One last point from me - we once had a bird feeding station similar to yours, with a 2-metre high pole and feeders hanging from arms like a sort of tree. We live near to grain storage barns, so in winter rats do tend to spread out and visit the neighbourhood. We sat in our living room and watched the rats climb the pole, shimmy down the chains and eat from the feeders. If your feeders are low enough for the hens to use, they will be a gift for the rats.