Did you ever see the Hitchcock movie The Birds. Me neither. But I have a yard full of swallows that makes me think of it.
The mix is barn, tree and bank swallows.
Every year the swallows from this area suddenly gather in my yard. I suppose it is the old seldom used barn and all the wires since an electrical line goes around our yard on the west and the north. Also we have a couple of unused wired that run from our yard light pole to the barn. So we have the perching area needed. This is what happens. It has been this way for about a week and then one day I will go outside and it will be empty and still.
I enjoy it while I can although the car doesn't look good at all.