Are my chickens racist?

I came home the other night at dusk and as I went to close the coop door I noticed that the 6 young chicks were all lined up on the roosting bar by breed. First came the two buff's then the two Plymouth rocks then the two araucanas and this got me thinking do they know they are different from each other and is that why they are sleeping next to their breed mate? And if they do know they are different breeds how do they know it. First I thought well they know they are different because they don't have the same coloring but then I said to myself well how the hell would they know that its not like I installed a mirror in the coop so they would know that they don't all look alike.

Now I really meant to do a study on this to gather some empirical data before I wrote about this and I envisioned maybe having a table or two for you or maybe a graph but all I have is the one night I saw this so I guess you can take it with a grain of salt and perhaps give my chickens the benefit of the doubt.