My coop is a small one. My DH and I can move it together. It does not have a floor. I move it around the garden on average 2 times a month. The garden has a slight grade to it, so there's good drainage. After I move the coop, I rake over the old site to stir it up and leave it.
I have had problems with rats tunneling last year. We'd move the coop and rake and you'd have collapsing tunnels everywhere. We do have neighbor cats who spend every day in our yard. (DH wants them to go... I want them to stay and hunt rats! Hey, leave it to the neighbor to get "presents" and deal with fleas. I'll keep my cats indoors!) The cats (all 5 of them from one neighbor) never bother our birds, and only one has shown interest in them at all. She sits in the sun and watches them for hours, but keeps a good 3 feet of distance from the fence.
I've had NO rats this year. We'll see what happens in the fall though. My hens all roost in the top of the coop, and I gather the eggs routinely, so that may be why the rats never bothered the birds. They just get a few pieces and go.
This is my first year with new chicks, but I'm brooding them indoors, and my guineas had only been in the coop for a few hours after they hatched. I worried more for their safety near the adults more than for preditor losses.
