Speckled Sussex Rooster or Hen?

[yanischickens]

In the 1st image this chicken was about 4-5 months old
2nd image chicken was 4-5 minths old
3rd image chicken was about 6-7 months old
4th image they are 8-9 months old.
We beleived her to be a hen but her feathers seem like that of a rooster and she started singing along with our other roosters today. She also frequently mounts other hens. She has also tried to fight one of our other roosters on multiple occasions. I feel silly for not knowing whether she is a rooster or not but i am a first time chicken owner and i would greatly appreciate any input! thank you!!

 

[yanischickens]

She is also not laying.

 

[fluffycrow]

Cockerel

 

[Egg Snatcher]

Cockerel

 

[SwampPrincessChick]

Cockerel.

 

[SwampPrincessChick]

We beleived her to be a hen but her feathers seem like that of a rooster and she started singing along with our other roosters today.

It's called crowing, not singing.

She also frequently mounts other hens.

When a chicken is mounting another one, it's a male. Only occasionally will a female mount another female, and when they do it is for dominance reasons when there are no males in the flock.

She has also tried to fight one of our other roosters on multiple occasions.

If a chicken is frequently fighting with the other males, then most likely that chicken is a male as well.