I'm currently sitting watch over the nest in my back garden. Sparrows have nested where usually we have tits. I keep seeing swoops of birds flying low and fast past my windows with a big black bird on the chase. That's what caught my attention, and the reason for my taking watch is I just saw one actually fly over and bother the nest and stand around on the ground below it. It's a bird house so it's pretty substantial. One of the parent sparrows just spent ages standing on top of the bird house calling out for a few minutes. I hope the spouse hasn't been caught.
I've just googled sparrows and apparently they are pretty aggressive birds and can go for blackbird chicks so maybe I'm seeing some retribution. How stressful!