Thanks @haphazard-hstead! I can tell you that I kept my eye on a few of these birds, looking for aggressive posturing. It's a good time of year to view them. If it was the Spring, they wouldn't have let me get this close and would have charged or flown at me. I approached with respect and didn't try to approach too quickly. There is another field right beside this one and it had more birds in it. I think the entire flock is over 100 birds in number.