So they knew that there was probably no (gusty)wind, perfect conditions and I really think that birds are being kept away during a show.
..because gusty winds don't come and go do they? And birds? We could put a sign up saying "Please stay away" but we'd better hope that any that were hoping to transit the area can read. Or saw the last bird scaring activity and decided to stay away.
We used to find it tremendous fun to practice visual circuits at Geneva in the simulator. At 50 feet. It was dead easy. Just because you can practice something in the simulator doesn't mean it's safe or sensible to do it in a real aircraft.