My geese and the shiver pass together. It is autumn, late autumn, and winter is no longer imperceptibly snapping at our heels. Its clawing fingers have finally gripped. I know there will be a piercing frost tonight. I pray that the rooks still gleaning manna from the barley fields are well prepared; bad luck for the hungry barn and tawny owls – I know that at least some of the wood mice have moved indoors. Like the robins and the blackbirds, the shrews have no choice: they have to keep going whatever the season, bound to the treadmill of twitching out from the dark confines of the leaf litter their own body weight of invertebrates every day.
The squirrels are well stocked up and these last, straggling goose arrivals will have joined the vast flocks that are gorging on the late spillings from combine harvesters on the stubbles of the Black Isle. A final few ash leaves gyrate silently to the yellow carpet of their own design. The crinkly oak leaves hang stubbornly on, only reluctantly releasing when winds scour through. And the silky-haired beech leaves will rattle like crisps until the spring when the new growth will finally force them off.
As I return to the house I see wood smoke pluming from a chimney. Lucy has lit the sitting-room fire, a sight that brings an inner glow and a smile to my tingling face. As the darkness closes in I shall repair to my old armchair with a book. The Jack Russells will yawn and sigh as they stretch themselves across the hearth rug at my feet. Winter brings blessings of its own.
3
So Great a Cloud of Witnesses
Wherefore seeing we also are compassed about with so great a cloud of witnesses . . . let us run with patience the race that is set before us.
Hebrews 12:1
Those few last geese to arrive from the Arctic, straggling down from the great heights at which they travel, often many thousands of feet, are special to me not just because I love to catch their excited voices on the wind and see their silhouetted chevrons against the clouds, but because they are living, crying witnesses to nature’s biorhythms present within us all.
We all migrate. We venture out and we return home. We send forth our young. The winged seed spiralling to Earth from a sycamore or an ash; the rowan berries ingested by Scandinavian fieldfares and redwings are cast to the hills; the lonely ‘outcast’ badger that dug himself a temporary home among the roots of one of our western red cedars last year; the spiders I witnessed ballooning down the wind on their silk threads; the rooks and jackdaws I was watching this afternoon, surfing the wind over the river fields; the swallows and house martins swooping low into the stables each spring; the salmon surging up the Beauly River to spawn every summer – all of these and myriad more organisms around my home, around all of us all the time – are responding to the secret codes emitted by the sun and the spinning Earth, received and processed to serve each species’ individual ends. ‘So great a cloud of witnesses.’
They’re heading out, patiently running the race their needs have set before them. They all need to feed, to breed and to survive, like surfers riding the waves of Fate. I, sitting tapping these words into my laptop, and you, reading them – whoever we are, wherever we may be and whatever our private pretensions – are also part of that same grand opera: the pull of life’s imperatives. We migrate, whether a few yards before finding a suitable place to put down roots or circumnavigating the globe, like the Arctic tern, which travels ten thousand miles to the Antarctic and back again every year, patiently making the most of our lot, our personal shout at the survival of ourselves and our species. That’s what migration is.
These days we understand it – at least, quite a lot of it. Seasonal bird migration in particular has been well and widely studied. We now know, for instance, that migration can be triggered by temperature, by length of daylight hours, by weather conditions and by diminishing food supplies, but we also know that it is genetically controlled. Glands churn and swell, hormones swirl. The imperative to get up and go when we need to is written into the electrochemical circuitry of human brains as well as bird brains.
In the case of geese, intricate studies have demonstrated that their innate circuitry and navigational skills are added to year on year by experience. Old birds get canny: they learn to read the wind. They know exactly the right moment to head off, and the youngsters follow. I’ve always loved the expression ‘wise old bird’. It’s never truer than of mature geese, sometimes individual birds that have made their twice-annual trek more than fifty times. A ringed (banded) snow goose hatched in Alaska and wintering in Mexico has been recorded still migrating at twenty-six years old – that’s more than 130,000 miles of reading the wind. I ask myself just what huge range of conditions and changes, trials and close-calls lurk behind the twinkle in that wise old bird’s eyes.
We also know that different families of birds respond to and navigate by different signals, reflecting each species’ needs and capabilities and determining their route and destination. Experiments in planetaria have proved that some Silviid warblers, such as the blackcap, are genetically wired to navigate by the stars, requiring them to migrate at night. Artificially exposed to different seasonal constellations, caged birds become restless and flutter to the north or south, according to their migratory instincts. Other species can detect the Earth’s magnetic field or memorise significant landmarks, such as coastlines, river valleys and mountain ranges. Yet others follow the sun, demonstrated by German ornithologist Gustav Kramer’s 1950s experiments with caged starlings. Most significantly, he proved, with mirrors and artificial cloud effects, that it wasn’t direct sun they required, but that sufficient light intensity was all they needed for the correct orientation – an important ability for birds since the sun is so often obscured by clouds.
One of the most remarkable experiments in bird navigation was conducted by my late great friend Ronald Lockley, a real pioneer of ornithological research and author of the ground-breaking monograph Shearwater (1946) – a study of Manx shearwaters nesting on the island of Skokholm off the Pembrokeshire coast of Wales. He took mature birds from their nesting burrows, then shipped them off to Venice and to landlocked Basel in Switzerland, many miles from any normal shearwater habitat or migratory route. They were back in their burrows fourteen days later.
Another bird was flown across the Atlantic to Boston, Massachusetts, some three thousand miles from home; a starting point completely unknown to that shearwater species. It took just twelve days to arrive back on Skokholm. What Lockley’s experiments proved conclusively was that shearwaters must use navigational aids other than landmarks. What we now know is that birds often employ a combination of abilities: stellar, solar, geo-magnetic and geographical recognition, to locate themselves and return to precisely the same wood, moor, field, tree or bush, swamp, stream, burrow or cranny they departed from many months before. Our swallows swoop home from Africa to the rafters of their birth through the same door in the same stable at approximately the same moment, year after year. Nowadays we know so much that we take bird migration for granted, but it was not always so.
In the early sixteenth century the Bishop of Uppsala, Olaus Magnus, was convinced that swallows and other similar birds spent the winter months under water or in deep mud. In his Historia de Gentibus Septentrionalibus he goes so far as to cite