Flock

Popped out to try and capture some (more) wondrous light on water - the joy of autumn.  When suddenly this great mixed flock of all sorts of birds whirled up in a protective spiral squawking for dear life. I could see no reason for this unusual behaviour and then a fighter jet screamed out of nowhere and disappeared behind the hills before I could even turn my body.  This is the gulls settling and calming themselves after it had passed.

Not actually the best photo I took today but I'm posting it in case any birding blippers know if birds react like this to the approach of low flying jets?  It certainly seemed to me that they heard or felt it long before I did.