My mom was right, what we found was a mole or vole and not the culprit. One night our mamaduck and her ducklings were really far from the coop and dh went to shoo them in. Lo and behold- there was a nice fat rat in the coop. Me, I would have screamed like a little girl. He simply shut the coop doors, went and got a gun and shot it. Since then we've had the have a heart traps out, as well as this special bait box with rat poison in it (it's only big enough for a rat or smaller to get in.) No more rats so far. But don't they travel in packs? Oh and we were putting blocks of bait directly in the holes and covering them with hardware cloth. The animals in the hole to the entire block and made off with it. I'm a little scared that this is a bigger problem than we thought....