A journey of 6,000 miles across two continents and fourteen countries is nothing to swallows: they do it twice a year. But for a writer and birdwatcher, this is the expedition of a lifetime. By trains, cars, buses, motorbikes, trucks, canoes, planes, one camel and three ships, Horatio Clare followed migrating swallows (Hirundo rustica) from reed beds outside Bloemfontein, where millions roost in February, to the eaves of a barn in Wales, where a pair nest in May.

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