We've had chickens (in a fairly dark, overgrown corner) for 8 months and I've never seen a rat, nor any sign of one. We have mice, because teh cat leaves their remnants by the door, but then not an infestation.
We feed in a hanging hopper. There are some minor spills on the ground but the run is fairly secure.
When we had the ducks in the garden, there was often some corn in the garden at night and it was always there in the morning still.
They're not inevtiable, providing you don;t have them now and if you do get them, there are steps you can take to get rid of them.
If you search on the forums for topics about them, there is some good advice from Bodger, Muntjac, and others.
Rob
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