Gary attended the Big Fresno Fair and found a "Copyright-protected area" sign by a stall where a busker was selling the chance to have your picture taken with a bird. The idea was to use copyright law to stop you from taking your own pictures instead of buying them.
One of the side-effects of the entertainment industry's war on copying is that it's created a kind of folk-mythology about copyright being a kind of magic word you can invoke to put a fence around anything that you want to police. There's no such thing as a copyright-protected area — it might be reasonable, if you're in the taking-pictures-of-kids-with-animals business, to take some steps to shut out the competition, but appropriating the extraordinary "author's monopoly" that is copyright is both lazy and dishonest.
Any businessperson has to contend with the realities of the world. Blacksmiths don't get to demand that we abandon the railroad and go back to riding horses they can shoe. Maybe it was once possible to take a studio photography business (where you could control who came in and hence set the rules about taking your own pictures) on the road with a county fair. But if your business depends on ensuring that your photons only enter the lens of your camera, then putting those photons in a public place is a bad idea.
You've either got to take the losses you get from amateur photographers, use norms ("Please don't take your own pictures without asking, I do this for a living") instead of threats, or get into another line of work. Inventing magical copyright protection for the patch of dirt where you pitched your tent is the wrong answer.