For a few more days, the screaming summer overhead. Then, almost overnight, silence. Sometime in the last few days — maybe without you noticing — the sound over your street started to change. That high, screaming chatter that's been there all summer, the one you stopped hearing weeks ago because it was simply always there. It's thinning out. Soon it will stop completely. Common swifts are leaving. Not in a slow trickle, the way some birds drift south over weeks. Swifts go fast, almost all at once, and almost without warning. One evening the sky above the rooftops is full of them, scything back and forth, screaming at each other in tight, fast circuits. A few evenings later, it's just sky. They are among the very first migratory birds to leave Europe each year — long before the swallows gather on the wires, long before the storks line up over the meadows. If you want to see them, this is genuinely it. Not "sometime this autumn." This week. A bird that is almost never still Watch a swift for a moment and you'll notice something odd: it never seems to land. It doesn't perch on wires like a swallow. It doesn't hop on the ground like a sparrow. Its whole life is built for the air — long, narrow, scythe-shaped wings, a body made for cutting through it at speed, and almost nothing else. That's not poetic exaggeration. A swift really does spend most of its life airborne. It eats on the wing, snapping up insects mid-flight. It drinks by skimming low over water. It even sleeps in the air, in short shallow glides thousands of metres up, switching off one half of its brain at a time. The only time a swift voluntarily touches anything solid is to nest — and even that happens high up, in a gap under a roof tile or inside an old wall, never on the ground. Some individuals, once they leave their first nest as fledglings, won't land again for nearly a year. They will cross deserts, follow weather systems, skirt entire mountain ranges — all without once resting their feet. Why the sky empties so suddenly The abruptness is the part people find hardest to believe. Surely a bird this common doesn't just vanish overnight? But that's exactly the swift's strategy. It arrives late in spring and leaves early — its whole European stay lasts barely three months, just long enough to nest and raise one brood of chicks. The moment the young are flying and the insect season starts to turn, there's no reason to stay. So the whole local population lifts off together, riding the same favourable winds south, and the rooftops that were full of screaming and wheeling birds are simply, suddenly quiet. It can feel like a small loss when it happens. The street sounds different. Something that was part of every warm evening is gone until next May. Where they're actually going Swifts that nested across Europe this summer are heading for sub-Saharan Africa — a journey of many thousands of kilometres, made entirely on their own wings, with no map but the one built into them. They won't stop there to rest the way you might imagine. They'll spend the European winter the same way they spent the summer here: in the air, hunting insects on the wing over equatorial skies, following the weather and the food, never quite landing. Then, next spring, with no real fanfare, they'll be back — often to the very same nesting gap under the very same roof tile, sometimes for ten years or more in a row. It's one of the quieter miracles of the bird world: a creature that barely touches the ground still finds its way home, year after year. What to do with the next few evenings There isn't a guidebook trick for this one. No feeder to put out, no special hour that guarantees a sighting. Just this: in the next few evenings, when the light starts to go golden and soft, look up. Find a patch of open sky above rooftops, a square, a stretch of street with some height to it. Watch for tight, fast, scythe-winged shapes wheeling and calling. If you see them, you're watching something that's about to disappear for nine months — a bird that has been over your head, unseen and unheard by most people, for an entire summer. By the time you read this, some of them may already be gone. That's not a reason to feel you've missed it. It's a reason to look up tonight, just in case — and to remember, next May, to listen for that scream returning to your street.