15 week BO girl or boy?

[featherz]

I think it's a girl... I do have an extremely biatchy chicken as well (not a BO) - she'll chase the cat and gripe at everyone, plus she'll peck everyone around her on the roost. I'd rehome her except she looks awful due to resisting the roo (he's gone now) and she's a very good layer. So yes, girls can be meanies too. If yours is a roo, it's a really late bloomer as that rear end looks all girl.

 

[MemphisChickens]

This morning she jumped on top of one of the younger chicks like a rooster does

I think she is just being bossy and dominant.

However I told her to coop up, twice, after putting the others up and she just strolled on in. She wants to be with the 2 other pullets that she has paired up with.
I was relieved to not have to chase her around.
I think she's just trying to be in charge, everything has to be her idea. I'm hoping she will settle down when she starts laying.

I've decided to separate her from the smaller ones so she can't hurt them or terrorize them.

 

[hokankai]

Do you mean flogging or mounting? Flogging is when they fly up and swat them in their feet, and mounting is when they grab the feathers on the back of the neck and jump on their backs. If she's flogging then yes, she is being dominant and if she's mounting...well...she may be a boy. I have never heard of a hen mounting other females.

Were the younger ones added recently? If so, they are establishing pecking order and the rule "no blood no foul" kind of comes into play. If they've been in there for awhile then that's a problem. Again, I would try the "chicken jail" thing if she's terrorizing the others even if they've been in there for awhile. It will bump her down in the pecking order. If the younger ones are significantly smaller than I would remove them until they are close to the same size.