Last October I was trying to get a video of the sparrows round the feeder. As if by magic all the sparrows flew away.
A second later this sparrowhawk flew in. I only caught it on camera for a few seconds. Apologies for the video being short and not 100% clear, .
This shows sparrows know when a predator is about.
I think it also shows that sparrowhawks do not only go for weak and ill birds