Redwings

Last night at about 11pm after checking the outside light for moths, I stood outside in the garden for a while admiring the moonlit and almost windless night. I started to hear faint "zzweep" calls - I though at first it was a Robin which had woken up, then realised the sounds were coming from several directions. It took a while for the penny to drop - migrating Redwings! I had read so much about this phenomenon but never heard it. I rushed indoors, switched on the PC and checked with Xeno-Canto - yes, the sound I was hearing was exactly right. I went back out and could still hear the sounds - but so frustrating not to be able to see anything or count anything or even work out which way they were going! And of course it was a perfect night for migration.