Goddess, I was able to buy piperazine solution from my local pet shop in NSW. I was advised to add it to the water every 3-4 months [dose according to number of birds].
We were dealing with a boggy bit of land around the side of the house, so I measured out a border and built a sloped brick edge to raise the interior ground level. Not knowing what predators might be around [we're next to bush], we laid ground netting which was later laced onto the side and roof...