sexing chicks

Hi! My frizzle silkie is 13 weeks. No crowing but I'm wondering if it's a cockerel the two white ones are about 9 weeks old and are constantly going at each other's with chest bumps

I have 14 Ameraucana chicks that are around 6 weeks. Maybe closer to 7 by now. I'm getting some mixed answers about what I am looking for to start to sex them. Am I right that the longer tails are pullets and shorter are cockerels? Some with the longer tails seem to have bigger, three row...

Looking to pick up a chick for my broody hen. Can anyone tell me by the feathering if there is a chance any of these are female? These chicks are less than a week old if that helps.