I had inquired about becoming licenses to sell eggs at the Farmer's Market. They require that you register your flock, which simply means that they know that you have a flock and of what (chickens, ducks, geese, etc).
The gentleman told me that if they found a proven case of Avian Influenza (Bird Flu) within a certain X mile radius, they would notify me and my flock would be on watch. They would lock down my flock and test periodically to be sure that my animals are not infected. I guess, if they deem it a health risk, they may destroy the entire flock.
As of yet, I am not selling anything other than from my house and I have not registered my flock. Although .... someone in the government knows that I have chickens, becaue I get notices about bio-security and such from the MD Dept of Agriculture.
I follow the SpeckledHen rules of Bio-Security and avoid bringing live birds in to my flock. On the rare occasion that I do, I quarantened for 45 days.
With all that said, I can see why they might have destroyed the flocks, but to say never have chickens again, that is really puzzling.