This is way out of my wheelhouse. A friend just got back into sheep and chickens. He has an Eastern Black Bear problem. They were told a donkey or a llama would be a good protector. They have a female Great Dane who is a pussy cat. I heard they are looking for a donkey or a llama. My thoughts are both animals would dinner for a determined bear.
A casual Google search says both donkeys and llamas are used as livestock guardians but not effective against bears. Anyone have any knowledge on the subject.