species with static young in a nest must be able to find its way back over distances appropriate to that species. But a quarter of a mile? That seems absurdly adventurous for even the most ambitious mouse foray. And yet I know very well that I shouldnât allow myself to be surprised by this amateur circumstantial evidence of my own concocting.
Lucy once had a Labrador dog that was accidentally left behind at a friendâs house some ten miles in a straight line from home. But those ten miles included crossing the Beauly Firth, a tidal estuary more than two miles wide, or a circumnavigation round the end of the Firth, increasing the journey to more than twenty miles. Frantic searches in the vicinity of the friendâs house revealed nothing, but twelve hours later the old dog turned up at its own back door, wagging its tail. It was remarkable enough that he knew his way home, but that his homing instinct had caused him to swim across open sea or had taken him many miles in the wrong direction if he had gone round also seems to indicate some powerful impetus at work. I marvel at animal behaviour but it never surprises me. Nature has had a long time to hone its secret skills.
Throughout the spring and summer, these engaging little mice are more than happy to live in the woods and fields where they belong, and are one of several small mammal prey species upon which so much of our wildlife depends. Tawny and barn owls, foxes, badgers, wildcats, pine martens, stoats and weasels, buzzards and kestrels, even herons, crows and brown rats all eat wood mice when they can. With bank and field voles, they are the staple diet of our owls. Without them the owls would perish and disappear altogether. But the wood mice are hard-wired to find a warm, dry place to nest for the long cold months. We have generously provided them with an endless selection of choices: garden sheds, byres, stables, garages but, best of all, centrally heated houses, often with a fast food supply readily tipped in for good measure.
In this old house (some bits are eighteenth-century and earlier) the thick outer walls are of large round whinstones of hard metamorphic schist gathered from the fields and burn beds, heaved and levered into position by men with aching shoulders and rough hands, whose craftsmanship was passed down from generation to generation. However skilfully the Gaelic-speaking Highland masons placed these stones to create a handsome vertical wall on the outside, there were always hollows and gaps in the interstices that had to be packed with lime mortar to hold everything together. Inside the walls, which were always two or more large stones thick (up to twenty inches), there were spacious cavities loosely filled with end-of-working-day lime tossed in, along with any handy rubble. (While plumbing in new heating I once found a George I halfpenny dated 1718 in one of the walls â Iâd treble your money for your story, Mr Highland Stone Mason, if only I could.) Lime mortar doesnât clench in a rigid chisel-resistant grip, like cement: it sets yet remains friable and crumbly, like damp Demerara sugar. Any diligent mouse can scrubble away at the weaknesses and burrow through.
Once inside the thick old walls, the mice enjoy a labyrinth all their own. They can go where they please. They travel through the hollows, up, down or sideways, as safe and secure as any city metro system. Modern insulation makes perfect bedding for a wood mouse â warmth and comfort laid on. At night I lie awake and hear them scuttling back and forth in the roof, up and down the ancient plaster and lath walls and occasionally popping up inside rooms. Fromtime to time I see them nipping out from under the kitchen units to sample left-over meal in the Jack Russell terriersâ bowls â a source of constant frustration to the dogs, which charge, skidding across the vinyl, to crash land among the bowls, always far too late.
We are lucky: our neck of the