There is actually quite a bit of documentation about female birds basically becoming male. In a nutshell, birds only produce eggs from one ovary. If that ovary becomes non-functioning, usually because of age or a tumour, the other ovary takes over and produces testosterone. If they live long...
Yes, and I still have this peahen/cock. She went from raising babies to having a male tail and coloring. Every year she has a longer train. Of course she can't lay eggs anymore.
I didn't think I'd have any bird eggs for the hatch along since my tortoise egg is using the incubator set at 88 degrees. Just so happens, I have a broody serama, so I put some very special serama eggs under her.