The term 'bird brain' is used for a reason. In a manner of speaking the birds are an invasive species (they weren't there before, they're there now, they invaded). I've never understood why nasty birds (repeat NASTY) are afforded such status.
Note...birds are supposedly the direct descendents of dinosaurs. That would mean that they managed to survive for over sixty million years with no help from us. I'd say don't worry about the birds. If they die (not likely) they die.