Two photos of two different chicks, siblings hatched at the same time. They are a month old. The one on the top has a very red comb already. Sorry it's hard to get a good image, they move so fast, but it does look a lot more red than the pic shows and the comb is also larger than the ones that still have small yellow ones . The one on the bottom has a yellow comb the way it was when it hatched and it's still small. Does the larger red comb this early indicate it might be a roo or is it just natural variation regardless of sex? These are rhode island red chicks. I have also seen a couple of them with the more red combs fighting. They stretch their necks up, bump chests, flap up and scratch with feet. I never saw my girl chicks from my previous flock doing that.