If you take close notice, they come out, crawl up the front, close to the top of the bottom deep, fly off, up and down side to side, they back off a little and repeat and make a bigger space each time till they get far back and up. They are oreintating to their area. The difference between this and robbing is theres no fighting. You will see a few crash into one another now and then, but then go their merry way.
What Moonshae said.