These traps have worked great for us John, the rats eventually learn, but you can catch quite a lot of them before that happen. Once they do learn you can just put it away and then bring it back a few months later and they fall for it all over again:
http://www.easypestsupplies.com.au/mult ... vQodsK0HEQ , I would definately recomend trying this style trap, it has done great for us, from what we have tried dog food is amazingly great for bait-the rats and mice both cant resist.