I was certain I had blogged about this phenomenon before, but cannot find any record of it.
If you'll look below, you'll see that the chicks are together according to their breed.
(Left to Right)
Eleanor and Ruth are Barred Rocks, Amelia and Marie are Speckled Sussex, Julia and Jane are Brown Sex-Links, and Rosa and Harriot are Australorps.
Most often, when they are moving about in their brooder, they stick to together in this fashion.
I might postulate that it is because they were shipped to the feed store according to their breed and thus might know/recognize each other.
That's a good theory, but the two that look like chipmunks (Amelia and Marie) were in "mixed pullets" box with 50 other chicks. They came in with many different breeds and kept with those breeds until I picked them.
The others were shipped according to breed to their feed store, but then mixed in with other breeds of an opposing color (say, yellow chicks and black chicks--easy to tell apart for the caretaker at the store).
In addition to all that, I am supposing that chickens have friends.
Very anthropomorphic of me.
I say I was certain that I had blogged about this before, because I have seen this very behavior in my current/former chickens. In my first batch of hens, they stuck together according to breed--always. Even when out free-ranging.
My poor, single Easter Egger, Penny, was always alone and was at the bottom of the pecking order until all the others died.
Nobody wanted to be her friend.
So what is this behavior about?
Do you have chickens? Do they do this too?
I'm thinking someone could do a Science Project on this, or a Master's Thesis.
Let me know what you find out if you do.