not sure about the mice,only what a mate told me,he had a mouse prob and it spoilt his nesting with night fright,upsetting the birds,and he said the tails looked liked they had feather mite or were chewed but they went like that over night,and some were chewed some not,got shut of the mice rodent proof bird hut no bad tail feathers since, do the hens look fluffed out of condition atb.