At the edge of a sheltered estuary in the Adventdalen, a valley on a cluster of islands halfway between Norway and the North Pole, a flock of arctic terns soar and wheel in the perpetual daylight.

and are waiting to regain energy for their take-off or perhaps for more birds to join them so they can fly off as a flock.” Yet another reason for the Arctic Terns’ spotting, said Mehta ...