Welcome to the LRB podcast. If you subscribe to the LRB, you can get the first 12 issues for just £12. To find out more, go to lrb.me forward slash listen. That's LRB.m e forward slash listen.

Consider the Swift by Catherine Rundle.

A common swift in its lifetime flies about two million kilometres,

enough to fly to the moon and back twice over,

and then once more to the moon.

Weighing less than a hen's egg,

with wings like a scythe and a tail like a fork, they eat and sleep on the wing.

They gather nesting materials only from what's in the air, which means there have been accounts of still flapping butterflies wedged in among the leaves and twigs.

They mate in brief mid-sky collisions, the only birds in the world to do so.

And to wash, they hunt down clouds and fly through gentle rain, slowly wings outstretched.

Most remarkable of all is their night.

Swifts can find a state of unihemispheric sleep.

They shut off one half of their brain at a time,

"'while the other remains functioning, alert to changes in the wind,

"'so that the bird wakes in exactly the same place where it fell asleep,

"'or, if migrating, on the precise course it set itself.

"'The left side closes first, then the right,

"'so that it sways a little in the air as it

sleeps. Chaucer knew it long before we did. In the Canterbury Tales he wrote about

small birds who, slepen all the night with open eye. And a French pilot during the First World War, flying by the light of a full moon

on a reconnaissance mission near Roche, saw a ghostly cloud of them, apparently hovering entirely still

in the air. As we came to about 10,000 feet, we suddenly found ourselves among a strange flight of birds which seemed to be

...