You know the old saying "Birds of a Feather flock together"? It must be true. I have one Delaware rooster in my hen pen. There are 4 Delaware hens, 1 Blue Lace Red Wyandotte hen and 4 red hens (Speckled sussex cross). All of the birds are very close to the same age (spring chicks, so at least 7 months old) and have been together for months. I have seen the roo mating with the hens on multiple occasions, but it's ONLY the 4 Delaware hens. I have never seen him mate with the other hens. I can't believe he recognizes there is a difference in the hens but why else would he only mate with the ones that look like he does? It just struck me as odd. Is this common?