Randy Oldman wrote:
You have, and should exercise, the right to shoot down anything flying less than 400 feet above your property.
"The landowner has exclusive control of the immediate reaches of the enveloping atmosphere."
"Invasions of that airspace are in the same category as invasions of the surface."
United States vs Causby, 1946.
Except that you don't have the right to shoot anybody for entering your property on the surface either. There'd be a lot of dead mailmen, door-to-door salesmen, and Jehovah's Witnesses if that were the case.
You generally have a right to self defense so if you were attacked by a drone and it satisfied your state's requirements for self-defense, then you could shoot it down, assuming you were using a legal weapon like a shotgun and not a Stinger missile.