The Snow Geese by William Fiennes

driver in conversation, but he didn’t respond; he was deadly graveyard serious on all matters of road safety. Behind me, a younger, dark-featured woman, dressed in an orange tracksuit, had immersed herself in a paperback entitled
Blues for Silk Garcia
, and across the aisle sat a burly man with a ponytail falling across his chest, black hair fanning out on a T-shirt that read,
Since I Gave Up Hope, I Got Much Better
. Behind him, through a gap between headrests, I glimpsed a woman in small, round, wire-framed spectacles, stroking the head of a sleeping baby.
    The toothpick clamped in the driver’s teeth pointed north up Interstate 35 like a compass needle. The coach hardly wavered from its cruising speed. Freightliner, Eagle and Kenworth rigs with sleeping cabins and gleaming silver chimneys drew level with the Greyhound, then accelerated past, hauling Utility, Stoughton and Great Dane freight containers. There were other Greyhound and Jefferson Lines coaches in the current of the highway; recreational vehicles with the names Jamboree, Chieftain, Prowler and Nomad splashed on their creamy white foreheads and mountain bikes lashed to their backs; state trooper cars with four trunk aerials bending backwards like grasses in the apparent wind; entire prefabricated houses proceeding with due caution along the inside lane; and station wagons, trailers, vans, jeeps, pickups, hatchbacks, sedans – the hard c sounds of American traffic: Mack, Cadillac, Pontiac, Camry, Buick – with mottoes (
Grace Happens!
) on rear fenders, and dogs leaning from open windows, nosing the windspeed. Stars and Stripes of immaculate parachute silk rippled at the gates of lots and salerooms. A great blue heron lifted from a marsh. A flock of ten or twelve ducks flew alongside us in compact formation, a tiny clutch of the millions of birds that were moving towards Canada with the spring, subject to circannual rhythms and Zugunruhe, far outnumbering the people in vehicles passing Denton, Gainesville, Marietta and Ardmore on their way to Oklahoma City and all points north.
    These birds possessed compasses as well as clocks. In 1949 the German ornithologist Gustav Kramer had observed young migrant starlings in an outdoor aviary. Kramer was interested in their ability to navigate. ‘Such a conspicuous phenomenon as the long-distance flights of birds,’ he wrote, ‘has profoundly penetrated into man’s consciousness, and it is a very simple further step to ask how they find their way.’ At the end of the summer, Kramer’s starlings, which came from the Baltic region, exhibited ‘a distinct tendency to migrate south-west’.
    The following year Kramer transferred these birds to circular pavilions in which vision was limited to six windows, distributed symmetrically round the compass, with landmarks carefully excluded from view. Mirrors were mounted at each of the windows, reflecting sunlight into the cages at ninety-degree angles. The drum-shaped pavilions rested on transparent Plexiglass bases: observers lay underneath, looking up at the birds, recording their behaviour.
    The starlings displayed Zugunruhe at the appropriate time, with a tendency to hop towards the north-east, the appropriate direction for spring migration. Then, by manipulating the mirrors, Kramer changed the apparent direction of the sunlight. The starlings changed direction accordingly: the birds were using a sun compass. Such a mechanism, Kramer noted, could not be effective without an internal clock. The sun’s position relative to a point on the Earth changes by 15 degrees every hour: the starlings must have some way of compensating for this apparent movement. ‘The migratory activity on some days lasted for six hours,’ Kramer wrote, ‘from the early morning until noon, which corresponds to a movement of the sun through about 90 degrees; yet the bird’s direction remained unaltered.’ He christened one of the starlings Heliotrope, like the flower, from the Greek for