Wow. I was just telling someone else that rats will kill young chickens and ducklings. Sorry that happened to you.We had rats in our coop a few years ago, when part of our (old!) concrete foundation cracked. They ate eggs, and killed three nice pullets at night, before we got them out. We had insulated two of the coop walls, so they were hiding in the cavities, and we had to tear that all out. And bait stations, and no more rats.
Having some bantams, especially younger bantams, the rat proof feeders don't work here.
Mary