We have both Black Walnuts and Hickory nuts (lots of both). The chooks pretty much ignore us when they realize we're cracking Black Walnuts. However, if we are cracking hickory nuts it's a pain to keep them away as they grab any bit they can get to. Off course, if all your chooks have access to are Black Walnuts, then they might eat the heck out of them (don't know).