I am glad you are asking this question because I am having the same problem. One of my hens , she already laid eggs, then stopped and is now showing rooster behaviour, including trying to crow, after we took away the roosters.
Is it possible that in an all hen society a hen takes over the ''rooster position''? I know there is a pecking order amongst only hens, but could it go to these extremes?

I have had a crowing hen as well as a fully hermaphrodite hen (stopped laying, seemed to start fertilizing). I've had friends with crowing hens, and I've seen it come up on other message boards a lot.

When you have a very small flock of all hens (in my case, both times it's been a flock of two), it's not unusual for one to act like a rooster. Sometimes they still lay eggs, sometimes not. They can get combs, wattles, etc. too. It can also happen from hormone imbalance or real physical hermaphroditism.

If yours never laid an egg, though, I call rooster.

I have a dominant hen who sometimes in the morning will try to crow, but it is much more of a croaking sound than a rooster crow, and she still lays. A rooster crow is very distinctive and usually occurs periodically throughout most daylight hours. In addition to crowing, some of the distinctive sounds I recognize are (1) the "bragging cluck" such as (but not always) after an egg or just to assert excitement, (2) the "grazing chuckle" to indicate position and contentment or a lack of threat, (3) the "gimme cluck" to show excitement over a delicious foodstuff and (4) the "panic chortle" to indicate distress.

There are variations, of course, but those five are clearly distinctive. My dominant hen's morning croaking is none of these.

I've had no "girls" (hens) for a few yrs now but had chickens and a few early on roosters for 20 yrs. Indeed, chicken hens (at least the ones i've had) will exhibit male tendencies w/o a rooster in the yard. I live in the "city" and have never had more than six chickens at once (the very first batch w/two guys i had to find homes for when they started crowing relentlessly). Seems to me the alpha female often develops a "pseudo crow" which is absolutely nothing like the real thing, and she doesn't "crow" relentlessly like so many of the roosters do. However, all of the "girls," even and especially the alpha hen wanted to be near me as much as possible (i allowed my girls free roam and even into my house to nap or hang out and absolutely many over most of the yrs chose to lay their eggs in the bed w/me and/or fought over lap space in my lap to lay their eggs. I apparently was not only the supreme alpha female of the group but also became the place they wanted to be re laying). I know so many different kinds of cluck, alarm, "i just layed my prize egg," etc sounds and have my own repertroir now. My goodness, how i love chickens and all they're about. So special to me! Friends are surprised i don't have any at present, but have been dealing w/pressing life->death issues, so here i am, living life and loving us all. Cluck, cluck. shar-on