Niederrheiner?

[NatJ]

On thing that seems weird though, is how small it was when I first got them. That one was about half the size of the rocks.

The size of the chick is determined by the size egg it hatches from-- and the biggest eggs are not always laid by the biggest chickens. So I'm guessing your Barred Rocks just hatched from bigger eggs than your mystery chick did.

 

[Chickhick]

Ah, that would make sense. He is almost as big as the others now.

 

[JYount]

I have a Bielefelder roo and yours looks similar to mine.

 

[Ais]

Yes, he looks like my Bielefelder roo. They are autosexing and the males have a white spot on their heads as chicks. And he was smaller than the Easter Egger chicks for many weeks.