I was taking the trash out when my attention was caught by a flock of pigeons, circling. They were circling the same space--not a holding pattern sort of circle, but a dramatic swooping flight, high on one end, low on the other, over and over, across this courtyard of the apartments next door, making a circle maybe a hundred feet in diameter, at least fifty or sixty pigeons in a flock, just...circling. For no apparent reason. Occasionally a little wedge of birds would get overexcited, calve off, and go at a tangent for a few dozen yards, then realize they'd broken formation and swoop back.
I watched them do this twenty or so times before I went back inside, and they showed no sign of stopping.
Pigeons are weird.