We keep our food in those plastic bins where the lids seal tight. We did have one rat in the yard who would grab some food and run away. Being we have 9 pet rats in cages in the house, we didnt freak out. We also have dogs and a cat so not many small rodents survive in my yard.
When my neighbors had chickens, we DID have a rat problem but they werent big ole city rats, they looked like gerbils on steroids..lol. More than anything, rats can be destructive. They will eat ANYTHING. Again, I have them as pets so I know. They also are EXTREMELY intelligent. Ive used glue traps for mice and rat poison years ago for rats. The only thing about the poison is you better know where that rat is otherwise it will stink after it dies.