January 2013
Now in the depths of the northern winter, we are all struggling to keep warm and free from illness. Nature outside our house walls is doing the same, and its resilience is testimony to the wonderful array of adaptations that exist out there to do just that. However cold the air gets, the soil just about 30 centimetres down remains about the same temperature all the year round. So many animals, such as earthworms, slugs and ants know that and dive down into the depths of the soil to escape the cold and ride out the winter. If there is a mild spell, some of them come back up and take a breath of fresh air before going back down again when the cold returns.
Deciduous trees have shed their leaves and carpeted the ground with a warm blanket of nutrients which provides food for fungi and bacteria. Micro-organism bodies in huge numbers generate heat which in turn keeps the roots of the tree warm, and the waste products of decay provide food for the trees in a wonderful process of recycling. The roots of the tree will continue to grow in the winter while its naked branches are mainly dormant. However, look closely and you will see the buds and in many cases catkins forming ready for the spring. The colour of the trees seen from a distance will change over the course of the winter as this physical metamorphosis occurs. Winter flying moths with antifreeze in their blood will mate and the females (often wingless) will climb the trees of their caterpillar days and lay their eggs on the base of these buds so that their caterpillars, when they hatch, can burrow into them and feast on the developing leaves in due time.
Hedgehogs, dormice and bats will hibernate, with slow heartbeat and low body temperature. But true mice, otters and most other mammals will remain active searching out food in their warm winter coats grown especially for the season. The coat of the stoat will often turn white and it will live up to its Latin name of Mustela erminea. The pelts of these animals used to be prized for their softness and warmth. Thank goodness we no longer steal them from their rightful owners who are allowed to live and hunt in peace, feeding mainly on rabbits whose numbers would be even greater without stoats. Perhaps the greatest wonders are the small birds such as wrens and blue tits who, at about 10 grams, survive by making body fat and growing warmer feathers.