over the past 2 weeks ive noticed the majority of my girls have developed a bald patch on the side of their necks (not the back, the left hand side) its on the same spot on all the girls. i thought at first it could be lice/mites? but have recently treated for that and cant see any signs on the skin. then i thought maybe they are catching it on the hen house door as they come out or something but nope? so my last conclusion is its where the roo is 'holding' on, but he's never done this 'damage' before to the girls? (he'z been with them 8 months and its only started in the last two weeks, they have no bald spot anywhere else) any ideas??