The plane trees in public places are often cut back harshly and as a result they develop these knots at the end of their branches. And sometimes the knot is a bird.
Those three birds (crows I think) were coming so fast overhead that all I got was this shot. At the time I thought: “Threes! Thursday Trios!” but swooshhhhhhhhhhhh and they were gone. I still like the photo in a weird kind of way.