Chickens are wild animals domesticated, all animals are
Nails, screws, moldy rye bread, Styrofoam don't exist in the wild that is why they think they are stones
Banty who found the pretty red muscaria mushroom, did it kill here?.
Try to taste a poisonous plant, then you know why.
Many plants are toxic to animals. the simple fact is animals don't eat those plants, genes that make animals find poisonous plants edible don't stay long in the chain of evolution. I have many poisonous plants around my chickens they simply don't eat them. if animals eat poisonous plants you...