THE SCREAMING SKY

BY CHARLES FOSTER

LITTLE TOLLER BOOKS, £15 (HB)

Every spring, swift-obsessive Charles Foster endures almost unbearable heartache during the nerve-wracking wait for his neighbourhood swifts to reappear from Africa. The UK swift population fell 41% between 2008 and 2018, and so he fears that one year they won’t return. Summer simply wouldn’t be the same without these high-octane visitors and their joyous screaming parties.

This wonderful little book is about one man’s passion for swifts (the beautiful cover and illustrations are by another ‘swift nut’, Jonathan Pomroy). It’s full of science but also wonder, because nothing about these birds is ordinary. As Foster wryly observes: “Self-esteem is hard when you look at swifts.”

We learn that at dawn and dusk they ascend to 1,800 metres, maybe to socialise or recalibrate their internal compass; that as the adults shoot into their nest cavity and come to a sudden stop, their tiny toes endure a “seemingly impossible” pressure of 40kg; that fledglings are ready to migrate at just 43 days old; that they comfortably fly 36,000 miles a year.

Foster perfectly captures the strange magic of swifts, as he tries to imagine what it’s like to be one. He points out that their screams, which thrill us on balmy evenings, must sound very different to their ears: more like hens clucking or old men muttering. Ultimately, he says, the wildness of swifts is what makes them special. It’s for the best that we don’t understand everything about them. We need them to retain their mystery.

Ben Hoare, naturalist and author