Anybody with a strip would be wise to have warning or no public admittance signs since in the case of any accident the lawyers will include the strip owner as one of the defendants.
In the case of a PPR strip, it is of course the PIC's responsibility to contact the operator beforehand. Perhaps it is the owner and his dog.
At our glider club, we do have signs up, shoo off the dirtbikers and other motorheads, and let the dogs and model a/c loose after the gliders have been put away
