I have noticed that the different breeds will hang out together in my little flock. Even though they were all obtained at the same time from the same place. Even as chicks, they seemed to prefer hanging out with their own breed.
This is particulairy sad though, when the last one is left alone. Right now, I have 4 five year olds who all hang together because they are alone in their breed. Five years ago, I inherited 2 of each. I now have 1 austrolorpe,
1 barred rock, 1 buff orphington and 1 easter egger. My older girls...so sweet.
I have GLWs, BLRWs, SLWs, Welsummers, Ameraucanas, BAs, & Marans and they all tend to hang with their breed. However, another factor could be the birds in each breed hatched together and weren't introduced to the flock until they were comparable in size. Looking at my birds there appears to be some validity to the old adage "birds of a feather flock together". Just this Old Rooster observations.