It looks like my columbian plymouth rock chicks. I'm not sure if mine are roos or pullets because they have red in the face, red combs, and red wattles...but their combs aren't growing any larger than the combs on my sex link pullets.
I agree, 4 hens to one rooster is just not enough for his "libido". The hens will be better off in greater numbers. I would suggest 10 to 12 hens for one roo. I had 7 hens and my male wore our their backs. After about 5 months of rooster action, the girls started to develop bare patches on their backs exposing their delicate skin to the elements and the rooster's claws.