We were told by someone who evidently raises a fair number of chickens about this odd-sounding way of sexing chicks that are a couple of weeks old (once they have tail feathers in). What one does is hold the chick around the middle and quickly tip their head down. If the tail feathers fan out, it's a girl. If the tail feathers stay mostly straight or form a sharp upside-down "V", its a boy. Has anyone ever heard of this? I tried it on a few of my 3.5 week old chicks and, sure enough, some fan and some "V", but I have no idea if that is at all significant or just a result of each one's mood at that moment? Understandably, it irritated the heck out of the chicks.