Hello! I have 5 two month old BTW Japanese bantams, I cockerel and 5 pullets. I bought all of them from the same two parent birds, both pure BTW japs. All 5 are doing well, but I noticed something strange recently. One pullet is developing barring on her tail! Not just on one feather, but it's gradually spreading to the entire tail! The barring is black and white and the white is turning into perfect barring on her pitch black tail. Both parents were 100% black tailed white japs though and the other 4 chicks have perfectly black tails! What happened to the one pullet?! Please help!