Then they were gone - NOT amateur radio

Until a few weeks ago, the skies were filled with the sound of swifts screaming overhead. Then, one day you realise they are no longer here. A few stragglers may still be around. Indeed, we saw a single one in Norwich as few days ago, but most have flown south after warmth and insects. They fly thousands of miles returning next April or May. To me the sound of swifts overhead is archetypal English summer.

See https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/swift/