We got our 4 chicks at the feed store last weekend. That was 8 days ago. They were visibly all different ages with one (the Black Australorp) at least double the size of the other chicks. They are all "standard" breed. The Barred Rock chick was at least twice smaller than the Black Australorp but had more flight and tail feathering than the 2 smallest chicks. The 2 smallest chicks (Red Sex Link and Buff Orpington) were about the same size with the tips of the wing feathers just coming in. Would folks be willing to share their chick photos, maybe showing different stages of feathering so I can have some idea of how old these chicks are?