My pekin/mallard mix female (Zorro - she was named before I found out she was a girl!) has lost her feathers on the edge/tips of her wings. Everywhere else is fine. SHe's one and a half years old. I know it's not molting, but I don't know what it is. I remember reading something about this illness, but can't find the information again. Can anyone help and tell me what I need to do? Thanks!