Last Monday, I was checking on my niece's hive and witnessed the eviction of the drones. The week prior, we found drone larvae. This week they were giving the boys the boot. I was able to see what goes on inside the hive during this process. It's hard to put into words, but just like when a colony is working on swarming, you can tell they were up to something. The mood was excited but definitely not focused on me. (Yes, I had the smoker going, iddee!) I think by the time the drones have reached the front door, they have been ganged up on, beat up, chewed on, and exhausted. There were several workers per drone focusing on herding them out. It was fascinating to watch from inside the hive instead of watching the front door.
Now if they were only that effective on small hive beetle.

Lastly, the eviction of the drones seems to vary from colony to colony. There doesn't seem to be a special sign of the moon, calendar date, or temperature to watch for. Honey bee democracy in action I would say.