Rats are incredibly smart. Everytime we put traps out, they dissapear. I mean, you will see them up til the day we put traps out, then, poof, they're gone. For about a week. Then, gradually, they will reappear, and, if we're lucky, we might catch one or two young ones. Removing the food is one big deterrent, but it's a pain b/c if your birds like to pick at the food throughout the day, they can't. The rats, prior to this last effort, were beginning to eat eggs, and that IS disgusting. We are going to try the plaster of paris mixed with powdered sugar or oatmeal next time we see them; we rigged a box to put traps or pop bait in, with a small hole for the rats to go in, (they can chew the hole to make it bigger, if they want) the box is taped shut to keep the chickens out. I think we need something like bacon or tuna to lure them into the box, though. Failing that, we are going to invest in a rat zapper, the local drug store here will order them and sell same price as we can get on line. Sewer rats (?) don't have any experience with those, as we have no sewer; all rats can get really big, and I saw an uncomfortably big one last time. Our barn is not, and probably will never be, pristine, and that's pretty much what you need, I guess, to keep them away permanently.
