My first Roo

I have 3 one year old hens that lay. My second batch of birds are 4 months old. The roo is a light bram and is huge. He has started mounting his little flock of hens. Well about 3 weeks ago I lost my black star just up and gone!! This was before he started crowing. I have not seen her since. I lost my second arcana this morning. My roo has been crowing for a week or so and loves to get on his two hens. My question is they are all 4 months old is that old enough to go broody?? I looked all over for my hen but I can't find her. I know I have hawks but I would have expected to see some feathers. I have never lost a hen until this batch and they have always free ranged. The problem with the second batch is the hens will not accept them into the coop and they all get the run around from my older hens. I am at a loss, I am so sad over loosing my two babies. But is it the Roo or predators?? Did he knock them up or did they get eaten? Uhh!!