At last I've figured it out though. I had an unreliable doorbell so I put in a cheap PIR sensor from eBay that sounds when anybody approaches the door. I replaced the doorbell with a Ring one which is reliable but some delivery people use the knocker instead and I don't always hear that so the PIR remains.
I've had litter blow around and set it off but it has been going off regularly the last few days and I couldn't find the reason until I spotted Mr. Blackbird. The olive tree out front has fruited again and the ripe berries are falling so he comes feeding regularly. They'll soon be gone so I won't unplug the PIR sounder. I'll just forget to reconnect it.
Love it..
My Olive Tree died over the harsh winter.. It was only a few years old so quite established..
They had a Ring door bell on QVC the other day, sounds simple to set up (she says :smiley: )0
I got mine on a Prime day. I went for the mains power one as they are much cheaper than the battery ones and I already had some wiring in place that I could use. It just needs Wifi and announces rings on an app and or Amazon speakers and screens. Setup is just following instructions. Living on a busy road makes the motion detect unusable.