The arctic tern

Bird migration is no longer a mystery — but it will always seem a miracle

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