Will a mother hen kill babies that are not hers?

No, in general, mother hens do not kill babies that are not their own. Mother hens are known for their protective behavior towards their chicks and will usually extend care and protection to any chicks that are present in their brood, regardless of their origin. Mother hens recognize their own chicks through a combination of sight, sound and smell, and they typically accept and care for any chicks that are within their visual and auditory range during the brooding period. However, there may be rare exceptions where a mother hen may reject or even harm non-biological offspring due to factors such as resource limitations or individual variations in behavior.