Gender Question for RIR and Black Australorp

[bremat]

Does the appearance of tail feathers tell you anything for these chicks? I have 2 BA's that were both supposed to be pullets, but one has tail feathers already started and the other one does not. I also have 5 RIR's, some with and some without. Is that any indication of them being a pullet or roo? Thank you! I can take pictures if you need me to.

 

[Balboaroc]

I have a black Australorp that is a Roo and the biggest indicator was it got its comb and wattles much sooner and redder than my other pullets. It finally crowed the other day at 10 weeks for the first time. He got his comb/wattles in early..I want to say at 4/5 weeks.