looks like having in store for us humans by way of Covid-19 and the consequences of the Brexiteers’ selfish crackpottery, I wouldn’t mind hibernating myself!

At Betts Ecology, we manage sites so that they are biologically and ecologically rich to provide the food, shelter and other resources that as many as possible of our native communities of species need to survive the winter and for ecosystems to function optimally.

 © Betts Ecology