What seems to be every weekday at 17.00 sharp, they make a circle around my house with ultrasonic speed. Today I managed to get a glimpse of one - maybe it is just one.
I am quite certain about this. The birds in the two trees opposite my terrace have a lot to say and fly arrends of all kinds, always busy as if they were up to something. Very cheerful.
The silence of my house:
"What is that sound?" friend said and then exclaimed: "Oh, now I know! It is me breathing."