When I was a kid growing up in the London suburbs in the 70s and 80s I could remember flocks of all types of birds especially starlings and blackbirds being com

When I was a kid growing up in the London suburbs in the 70s and 80s I could remember flocks of all types of birds especially starlings and blackbirds being common place, and then, reading this article, it reminded me that I stopped seeing flocks. Even now, living outside London, I rarely see flocks of birds, and if I do, nowhere near as large as I remember, and I don't think its observer bias either.