One of my buff orpingtons was the champion layer this summer, cranking out an egg a day with hardly a break. About a week ago she stopped laying one day and I haven't seen an egg from her since. She has also become more aggressive to the other birds and more skittish around me. She was always the friendliest and now she runs and when she sees me and she hasn't done the "squat" for me in a long time. She's not molting. She's not broody (I have another BO who was broody and now has chicks). I am in Alaska and we still have plenty of light (one of my pullets started laying right about when she quit). She's eating lots and her poop looks normal, although it is much larger than before). She looks as healthy as ever with no lice or signs of worms (I'm going to be worming them all soon anyway). She's a little over a year old. Any ideas on what could be going on?