Reports in the press of daffodils and forsythia flowering in Yorkshire gardens, magnificent hazel catkins glowing yellow along the Addingham by-pass, and everyone saying we haven’t had a proper winter. That was last week. As I write, the weather forecasters warn us that proper winter is about to hit us and it’s time to get out those little used overcoats! Wild animals which are active throughout the winter are already in theirs. As well as developing thicker coats, many show marked variation in colour during this season. Roe deer, common in and around Ilkley, change from chestnut brown in summer to a dark greyish brown, passing like ghosts through the leafless trees of our local woods. Squirrels, also, have darker pelage and longer ear-tufts – markedly so in red squirrels. But one of our commonest mammals can show a much more dramatic change.
Some stoats, those feisty little relatives of the badger and the otter, change from light brown to snowy white. It’s quite rare to see a stoat in ermine nowadays, but they do turn up in our WNS records from time to time, indeed one was reported last year. In the harder winters of the past, it must have been a useful adaptation for an animal which has to hunt down its prey of rabbits or voles whatever the weather, and which itself is potential prey for birds like buzzards or eagles. It would be virtually invisible against a covering of thick snow or hoar frost. It must be a great disadvantage now, a bright white form will be super-obvious on muddy fields and grey-brown moorland. Presumably, as climate change accelerates, animals with this particular genetic inheritance will be selected out and all our stoats will remain brown.
The other British mammal which assumes white for winter is the mountain hare. In Wharfedale we are familiar with the brown hare, but its cousin, the mountain hare, is duskier, smaller and has much shorter ears. Seeing one crouched down grazing, you might mistake it for a large buck rabbit, but, when it moves off, there is no mistaking those long legs and that graceful loping gate, so different from the rabbit’s flustered scoot. Most people have only seen mountain hares on the Scottish highlands like the Cairngorms where its white winter coat gives it perfect camouflage from circling eagles and its large furry feet provide it with efficient snowshoes. There is, however, a thriving population living on the Derbyshire moorland just south of Sheffield. I remember hearing a talk by a Sheffield naturalist who described how he and fellow naturalists do an annual count of hares each New Year – walking in long lines across the rough moorland terrain recording each hare flushed out and carefully noting the degree of white and brown in its coat.