At only 10 weeks, I agree the brown bird pictured last is your only pullet. It's quite rare for birds of this age to fight that severely, though, even males housed together. How much space do they have? My first thought is it's from overcrowding, not a gender issue.
Agreed - it looks like a lovely space you took the photos in, but is that where they spend the majority of their time? If not, what is the area they do spend most of their time in like?
