Bird Identification: CLOSED: Strange flock, 1 by rntx22

rntx22 wrote:
While I was out shooting by the lake this am, I kept seeing this large flock of birds congregating in a very large group, swirling around for a while, and then disbursing. I would see the big group (like the one pictured) and still more birds flying in a long line to join them. This happened several times in the 2 hours I was out there. They were always so far away I could never tell what they were. I thought maybe vultures, but could there be so many?? The only clue I got was I think I heard some laughing gulls calling as they flew towards the group, but they may not have really been going to join it. I know it's hard to tell from these photos, but has anyone ever observed anything like this?