Fortunately I had posts and tape in the car so decided to put a fence around the nest site. Soon the adult bird return to the nest initially pecking at one of the posts but then settling down on the nest.
Reading the new experimental hand written signage at this Wildlife Reserve I was dismayed to read and hear later from Bob and Jenny who care for this site that 9 eggs were taken over the Labour day weekend from this site and dog prints had been seen in the area too.