I have found that in flocks with multiple breeds, individuals of the same breed do tend to hang out together.  It was a bit unexpected, but I've had it happen with 3 separate flocks.  In one flock I had several birds each of three different breeds, plus one single bird of a fourth breed.  The single bird kept going from group to group, looking for a place to fit in.  Just another way that chicken flocks mirror the social structure in high school -- nothing but cliques and full of bullies!!
 
Seventy eight chicks!!!  Wow, you've got your hands full.