I didn't mean to imply it was the same bird. That would be really unlikely, not only by the time, but also the different place i live in now. Just that it remembered at least my signal yellow wind jacket, and deemed it worthy to come down from the high up swarm alone and doing aerobatics for a few seconds while making untypical sounds in front of my face.

Why else should it do that(alone), apart from its swarm maybe 50 to 100meters up, not coming with it?

So what i meant to say was rather something like they(wild Birds in general) do remember you, even though not being grown up with/by humans.

Maybe it was morphic resonance.

I assumed that was “a few days later”, a second swift, not the one from 30 years earlier.

I believe OP was referencing the bird rescued when coming back home, which came back a few days later, not the one 30 years ago which OP never saw again.