BACK DALE

Derbyshire, England

The sky was intermittently blue and weak sunshine sparked a faint chorus of grasshoppers. Otherwise, this was a landscape wrung dry of all summer and the grasses were grey, the thistles dead. The only sounds were the notes of young buzzards, suffused with a sense of melancholy.

There were seven birds – adults and immatures – careering at one another in mock squabbles, or they would flap with deep rhythmic wingbeats, before paddling up on the bluffs of warm air. Perhaps it was the way their movements perturbed the currents, but 50 house martins and swallows circulated among them. It was a glorious gyre of different flight modes.

Then I spotted the swift. It must have been a lone Scottish breeder or a Scandinavian migrant drifted to these islands, alone and detached from the movement of its kind, much of which occurred in late July.

House martin flight is beautiful and quick, and the strokes not easily countable, but in swifts you barely register wingbeats at all, each swerving into the blur of the last. If an absence of straight lines defines nature, then swift flight is its apotheosis. My bird jinked left and right, repeating the twists seven to eight times, as if there were invisible obstacles and the bird must plot a tight route through all that free air.

With each bend of its path, some insect was also being snaffled by the bird’s immense maw. A parent can take prey like this, one after the other, until an invertebrate ball, adhering as a bolus in its sublingual pouch, can number 1,000 items. Swift flight is precise and practical, but also purer than in any other bird; watching it feed among martins was like seeing a wolf hunt among dogs. It was a joy to savour it one last time until next spring.