Can chickens change sex?
It might seem like a bit of a daft question to ask but if you bought your chickens with the intention of the them laying eggs and avoided having a cockerel in the flock because of the noise they make then beware…. it is perfectly possible for Hetty to become Henry in what seems like overnight transgender transition.
It is a phenomenon that occurs (with increasing frequency if the last decade is anything to go by) where there is a part change of gender within a hen. This is not a regular occurrence given the millions of hens that inhabit our island but by the same measure it is not infrequent, and from my observations it seems more prevalent in the light laying breeds such as Leghorn, Ancona, Welsummer etc.
A hen who has been laying eggs will appear to suddenly become a cock bird. She will no longer lay eggs. Her comb and wattles will develop, her feathering will become more male in appearance and feather structure and she will even begin to crow. She is however still a she. She has only phenotypically transitioned into a male, genetically she remains female.
The reason this occurs is usually due an environmental stress or illness such as a tumour, problems with the adrenal gland or an ovarian cyst. It only occurs though in hens that have one ovary.
Not all hens develop both ovaries during their embryonic stages and instead have one developed and the other remains as a regressed male gonad. In the event of the developed ovary becoming damaged and ceasing to function, the gonad can take over and the increase in male hormone causes the hen to develop male characteristics. She will however remain female and will not be fertile. The opposite effect of male becoming female has not been observed.
Breaking news? Not really as it’s been observed for centuries but I suspect with the numbers of chickens kept in backyards these days it will become a regular topic of conversation amongst keepers and make the odd appearance in the newspapers. 🙂