Firstly we suggest that if you were to move your Hawks every now and then this would help. If you have mounted them on the end of poles then all you need do is to hammer in a few more star post or steel posts around the area that you are trying to keep the birds away from and move the pipe with the scarer on the end to the new location as the birds become used to it in the one location.
You would also find that you could increase the effectiveness of your scarers if you were to use the fishing line method instead of the poles. An alternative way of using the fishing line is to string 2 parallel wires across the area approx (250 to 300mm apart) or (25 to 30cm apart) over the area that you need to protect and then put a wire hook from the head of the Hawk onto one line and 2 other wire hooks from the back of the wings onto the other line.
This method allows the Hawk to move up and down the parallel lines as the winds change direction making the Hawk look even more real. I do hope that you can use one of these suggestions to help your situation.
Peter N, Kyogle, NSW