garden. This time it took a week, but back he came, straight into the trap, proudly showing off his tell-tale smudge of oyster-shell pink. I was left scratching my head, pondering the mysteries of animal behaviour. Just how does a mouse, two inches high and six inches long, find its way over a quarter of a mile of what, presumably, must have been entirely strange and hostile territory? Is it scent? (We know that a male moth can detect a female’s pheromones up to a mile away.) Or is it some electro-magnetic homing compass we don’t properly understand? It seems entirely logical that any foraging 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 shouldn’t 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 friend’s 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 friend’s 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 – I’d treble your money for your story, Mr Highland Stone Mason, if only I could.) Lime mortar doesn’t 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 – 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. From time to time I see them nipping out from under the kitchen units to sample left-over meal in the Jack Russell terriers’ bowls – 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 Highland woods does not have the very destructive and invasive house mouse, Mus domesticus, originally an alien species from Asia, trans-located all round the world by man, and the progenitor of all pet and laboratory mice, which can carry unpleasant diseases such as leptospirosis, typhus and meningitis – even bubonic plague. They are present in the Highlands, but mainly restricted to the grain-growing areas of the east coast and to towns and cities such as Inverness. Happily, they don’t venture up the glens. House mice will gnaw through just about anything: lead and copper pipes, electrical cables, plastic, woodwork, plaster, skirting-boards and structural joists, even limestone.
Our wood mice, alas, are not entirely blameless: they delight in shredding polystyrene pipe insulation, and if they elect to nest in a wardrobe of stored clothes their actions can be very distressing. By comparison with house mice, though, the damage they do is slight. They are very clean living and are not known to transmit disease. When I find their nests in the woods, exquisitely crafted balls of grass, moss and leaves, often lined with sheep’s wool, there is virtually no smell.
Years ago I brought some reindeer skins back from an expedition to Lapland. I thought they would make cosy bedside rugs for our growing family, but I was wrong. Reindeer fur has a fine woolly undercoat but the outer fur consists of longer, hollow, air-filled hairs for efficient insulation in an Arctic climate. These hairs are brittle. The regular passage of children’s little feet broke the outer fur into a constant fall-out of shards, which stuck to everything, itched in their socks, clogged the vacuum-cleaner and drove their mother to drink. The pelts were banished to a cupboard in the cellar, securely contained (we thought) in sealed polythene bags.
The wood mice said, ‘Thank you very much.’ It took them no time at all to find the bags, nibble in and rearrange the rolled-up skins to their liking. Several months later, one of the field centre’s education officers needed a piece of reindeer fur to demonstrate the efficiency of natural fur insulation to some visiting school-children. I opened one of the bags and was astonished to find that large patches of the pelt had been shaved clean down to the leather and the removed fur, both woolly and brittle, had been skilfully woven into an orb-shaped nest the size of a cantaloupe melon. On pulling it gently apart I found that the hairs had been systematically sorted and separated: the long hairs for the structure of the ball and the softer wool for the inner lining. The inside of the nest issued the essence of fertility, like leaf mould, making me think of wood anemones and unfurling ferns in spring – none of that uric rodent reek I remember from keeping pet mice as a boy. I was sorry I had disturbed it and put it back carefully, glad that they had found a use for the reindeer skins and happier to have them living in the cellar than in my wardrobe. It would be hard to imagine a warmer, cosier or more secure winter refuge from which to produce a family.
* * *
As I walked back to the house from the rookery, the unmistakable yelping chorus of geese floated to me on the damp air. I stood still and squinted into a sky of dulled metal. They were high, just below the ruffled cloud base at around three thousand feet; it took me a moment to locate them. There they were, in an uneven V-formation, shifting and flickering in a large wavering skein of tiny silhouettes, like flies on a high ceiling. I shivered. Not a shiver of cold – I was well wrapped – but a shiver of deep, transcendental unity. No sound in the world, not even the rough old music of the rooks, etches more deeply into my soul than the near-hysterical ‘wink-winking’ of pink-footed geese all crying together high overhead. It is a sound like none other. Sad, evocative, stirring and, for me, quintessentially wild, it arouses in me a yearning that seems to tug at the leash of our long separation from the natural world.
Their arrival in the early autumn sets a special seal on the turning year, repeated again with their departure, back to their Arctic breeding grounds in the spring when the last few rise, with rattling pinions, and wheel away into the north. Autumn or spring, I never tire of their unrestrained dissonance, which surrounds us during the winter months when tens of thousands of grey geese gather on the Beauly Firth. Scarcely a day goes by without a skein or two passing over, or when we go east to the Black Isle, the moist coastal fields are always cluttered with their corn-gleaning and grass-plucking flocks.
It seems that naturalists (and perhaps not just naturalists) need these sounds to help us locate our passions, to ground us in