Female Zebra Finch losing tail feathers

by Fran O.
(Streamwood, IL)

I have 2 female and 2 male Zebra Finches in one large cage. The 2 males and 1 female I have had for 3 to 4 years. The other is a new female I've had several months.
The older female is loosing her tail feathers to the point that I can see her bare skin and the protrusion where the tail feathers were. This all seemed to happen in one day as I look at them carefully each day. She also seems to be loosing some feathers at the back of her neck. Can you please help me? Thank you.