Ornithology

It happens usually in the second week of May, between about the 8th and 12th (this year it was earlier, the 2nd): a distant sound, building as it approaches, and then the doppler dip as the first of the returning swifts screeches past the roof of our Cornish farmhouse. It’s the opening bracket of the summer months, one that closes with their departure just 12 weeks later. But it is a reminder, too, that while we might think of our house as home to two adult humans, two teenagers and a dog, it is also the habitat for several nesting swifts, swallows, house sparrows, pipistrelle bats, mice, occasional winter rodents

Bird migration was once one of those unassailable mysteries that had baffled humankind since Aristotle. A strange hypothesis, genuinely advanced in the early modern period, was that birds flew to the Moon for winter, and barely more credible was a notion, which haunted the patron saint of British naturalists Gilbert White, that swallows buried themselves in mud. A modern understanding really began in the 20th century, when ornithologists started to place numbered metal rings on birds’ legs. Scott Weidensaul is one of many researchers worldwide who have helped to map this avian story. He then captured the findings in his Pulitzer-nominated Living on the Wind (2003). Yet he was also