Mellowmalt
Songster
I did my own test on my lot which are 6-7 weeks by giving them some seeds. Probably nothing scientific about it but it confirmed one I thought was a boy started clucking - not sure if all cockerels do this or not but it's something I've found only the boys do, they seem to get more excited over seeds than females do that just tuck right in. Might not be relevant for every breed.