I use a regular rat trap, the kind with the spring and latch. I tie gauze around the bait piece, then squeeze a dark chocolate chip into under the little clip inside the gauze and coat the gauze with peanut butter. they seem to love the chocolate chips. I caught 3 rats in the same trap the 1st week I set it in one location near our coop. I built a boxed in area, with rat sized openings and a cover, put the trap in there (which was inside the coop), loaded with the gauze, dark chocolate chip and peanut butter last night and got a 10 - 11 inch rat this morning. Not in the trap, but the trap must have tripped and clobbered the bugger to death. We will see if I get another one this evening. They sure do seem to like the chocolate.
Sami