my duck is turning into a drake

[starting out]

I have had three saxony ducks for four years. This year one is colouring up as a drake and even has the curly tail feather!! Is this possible?

 

[Pyxis]

It is! Female ducks only develop a single functional ovary, which produces all the female hormones. These hormones inhibit the Z chromosome genes that would cause male characteristics, like plumage color and the drake feather.

So if that single ovary is damaged, hormone production stops. That means the male genes on her Z chromosome are no longer being suppressed, and there you go, male characteristics develop.

Since her ovary is damaged, she also won't lay eggs. Now, she is not really a male. She won't produce sperm, she can't fertilize eggs.

Well, most of the time. In extremely rare cases, it's been found that the dormant right ovary, which never develops since females only ever have one functional one, the left one, can start to develop under the influence of the male hormones that are not being suppressed any longer. It can turn into a testis and produce sperm.

https://www.bbc.com/news/science-environment-40016817

 

[starting out]

That is absolutely amazing. During the last laying season, she was having real trouble laying eggs and got very down at times. Then after the season finished she became very aggressive toward one of the other ducks, it has settled down now, but she/he has now started honking a lot, as though the boss of the show.
Thank you so much for your help in this matter, you are wonderful.

 

[Ratchnick]

I have heard that keeping a group of ducks with no drake can cause this.

 

[Daphne_loves_mealworms]

It is! Female ducks only develop a single functional ovary, which produces all the female hormones. These hormones inhibit the Z chromosome genes that would cause male characteristics, like plumage color and the drake feather.

So if that single ovary is damaged, hormone production stops. That means the male genes on her Z chromosome are no longer being suppressed, and there you go, male characteristics develop.

Since her ovary is damaged, she also won't lay eggs. Now, she is not really a male. She won't produce sperm, she can't fertilize eggs.

Well, most of the time. In extremely rare cases, it's been found that the dormant right ovary, which never develops since females only ever have one functional one, the left one, can start to develop under the influence of the male hormones that are not being suppressed any longer. It can turn into a testis and produce sperm.

https://www.bbc.com/news/science-environment-40016817

This is absolutely the best description of this phenomenon I have read. Thank you!