Glad to hear you have no rats now. They often come over fences or underneath fences. My run had partly strong netting against birds of prey but the rats was chewing until he got through and then got through a pop door to the coop during the day.
The chicks where all over the run and coop whee...
Good question. I suppose they don’t eat and drink when its dark. Do you have a brooder and a chick setup?
I you have rats where you feed the chicks , they can kill the chicks too.
Please keep them in a safe place where no predators like rats, cat’s and many more 🐥 predators can get hold of...