There's a town about an hour and a half from me that has a big celebration every spring when the buzzards return. I've never got over there to see it.
They roost on phone poles and dead trees in and around fields waiting for the morning thermals to kick up enough for them to lift off and cruise for the carrion left over from the night before. You get a real idea how big they are when they're basking in the sun on the roost with their wings spread fully.
When I was a kid a bunch of ravens took over a neighborhood. There were so many they were breaking tree limbs and having a good old time making deposits at the local Ford dealership. The Mayor called the DNR for tips on getting rid of them. The DNR told him to wait two or three weeks, "They'll go when it gets colder and there's nothing to eat." The Mayor had the cops out firing birdshot at them and suggested homeowners put up fake owls to scare them. 6 cops and a few dozen fake owls against an estimated 100k ravens. The ravens won.
Just as the DNR said, a couple of weeks later, they were gone.