Some use a water bucket trap for rats and mice, they have them on youtube, its a 5 gallon bucket a little less than half full of water, some put a rod through it near the top with a soda bottle on it so the rat steps on it and it spins and they fall in the water or some have said to sprinkle some feed on the water and cover the bucket with chicken wire, the rats will go through the wire and fall in the water, they can't escape. Just prop a stick or something up on the bucket so the rats can climb up to the top of the bucket. It is supposed to be quite effective. Just try and make sure there isn't a bunch of spilled feed for them to eat instead of going in the trap.