Hen acting wierd...

[Poultry keeper12]

Hello. So this morning I went outside too do my regular chicken stuff, and something wierd happend that I have never seen before. One of my hens was on top of another one of my hens, doing you know what roosters do. I am only raising hens right now, and each one of them I have seen lay an egg. What's more, the hen I saw doing it did not look like a rooster at all. Any help on this I would really appreciate.

 

[ketojenn]

Picture of 'hen' ?

 

[Poultry keeper12]

Picture of 'hen' ?

 

[aart]

'Mounting' is not always about sex...but is also a dominance behavior.
Females can also employ this technique, not common, but not unprecedented either.
How old are these birds?
Any recent changes to the flock?