About half of my chickens do this clicking thing with their beaks. Sometimes it's really loud and other times there is no sound at all. Is this a normal behavior or do they have "something"? Here's a video of 2 of them. coincidentally enough, it's my "dark" ones. My Delawares, Buckeyes, NHR, and RSL don't do it at all but my Blue Andy, Black Ameraucana's, Black NN, SLW do.